Spring & Dampers

[erictharg]

Ok - who has messed around with their springs and dampers? Jan - I'm sure you must have! Mine is still all stock, without ARB. But at Silverstone last time out I was getting wasted in corners by Locosts. Very similar suspension set up, and no more power then me. But they could dive in way too fast and as their car started to get out of shape it was clearly easier to get back than my Eleven is. When the back end goes on mine, it goes.
I've heard softer springs are a good move allowing the dampers (and suspension full stop) to work better. Certainly the car feels jittery on a bumpy road. From memory the factory fit 340 front and 200 rear. From scanning the Locost forum they are down to 120 lb at the rear if running rubber bushes (which I do). The front is brilliant - no hint of understeer. Just goes where you want.
Input invited...

[adamwilkinson]

200 sounds too high for the rears, we're running 120 i believe.
I also think that our fronts are around 400 - which is possibly a little too stiff but as it's no longer road registered it works for me. We have fitted a front ARB but havent had time to play around with it.

I used to race a Locost - one of the first infact. They run a wider track which helps them in the corners, spring rate wise they are similar to our 11 (probably why i chose to run these rates on the 11).

Don't feel disheartened by them being quicker through the corners, most of the front running Locosts afre fairly well sorted in the suspension department. Once you find the sweet spot you'll find yourself atleast 2seconds per lap quicker than the fastest Locost (i've just been comparing my times with their fastest laps )

The only issue I can see is that you need to compromise on the set up so that its still drivable on the road - or carry a second set of springs and dampers and swap them at the track...

[erictharg]

Thanks Adam - confirms what I suspected. Softer rears it is then. Are you still on stock dampers? I'd like to go to Pro Tech's but not sure the budget will allow it yet (set of new dampers or one of the events at Spa - easy choice!).
Any changes for racing can only help it on the road - it's pretty horrid on anything but a smooth road as the suspension can't really do it's job with such hard springs. Don't think the budget will run to a trailer either yet!

[adamwilkinson]

Not sure what you mean by stock dampers.
We're running 1-way adjustable and height adjustable GAZ all round.

[LA 11 builder]

When you say you have height adjustment, do you mean there is an adjustable Clevis that you can use to adjust ground clearance without altering spring preload. Or do you just change spring preload and thus change ride height?

[erictharg]

By stock I meant standard Westfield factory dampers - you've answered the question! Thanks.

[adamwilkinson]

LA 11 builder wrote:
> When you say you have height adjustment, do you mean there is an adjustable
> Clevis that you can use to adjust ground clearance without altering spring
> preload. Or do you just change spring preload and thus change ride height?

The latter, an adjustable spring platform. Most of our height adjustment was made by selecting the correct length springs and then only adjusting the platforms for corner weight correction - infact we run minimal preload, literally just enough to hold the spring collar in place when the car is up on the quicklift.

[Westfield 129]

I have tried SPAX and AVO. Not happy with either.

But... You may want to try softer rear springs, and make sure that you have enough ride height.

The current GAZ setup from the factory uses a damper that is too large in diameter in the front, which limits the suspension travel, especially in droop.

In the rear, the dampers just lock at about half travel in a high force/velocity situation. If the damper is required to move quickly, it doesn't.

I am running a spring rate that is about 150 lb/in in the rear. Softer than the current setup. This helps with grip, and predictability.

Also, you need to look at the whole chassis.

Check the rear bushings to see if they have destroyed themselves. This is a pretty standard condition for the rear suspension, as the bushings don't like to be in a full tight condition, as any suspension movement or roll will shear the rubber. Typically, the bushings last only about 500 miles in the rear. Check them for play, and replace as necessary. The life of the bushings, and the handling can be improved by not tightening the bushings so much that they can't rotate with the suspension arms. I know that this practice may sound unorthodox, but it works, and greatly improves rear end grip as well. Same for the front. Probably around 14 lb.ft should do it. Use fresh Nylocks so that the nuts don't come loose. Cotter pin with aircraft bolts and nuts is best.

The new chassis has the rear suspension chassis mounts in double shear. it would be a good idea to add these shear plates to the early chassis. They are an easy fit, and are welded in. You can buy the plates from Westfield Spares. The plates stabilize the rear suspension bolts, and allow the rear bushings to be set up a bit looser, greatly extending their life, and increasing rear grip.

The front bushings last longer, but also benefit from not being set up tight.

Just remember that bolt retention is important when figuring how tight to run those bushings. I tighten enough so that I can turn the bolt/nut assembly with about the same torque that I tightened the nut with. Also, I don't want any deflection of the suspension bolts visible on the early chassis. Use fresh Nylocks nuts, or, better, aircraft bolts/castle nuts and cotter pins.

The front anti roll bar is useful in keeping the rear more or less on the road. Limiting the body roll helps with the high rear roll center that causes the axle to follow the body roll, and lift the inside rear wheel, sending your power to the atmosphere, rather than to the road surface. This high roll center is why your handling is a bit twitchy.

If you want to get those Locosts out of corners, install a TranX LSD.

Also, check your front toe setting. SET THE TOE WITH THE DRIVER INSTALLED! You get a lot of toe out if you try to set the toe without the driver, I use a setting of 1/16" IN for the front. Camber should be -1.5º if running radials, about _.5 ~.75 if running the bias ply 15" Dunlop vintage race tires.

Take care to set the front ride height so that the lower arms are parallel to the ground with the driver in the seat. This should be around 5~6" ride height, measured at the front frame, beneath the front suspension.

The rear should be about 1/2~1" higher. The driver's side of the car will end up, static, unladen, about 1/2~3/4" higher (depending on the driver weight. Heavier equals higher) than the passenger side. Finish your setup on the scales. Get the 'wedge" or diagonal weight to 50% with the driver in the car. This should take minimal adjustment.

Damper settings should be full soft in the rear, maybe one click higher in front.

As far as damper measurements go, I need to know if you have a new chassis, or the early chassis. The measurements are the same for both.

The new chassis has dampers that are too short, springs that might be too stiff. I have not driven my new RHD car yet, so I don't have any recommendations yet. Perhaps mid January.

I plan to run a set of Protec double adjustable dampers. The units I have spec''d out increase suspension travel by an inch. They will be for my Old style W11 chassis.

[erictharg]

Thanks Jan (it is Jan isn't it?). Appreciate the feedback. Geometry is pretty much as you suggest (set for racing crossplies). I hadn't thought about the roll centre effect of a front ARB - just the fact that it ultimately decreases front end grip. But your point is a good one and makes that front ARB worth considering. Body roll is minimal, but with the overly stiff rears is probably still enough to cause that lifting on the inside rear leading to the inevitable spin. I'll start with those softer rear springs - one change at a time!
I'm curious about your view on rubber bushes. The whole point of a rubber bush is that the movement is provided by shear within the rubber, providing a quiet, wear resistant pivot mechanism. I checked mine recently and all are still good after some 9000 miles. I'll pull them over the winter to check more carefully but personally I'll stick with torquing up the bolts so that the movement is in the rubber. It's always worked for me in the past. The big disadvantage when racing is that the bushes are another element of undamped suspension in the whole system. But they're predictable. And the sizes used on the Westfield don't yield enough radially to cause problems with geometry changes - the usual reason for changing them when uprating suspension. Be interested in your feedback on the ProTech's. The Westfield & LoCost guys seem to rate them.

[adamwilkinson]

Charles,

I'm with you on the bushes, just make sure that when you tighten the bolts the car is on the ground with you in it - i appriciate that this will be an impossible task so maybe get someone to help...

We run 2.25" dia springs on the front and 1.9" on the rear.

Damper settings is down to driver preference and driving style, again we run quite stiff on the damper settings in the dry but thats suits my style.

On a seperate note, I'm hoping to get to either a test day or track day before Spa (not sure what other races I'll be doing) next year, i'll drop you a line when i do incase you fancy coming along?