At wit's end with lack of inside rear traction...

[MattW]

If this is temperature related it might still be the control arm bushings, right? Or do those never get warm?

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[Norm Peterson]

I have had this happen only really when first going out in the morning just from a stop. I have no problems putting power down during autocross. I have just figured the diff doesnt like high turning, low temperature situations.

There's probably enough sliding around going on at autocross such that little or no differentiation in terms of wheel rpm differences actually needs to happen. Never mind that the tires are operating at temperatures much more favorable to coping with slip and slip angles.

Differentials that lock need for there to be some other way of accommodating the difference in turn radii, inside to outside. Or IOW, the tires and however much slip they can carry . . . or a driving technique that has both of them sliding and slip-angling enough to minimize the actual amount of differentiation needed.

I think basically it's your cold tires objecting to being forced to do what an unlocked diff does for them.


Norm

 

[Cowfy]

I have experienced this from day 1. Not as bad as it used to be when I first got the car. I think I noticed a big difference after I changed tires - wierd.

I had it slightly today in a spot were it usually happens. - Backing st8 out of driveway, full turn left of the steering wheel turning uphill. This movement is the only time i get the funky little hops

I have a GT PP and experienced the same issue. Mine occurred only after pulling out of the driveway and turning left at a stop sign. I never noticed it after driving for a while.

When I switched out my stock Pirelli P Zeros for NT05Rs, I never had the problem again. I'm guessing it has something to do with the stock tires being awful when cold. The NT05Rs do MUCH better when cold for me, but they're also a wider tire (305 vs 285).

 

[MattW]

As mentioned, I do experience this and it seems to me also that it subsides after like 10 min of driving.

I don't think the console has display for diff temp but could there be a diff temp channel in the OBD 2 output?

 

[EricSMG]

Installed Boomba vertical links (poly at both ends) today and noticed a positive difference in various aspects. First, the inside rear wheel hop is calmer - the wheel still spins faster than the outer wheel but the slip/grip/slip action is smoother and more consistent and the car accelerates easier. Now - it is pretty warm today so there's that variable but so far I'm pleased.

The links also seemed to have calmed down the "jiggle" in the rear suspension over bumps, providing a quicker settle-down and overall less nervous driving experience.

Finally, I cannot, so far, feel any difference in NVH but do to less jiggle I'd dare say that comfort is slightly better. I'll report back after a few more drives/temps.

Next are Steeda red diff inserts and LCA bearings.

 

[Bluemustang]

Installed Boomba vertical links (poly at both ends) today and noticed a positive difference in various aspects. First, the inside rear wheel hop is calmer - the wheel still spins faster than the outer wheel but the slip/grip/slip action is smoother and more consistent and the car accelerates easier. Now - it is pretty warm today so there's that variable but so far I'm pleased.

The links also seemed to have calmed down the "jiggle" in the rear suspension over bumps, providing a quicker settle-down and overall less nervous driving experience.

Finally, I cannot, so far, feel any difference in NVH but do to less jiggle I'd dare say that comfort is slightly better. I'll report back after a few more drives/temps.

Next are Steeda red diff inserts and LCA bearings.

Right on man! Let us know how the next round of mods goes. I may do diff bushings and LCA bearings in the spring, and if I have time BMR CB006 front chassis brace.

 

[West TX GT]

I did diff bushing lockout, LCA and toe link bearings and it solved this problem completely. Now I need the vertical links to help my straight line wheel hop. I'm pretty sure the problem is the P zeros and the IRS moving in ways it should not. Solidify the IRS and be done with it. The bearings added no NVH, the diff bushing lockout (BMR aluminum) did add a little. The driveline is still quieter than my 2014 track pack stock.

 

[EricSMG]

I did diff bushing lockout, LCA and toe link bearings and it solved this problem completely. Now I need the vertical links to help my straight line wheel hop. I'm pretty sure the problem is the P zeros and the IRS moving in ways it should not. Solidify the IRS and be done with it. The bearings added no NVH, the diff bushing lockout (BMR aluminum) did add a little. The driveline is still quieter than my 2014 track pack stock.

Do you have IRS bushing supports (Steeda inserts or BMR lockout)?

Regarding the LCA bearings - do you notice a firmer/harder/sharper ride quality over sharp edges?

 

[West TX GT]

I have cb005. I installed them at the same time I did steeda shocks and struts and BMR handling springs so the whole setup is much stiffer. I remember seeing someone say something about increased harshness, but I can't imagine it being that much if any. To me the bouncing down the road is what bothered me as far as ride quality goes and that is gone. I may be more tolerant of firmness than many. That being said with front and back set to full soft the car floated around and felt more plush than stock (but bounced) even with the springs and I didn't notice any sharp jaring over bumps and I crossed train tracks. I have it set pretty firm now and the ride surprisingly isn't bad. I have ridden in plenty of lowered cars that felt much more harsh. I wouldn't even categorize my ride as harsh, just firm without any jiggles. The planted feeling under acceleration is the biggest change in the car before and after mods except for when I wheel hop in a straight line, that still sucks.

 

[EricSMG]

It was cooler out tonight and the inside wheel hop mostly returned. I might say it's marginally better with the links but not enough to consider them a viable solution to this problem, unfortunately. Overall the car is marginally better in general with the links and no worse so $165 and 30 mins of my time well spent.

The Steeda red diff inserts are going in next and I will be removing the CB005 at the same time to see how much comfort I can get back. I've found over the years that gaining back comfort is far more noticeably than originally losing it.

 

[EricSMG]

Raining today and the car is a mess, per usual. Light throttle results in major wheel hop/lack of forward push.... lots of banging and clunking.

Current mods: lockout and vertical links.

I've high hopes for the LCA bearings.

 

[West TX GT]

Raining today and the car is a mess, per usual. Light throttle results in major wheel hop/lack of forward push.... lots of banging and clunking.

Current mods: lockout and vertical links.

I've high hopes for the LCA bearings.

Did you do the toe link bearings already? If not, do those at the same time. They help also and since you will already be pressing things out you might as well

 

[BMR Tech]

Raining today and the car is a mess, per usual. Light throttle results in major wheel hop/lack of forward push.... lots of banging and clunking.

Current mods: lockout and vertical links.

I've high hopes for the LCA bearings.

The banging and clunking in those scenarios are the diff, half shafts and driveshaft going absolutely bananas.

Interested to see how well those links hold up. My customers have not had much luck with the Poly lasting very long on the links.

 

[EricSMG]

Did you do the toe link bearings already? If not, do those at the same time. They help also and since you will already be pressing things out you might as well

Not yet but I think I'm going to do those before the LCAs. It's important to me to install one mod at a time so I can evaluate the good/bad and decide if the mod stays or not.

So, my next mods will be in this order:

1. Diff bushing inserts, then
2. FR toe bearings, then
3. LCA bearings

The banging and clunking in those scenarios are the diff, half shafts and driveshaft going absolutely bananas.

Interested to see how well those links hold up. My customers have not had much luck with the Poly lasting very long on the links.

Oh yes, totally, not to mention the LCA bouncing fore/aft as the wheel fights for traction. I've also got high hopes for the diff bushings.

Note taken on the poly links although my car will never see a drag launch if that's worth anything. That said, once the diff/toe/lca parts are in I will remove the links to see if anything is lost, since, they seem to provide only a marginal benefit at this point.

 

[BMR Tech]

Love the process sir.

Interested to see your thoughts on the components.

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