Uh oh, what happened to the diff? Are they inherently weak? Have a lot of people broken them either by autocrossing, street or track use?

Warren

 

Take that as you will, I just don't see it as smart to pick up an inside tire spin the car to redline then sit the tire on the ground multiple times during a run. Weak or not thats abuse that if you can avoid, Why not avoid.
Think of it like driving around on the rev limiter all day long. The engines not weak but if you do that your going to Blow it up!

 

Shockloading a diff is bad, period. That's why they make specific rear diff fluids that address those issues but of course that makes them less competent for street use etc. etc. The best way to deal with it of course is to try to prevent the shockloading in the first place.

 

You're talking about how to deal with inside rear wheel lift. I'm talking about not lifting the inside rear wheel. If you have one wheel in the air then that's what you have regardless of the diff configuration. All you can do in that situation is either deal with the loads that creates by using a more resilient diff or not have the wheel in the air at all.

Yes there are better ways to get power down with only a single drive wheel on the ground than a torsen LSD but the more ideal solution is to have 2 drive wheels on the ground. Making the rear suspension fully independent is the current way this has been achieved.

 

If 2 setups have the same rear roll resistance and setup A is all spring and setup B is softer spring + bar, the 2 setups will have identical loading on the inside and outside rear wheels while cornering. Removing the swaybar and making up for the reduced stiffness through springs doesn't do anything do plant the inside rear other than eliminating the relatively inconsequencial swaybar bind/sticktion component.

I think the important thing here is try to get the front end of the car do more of the "cornering work", which frees up the rear of the car to do more "accelerating work". Stiffening the front in roll vs. the rear is key; combined with larger front tires (as you mentioned) balance is retained in cornering, and more tractive grip is available at corner exit.

 

This past weekend at Thill my car handled extremely well (as I think the times indicate), and I had the OEM rear and front bars in (along with 750 lb rear and 650 lb front springs with JRZ's on softer than usual settings). And as I mentioned earlier somewhere also, all three Honda Challenge S2000's that I am aware of all have rear bars and each driver feels their car's handling is optimal with it. So, at least on RA1's, I don't think it's absolute that no rear bar is better. I had terminal understeer without the rear bar. I am sure I could have reduced it with more front camber (and this would also help even now as I still have some understeer), plus wider front tires, but the rear bar solved most of the problem with minimal inside wheel lift and allows easier steering with the rear than without the rear bar. Less inside wheel lift but more understeer/less rear steering doesn't necessarily result in faster laps, IMHO.

 

Richard, what size tires are you running? I thought you'd removed the rear bar, when/why did you replace it?

 

235/45 17 front and 275/40 17 rear. I definitely need wider front or smaller rear tires as the rear bias is too high. So without the rear bar there was excess understeer that I could not tune out even with 500 front 750 rear springs and OEM front bar (and max -2.0 front camber). I do believe that if I had 900 rear springs, -3 to -4 front camber +/- 245 front tires it would probably be balanced with no inside wheel spin, but that means extra mods to upper front arms or balljoint and wheel wells that may or may not get done soon. Remember, mine's a street car so I can't go crazy. One clear downside as it is is that I go through front tires maybe 2-3 times as fast as rears.

 

What are the softest rear bars on the market ?

Spoon and Mugen have some less stiffer than OEM, is that correct ?

Regards

Walter