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sinhumane
01-31-2008, 03:18 PM
is there any discrepancy between cobra upper control arm, subframe mount and lca bushings to the frame, and the sc ones?


i'm thinking about picking up a kit to see if itll work... anyone have any insight?

Mercutio
01-31-2008, 03:19 PM
LCA bushings will fit, though there is some debate as to whether they're worth the effort. Urethane could inhibit the active toe system on the MN12.

sinhumane
01-31-2008, 03:24 PM
but, on a 5-speed would DRASTICLLY reduce wheelhop.


anyone know if the uca bushings will fit? or even aftermarket lakewood ucas?

ricardoa1
01-31-2008, 03:26 PM
I think the problem is in the Upper control arm.

Added Lower is also a culprit.

sinhumane
01-31-2008, 03:30 PM
marc petillos car had the subframe welded on instead of bushings... still had wheelhop. i think its really the upper and lower control arms that are the main factor.. thats why i want to know if cobra poly bushings will work...

XxSlowpokexX
01-31-2008, 03:59 PM
As has been said changing the bushing durometer will effect the handeling characteristics of the SC. The wheels are made to tow under hard cornering in essence making the car more predictable and have less of a tendancy to swing out. Almost like a crude 4 way steering if you will. so Many will say DO NOT CHANGE THEM!

Now...Knowing hwo well these bushing hold up I am wondering just how long this crude 4 wheel steering holds up before it actually hurts performance. Because of its tendency to deflect for the added toe i assuem it wears quicker as well.

That being said if your willing to give up the possable advantage of the factory bushing go for it.

Me I'd go with the Delrins...And they make them for the lower control arms...The uppers I believe are different as are the subframe and rear diff bushing. The front bushings onteh diff are the same

90blkbrd
01-31-2008, 08:54 PM
marc petillos car had the subframe welded on instead of bushings... still had wheelhop. i think its really the upper and lower control arms that are the main factor.. thats why i want to know if cobra poly bushings will work...

Really? I sure wasn't told about that modification.

Duffy Floyd
01-31-2008, 11:21 PM
As I have stated before wheel hop is due to drive train resonance. While bracing and changing bushings and etc etc etc may mask the symptoms, they are NOT stopping the source of the problem. Stiffening the rear LCA front bushing is a VERY bad idea for the reason stated by Damon. You are essentially defeating the purpose of the toe link compensator. If you chose to do so it might work out fine straight line but expect abrupt sharp transitions from neutral or slight understeer to oversteer in the twisties.

XxSlowpokexX
01-31-2008, 11:42 PM
On with what Duffy said..If we could have a manufacturer produce a dual clutch disk setup for us that should help mucho

Duffy Floyd
01-31-2008, 11:49 PM
Actually what you want is called a Dual Mass Flywheel.

The dual mass systems are designed to transmit less engine vibration to the driveline, and give a better more car like driving experience. They also reduce some of the jarring and stress on the transmission and remainder of the drivetrain. They work fine as long as the engine remains unmodified and the vehicle is not used/abused beyond manufacturers recommendations.

As soon as you start to increase the engine power over stock, or load the vehicle beyond design parameters, you run into problems. Dual mass flywheels are tuned systems and must be matched to the engine torque curve, engine resonant characteristics, vehicle load curves (including axle ratio/tire size calculations). They work by having a set of springs inserted between two rotating masses (thus dual mass). The springs are sized to soak up some of the resonant vibration from the diesel engine under load conditions. A dual mass fly wheel generally also contains an over torque friction release, so if it gets suddenly overloaded, rather than damage the springs, it slips. This works fine as a safety valve, but if it does it much it burns up. In short, overloaded they burn up and the springs get destroyed and they are worse than if it were a single mass FW.

The single mass part WILL tend to transmit more engine pulse (vibration) to the drivetrain, and will seem a bit rougher. But it is straight forward to design a single mass flywheel and clutch package for pretty much any engine torque curve and vehicle loading combo you can come up with. Drives more like a TRUCK, but has much better reliability at extreme use levels.

Bolded section is the RUB. How to come up with a system that works for all the possible combinations people run around here. Forget about it.

I did contact Luk a few years back about doing one for our car. They showed little interest but they do make them. See below..............

http://www.lukclutch.com/support/clutch_basics_photo.phtml?file=page04&name=&subnav=03&prinav=01&dir=flywheels

ricardoa1
02-01-2008, 11:31 AM
Looks heavy as hell.

QuickMustang
02-01-2008, 12:07 PM
Yes, I work at LuK and they are heavy. That much rotating inertia will probably slow your car down by about 0.5 sec in the quarter...That's why we don't put them in performance vehicles. They are really best used in diesel truck applications because diesels vibrate like crazy and aren't meant to rev up quickly. I would avoid it for a SC...

Duffy Floyd
02-01-2008, 01:48 PM
While I am sure the truck versions are heavy....dual mass flywheels have been used on the Corvette as well as some Porsches and other cars as well...specifically to reduce or eliminate wheel hop on these IRS equipped cars. :rolleyes:

2TonCat
02-01-2008, 01:59 PM
As has been said changing the bushing durometer will effect the handeling characteristics of the SC. The wheels are made to tow under hard cornering in essence making the car more predictable and have less of a tendancy to swing out. Almost like a crude 4 way steering if you will. so Many will say DO NOT CHANGE THEM!


Where can I find out more about the toe compensators? I ran a seach but didn't come up with what I wanted to know.

XxSlowpokexX
02-01-2008, 05:37 PM
The bushings themselves and arms are designed to do that. Duffy would be a godo source for the actual information. He may have something lying around

Duffy Floyd
02-01-2008, 07:34 PM
What do you want to know about them?

sinhumane
02-03-2008, 03:08 PM
know anyhting about torsen diffs duffy?

Duffy Floyd
02-03-2008, 03:16 PM
Nope...my car had an Auburn Diff when I got it and now I have an prototype Eaton Diff. Prototype in the sense that they modified the side gears to work with the IRS Cars but never released the unit for production.

96sport
03-20-2008, 10:35 PM
As I have stated before wheel hop is due to drive train resonance. While bracing and changing bushings and etc etc etc may mask the symptoms, they are NOT stopping the source of the problem. Stiffening the rear LCA front bushing is a VERY bad idea for the reason stated by Damon. You are essentially defeating the purpose of the toe link compensator. If you chose to do so it might work out fine straight line but expect abrupt sharp transitions from neutral or slight understeer to oversteer in the twisties.


Are the bushings that you are talking about the outer (aka knuckle bushings) or inner LCA bushings? I would assume the inner since you are talking about the toe compensator link, but I wanted to make sure. Thanks.

Russell

Duffy Floyd
03-21-2008, 12:39 AM
Russel,

The bushings in the rear suspension of most concern are the inner lower control arm bushings. And of those two...the front bushing is the one with designed compliance specifically for the toe link compensator.

96sport
03-21-2008, 03:14 PM
Russel,

The bushings in the rear suspension of most concern are the inner lower control arm bushings. And of those two...the front bushing is the one with designed compliance specifically for the toe link compensator.

Thanks alot. It made sense to me that it would be the inner LCA bushings after I posted. It is pretty obvious after you have looked at the tie rod setup on a Cobra. I have been experiencing some of the conditions that you said would be a consequence of polyurethane inner LCA bushings, but I believe I am having the problems because they are worn out (original rubber).

Russell