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trapper
I need some suspension advice! I bought a 914-6 track car last spring and it is very soft. I don't know what I have installed yet but I suspect I need an upgrade over the winter. The car is a 2.8 liter with full cage. Any recommendations as to torsion bar size and rear springs? The car has front and rear sway bars, Bilsteins and monoball
front mounts. beer3.gif smash.gif
PeeGreen 914
First of all.... do you have a limited slip?

The set up I am trying to do is.

Front:
- 23mm hollow torsion bars
- 22mm Anti-Sway bar
- Turbo tie rods
- Weltmeister camber plates
- Elephant racing bushings
- Koni yellows

Rear:
- 250 lb springs
- no anti-swaybar
- Elephant racing bushings
- Koni yellows

This set-up was what I was told to do by a very well respected Chief engineer of a porsche race team. He has a 914 set up similar to this, and it is aways one of the top times of day at all AX events, and it is a killer track car.
trapper
QUOTE(Blood red 914-6gt @ Sep 24 2007, 03:42 AM) *

First of all.... do you have a limited slip?

The set up I am trying to do is.

Front:
- 23mm hollow torsion bars
- 22mm Anti-Sway bar
- Turbo tie rods
- Weltmeister camber plates
- Elephant racing bushings
- Koni yellows

Rear:
- 250 lb springs
- no anti-swaybar
- Elephant racing bushings
- Koni yellows

This set-up was what I was told to do by a very well respected Chief engineer of a porsche race team. He has a 914 set up similar to this, and it is aways one of the top times of day at all AX events, and it is a killer track car.



Thanks for the info. I have Bilsteins front and rear with monoball front upper mounts. The car does have a limited slip and rear bar. The hard bushings are binding and need to be redone and zerk fittings installed. It does have turbo tie rods also.
sean_v8_914
dsaeagf
trapper
QUOTE(sean_v8_914 @ Sep 30 2007, 08:42 PM) *

dsaeagf

Thanks a lot Sean, I have a lead on some 22mm torsion bars.
Glenn
grantsfo
I run 250 lb rears with Koni sports and 19mm front torsions with 22 mm front bar. Nothing special and car feels very nice on the track.
trapper
QUOTE(grantsfo @ Oct 1 2007, 03:49 AM) *

I run 250 lb rears with Koni sports and 19mm front torsions with 22 mm front bar. Nothing special and car feels very nice on the track.

Thanks, I would like 250 lb springs but only seem to see 180 lb on the popular websites. Any suggestions as to who would carry 250 lb springs for a 914? Thanks in advance.
ChrisFoley
No one makes a 914 spring in higher rates than 180. You have to go with a coilover adjustable perch kit and 2.5" id springs from someplace like Ground Control.
Nicke Nilsson
...But how do we calculate.At one sourse I saw that 22mm front torsions bars is = 298 lb/in..!!..If that is correct,should the back end be softer then the front..???
ottox914
The front and rear of the 914 have different motion ratios. In simple terms, the motion ratio is a way to express what spring rate the tire on the track "sees" when taking into account the angles, attachment points, and "leverage" the suspension applies to the spring or torsion bar. An example would be if the rear suspension has a motion ratio of 1.0, and the front .90. If you had 200# rear springs, the fronts would need to be 180# to have matching "wheel rates" front to rear.

180/90=2.0. 200/100=2.0.

J P Stein
The front end is lighter than the back,,,,,duh...
Less spring rate there, more in the back.
My car has 700 lbs on the front tires & 1000lbs on the rears (rough numbers). So a 30% difference should be about right....disregarding the motion ratio for the moment.
The idea is to get the rates close enough to be able to adjust your anti roll bar for both oversteer & understeer as desired......this means half hard at neutral. (I use a front AR bar only).

There is more to consider, of course.biggrin.gif
I found I had to raise my rear rates to keep both rear tires firmly in contact with the ground at AX. With an LSD, lifting one (or just unloading it) will cause severe oversteer, with an open diff forward progress ceases. OK, we fixed that without too much problem, but had to stiffen the AR bar to take out some (but not all) of the oversteer.

My spring rates aren't gonna tell you much as not many folks run as much tire as I do and it is an AX only car. It's too unstable to do much with on a track as it is set up.
betegh9
I have recently obtained Bilstein front 911 struts that will accept coil overs, and have a raised spindles. These, I plan on using on my 914 together with rear coil overs. The car is a 2.0 4 cylinder in stock form. This will be a IMPROVED class (any suspension modification allowed) AX car, driven to and from the events. the car will be driven with Toyo RA-1, and switched to Hoosier A6's for competition. The tire sizes will be 225/45 x 15 all around.

My question is this: 1. What spring rates should be used with a well lowered suspension, front and rear? 2. What damping shocks would be best? 3. Is there a need for finding double adjustable shocks?

Any help would be greatly appreciated! THANKS,

Nick
SirAndy
QUOTE(J P Stein @ Nov 28 2007, 08:14 PM) *

The front end is lighter than the back,,,,,duh...
Less spring rate there, more in the back.
My car has 700 lbs on the front tires & 1000lbs on the rears (rough numbers). So a 30% difference should be about right....disregarding the motion ratio for the moment.
The idea is to get the rates close enough to be able to adjust your anti roll bar for both oversteer & understeer as desired......this means half hard at neutral. (I use a front AR bar only).

There is more to consider, of course.biggrin.gif
I found I had to raise my rear rates to keep both rear tires firmly in contact with the ground at AX. With an LSD, lifting one (or just unloading it) will cause severe oversteer, with an open diff forward progress ceases. OK, we fixed that without too much problem, but had to stiffen the AR bar to take out some (but not all) of the oversteer.

My spring rates aren't gonna tell you much as not many folks run as much tire as I do and it is an AX only car. It's too unstable to do much with on a track as it is set up.


agree.gif


i'm back to the drawing board myself after dropping in the 3.6L. the added weight and additional "umpf" have changed the balance of the car, my old setup is not adequate anymore ...

i'm leaning towards 22mm torsion bars and 350lbs springs ...
bye1.gif Andy
J P Stein
I am in the ongoing process of strengthening my chassis to adsorb the loads that my relatively stiff springs, sticky tires, and metal suspension (in place of rubber) bits place on it...albeit a bit late. The metal bits are necessary, IMO, to hold suspension alignment which would otherwise deflect with rubber...toe in particular. As I wrote, I did find a bit of cracking/shifting at the very bottom of the rear tower/long interface.

I hesitate to recommend stiff springing to anyone that is not willing to go the some
radical lengths to protect their chassis from the punishment of these "improved" pieces.
The car rides very stiffly, but the revalved shocks are up to the task of keeping the tires under control 98 % of the time. There always seems to be a very rough patch on every venue I run.

That said Andy, your planned springing seems a bit stout. My 21mms & 275s give me about 2 inches of shock travel with a bit of safety margin thrown it. I ran 300s for a while but backed off as they gave a bit too much oversteer with the front bar at half hard. Your 3.6 is maybe 50-60lbs heavier than my 2.7, so 25 lbs stouter at each rear spring should do the trick. Are your f & r shocks up to these spring rates? Is your chassis?
d914
ok jumping in, building my car now, street and track day use. Current plan is to have:

911 stock front end, bilstiens, and sway bar(911). Raised spindle 19mm, full delrin bushings through out including top of strut.

rear, coil over some where around 150-180lbs on the springs, elephant racing bushings.

Engman chassis up grade
Racer chris rear console stiffener inner and outer.
suspension ear upgrade

overall weight close to a stock 4, 300hp...

A little soft but under control??? More sway and or torsins's???
J P Stein
Are you using the 911 T bars....19 mm IIRC? If so, the 180s would be better.
I would highly recommend not using the stock underbody 911 AR bar as they are non-adjustable. A decent (Weltmiester) 19mm should do it for you. These do require
U-tabs on the tops of your A-arms.......I'm hyphened out. biggrin.gif

I am not a fan of derlin. Elephant makes polybronze fronts also.
d914
sway is through body with welded tabs done already. The delrins up front cut to fit with grease fittings and already bought...oringinal plan was for elephant all around but went with the racerchris prep'd stuff. we'll see.. Basically SC spec up front. Again 180's were the orignal plan. I was thinking of running a little softer for street and go to the 180's for track....but I'll probably default to the heavier ones..
SirAndy
QUOTE(J P Stein @ Dec 1 2007, 09:07 PM) *

That said Andy, your planned springing seems a bit stout. My 21mms & 275s give me about 2 inches of shock travel with a bit of safety margin thrown it. I ran 300s for a while but backed off as they gave a bit too much oversteer with the front bar at half hard. Your 3.6 is maybe 50-60lbs heavier than my 2.7, so 25 lbs stouter at each rear spring should do the trick. Are your f & r shocks up to these spring rates? Is your chassis?


good question ... idea.gif

i currently run 19mm t-bars in the front with a 21mm sway bar. the rear has 250lbs springs on adjustable perches with a stock rear sway bar.
full rollcage but no other stiffening.


that setup worked fine with the 1.7L motor.
but now with the 3.6L, the car *understeers* confused24.gif

and i get front wheel lift again. also, the front is too soft, the car rolls too much under heavy load.
i also get rear wheel lift now under power in tight corners. probably time for a limited slip ...

the 2" shock travel is about right. i run koni adjustables front/rear.
bye1.gif Andy
J P Stein
I know you're running cantis on 7s, but do you have spacers behind the fronts?
If so, there is your push.
SirAndy
QUOTE(J P Stein @ Dec 2 2007, 12:38 PM) *

I know you're running cantis on 7s, but do you have spacers behind the fronts?
If so, there is your push.


yes, spacers front and rear to fill out the flares ...

shouldn't a wider front track give you more stickage???
idea.gif Andy
J P Stein
Excessive scrub radius......BTDT and pushed. No amount of suspension tuning will get it out but will increase oversteer on wide corners. It the tighter stuff...most autocross corners, you need so much steering lock that the tire actually gets out ahead of the ground/strut center interface making the tire shuffle sideways. I replaced my 10 inch wide fronts with 8 inchers ...a 1 inch reduction in scrub (no other changes except new tires for the wheels) and now the front end bites. There ya go, a freebie that took me over a year of misery to finger out.

The other solution is wheels with 1 inch more backspace.....which won't fit as the strut gets in the way. headbang.gif
drgchapman
QUOTE(J P Stein @ Dec 2 2007, 05:06 PM) *

Excessive scrub radius......BTDT and pushed. No amount of suspension tuning will get it out but will increase oversteer on wide corners. It the tighter stuff...most autocross corners, you need so much steering lock that the tire actually gets out ahead of the ground/strut center interface making the tire shuffle sideways. I replaced my 10 inch wide fronts with 8 inchers ...a 1 inch reduction in scrub (no other changes except new tires for the wheels) and now the front end bites. There ya go, a freebie that took me over a year of misery to finger out.

The other solution is wheels with 1 inch more backspace.....which won't fit as the strut gets in the way. headbang.gif


YUP. agree.gif
davec
Also BTDT. Now running 400lbs up front, 300lbs in the rear. Got rid of the rear sway bar. It is not needed. For reference, I am 2200lbs wet, have 10.5 inch slicks and coil overs all around, 300hp, custom valved bilsteins. Never got good response from the Koni's. I turn a solid low 62 seconds at LRP.
sww914
Where's the good deal on rear coil over sleeves and tops?
J P Stein
Coleman Racing has a decent price. It takes a bit of fooling with them to get the fit right. They need your shock tube OD.
dougcoup
I have a lighter car it appears than those posted 1865lbs. with 2.8ltr.
10" slicks. for track not ax. I have coil overs all the way around and rear and front sways (stock).

Spring rates not writen on springs when I purchased set up but I would say in the 350 F to 500 rear based on beefyness compared to my 911 springs.

I took out the front torsion bar. I found no difference.

Has anyone else done this?
J P Stein
QUOTE(dougcoup @ Jan 13 2008, 12:23 PM) *

I have a lighter car it appears than those posted 1865lbs. with 2.8ltr.



Mine is at 1724 before ballast to 1781.....strictly an AX car tho.
bumble
I found the following to be near perfect:

23mm torsion bars
22mm front sway bar

300lb rear springs
no rear sway bar

Poly Bronze bushes throughout
monoball top mounts

3.2 Carrera struts with raised spindles

Very stiff chassis - full roll cage tied into the rear shock turrets, chassis stiffeners etc.

Koni sport shocks.

2.7L engine (~180 RWHP). Quaife Torsen diff.

This setup is extremely sensitive to sway bar settings - 1/4 inch either way is quite noticeable. Konis are the weak link - soon to be replaced with custom built Proflex shocks.

Cheers,

Mark.
dougcoup

jp
do you really need to run torsion bars with coil overs?


QUOTE(J P Stein @ Jan 13 2008, 08:15 PM) *

QUOTE(dougcoup @ Jan 13 2008, 12:23 PM) *

I have a lighter car it appears than those posted 1865lbs. with 2.8ltr.



Mine is at 1724 before ballast to 1781.....strictly an AX car tho.

J P Stein
Well.....I don't run coil overs, but I would think T bars would be redundant with the coilovers in place.
Since you noticed no difference, your T bars may have not been under tension....the adjustment screws backed off....which makes some sense, but not much.biggrin.gif
SirAndy
QUOTE(J P Stein @ Jan 17 2008, 10:20 AM) *

Well.....I don't run coil overs, but I would think T bars would be redundant. with the coilovers in place.

agree.gif seems like you would want to eliminate the guesswork for the T-Bars out of the equation ...

driving.gif Andy
PeeGreen 914
QUOTE(bumble @ Jan 14 2008, 04:37 AM) *

I found the following to be near perfect:

23mm torsion bars
22mm front sway bar

300lb rear springs
no rear sway bar

Poly Bronze bushes throughout
monoball top mounts

3.2 Carrera struts with raised spindles

Very stiff chassis - full roll cage tied into the rear shock turrets, chassis stiffeners etc.

Koni sport shocks.

2.7L engine (~180 RWHP). Quaife Torsen diff.

This setup is extremely sensitive to sway bar settings - 1/4 inch either way is quite noticeable. Konis are the weak link - soon to be replaced with custom built Proflex shocks.

Cheers,

Mark.


This is almost what I have, and I would venture to say that this would be perfect.
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