I should have some good pictures of the Sound Performance Differential Brace tomorrow that converts your stock SINGLE bolt holding up the diff to 4 bolts!! It sure makes a difference. It's a small price to pay to keep you from spending 4 digit price tags to build or just re-build your stock rear end.

Some aftermarket axles are also pretty important on the Z.

Reid

 

the problem with slicks is that if you run bias plys on the rear and radials on the front you get a very uncomfortable swaying back and forth of the car (at least in higher powered cars). that's why a lot of guys don't like to run slicks without skinnies.

 

so with a 4" bias ply in the front, it wont sway?

I've have good luck and 1.6x 60's with my M&H DR's.

 

i have never had this problem, are you speaking from things u have read over time or from experience...I pull consistent 1.6 60ft.'s and run hard the whole way and have never had a swaying problem with my et streets on the back on a 17" wheel and my normal 19's on the front

 

I used to get some way on my FWD turbo car on 24.5x10x13 MT ET Streets......nothing severe though.

 

I've experienced it in high-ish power RWD cars and many of my friends have (Briguymax switched from ET Streets to ET Street Radials solely because of it in fact, otherwise he'd have gotten another set of bias ply slicks when his ET Streets were done).

It's not felt in my FWD car, I run that on slicks at the track and feel no ill effects.


edit: wait, do you have ET Streets or ET Street Radials? If you have ET Street Radials of course you wouldn't feel swaying on that. I'm talking about bias ply tires here, not radial construction tires.

 

With bias plys on the front and back the swaying is equalized front and back and the car will just sort of crab a little bit down the track. with bias plys only on the back of a RWD car the back will try to crab a bit because the sidewalls are so mushy, but the front won't at all because it has nice stiff radial sidewalls, making it feel like the back of the car is trying to come around the entire time you go down the track (if your car has enough power).

 

My car swayed BAD. To the point where every once in a while I'd have to actually get out of the gas near the 1000 ft mark because I felt like the rear end was going to come around on me.

Got myself some MT DRs for my 15in welds and the swaying is completely gone.

 

i have MT ET street 3743 tires mounted on a set of wheels for track tires...they are bias ply and i have never had a issue with the swaying.. i even drove home once from the track with them on the thruway at 75-90mph in and out of traffic switching lanes and had no issues with that either..I mean it doesnt feel as if i have all my 19's on with street tires but its nothing worth calling swaying...

what setups are u guys having the swaying with?

I run 16 psi in them and leave the 19's on the front alone

 

i do see what u are saying here, but i havent gotten anything with my setup like i said, good to know though

 

I had MT ET street 3752 tires with weld 15in prostars. They started to sway when I lowered the pressure below 13-14psi IIRC. With the power that my car makes, I needed lower pressure to keep them from spinning. With my new MT DRs. (275/60-15), I can lower the pressure as much as I want and they hook fantastic and are stable as hell. Only problem is increased shock on the drivetrain, which took care of a DSS level 2 axle quite easily.

http://www.youtube.com/watch?v=TuucgawUibw

 

The swaying you guys are reffering to is the difference between running the bias ply slicks in the rear and radial fronts. This is something to be aware of for sure, but isn't completely unsafe as long as your aware. I ran this setup all of last season.

I would recommend running a proper skinny setup with a bias ply skinny tire. When you run a bias ply up front and at the rear, the swaying cancels out and is no longer a problem.

Reid

 

That is pretty much exactly what Neal said.

 

Im looking at running my car this season before it blows up again. I thought long and hard about either running a good DR out back or bias play skinnies up front. Im going to try the ladder. I need to find one TRACK model spare and Im mounting skinnies on em.

I know all about the sway a WIDE radial up front and a bias play rear can cause.

255 up front, 10.5" X 27" rear = this vid below

It was fun as hell but was horrible for times!

I sold the 27" tires and went back to the 26" and it helped my sway SOME but not completely.

http://www.youtube.com/watch?v=qe8bBfMi6uw

 

Probably has a lot to do with the sidewall size difference between the tires I've felt it on and your sidewall size. You've got the 17s which have a smaller sidewall and should theoretically be more stable than the 15" ones I was on. Also pressure differences.

It's good to know that the 17" ET Streets don't have this problem or not nearly as bad, something for people buying tires to consider especially if they have brakes in the back that are too big to fit a 15" tire.

 

Here's the SP Diff Brace pics I promised!







Reid

 

price. . .?

 

same concept as the $150 one that Injected has been selling for a while now. I have the injected one and its nice.
Of course anyone with a welder could make those for 30$

 

yeah, that's the problem. . .i look at stuff like this and know i can fabricate and weld it myself but without a machine i have to end up paying some monies to businesses. . .

 

Just reiterating and clarifying so others understand

The pirce for these is $199. I also wanted to mention that you must drill a hole in your subframe to install the Diff Brace. Not a big deal, especially considering those who are serious about drag racing.

The Injected version is based on the same concept but it is definitely not the same. Our's converts your single rear mounting bolt to 4 mounting locations. I believe the Injected converts it to 2. Considering the cost of materials, labor, and the beefy hardware we use on these, I promise you couldn't produce our SP Diff Brace for $30.

Reid