Fishey

Just kinda wondering how effective the coilovers are compared to the torsionbar..

I thinking that the Coilovers(along with stock torsionbar) are alot easier to do (install) but in the back of my head. I just don't think that the coilovers will proform to the same level as a larger torsionbar

Any input?

Stan944

I'll probably be crucified for this, but I think adding coil overs to the torsion bar is like fixing a patch - not very elegant. I know it's easier but two suspension systems instead of one good? It also adds unsprung weight (a stiffer torsion bar wouldn't), and the top mounting points are probably not strong enough, so the chassis would flex more.

Dave

Hopefully someone with more knowledge than me will help out but in the meantime...
FWIH the stock torsion bars need to be reindexed when coilovers are added so there isn't much of a labor savings over just installing bigger T-bars. Down the road a second (and third, etc) spring rate change is easier because you won't need to re-index again (not positive about that, I'd imagine that a significant change in rate might require another round of re-indexing). I've heard questions about the chassis' ability to handle the stress at the shock mounts but there are people running big coilovers with no t-bars and no problems so there must be a way around it.

Jon Moeller

Fishey,
I've removed my T-bars, and I'm looking forward to trying it out this spring. The coil-overs (and coil springs in general) provide faster response and more predictable transitions than t-bars.

I would bet that this is one of the primary reasons that the newer 911's have done away with the t-bars.

Oh, and I'll post when the shocks break through the rear mounts. Don't hold your breath, though.

-Jon

Stan944

Here are my thoughts:
My understanding is that a coilover may provide faster response because of lower moment of inertia around the pivoting axis (being partially a consequence of a less bulky design), but adding a coilover to a torsion bar system is NOT equivalent to having a pure coil over design. It's just increasing the moment of inertia even more.
On the other hand, a stiffer torsion bar will not significantly increase the response time because the heavier torsion bar is AT the axis of swinging motion:
Just to clarify, from the physics course:
inertia_moment = sum [r^2 m]

Jon Moeller

I agree with you that adding the coil-overs to a t-bar system is not the equivalent, which was my reason for removing the t-bars.

The issue regarding transitions can never be rectified with t-bars, though. Many guys far more knowledgable than I have explained the reasoning, and I went this route for the reasons that they provided. We'll see if any of these guys comment.
-Jon

Sam Lin

I'm dumping the torsion bars for coilovers as well, the coilovers have more flexibility and adjustability.

Sam

tifosiman

I'm no expert.

But remember that the factory used coil-overs in conjunction with torsion bars (that were indexed properly to work with the coil-overs). Take a look up underneath a 951 cup car.

Provided that it is done correctly, I think it's the way to go. You have the ability later to change out the spring rates later without re-indexing the t-bars, and also you are putting less stress on the shock mounts this way than deleting the t-bars all together. Although, I have never seen any failure of the mounting points, firsthand, from t-bar deletes.

Fishey

I wonder why they went with coilovers.. Prolly for faster changes? but does that really matter if its a DD-AutoX machine?

M758

Here is my take.

Bigger torsion bars are the way to go for most applications.

I run 30 mm bars in my spec.

Torsion bars are cheaper than coilovers and not as hard to install as most people say.

Problem with t-bars is that 30 mm is about the max. Custom ones can go to 32 / 33 mm, but are not common. 30 mm means 330 lbs/in at wheel. If you need to go stiffer you are limited.

This is where coilover's help. They can take you to a much higher spring rate and are much easier to change and adjust. However to gain this easy adjustment you need to ditch the t-bars. This requires non factory parts and really a stiffer chassis to take the new load paths. Good for fast racers not so good for street cars.


I don't like the combo of coil overs and t-bars. Reason is that they cost as much as coilovers, but don't have the easy adjustments as you really need to reindex at any change in ride height or spring rate. In some cases you maybe lucky and be able to do this with the spring plate.


So for rates under 350lbs/in stay with t-bars. For higher rates go full coilovers. Exception is PCA club race stock class which requires you to keep the bars in place. Best to go with small ones however.

car_slave

I went with coil-overs on stock T-Bars because it was easy, and I'm really happy with how it turned out. Unless you "really" want to drop your ride (more than an inch), no re-indexing is required. More time driving less time under the car

Fishey

Anyone know what size Tbars to go with these mods..(also maybe a place to buy them)

220#front springs, M030 front and rear sways, Strut Tower Brace, koni Yellows?

Red 944

I've got coilovers with no t-bars in the back, nothing but good stuff to say.

tifosiman

Looks to me to be about 27mm. Call or email Jason or Skip to verify..................

Fishey

Thanks alot Tifo - and everyone else... (These will be ordered when I get money) so maybe by the fest .