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jonnywachter
2009.03.24, 05:14 AM
new concept, to mini-z

http://i87.photobucket.com/albums/k131/jon_wachter/P3251244.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3251247.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3251245.jpg

herman
2009.03.24, 05:37 AM
it looks evil... in a good way...
who makes it? any reviews?

jonnywachter
2009.03.24, 05:40 AM
I made it, after 4 hours of dremeling. The concept is pretty much from a 1/12 pan car, just scaled down

GIHOSU
2009.03.24, 09:55 AM
Hey Jonny,

Great idea and execution, I like the concept you have there.

It wouldn't take too much work to produce these parts. If they work well it might be worth the time and trouble of making them.

I want to know how it drives with your setup...

hrdrvr
2009.03.24, 10:05 AM
Very nice execution Jonny! Im suprised you were able to fab up the small parts in the tolerances they need to perform well. That was some tidious work!

Its not a totally new concept though :D PN is working on a proto-type front end system very similar to yours. Lukas ran it on his car at the rcent KO race and has pictures up in the MR02 image thread.

http://i141.photobucket.com/albums/r67/luketob/IMG_1857.jpg

CristianTabush
2009.03.24, 10:28 AM
He did not claim it to be a new concept ;) Much better design than the PN racing front end though. The PN has too much bump steer and with the double swing arm design also has more parts and is more complex than Johnny's Great job! I have been wanting a true dynamic front end like than forever! One of the best features about Johnny's design is the fact taht it can very easily be widend to adjust track width with the turn of a couple of screws :)

hrdrvr
2009.03.24, 11:09 AM
new concept. :p

I really like the simplicity of Jonnys compared to the PN one as well. How does the bump steer differ that much from the pn version? Im just curious, as Im definitely not as versed as you guys when it comes to suspension geometry.

Davey G
2009.03.24, 11:20 AM
The PN ft end looks like there is a good amount of camber change, due to the low height of the top tower bar (lower roll center) As the camber increases throughout travel the toe will change as well. In this case it will toe out)

Johnny nice execution for sure on that ft end. You are def a losi guy with that handle dremel work. Check your PM's

PNracing
2009.03.24, 11:53 AM
Lukas running on 1st prototype version, me and Grant running on 2nd prototype version, today we will get the 3rd production version, I post more information and pictures later.

One of the difference of Jonny and us, our wheel width i same as Kyosho, so you can run all the body.
Jonny desgin one seem like +3 super wide track, I'm not sure.

jonnywachter
2009.03.24, 12:32 PM
Thanks for the support guys! This front end was originaly inspired by the PN front end after I saw grants car in person. I wanted to design a front end completly different from any mini-z I had seen before. This Is not a new concept to r/c, 12th scale pan cars have used this front end for EVER and all I did was adapt it to a mini-z. I have no plans to produce it but I would like to see a company like reflex ;) take on the idea. My original idea was to make it adjustable from standard to widetrack, but with the precision of a dremel and my eye it wasn't possible. I can already tell you that the front end pictured above won't even hit the track I have already come up with better ideas and will try to make them Wednesday. I will keep you guys updated. Thanks again for the support.

Cherub1m
2009.03.24, 12:33 PM
Very nice, I could only pull up the pics on my blackberry my work computer will no longer accept pics. It looks like its plastic, is that correct? plastic is great due to weight factor. Also, are you planning on making one for the AWD?

ambind
2009.03.24, 12:51 PM
The PN has too much bump steer and with the double swing arm design also has more parts and is more complex than Johnny's Great job!

Since there is no ackerman in MiniZ, bump steer could be easily adjusted by changing with different degree of toebar. Upper section of the front end is very low that's why I'm running only 0.5 camber and +1 toe to get the neutral feeling on my car.

jonnywachter
2009.03.24, 12:51 PM
The material is kydex it's what oval guys use for bumper blanks but it's a little thicker. No plans for an awd, I don't have one. Also This design wouldn't be near compatible to the awd. PN's front end would be a much better concept for the awd with the double swing arm style.

ianc
2009.03.24, 12:58 PM
It's difficult to tell from these pictures, but from what I can see, only the PN design would give the benefits of the classic unequal-length control arm front end, which would be to minimize camber changes with suspension deflection.

It appears to me that Jonny's design does not allow the bottom link in the front end to move up or down, only the top. This would tend to create larger camber changes than the dual wishbone design in the PN offering.

Or am I just reading the pictures wrong?

ianc

jonnywachter
2009.03.24, 01:17 PM
It's difficult to tell from these pictures, but from what I can see, only the PN design would give the benefits of the classic unequal-length control arm front end, which would be to minimize camber changes with suspension deflection.

It appears to me that Jonny's design does not allow the bottom link in the front end to move up or down, only the top. This would tend to create larger camber changes than the dual wishbone design in the PN offering.

Or am I just reading the pictures wrong?

ianc

Your rite, the purpose was to achieve some chamber gain. It's able to be very fine tuned because all u have to do is shim up the top mount to achieve less gain. The PN has alot more gain because the pivot point of the top inner arm is closer to the bottom than the outer pivot. I'm not sure how fine you will be able to adjust it tho.

color01
2009.03.24, 03:14 PM
Also, with the minute travel required of the MR02's front suspension, having more camber gain is not a bad thing. It looks like Johnny's upper arms are also longer than PN's (due to the wider front track), so that would also put the camber gain at about the same amount between the two front end systems.

I'm extremely curious as to where you got those arms and ball joints though. Hope you can tell us? :)

CristianTabush
2009.03.24, 03:22 PM
The PN ft end looks like there is a good amount of camber change, due to the low height of the top tower bar (lower roll center) As the camber increases throughout travel the toe will change as well. In this case it will toe out)

Johnny nice execution for sure on that ft end. You are def a losi guy with that handle dremel work. Check your PM's

Opposite, as the supension compresses, the car starts to toe-in the tires. This would not present such a problem if RCP was smoother, such as carpet, but due to the nature of the bumps on RCP, bump steer makes it harder for a car to center since the second the car hits a bump, the car will have a bit of "bump- induced steering".

jonnywachter
2009.03.24, 03:33 PM
Also, with the minute travel required of the MR02's front suspension, having more camber gain is not a bad thing. It looks like Johnny's upper arms are also longer than PN's (due to the wider front track), so that would also put the camber gain at about the same amount between the two front end systems.

I'm extremely curious as to where you got those arms and ball joints though. Hope you can tell us? :)

no problem, the ball joints and ends are mini-t oil shock ends. They fit PERFECT, exact size of the hinge pin and super smooth. as for the top inner arm its a micro-t spindle carrier shaved down a lot!


I had no idea there would be this much interest in this front end, i seriously thought you guys would think its stupid. Considering its not a "new design" im surprised it hasn't been done before. Maybe it has and im unaware of it. Maybe I will take this to a company, I need to learn more on Autocad or Solid works to be able to design it tho I am taking classes at the moment its taking forever!

benmlee
2009.03.24, 03:43 PM
Opposite, as the supension compresses, the car starts to toe-in the tires. This would not present such a problem if RCP was smoother, such as carpet, but due to the nature of the bumps on RCP, bump steer makes it harder for a car to center since the second the car hits a bump, the car will have a bit of "bump- induced steering".


I did an extreme test for the bump steer on the PN suspension. I purposely put series of wooden dowels on one side of the track and have the car drive down the middle one side on the bumps and other on smooth RCP. Car went very straight with no hint of wandering. It was surprising as if there were no bumps there. Think the reason is when one wheel hits the bump, it puts a drag on the car, and jerk the car off in the direction of the bump. The slight bit of toe in on that side actually corrects for that drag, and keeps the car going straight. Works pretty well.

As a further experiment, tried the same thing with regular MR02 front suspension. The car was bouncing much more. Think is because the regular MR02 knuckle has much more friction sliding up and down on the kingpin. Friction gets worse with wide offset wheels. So it doesn't handle the bumps well. The bouncing on the regular suspension is what really threw the car off line. On the other hand, the A-arm suspension was quite smooth thru the bumps since it has much less stiction.

yasuji
2009.03.24, 03:44 PM
Opposite, as the supension compresses, the car starts to toe-in the tires. This would not present such a problem if RCP was smoother, such as carpet, but due to the nature of the bumps on RCP, bump steer makes it harder for a car to center since the second the car hits a bump, the car will have a bit of "bump- induced steering".
imo a stationary lower control arm and a pivot top arm will yield even more active camber and toe in ,bump steer
with the pn front end both top and bottom A arms travel in the up and in direction thus providing the amount of active camber gained through outits travel.....bump steering is the +/- side...due to the fact that it rides in a stationary toe bar.unless this is changed to a pivot type system, this will not be changed
jonnys 12th scale derived proto will yield a bit more camber gain resulting in as much or more bump steer
imo.... as i have run both version 1 and 2 of the pn front end the advantage to this front end is ,for my driving style, i need to use less of my rear steering technique ,which means less braking, with the ability to hold a tighter more consistent line;)

Davey G
2009.03.24, 03:50 PM
Opposite, as the supension compresses, the car starts to toe-in the tires. This would not present such a problem if RCP was smoother, such as carpet, but due to the nature of the bumps on RCP, bump steer makes it harder for a car to center since the second the car hits a bump, the car will have a bit of "bump- induced steering".

Your right, without seeing it, its hard to tell.

PNracing
2009.03.24, 04:04 PM
Here is the instruction, will be more information, the pictures will be coming soon.

http://pnracing.us/MR2500/MR2500instructions.pdf

jonnywachter
2009.03.24, 04:17 PM
benmlee is rite I hadn't thought of the friction aspect with my front end, if put it to standard width and used +3 wheels there would be more friction, but its all pivoting on metal balls so there isnt much. The PN front end no matter what wheel offset used would not have near the friction. That should seem to allow a more consistant setup on all cars and bodies regardless of wheel offset.

ianc
2009.03.24, 04:18 PM
Phil, did you forget the link? Would be quite interested to read the docs...

ianc

CristianTabush
2009.03.24, 04:18 PM
I understand what both Grant and Ben are saying, but if you can achieve less stiction on the front end with regular knuckles the car will center better than a car with massive bump steer. So long that your front end is not binding, (or bouncing) less bump steer= less wandering, period. The benefits from this front end come more from the actual compliance to the track, but much like an AWD, it will have a bit harder of a time centering when coming on to a straightaway. Lap times can and I am sure will improve over the regular front end, (if this is not built properly,) but having as much bump steer as it does simply makes your car imprecise in the middle and exit of a corner. Bump steer is not your friend, no matter what you guys want to argue.

jonnywachter
2009.03.24, 04:32 PM
Angling the pin that extrudes from the knuckle would in theory (in my head) take the bump steer away. But I feel with a little bit of chamber gain and bump steer I feel it will be faster

yasuji
2009.03.24, 04:43 PM
Angling the pin that extrudes from the knuckle would in theory (in my head) take the bump steer away. But I feel with a little bit of chamber gain and bump steer I feel it will be faster

when testing the front ends back to back i found that it is easier to go 2 or 3 tenths faster and more consistently withe the A arm fr end than with the king pin fr end

jonnywachter
2009.03.24, 05:31 PM
When will the front end be avalible and what colors will it come in?

yasuji
2009.03.24, 05:50 PM
When will the front end be avalible and what colors will it come in?
i think it will be in today.....hopefully if it comes in today i will have it in stock tomorrow;)

PNracing
2009.03.24, 05:58 PM
When will the front end be avalible and what colors will it come in?

If no problem, should be tomorrow, and same as PN products, SIlver, Blue and Orange.
But we only have limited stock, should be less than 10 sets each color.

pedrocamp
2009.03.24, 06:22 PM
Pretty cool stuff. The purpose of double A-arms in full scale racing cars, among other things, is to be able to tune the camber gain to keep the contact patch of the tire in maximum contact with the track as chassis roll occurs in a corner. With the kingpin MiniZ suspension, much like a McPherson strut front suspension on a street car, the chassis roll moves the contact patch to the outer edge of the outer tire in a corner. Road racing production cars with strut front suspensions usually have a lot of static negative camber to counteract this. Rounder tires work better on kingpin or strut suspensions since the contact patch is moving across the tire, kinda like a motorcycle but opposite. Due to the arcs of a double wishbone suspension the contact patch can be kept relatively stable during cornering, not moving across the tire as much. Camber gain is a good thing, just how much depends on chassis roll, based on suspension stiffness and traction, and a well designed single or double wishbone setup well let you tune this. Bump steer occurs when the arcs of the wishbones and steering tie rods are not properly designed or adjusted. Even the best designed full size racing cars have some bump steer, very little, but the bump steer is minimized during its expected suspension travel. Cristian is right, bump steer is very rarely you friend since it can make the car unstable as the suspension extends and compresses. The MiniZ steering design does not allow you to adjust this steering “arc” so the only way too minimize the bump steer it to minimize the camber gain which defeats the purpose. On larger RC cars, most with double bell crank steering setups you can raise or lower the inner or outer steering points to minimize the bump steer. It is possible that the negative effects of the bump steer might be overshadowed by the increase in traction that the camber gain might provide. These little cars have a bit of steering play; the bump steer may not be noticeable. Be interesting to see what you guys find with these new front suspensions.

yasuji
2009.03.24, 06:30 PM
Pretty cool stuff. The purpose of double A-arms in full scale racing cars, among other things, is to be able to tune the camber gain to keep the contact patch of the tire in maximum contact with the track as chassis roll occurs in a corner. With the kingpin MiniZ suspension, much like a McPherson strut front suspension on a street car, the chassis roll moves the contact patch to the outer edge of the outer tire in a corner. Road racing production cars with strut front suspensions usually have a lot of static negative camber to counteract this. Rounder tires work better on kingpin or strut suspensions since the contact patch is moving across the tire, kinda like a motorcycle but opposite. Due to the arcs of a double wishbone suspension the contact patch can be kept relatively stable during cornering, not moving across the tire as much. Camber gain is a good thing, just how much depends on chassis roll, based on suspension stiffness and traction, and a well designed single or double wishbone setup well let you tune this. Bump steer occurs when the arcs of the wishbones and steering tie rods are not properly designed or adjusted. Even the best designed full size racing cars have some bump steer, very little, but the bump steer is minimized during its expected suspension travel. Cristian is right, bump steer is very rarely you friend since it can make the car unstable as the suspension extends and compresses. The MiniZ steering design does not allow you to adjust this steering “arc” so the only way too minimize the bump steer it to minimize the camber gain which defeats the purpose. On larger RC cars, most with double bell crank steering setups you can raise or lower the inner or outer steering points to minimize the bump steer. It is possible that the negative effects of the bump steer might be overshadowed by the increase in traction that the camber gain might provide. These little cars have a bit of steering play; the bump steer may not be noticeable. Be interesting to see what you guys find with these new front suspensions.

hey pedro.... i have no negative feed back from this suspension
i will NEVER go back to the king pin front end.....

Cherub1m
2009.03.24, 07:14 PM
The PN ft end looks like there is a good amount of camber change, due to the low height of the top tower bar (lower roll center) As the camber increases throughout travel the toe will change as well. In this case it will toe out)

Johnny nice execution for sure on that ft end. You are def a losi guy with that handle dremel work. Check your PM's

Opposite, as the supension compresses, the car starts to toe-in the tires. This would not present such a problem if RCP was smoother, such as carpet, but due to the nature of the bumps on RCP, bump steer makes it harder for a car to center since the second the car hits a bump, the car will have a bit of "bump- induced steering".

Ok this is what I found in Wikipedia about Bump steer and Roll steer:

Bump Steer
From Wikipedia, the free encyclopedia
Jump to: navigation, search

Bump Steer is the term for the tendency of a wheel to steer as it moves upwards into jounce. It is typically measured in degrees per metre or degrees per foot.

On modern cars the front of the tire moves outwards, as the suspension is raised, a process known as the front wheels "toeing out". This gives roll understeer. The rear suspension is usually set up to minimise bump steer, where possible.

A typical value is two degrees per metre, or perhaps more, for the front wheels.

Excessive bump steer increases tire wear and makes the vehicle more difficult to handle on rough roads.

Solid axles generally have zero bump steer, but still have roll steer, in most cases. That is, if the wheels move upwards by the same amount, they tend not to steer.

Roll steer is an important part of the budget used to define a vehicle's understeer, known as a Bundorf analysis.

[edit] Difference between Bump Steer and Roll Steer

In a bump steer, both wheels rise together. In roll steer, one wheel rises as the other falls. Typically this produces more "toe in" on one wheel, and more "toe out" on the other, thus producing a steering effect. In a simple analysis you can just assume that the roll steer is the same as bump steer, but in practice things like the sway bar geometry have an effect that modifies it.

Roll steer is usually measured in degrees of toe per degree of roll, but can also be measured in degrees of toe per metre of wheel travel.

skyler
2009.03.24, 07:24 PM
If no problem, should be tomorrow, and same as PN products, SIlver, Blue and Orange.
But we only have limited stock, should be less than 10 sets each color.

Has anyone mentioned price?

yasuji
2009.03.24, 07:42 PM
Has anyone mentioned price?

worth every penny;)

byebye
2009.03.24, 08:18 PM
So when and where to buy???

Or reserve...

Kris

Cherub1m
2009.03.24, 08:35 PM
Has anyone mentioned price?

Price is important, but what about weight... how much does this thing weigh?

TALLGEESE
2009.03.24, 08:36 PM
So when and where to buy???

Or reserve...

Kris

I was about to ask the same question, I'm definately trying to pick up the new PN front end, preferably in orange..

yasuji
2009.03.24, 08:38 PM
I was about to ask the same question, I'm definately trying to pick up the new PN front end, preferably in orange..

im hoping they will be available as soon as tomorrow....headed to pn rt now ill let yall know when i get back:p

TALLGEESE
2009.03.24, 08:51 PM
im hoping they will be available as soon as tomorrow....headed to pn rt now ill let yall know when i get back:p

Thanks Grant, I really appreciate it...

byebye
2009.03.24, 10:00 PM
Standing by....

Kris

herman
2009.03.24, 11:08 PM
---> brain freeze <---
anybody got any anti brain freeze?
pretty interesting read...

jonnywachter
2009.03.24, 11:56 PM
so anybody got a 3D printer for sale?

yasuji
2009.03.25, 02:12 AM
ok....heres the skinny....there are very little i quantity.....philip and i assembled one for testing....without any set up he broke his personal best within 2 minutes
unfortunately i think it eill be a few days till they are avail....:o

jonnywachter
2009.03.25, 02:21 AM
Grant, will you have them in your shop? I would like to put one on hold if its possible but id like to know the price first. hopefully in silver. Im planing on coming out on saturday.

yasuji
2009.03.25, 02:37 AM
Grant, will you have them in your shop? I would like to put one on hold if its possible but id like to know the price first. hopefully in silver. Im planing on coming out on saturday.

i hope to have a few in stk b4 this sat.....cross you fingers.....

jonnywachter
2009.03.25, 02:51 AM
i hope to have a few in stk b4 this sat.....cross you fingers.....

check your pm's

jonnywachter
2009.03.25, 03:52 AM
one thing no body really touched on was the upper arm angle. I am goin to make a few blocks that have different- pitch?- I dont know the technical term. Any ways I was going to start from zero and go to 10 deg, then 20, and 30. This angle in the front arm actually pushes the pin forward reducing caster. Now I don't know the actual math but an example would be at full travel /ridehighth the caster would be 1deg but as the suspension progresses the caster reduces till you get to full compress wich would be 0 degrees caster. This could provide more steering into the corner yet on exit make the car more controlable. I am not at all saying this is what will actually happen, it's just theory in my head and from experiance with off road cars. My reasoning could be completly opposite of what is actually going on.

yasuji
2009.03.25, 04:52 AM
one thing no body really touched on was the upper arm angle. I am goin to make a few blocks that have different- pitch?- I dont know the technical term. Any ways I was going to start from zero and go to 10 deg, then 20, and 30. This angle in the front arm actually pushes the pin forward reducing caster. Now I don't know the actual math but an example would be at full travel /ridehighth the caster would be 1deg but as the suspension progresses the caster reduces till you get to full compress wich would be 0 degrees caster. This could provide more steering into the corner yet on exit make the car more controlable. I am not at all saying this is what will actually happen, it's just theory in my head and from experiance with off road cars. My reasoning could be completly opposite of what is actually going on.

i have found that more caster= more corner exit steeringi run maximum castor angle on all of my mod cars

pedrocamp
2009.03.25, 07:14 AM
Angling the upper arm, or the lower arm for that matter, fore or aft - or pivoting it relative to the outboard joint - also changes the anti-dive and/or anti-squat of the suspension which reduces weight transfer during acceleration or braking. Angling the upper or lower arm up or down, or the height of the inboard joints relative to the outboard joint not only changes the camber gain but also changes the roll center - which can either increase or reduce weight transfer during cornering depending on change. Increases in front caster introduce a weight jacking effect, that is as the wheel is turned to the left for example there would be more weight on the left front and right rear. As steering is reduced coming out of a corner the weight is shifted back to the right front and left rear which could help to reduce the effect of weight transfer to the right rear wheel due to acceleration - helping corner exit steering. Some of this weight transfer can be managed with the above mentioned anti-dive/anti-squat as well. Anyway there are plenty of books on this stuff. You can do all this on the larger scale cars, be interesting to see how it translates to our scale.

ianc
2009.03.25, 11:01 AM
This is extremely cool. I can't believe we are finally getting a fully adjustable front end that doesn't require complete disassembly and replacement of parts to do so.

Can't believe bump steer would be much of a problem with the minimal deflection that an 02 front suspension sees.

Am eager to get my hands on one for testing, but am also gritting my teeth waiting for the price. And again, has anyone weighed the parts?

Christian, will you be carrying them?

ianc

Davey G
2009.03.25, 11:08 AM
Johnny See what you started and you havent even driven your car yet!!! LOL :D

jonnywachter
2009.03.25, 11:49 AM
This is extremely cool. I can't believe we are finally getting a fully adjustable front end that doesn't require complete disassembly and replacement of parts to do so.

Can't believe bump steer would be much of a problem with the minimal deflection that an 02 front suspension sees.

Am eager to get my hands on one for testing, but am also gritting my teeth waiting for the price. And again, has anyone weighed the parts?

Christian, will you be carrying them?

ianc

I'm pretty sure your taking about the PN front end and not mine. Those are said to be avalible next this week, but very limmited quantities

jonnywachter
2009.03.25, 11:51 AM
Johnny See what you started and you havent even driven your car yet!!! LOL :D

I know! LOL I had no idea that it would be this big of a deal

jonnywachter
2009.03.25, 02:08 PM
Can someone break out a set of calipers and measure the distance from the center of the screw hole on the top mount to the center of the kingpin on a standard front end? please :) And the over all width from kingpin to kingpin.

So Grant is saying he runs the maximum amount of caster for more steering, so in theory what I was saying is opposite. The car will loose steering off power and gain steering on power. As the suspension compresses the caster decreases: reducing steering? BUT with the chamber gain and bump steer, the outside wheel will be exponentially steering more then at ride hight increasing the steering, except were not dealing with the standard link on the steering, so as the "bar" moves back and fourth to turn the wheels, does the bump steer change?. lol I think I just confused my self even more.

I just need to run this thing so i really know what is going on!

ianc
2009.03.25, 02:33 PM
So Grant is saying he runs the maximum amount of caster for more steering, so in theory what I was saying is opposite. The car will loose steering off power and gain steering on power.

I have limited experience with this, but I don't see how this can be true. Increased caster gives an increased tendency for the wheels to return to center, thus reducing steering.

I tried a caster bar on one of my cars and it completely killed any initial turn-in it had, so I've never used it again. YMMV,

ianc

pinoyboy
2009.03.25, 03:04 PM
I have limited experience with this, but I don't see how this can be true. Increased caster gives an increased tendency for the wheels to return to center, thus reducing steering.

I tried a camber bar on one of my cars and it completely killed any initial turn-in it had, so I've never used it again. YMMV,

ianc

By running positive caster, you gain more camber as the wheels are turned.
http://mini-zracer.com/forums/showpost.php?p=326019&postcount=8

What you're describing is what happens after you make the turn. Pedro goes over that effect a few posts above in this thread
http://mini-zracer.com/forums/showpost.php?p=340987&postcount=50

yasuji
2009.03.25, 04:24 PM
I have limited experience with this, but I don't see how this can be true. Increased caster gives an increased tendency for the wheels to return to center, thus reducing steering.

I tried a caster bar on one of my cars and it completely killed any initial turn-in it had, so I've never used it again. YMMV,

ianc
i did not say that it increased my initial turn in.....it in fact makes it want to push off throttle....however....if you r off throttle u r slowing down;)
what i did say castor does for me is give me more on throttle steering
i can hold the thottle on longer going into a corner tap the brake to initiate the initial pivot and immediately back in to the throttle and it will follow the radius of the sweeper
i dont know how to coast....:D

yasuji
2009.03.25, 04:28 PM
Can someone break out a set of calipers and measure the distance from the center of the screw hole on the top mount to the center of the kingpin on a standard front end? please :) And the over all width from kingpin to kingpin.

So Grant is saying he runs the maximum amount of caster for more steering, so in theory what I was saying is opposite. The car will loose steering off power and gain steering on power. As the suspension compresses the caster decreases: reducing steering? BUT with the chamber gain and bump steer, the outside wheel will be exponentially steering more then at ride hight increasing the steering, except were not dealing with the standard link on the steering, so as the "bar" moves back and fourth to turn the wheels, does the bump steer change?. lol I think I just confused my self even more.

I just need to run this thing so i really know what is going on!
i believe it has alot to do with driving style.....u r a smooth calculated driver
i however BANZAI every corner
lukas drives similar to you...i do not think he uses max camber...somewhere in the middle
however when he drives my car he can drive it within .1 sec of mu lap record

benmlee
2009.03.25, 04:56 PM
Can someone break out a set of calipers and measure the distance from the center of the screw hole on the top mount to the center of the kingpin on a standard front end? please :) And the over all width from kingpin to kingpin.



Jonny, I am amazed what you can do with a dremel. Looks nice. I can get you the center to center distance tonight if someone else does not have it.

You can angle the upper arm backward to gain more caster as the suspension compress. Looks like from the picture, you would have to increase the base width of the upper link to get the full effect of caster gain. Otherwise, the freeplay from the link may cancel out any angle effect of the upper link. BTW, angling the upper arm backward will not give you anti-dive in a mini-z since there is no front brake. Anti-dive use the torque of front brake to react against diving force.

You can also angle the upper link down to get more camber gain in compression. Just watch for the link hitting the knuckle at steering lock. Like what others have said before is that camber gain is tied to bump steer. With both rigid lower arm and double A-arm setup, as you increase camber gain, you will get more bump steer. Which one has more depends on geometry. However, with a double A-arm configuration, you have more flexibility with the design to find an optimal point besides lowering friction. Double A-arm basically acts like a 4-bar linkage. You can locate the instantaneous center almost anywhere. By strategically locating the instantaneous center, you can almost eliminate bump steer, and yet still have camber gain. Is like having your cake and eat it. But, as the saying goes, just because you can doesn't mean you should. If you eliminate bump steer, you will compromise on other areas. Geometry start to look strange, roll center gets higher, and you will introduce more jacking force. Remember the Chevolet Corvair and early VW bug rear suspension. They have swing arms on them with high jacking force. Very bad suspension. Jacking force is there for both rigid lower A-arm and double A-arm. PN had a prototype double A-arm that was designed to have less bump steer, and compromise on other suspension parameters. Stability actually got worse rather than improved. Is probably because of jacking force along with roll center height increased. Is a trial and error process. The goal of the design is to arrive at an optimal geometry. Of course, you can play with it forever, but I think the double A-arm geometry is quite good right now. That is just the way a suspension is, finding that narrow compromise.

jonnywachter
2009.03.25, 11:39 PM
im revising the front end rite now putting all the details in it that i had missed the first time around. When you add more caster, does it move only the top bar back or does it move the bottom a little forward and the top a little back?

benmlee
2009.03.26, 01:43 AM
You can either move the top back or the bottom forward or a little of both. The very slight change in wheelbase would not matter. Only consideration to moving the top back too much is you run out of room in the slot on the tie-rod where the steering post on the knuckle pass thru. Nothing a little dremel can't take care of.
The kingpin post to post is 46mm. Mounting for the towerbar is 21mm wide, and kingpin is set back from towerbar mounting screws by 2mm.

jonnywachter
2009.03.26, 11:28 AM
revised. im going to test it today at chad's track.

http://i87.photobucket.com/albums/k131/jon_wachter/P3271254.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3271257.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3271258.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3271259.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3271261.jpg
http://i87.photobucket.com/albums/k131/jon_wachter/P3271262.jpg

ianc
2009.03.26, 11:39 AM
The bottom link of this design is fixed and employs a ball joint through which the kingpin moves up and down, correct?

Will be interested to hear how it does,

ianc

Felix2010
2009.03.26, 12:09 PM
jonny - That's some great work you've done there.:D I am also interested to hear about how your front suspension works on the track. Great pics showing all the details of the front end too.

Very cool stuff indeed:cool:

PNracing
2009.03.26, 07:45 PM
Here some pictures
http://pnracing.us/MR2500/MR2500-1.jpg
http://pnracing.us/MR2500/MR2500-2.jpg
http://pnracing.us/MR2500/MR2500-3.jpg

EMU
2009.03.26, 09:23 PM
Out of stock already :(

Cherub1m
2009.03.26, 10:53 PM
Here some pictures
http://pnracing.us/MR2500/MR2500-1.jpg
http://pnracing.us/MR2500/MR2500-2.jpg
http://pnracing.us/MR2500/MR2500-3.jpg

Very nice guys, Very nice. Please make something like that for the AWD:D

Also, a pic of the 90mm Mid mount motor mount:D

Thanks

jonnywachter
2009.03.27, 02:43 AM
So, getting back on the topic of this thread, I ran for a good 4 hours today at Chad Nelsons track and my car was awesome! Chad drove my car for a few laps and liked it a lot, saying it had a lot of steering. I felt the same way, there was a lot of turn in but it was very smooth. I could push it really hard. Now this was only my 2nd time running on an RCP track and at this scale, and only my 3rd or 4th time running onroad at all. Altho i have little experience i can still tell what is good and what's not and what needs to change. The only part i changed in setup was, i went to gold springs in the front and added 1mm shim to limit uptravel also i changed the rear axle inserts from 2 down to 1 up's and that made the rear more planted. Honestly i didn't think it would be this good and not need any changes. I told everyone that I wanted to put the standard front end on just to try it, and they told me to not waste my time.

tudor_47
2009.03.27, 03:16 AM
Johnny,
will you be producing your kit?
if not will you make a howtoo create the front end? with material list and sketches of how much to remove here and what to put where??

jonnywachter
2009.03.27, 05:05 AM
Johnny,
will you be producing your kit?
if not will you make a howtoo create the front end? with material list and sketches of how much to remove here and what to put where??

At this point, i really wish I could produce it. But I don't have the resorces or the knowledge of how to do so. I have so many great ideas for further adjustability and simplicity that i couldn't incorporate in my design. As for an article of how to, the only parts I used where mini-t shock rod ends and the rest was hand fabricated and very dificuly to do, or explain for thAt matter. I don't want to say production is out of the question just yet tho. Alsoi was going to try to duplicate it, but with different parts that are similer to other companys production parts. If this is possible I will try to make a tutorial of how to build it.

Tjay
2009.03.27, 05:19 AM
Awesome product Philip! I was able to test this and damn it is sick! I can't wait to get mine... very soon :D!

ianc
2009.03.27, 10:34 AM
Looks really good Phil, thanks for the pics!

If I might be permitted to make a suggestion: I don't know if you have these in full production yet, but it would really be great if you could include some spare hardware with the kit. Perhaps one spare set screw, one e-clip? I've lost those things before and it's really a drag...

Hopefully the added cost of a couple of small items like that wouldn't hurt your bottom line too much and it would sure make some people very grateful when a new e-clip flies under the bench and renders the front end unusable until a replacement is obtained. Atomic in particular was very stingy about this with the SAS...

Looking forward to grabbing one,

ianc

PNracing
2009.03.27, 10:44 AM
Looks really good Phil, thanks for the pics!

If I might be permitted to make a suggestion: I don't know if you have these in full production yet, but it would really be great if you could include some spare hardware with the kit. Perhaps one spare set screw, one e-clip? I've lost those things before and it's really a drag...

Hopefully the added cost of a couple of small items like that wouldn't hurt your bottom line too much and it would sure make some people very grateful when a new e-clip flies under the bench and renders the front end unusable until a replacement is obtained. Atomic in particular was very stingy about this with the SAS...

Looking forward to grabbing one,

ianc

Thanks your comment, I will add on spare small part in next production.

JuniorWKR
2009.03.27, 12:10 PM
Very nice guys, Very nice. Please make something like that for the AWD:D

Also, a pic of the 90mm Mid mount motor mount:D

Thanks

Yes i second that for the AWD also... also if you guys could make ur own verion of the SAS which would be capable of having an adjustmennt for camber and toe without having to take the entire friggin kit apart would be awsome....