Author Topic: Advanced Suspension Discussion  (Read 2424 times)

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Offline chr1S

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Advanced Suspension Discussion
« on: May 21, 2009, 12:29PM »
Referring to dozer's project thread.

Lgee - I just had a think about the literal terms, slip and grip angle, they technically mean the same thing, the amount of slip and the amount of grip. If you think about it, you can't have grip with no slip, you can't have slip with no grip.  ;)

Ackerman angle only occurs in the front end of the cars yes, but this is not a bad thing in race cars as the inside tyre suffers the greater toe out during cornering, now when turning in that direction, weight transfer will go to the outter tyre, which means less load will be on the inside tyre, since there is less load the greater toe out causes a greater slip angle which is desirable as the tyre can handle the greater slip angle.

I think we need a good discussion about the geometry of the suspension overall.

Adjustable caster arms
Adjustable camber tops
Roll centre spacers/adjusters
Aluminium lower control arms that rectify non-parallel alignment once lowering of the chassis is performed

Ideas, K go.
Don't let the opinions of the average man sway you. Dream, and he thinks you're crazy. Succeed, and he thinks you're lucky. Acquire wealth, and he thinks you're greedy. Pay no attention. He simply doesn't understand.

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Offline lgee

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Re: Advanced Suspension Discussion
« Reply #1 on: May 21, 2009, 03:43PM »
Ackerman is probably the most important geometry setting for a race car or trying to get a car handling well, for those who dont know it is measured in percentage, the closer  you can get your car to 100% ackerman angle the better, unfortunately most car come no where near that, so in racecars the extend arms out at the bottom for 3 reasons 1. neg camber 2. ackerman angle 3.caster  how do we work out this angle, well from memory and chris could help on this, draw and imaginary line across you car from ball joint to ball joint, then using the centreline of the car you now have a big T, draw a line at 30 deg inward on each side i think  and this will give you your ackerman point on the car where the two lines intersect, to get the percentage you count the front line as 0% and the centre of the diff/swing arm as 100%, so with a tape measure to measure the distance and apply that to a percentage graph.
Now there are other tools to help with this as well the easiest to use is a tremmel, panel beaters have been using them for years to fix chassis, because built in to your cars subframe is a bunch of reference points, how does this help us  well fuk all really because of the way the lower control arms are mounted, which is why race cars run double wishbone suspension so these arms can be spaced out accordingly or have the amount built into them at the time of manufacture,to get things further out you need to start modifying arms and mounting points and making offset bushes, now we cant put it all into one post this is supposed to be a resource for all so if you put your FAQ here we will do our best to help you out

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #2 on: May 21, 2009, 03:45PM »

I think we need a good discussion about the geometry of the suspension overall.

Ideas, K go.

"Aluminium lower control arms that rectify non-parallel alignment once lowering of the chassis is performed" you have seen the WRX anti-lift kit, this is what this corrects, but they never made them for nissan not enuf demand for the product compared to WRX.

"Adjustable camber tops" Is only possible with coilovers due to the physical constraints of the strut cavity in the body unless you get new springs made that taper at the top and run a smaller spring retaining plate easy enuf to make out of aluminum and a lathe.

"Roll centre spacers/adjusters" well do you want to lower the diff in the original carriage or do you want to use pineapples to space down the rear, now to do it the race car way we need to lower the diff centre in the carriage althought buy spacing down the rear carriage it will give you a virtually same effect and by putting better bushes it it it will have less tendency to "walk" under load.

"Adjustable caster arms" well again we come up with the problem of the rear mounting point on the lower control arm, possibilities are 1. offset nolathene bushes set and forget which will give you about 7-10 mm at the ball joint which will be about 1 deg more pos caster. 2. replacement nolathane bush with an eccentric sleeve inside to which the lower control arm goes thru then you adjust the eccentric sleeve and tighten thenut at the back locking it in place. (not a fan of this) 3. Nolathane offset bush  combined with a adjustable top that will slide inward (camber) and backwards (caster) to give to a much larger scope for adjustment (my fav).

OK now chris and i will be making all of these parts and selling them off, JOKE STOP DONT SEND YOUR ORDER THRU ;D


« Last Edit: May 21, 2009, 04:19PM by lgee »

Offline chr1S

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Re: Advanced Suspension Discussion
« Reply #3 on: May 21, 2009, 04:30PM »


Here is a simple exaggerated diagram of Ackerman for those who need visual aids, the dotted red line is the direction of the wheels, you can see the larger angle on the inside (right) wheel.

"Aluminium lower control arms that rectify non-parallel alignment once lowering of the chassis is performed" you have seen the WRX anti-lift kit, this is what this corrects, but they never made them for nissan not enuf demand for the product compared to WRX.

I would much rather a new lower control arm from alumnium which would be lighter than the OE item. Less bushes to worry about too.

Quote
"Adjustable camber tops" Is only possible with coilovers due to the physical constraints of the strut cavity in the body unless you get new springs made that taper at the top and run a smaller spring retaining plate easy enuf to make out of aluminum and a lathe.

This is currently what i'm looking at into at the moment, I'm not going to pay someone to do it, don't see a point, I'll just get the coilover kit, weld it myself and get springs to suit.

Quote
"Roll centre spacers/adjusters" well do you want to lower the diff in the original carriage or do you want to use pineapples to space down the rear, now to do it the race car way we need to lower the diff centre in the carriage althought buy spacing down the rear carriage it will give you a virtually same effect and by putting better bushes it it it will have less tendency to "walk" under load.

Well FWD is clearly different to AWD. I know AE86's run a spacer that sits between the hub and bottom of the shock.

Quote
"Adjustable caster arms" well again we come up with the problem of the rear mounting point on the lower control arm, possibilities are 1. offset nolathene bushes set and forget which will give you about 7-10 mm at the ball joint which will be about 1 deg more pos caster. 2. replacement nolathane bush with an eccentric sleeve inside to which the lower control arm goes thru then you adjust the eccentric sleeve and tighten thenut at the back locking it in place. (not a fan of this) 3. Nolathane offset bush  combined with a adjustable top that will slide inward (camber) and backwards (caster) to give to a much larger scope for adjustment (my fav).

Unless the front strut tops are modified to a point where they are moved back towards the windscreen to allow for more caster, I don't see much adjustment there? In FWD racing i'd like to have anything from 4-6degrees of caster. I don't think this modification would be all that difficult, engineering just gets in the way.

You U13 guys seem to be spot on for coilovers, even then you don't have any decent manufacturers out there producing anything great. Anyone on here opened up a shock to revalve it themselves?
« Last Edit: May 21, 2009, 04:42PM by chr1S »
Don't let the opinions of the average man sway you. Dream, and he thinks you're crazy. Succeed, and he thinks you're lucky. Acquire wealth, and he thinks you're greedy. Pay no attention. He simply doesn't understand.

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to be fair, it wouldn't be ANTRX if we stayed on topic.

and if someone wasn't cranky at Chr1s for something he said...

Offline SSS

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Re: Advanced Suspension Discussion
« Reply #4 on: May 21, 2009, 05:09PM »
Anyone on here opened up a shock to revalve it themselves?

I will be. Changing the "adjustable" valving on my rear Koni's to fixed valving; i'm lucky that they do not use a dividing piston with a high pressure nitrogen charge. My front bilsteins however...i will be converting them to use external reservoirs so i can regas them myself.

A good mate of mine is an absolute guru with tuning passive dampers, that is why i'm not going for a modified "off the shelf" aftermarket coilover. It will take a bit of time to get the valving right to get a good comprimise between corner grip and ride harshness, but it can be done.

Aluminium LCA's FTL....not a good idea as they will be severly prone to cracking from impact loading at the weld joints. Tubular chromoly would be a far better option, and probably lighter in the end depending on the wall thickness of the tubing required.

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #5 on: May 21, 2009, 05:17PM »


[quote This is currently what i'm looking at into at the moment, I'm not going to pay someone to do it, don't see a point, I'll just get the coilover kit, weld it myself and get springs to suit.] i have such a kit at my house with 400lbs springs with adjustable platform, wanna play?

[quote Well FWD is clearly different to AWD. I know AE86's run a spacer that sits between the hub and bottom of the shock.]
pleas tell me in detail how it mounts see if we cant get a solution like trailing arms or just bolt in some pics would help.

[quote Unless the front strut tops are modified to a point where they are moved back towards the windscreen to allow for more caster, I don't see much adjustment there? In FWD racing i'd like to have anything from 4-6degrees of caster. I don't think this modification would be all that difficult, engineering just gets in the way.]
engineering IS the answer what we used to do and still do is make a strut top out of billet with a recessed encapsulated spherical bearing so the nut that goes on top of the strut is actually below the level of the top where you bolt it to the tower so that way you can crank it back as far as it will go and the nut and strut shaft ar not protruding past the strut tower in the engine bay, so when you look at the strut tower from the engine bay all you see is a plate of alloy with 3 bolts holding it in place, get my drift and by doing it this way you are changing the SIA giving you good caster gains

[quote You U13 guys seem to be spot on for coilovers, even then you don't have any decent manufacturers out there producing anything great. Anyone on here opened up a shock to revalve it themselves?] me, so the u12 runs a Chapman strut in the front and a Mcpherson strut in the rear doesnt it, just a matter of getting them built and valved, koni, bilstein pedders can do a modified version as well i think.


well i made that look ugly didnt I
« Last Edit: May 21, 2009, 05:27PM by lgee »

Offline chr1S

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Re: Advanced Suspension Discussion
« Reply #6 on: May 21, 2009, 05:24PM »
Good learning curve here for you how to use quotes eh lgee  :D.

Good point Adam, I completely disregarded material in the idea itself.

Re: revalving, this is something I would do sooner rather than later, I was told s13 inserts work in our cars? I'm not 100%, just need to open up a standard unit and set the insert in there. I've never pulled a shock apart before so I wouldn't know where to begin, I should learn.
Don't let the opinions of the average man sway you. Dream, and he thinks you're crazy. Succeed, and he thinks you're lucky. Acquire wealth, and he thinks you're greedy. Pay no attention. He simply doesn't understand.

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to be fair, it wouldn't be ANTRX if we stayed on topic.

and if someone wasn't cranky at Chr1s for something he said...

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #7 on: May 21, 2009, 05:31PM »
could be Chris but dont quote me on that ;D

ok so i had a thought about the lower control arm problem, why cant we make an adapter that bolts on where the lower control bolts onto that accepts an "A" style arm that bolts onto that adapter plate and using shims or different length ferals, to push it out and forward to give camber and caster then depending how you made the adapter plate you could build in "anti lift" to correct the non-parallel  chassis alignment issue, 1 product solving 3 problems,

Oh we are good, except it would cost about 2k to do both sides ;D
« Last Edit: May 21, 2009, 05:48PM by lgee »

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #8 on: May 21, 2009, 06:42PM »

Offline dozer

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Re: Advanced Suspension Discussion
« Reply #9 on: May 21, 2009, 07:57PM »
as of a few days ago i have got a gtir caster/anti lift kit which i will be attempting to fit to the bluebird.

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #10 on: May 21, 2009, 10:23PM »
cool let us know how it goes mate, in the mean time chris and i are going to re engineer the front end.

Offline chr1S

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Re: Advanced Suspension Discussion
« Reply #11 on: May 22, 2009, 02:37PM »
lol @ re-engineer the front end

I don't think i'm anywhere near ready yet to take on nissan engineers! Then again, we are talking about a pintara  :D Blasphemy? I said it  :P
Don't let the opinions of the average man sway you. Dream, and he thinks you're crazy. Succeed, and he thinks you're lucky. Acquire wealth, and he thinks you're greedy. Pay no attention. He simply doesn't understand.

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to be fair, it wouldn't be ANTRX if we stayed on topic.

and if someone wasn't cranky at Chr1s for something he said...

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #12 on: May 22, 2009, 10:45PM »
lol @ re-engineer the front end

I don't think i'm anywhere near ready yet to take on nissan engineers! Then again, we are talking about a pintara  :D Blasphemy? I said it  :P

Do you think Nissan's race cars run that type of suspension, aaaahhhh no

Offline dozer

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Re: Advanced Suspension Discussion
« Reply #13 on: May 23, 2009, 01:41PM »
hmmm, always liked the idea of tube frame front end, do what ever suspension set up you want. ;D

how much preload can be placed on a spring before it should be replaced with a higher rate spring, and is no preload a good starting point?
« Last Edit: May 23, 2009, 01:50PM by dozer »

Offline lgee

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Re: Advanced Suspension Discussion
« Reply #14 on: May 23, 2009, 03:31PM »
hmmm, always liked the idea of tube frame front end, do what ever suspension set up you want. ;D

how much preload can be placed on a spring before it should be replaced with a higher rate spring, and is no preload a good starting point?
With pre load, you would get your car on the corner weight scales then put the amount of weight in the drivers seat that represents your weight, and the amount of fuel in the car that would normally be in it during a race meeting when you start, now the car will be heavier on one side compared to the other, so by preloading the spring it will try to push that wheel harder into the ground, but it cant so it transfers the load across to the other side, remember we are trying to get the balance of the car as even as possable, so if it looks a little higher on one side compared to the other never mind, its how it spreads that weight on the ground that is important, for the anti roll bar to work properly its better to start off with an even spread of weight that way it will work properly in both directions making it nice and predictable, but if you have a lot of weight down one side of the car the when you go around the corner with all the weight to the outside, the roll bar cant transfer all that weight to the other side as per your photo,
contact someone who racers in your town and get your car on the scale once the car is balanced as best  as it can be spreading the load as evenly as possible, then work on the right anti roll bar to keep it all under control.

Offline squizz taylor

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Re: Advanced Suspension Discussion
« Reply #15 on: Jun 1, 2015, 04:38PM »
cool let us know how it goes mate, in the mean time chris and i are going to re engineer the front end.

Dredged this one up from a long time ago. How did you go with sorting this out Dozer, did you get it to fit, or go a different path.

Deviate is trying to get some caster back into his newly purchased U12 attesa and is struggling to find bushes to

Offline deviate

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Re: Advanced Suspension Discussion
« Reply #16 on: Jun 2, 2015, 08:07AM »
I have since managed to find a set of caster bushes, from polytuff the part number is CA0036K unfortunately they couldn't confirm just how much caster it adds, but once they're installed I will post up the difference

Offline SSS

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Re: Advanced Suspension Discussion
« Reply #17 on: Jun 2, 2015, 09:28AM »
Lower control bushes will never give enough caster.

You physically need to shift the strut mounts in the shock towers rearward to obtain any sort of decent gain.

Offline deviate

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Re: Advanced Suspension Discussion
« Reply #18 on: Jun 3, 2015, 08:40AM »
At the moment I'll settle for any gain, purely because I currently have 0.40 of caster making it twitchy as hell at higher speeds

Offline SSS

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Re: Advanced Suspension Discussion
« Reply #19 on: Jun 3, 2015, 09:40AM »
Pulled directly from the FSM, the U12 FWD caster spec for the front is from -0deg25min to +2deg05min. That's a pretty big range for caster.

The bushes should at least get you to +1deg caster total - not ideal, but as you said, better than nothing. Hopefully the bushes will push it out to +1.5deg.

With my black U12, my aim is for at least +5deg caster total - not that high speed instability is my issue, but I need the camber gain from the increased caster. My static camber is sitting at -2deg which is costing me entry and mid corner speed at a track like Winton.

Part of my plan is to fabricate tubular lower control arms, and shift the ball joint forward and outward of it's current position to give me both increased caster and the ability to increase static camber. I have to tread a fine line between static camber and grip, otherwise it'll be wheelspin galore.

For your application, to further increase caster, you would physically need to cut out the strut towers, and shift them back at least 10mm. This would probably yield you another +1deg on top of what you have (at a guess, I haven't done the maths on it).
« Last Edit: Jun 3, 2015, 09:41AM by SSS »

Offline squizz taylor

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Re: Advanced Suspension Discussion
« Reply #20 on: Jun 3, 2015, 10:22AM »
SSS, Have you looked at where the pillow ball mounts into the sturt tops, is there an ability to remanufacture the strut tops to change the location in relationship to the centre of the strut top, and therefor gain the caster and the camber that you need. That is if you are using coil overs.


Offline SSS

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Re: Advanced Suspension Discussion
« Reply #21 on: Jun 3, 2015, 02:10PM »
I have, yes.

In order for me to gain more caster and static camber through the top mounts on my Shockworks coilovers, I'd need to cut the top of the strut tower out, and make up a new strut tower top with the holes shifted roughly 10mm back and 10mm closer to the centre of the car. Not keen on doing this yet until I start doing the cage, in which I plan on tieing the front of the cage to the strut towers.

As for changing the actual pillow ball mounts, yes, it could be done that way, but I tend to think that there would only be enough room to shift it back 5-10mm to gain caster. Camber is limited by the stud that is closest to the centre of the chassis.