Heads Up on Differential Bushings
 

I'm sure a lot of you all would know better than this, but for those that don't let me share my differential bushing experience with you.

I had a shop install differential bushings (along with other mods) in my 2011 SS, and basically left him make the call on which version to install, since he knew I was a drag racer and he is a BMR dealer. He chose to install the "Street" version bushings (68 durometer) on my car while doing a 3.91 gear change. After about thirty (30) 1/4 mile passes and about ten (10) WOT data logs for my tuner, along with about 500 miles of street driving, I noticed the bushings were disintegrating. After removal, all three bushings showed severe wear/abrasion at the 12 o'clock location, almost to the point of the metal sleeve touching the differential mountings lugs. I think that it might have eventually caused the cast aluminum differential mounting lugs to break. I had them replaced with the BMR 95 durometer "Pro" version bushings, and hopefully they will hold up to the rigors of my drag racing hobby. After seeing the 68 durometer bushings after they were removed, I'm wondering if I should have moved up to the Delrin bushings at this time. Time will tell.

I'm sharing this experience for one reason only, that is to hopefully keep someone else from making the same mistake.

Jeff

Wow. That's really quick for a set of bushings to wear out.

I have the pro 95 duraometer bushings installed and I'm hoping the same thing! Time will tell!

Shocked me. If I hadn't seen them when they were being removed I probably wouldn't have believed it. I was too dumbfounded to take pictures or keep the bushings, I guess because I couldn't believe my eyes.

IMHO there is no reason to change from the OEM differential bushings unless you go with the 95 durometer set or the Delrin set.

I still run the oem rear diff bushings. They work fine.

As P. T. Barnum said there is a sucker born every minute. That may be my case with differential bushings.

I am running the Pfadt "race" durometer differential bushings (these were discontinued long before Pfadt discontinued their "street" version). I haven't had much problems with them so far, but then again, I'm not on the track every weekend like you guys!!! I've seen posts where Justice Pete (from Pedder's) has said there is absolutely nothing wrong with the design or capabilities of the OEM diff bushing. So....if I ever do have problems with these Pfadt units, I'll probably just go back to stock. ......There's probably a good reason that Pfadt stopped making them completely!?!?!?!?

I figured you had an aftermarket rear diff with as much drag racing as you do. So everything has held up pretty good so far?

Stock diff, stock diff bushings.

Just did the pfadt motor mounts, subframe bushings, Farks upper control arm, pfadt lca upgrade, full drag specific coil overs customized from Farks, with pfadt trailing arms.


Results in the near future.

All the stock stuff was fine up until about 725 rwhp and 9.80. Then it was holding the car back.

That makes me feel a littler better about my set up. I have the Lingenfelter 3.91 gears and bmr drag set up. So far so good.

The "street" differential bushings were developed for high performance street use and since they are a little on the softer side they don't like the abuse of drag racing all that much. The "pro" differential bushings should have been what they provided with initially and now that you have them you should be taken care of, they are by far our most popular bushings and are what I recommend 99% of the time because they are stronger and offer more movement control but they transfer very little noise. The "race" delrin differential bushings tend to transmit quite a bit of gear noise so I don't generally recommend them to unless the person is going to be racing the car a bunch and is willing to deal with some added noise.

The OEM differntial bushings are fine for a very very high percentage of users. The more aggressively you launch combined with increased RWHP and grip determine when differential bushings are appropriate. Differential bushes reduce movement of the differential case. You have to drive hard to see a benefit from the upgraded bushes.

Run a road course on slicks, hit a very well prepped strip on slicks, you get the idea. Torque twists the differential within the range allowed by the bushings. Increased grip increases the torque load increasing the movement. Keeping the differential stable helps keep the driveline healthy and transfers power more efficiently.

It's ALIVE!!! Resurrection machine works!


My rear end has been making this really annoying squeak. Well Today I figured out what it was, Differential Bushings. With the foot on the brake and shifting into reverse, then into drive you could watch the bolt move about a 1/4 inch, and make that nice squeak. Hope the hole isn't elongated but I guess that's what the welders for. Time to order new Bushes. (factory bushes on L99 with 3.91 gears 20k+- at this setup)