Juddering rear end (lets talk about CARS,eh?)

The car: 1988 Supra Non Turbo, AT, LSD rear end

Problems: AT not functioning properly Needs U-Joints

Replaced the LSD gear oil Friday with Mobil 1 synthetic gear lube 75W90

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LS (Limited Slip) grade. Juddering from the rear of the car got WORSE. These are the circumstances:

Shift into reverse, and then shift into 1st, and the rear of the car shakes.

Stop at a stop sign or traffic light, take a left or right turn. 1/3 of the way into the turn the rear starts shaking.

Stop at a light or stop sign, and take off going straight. No problem.

It feels like the Limited Slip is trying to kick in going around corners. It is heavily pronounced in 1st gear, less so or non-existent in 2nd gear and not at all while at cruising speed in Drive. Sometimes the rear of the car shakes badly.

I'm replacing the u-joints Friday, but I have a feeling something else is going on as well. Also, some other suspects: the suspension needs to be redone: I have new springs, it needs shocks. The bushings look OK for a car this old (they look good, period)

This car has an Independent Rear Suspension (IRS) so it has CV type drive shafts; boots look OK. When we get it on the lift I'm going to give the rear end a good going over, and also check for loose body/suspension bolts.

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Reply to
hachiroku
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Additional info: Manual calls for 80 weight above 0 Degrees.

Also, this time I did *NOT* add LSD additive, since Mobil 1 LS is supposed to be Limited Slip oil to begin with.

Reply to
hachiroku

might as well add some whale oil anyway, just from reading your description that sounds like what you need.

I'm using Redline Heavy Shockproof in my '55 Stude (with 3.73:1 limited slip out of who knows what Studebaker that gave its life so that mine could kick more butt.) Have not noticed any juddering, but then again, I don't know that the limited slip is working as I haven't had a chance to try a proper two wheel burnout yet :( I used it also on my '62 which also had a limited slip with good results.

nate

Reply to
N8N

Shuddering, perhaps?

Of course. Even "LS" grade gear oil still really needs an additive to work properly in a limited-slip rear. Says so right in the owner's manual (of my Jeep anyway- and they all basically work the same): Limited slip rear ends REQUIRE limited slip additive. No exceptions. The more aggressive (read that "performance oriented") the LS rear is, the more the need for the additive.

When you changed the rear end oil, you purged out whatever additive remained from the previous fill.

Reply to
Steve

Add some limited slip additive to the oil. The reason it got worse after the change is no LS additive. Mobil 1 claims it is not required in most applications but it seems like yours is one of the few that need it.

Reply to
Mike

Reply to
None4You

I guess so! Guess I know what I'm doing Friday afternoon!

Reply to
Hachiroku

Ah,so! *THAT'S* what it is!!!

Reply to
hachiroku

Hmmmm...I'm actually not a synthetic fan. I thought *maybe* it might be better than regular gear oil. Not really, I guess...

Reply to
Hachiroku

I *am* a synthetic fan, but then again, I have no experience with the Mobil 1 product. In fact, everything I own is running Redline Heavy Shockproof, although the Porsche and the Ugly Truck are depressingly LSD-free.

nate

Reply to
Nate Nagel

I'm just wondering if I should drain the lube and go back to mineral oil, or take a chance and hope the whale oil does the trick.

Reply to
Hachiroku

It depends on how much your investment in the LSD additive is worth to you. IOW, if you're willing to risk the cost of the additive in case it doesn't work, then just add it to what is in the diff now, otherwise, drain & refill.

Reply to
Ray O

I thought I read in a Tundra group it's $16 for 7 ounces!!!

I think perhaps we'll do the drain and fill! :o

Reply to
Hachiroku

Holy cow! I haven't priced LSD additive in a long time. See if the local GM or Ford dealers carry the additive. I have always had good luck with GM & Ford chemicals.

Reply to
Ray O

Funny thing was, a few years ago (>8, anyway) when I replaced the gear oil in the Hachiroku, they sent me to the Ford dealer!!

Reply to
hachiroku

I'm a synthetic fan too, and I consider Mobil 1 to be generally reliably good products, especially the extended-life engine oils which have a good additive package for older engines. Certainly better than the faux synthetics like Syntec. But Mobil has gotten particularly proud of their stuff (translation: $$$) in the past few years. I've switched my older cars to Shell Rotella-T synthetic diesel engine oil, and am considering it even for the '99 Jeep (the 4.0 six has slider lifters, interestingly enough). Its also $18 a gallon as opposed to $8 a quart for Mobil 1 extended life. It also depends on what kind of oil you need. Synthetics are a non-starter for ATF, in my opinion, because most synthetic ATFs (including Mobil-1) are just Dexron III/ Mercon replacements. The exception is Mopar ATF+4, which is both synthetic and suitable for both Dexron-III and post-1990 Mopar applications.

Reply to
Steve

I did the same but I noticed that the Rotella-T 5W40 resulted in lower oil pressure than the Mobil 1 at high engine temps so I switched back to Mobil 1. Just my one data point.

nate

Reply to
N8N

No change at all for me in two different cars. But both of them do have high-volume oil pumps so they have very solid oil pressure across all engine speeds and all temperatures.

Reply to
Steve

When Toyota first introduced LSD's in the U.S., they did not offer any factory replacement fluid so we just told dealers to visit their friends with GM and Ford franchises. The service managers and techs I called on at duals were always telling me that their chemicals worked well, and so I started using them whenever Toyota didn't have a similar product. GM used to sell a manifold heat riser lubricant that was awesome - I used it on everything that I used to use lithium grease on, and it was much neater and didn't attract as much dirt. Ford rubber bushing lubricant worked well on Camry rear sway bar bushings.

Reply to
Ray O

Still is. When I say I'm 'soaking' bolts with 'penetraing oil', it's GM Penetraing Lubricant and Rust Preventer. $8-12 per can. Awesome stuff. Removes rust and keeps rust from returning.

I used it on bolts on my Tercel, and they looked NEW within a couple of days. Truly amazing stuff...

Reply to
Hachiroku

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