My 08 with the 3.73 limited slip I believe is making a shudder on takeoff. It just started maybe a month ago from a dead stop turning. Well its starting to do it going straight. It feels like a clutch pack shudder to me but the straight takeoff makes me wonder. It has about 130k on the truck and I don't know if the fluid has ever been changed in the rear. I'm planning to do it but wonder if that's what is causing it.

Thoughts??

Usually when your get the "studder" its the fluid being bad or the friction modifier's life is gone. I know my 07 is doing the same thing. I'm going to be changing all my fluids. You should think about doing the same. Just don't forget the friction modifier in the rear

Almost always a fluid change gets rid of this problem. It has for me twice, once on my 1965 Chevelle that had a 12 bolt eaton posi-traction back in 1968. More recently it got rid of the problem on my 2000F150 5.4scab 4x4 that had the 9.75" ford traction lok. On my 2000 I had to put two bottles of friction modifier in it because that year the clutch pack was shimmed a little too tight.

My '05 started shuttering while turning at a start at low speeds. I finally went to the parts store and bought a bottle of friction modifier.
I added it and the shuttering stopped.

I agree with what these guys have said however, every case is different. Change out your fluid and be sure to add a bottle of XL-3 friction modifier. Hopefully this cures your condition but if it doesn't then it is time for a LS repair.

If you're like me and don't ever want to worry about this issue coming up again, then replace the factory LS with a Detroit Truetrac. The truetrac is all helical gears that won't wear out like the factory LS clutch packs will. I never had the shuddering issue with my LS but I changed it out to the truetrac anyway because I never wanted to encounter the problem. The truetrac works better than the factory LS anyhow.

How much that end up running you? I always wanted to go that route, seeing as my old truck used to always see mud and I predict the same future for my new truck.

I can sense a slight shudder even after an all fluid change a few thousand miles ago (by a dealer so I assume FM was used). Would another bottle of FM help? Any downside to a second FM dottle?

Check your receipt. Should be a charge for it specifically.

I wish I could help but I'm in crapghanistan and the receipt is in my truck. I had the 4.56 gears and the truetrac installed at the same time and it was 2400 out the door for all of it.

Receipt shows dealer used FM. So would a second bottle help any, or is there any downside?

Like I said I put two bottles of viscosity improver in my 2000 at 80k miles. I sold it to a friend at 105k miles. The last I heard the truck had 170k miles on it and the rear was working great.

My 05 with the 3.55LS has been doing the same for a while now. it has over 154k on it. plan on getting the fluid changed soon to see if it helps.

There shouldn't be any issues by adding the extra bottle of friction modifier. I've read many posts on other forums where folks did that and everything was fine.

I changed the diff fluid on my truck long before I took it in for the gears and truetrac and I used nonsynthetic gear oil with 2 bottles of XL-3 and the truck behaved the same as it always did.

Hey all, My truck is shuddering as well. This is the first I have heard of a Friction Modifier. My truck has 90K on it. I did a transmission fluid change about 5K ago. Still shudders.

Would the FM help in this case? Transmission only or other fluids as well?

Thanks in advance.

The friction modifier is for the rear dif only, and if you have limited slip.
When does your truck shudder? On turns only or all the time?