I have not used the 75W140 before in a Ford LS diff but I have used the 75W90 in 2 different Fords with the LS. Both of those worked OK without the additive and I didn't have a problem.

The 75W90 looks quite different than the other, it is blue and feels slicker when you rub it between your fingers.

I have been running the truck with the 75W140 for about a week. The 75W90 and the additive should be here today so I can change it again.

I might try the 75W90 alone and see if that fixes it. If it doesn't I can use a suction gun to remove enough to get the additive in.

Jim

 

I changed the diff lube again and added the LS additive.

It didn't make any difference in the shudder. I drove slowly in a tight figure 8 several times and there is no "chatter" from the LS when turning in a tight circle like there would be if the LS was not working correctly.

Anyone have any ideas?

 

Wiggles, i had a low speed shudder, and a shudder in reverse, turned out to be the u-joints.

A tell tale sign of bad u-joints is a squeeking while backing up.

 

Thanks for the info Blizzard, I'll take a look at it tomorrow.

I had not thought to take a look at the U Joints because the truck only has about 10,000 miles on it.

 

My 2000 F-150 just started this "shudder" about 3 weeks ago. I've finally gotten it looked at at the local Ford dealer. They "have no idea whats causing it." They are freak'n morons. At first they suggested getting an alignment but when i told them AGAIN that it didn't do it all the time he suggested maybe that wouldn't really help. So they are going to flush out the tranny, add all new fluids, filters, whatever else they need to do. $145 on top of whatever they will charge for initially looking at it. Freak'n ridiculous. I hope it helps though, i'm really getting annoyed. Seems to do the shudder thing at around 45-50 mph when it kicks into overdrive. Noticed it mostly going uphill. I drive an hour each way to & from work and the road is very hilly and curvy so it does it a lot.

People had some great suggestions on here. Wish y'all luck. If anyone ever gets it to stop permanently, please let me know! I love my truck (named her Haides) but just might have to think twice about getting another the next time around (perish the thought!).


Vixxen

 

Go try the LubeGuard.

I used it just after I got my trans fluid changed and the shudder returned. After the LubeGuard....no more shudder!!

I think I posted the link in an ealier thread.

There is other stuff out there as well (like Lucas, etc...) but Lube Guard did it for me.

It's cheap...try it and tell me what happens. I'm anxious to see if it's just my truck being weird or if the stuff really works.

 

Thanks. My brother had mentioned Lucas but wasn't sure if i was remembering the name correctly. I'll have too look for either it or LubeGuard incase it ever does it again. I'll look for the link you posted.

Thanks.

 

My 2003 has had the tranny/rear end shudder since it was new and now has 4800 miles on it. Seems to only shudder from a dead stop and then taking off and also from a slow stop and turning right. I'm taking it into the dealer on Friday morning, I'll let all know what they say. I have the limited slip rear end.. not sure if this may be a factor or not.

 

Well, its been over a week since i took my truck in to the dealer to have the tranny shudder checked out. They gave me some bull that they didn't know what it was. I told them again what it was doing then they decided to flush out the tranny (which i had mentioned to them before). Amazingly, it hasn't shuddered once since they flushed it out (it better not for $145!). I'm waiting now to see if it comes back. Plan to add some LubeGuard though just in case. Good luck to everyone.


Vixxen

 

I think I stated earlier that I had the trans flushed and that the shudder disappeared, only to return again several weeks later.

I would be curious to hear if yours stays fixed or if it returns as well. Let us know if you hold off on the LubeGuard and the shudder returns.

 

After 3 differential lube changes my shudder is gone. It only shuddered while accelerating lightly and turning. The driving in a tight figure 8 was OK.


First I changed to Amsoil 75W140 then to 75W90 (see posts above) with friction modifier but the shudder was still there.
I added another bottle of friction modifier (8 oz total) to the 75W90 but the shudder while turning & accelerating was still there.

I pulled the cover again and changed back to the Ford 75W90 synthetic & 1 bottle of friction modifier and it's gone.

 

Vixxen,

I just posted on this forum with almost an identical condition. What did you try and did it fix it a month later?

I have an appt with the Ford dealer on Tuesday?

Thanks,

Dan