Ok we all know guys that go and throw 30k at a suspension on a car without having a clue what anything does. I'm trying to learn some stuff so I'm going to list a few things and see if some guys here can post their knowledge of what the parts do and their impressions of how it's done and how it helps, or if you could even tell the difference after you added them.

BTW, I'm not one of those guys.

Anyways, here is the list: (Assuming adjustable aftermarket or motorsport parts)

- Lower Control Arm
- Upper Rear Arm
- Toe Link
- Dog Bone

For a 996.

 

Wanna911,

Not sure which car you are speaking about for these components but for these brief descriptions I have a 997 on my mind.

Lower control arm - usually the reason to upgrade this component is to get the two part design that allows you add or remove shims for your camber. Also when ordering you can get the RSR or Grand Am Spec components to help remove the rubber bushing on the inner half.

Upper rear arm - I could be mistaken but I believe that this is also the same as the last item you had a question about; the dog bone. These are solid non adjustable mounts from PMNA. The only reason why I would see any reason to upgrade these would be if your original components had rubber bushings and you wanted the spherical bearings with steel hats for a solid mount.

toe link - Again the reason for upgrading depends on original equipment, stock is a solid item with all adjustment being done off of the eliptical(sp?) bolt adjustment which can be frustrating at times. An upgraded toe link in the rear would offer more adjustability with a tie rod adjustment and no rubber bushings but the steel solid mounting.

Hope this helps, if you have any further questions please feel free to give me a call at 434-822-8180x103.

 

Helps to know what kind of car this is for. 996/997 right?

 

996, yes, sorry.

And is there any benefit to adding shims for camber as opposed to camber plates?

 

I agree with everything Kerrigan said plus, the ball joint at the ends of the rear toe link fail frequently when used on the track. I think early cup cars had the same issue. Replace them with the later 996 cup toe links and you will be fine.

The bolt on the ball joint that holds the stock lower control arm to the upright has a weak point just below the threads. I broke two of them on my 996 before going to the cup control arms. I had one come apart in a slow corner and the other when I hit a bump in the pits. Needless to say it would not have been good in a high speed corner. Get rid of them.

I had adjustable upper control arms in back instead of the dogbones. I did it to get solid bearings but we did use the adjustments from time to time to make bigger tires fit with the alignment I wanted.
Jim

 

I think adjustability with shims on the front end is preferable to using camber plates. If you're moving the piston rod in the inboard direction at the top with a camber plate to gain neg camber then you limit the tire/wheel width combo moreso than using shims at the bottom which would provide a stationary pivot point at the top. At some point the springs will rub the tire. I guess there woluld also be a miniscule ( as in really really tiny) benefit by increasing track width. I never found the springs getting in the way in the rear, even with the 12.5" wheels. I have the GT3 control arms back there and also use shims for camber.

 

You really do not want to use too many shims as it extends the control arm which causes the locating link to pull the whole assembly forward, which increases the caster above it's already high 8.5 degrees (or so). This can affect the handling and may cause interference between the tire and the front fender liner. The trick with the GT3s was to turn the upper strut mount 1/6 of a turn to get more camber without the caster change. Camber plates will accomplish the same thing. I do not see where the minimal increase in track is worth it, though there have been some who have flipped (or moved) their control arms to the "other hole" and then shimmed them out pretty far. This method also avoids increasing the caster. LVDell should have info on this.

 

My dog bones are adjustable. They add a bit of toe in under load and control camber changes under load.

 

Controlling camber changes under load is a big deal to me. I think I'm going with Dog Bones for sure.


As for the front camber, now I'm really confused. I plan to run a 9-9.5 inch wheel in the front and nothing bigger than a 265 tire. Probably around 3.5 degrees max camber in the front. Should I go with camber plates or shims?

 

BTW what are thrust arm bushings?

 

No need to be confused. If you are going to run wider wheels with wider tires on a 996 you must use the camber plates. If you get any more caster, the front tires will hit the front of the fender liner because caster (along with scrub radius) causes the front tires to swing in an arc as you turn them. More caster = bigger arc. Also with the wider combo you will start to have outer fender clearance issues, and a wider track will cause problems in that area too.

 

Larry,

I always appreciate it when you join in these discussions. I learn every time. Not having any meaningful track experience with my new suspension setup yet, I am trying to learn as much ahead of time so I know better what to do when I do get some good track time. That should be next Friday if the weather is suitable.

I didn't mean to convey that the using of shims to gain some track width was significant at all, hence calling it miniscule. I can see how a combination of shims and pulling the piston rod more inboard with the adjustable plates could allow for a larger wheel to be used. I thought I was getting adjustables but when I picked up the car they had installed fixed-position mounts. Pillow *****, I think they're called.

As far as caster increases with too much shimming goes, it wasn't a problem on my car (996 turbo). Front camber is about -4 degrees and caster is slightly under 8. I have no rubbing problems with the inner liners except with tight turns in the paddock, etc. The tires are quite large 27 X 65 -18 and did require fender rolling but they don't rub against the fronts of the liners.

I assume the locating link you mentioned is the leading arm with the clevis end that attches to the lower control arm and a point further forward on the chassis, is that correct? I see 2 holes in the control arm where the clevis end mounts but I can't see how the rear-most hole could be used without messing up the angle where the inboard part of the control arm attaches. I'm sure I'm missing something.

I have other issues I don't understand either but I am going back to another thread and seek understanding there, i.e. my roll centers are subterranean. That would be OT here.

 

Do not run -3.5 degrees camber up front.

Your car will have incredible turn in, then snap oversteer at mid phase and exit. Try to keep a sensible difference between front and rear camber, usually -.5 or less.

Others may wish to debate this point, but anyone who was at the last Lone Star DE at TWS saw what -3.5 camber up front did to my car's handling. Nothing over -3.0 on a 996 with Toyo, Nitto, BG's IMHO.

 

+1









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How about -4 F and -3.0 R with Michelin racing slicks and a good bit of downforce. Is that going to be OK in your estimation?