Re: who sells preload rear dif covers
On a low HP car it is a show piece.
On a high HP/torque car it helps hold the ring gear in place for maximum tooth engagement with the pinion gear to reduce stripping.
There nothing more than an appearance item.. better off spending your money elsewhere.
T/A Performance covers are about $165.
I first used these covers back in the 80,s on my S/G,S/C Vega. That car had a Chrysler Liberty 4 speed, and I used to leave the line at 9,000+ RPM, it also had a Dana 60 and would eat up Ring & Pinions in approx 25-30 runs. I installed a T/A Rear Cover/Steel Main Caps and used to get 50-60 runs on a Ring & Pinion after this. I attributed the extra gear life to no Ring Gear deflection. My Lumina Z34 also has a Dana 60 and it too has a TA Cover and Mark Williams Main Caps, so far it has approx 40 runs with no troubles, and it is far from a 2,100 S/G car.
If you look inside the 10, 12, bolt etc. as well as Dana 60 you will see that the area under the side brg saddles are not very reinforced and the caps try to move rearward and stretch and walk around upon intial launch which deflects the ring gear causing increased tooth backlash and ultimately gear failure. This is the reason Mark Williams as well as others offer Billit Steel caps as well as support covers for Integral Rear axle hsgs.
Mark Williams as well as Dewco also offer a ring gear Load bolt that stops Ring gear deflection in the 9". It simply threads in the side of the case and runs close proximity to the ring gear, stopping deflection. They are used on lots of Pro Stock and Pro Mod Cars.
If you take a Support Cover off after it has been used for awhile you will notice a wear pattern on the cap from the load bolt foot, which leads me to believe that they are doing the job they were designed to do.
IMO, I think a diff cover like TA products etc., with the load bolts would be a wise investment on any high horsepower application, they look Cool, and they hold the caps firm.
