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

Technical aspects of automobiles, et. al., post #20,033
Author:
Date:
Subject:
 hachiroku
 2008-06-03 20:34:50
 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
http://tinyurl.com/cwpvp

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.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=16
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=49
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=56
Author:
Date:
Subject:
 hachiroku
 2008-06-03 20:39:57
 Re: Juddering rear end (lets talk about CARS,eh?)
On Tue, 03 Jun 2008 20:34:50 +0000, hachiroku wrote:

> 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
> http://tinyurl.com/cwpvp
>
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.
Author:
Date:
Subject:
 N8N
 2008-06-03 13:47:51
 Re: Juddering rear end (lets talk about CARS,eh?)
On Jun 3, 4:39 pm, hachiroku <[email protected]> wrote:
> On Tue, 03 Jun 2008 20:34:50 +0000, hachiroku wrote:
> > 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
> >http://tinyurl.com/cwpvp
>
> 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.

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
Author:
Date:
Subject:
 hachiroku
 2008-06-04 12:26:24
 Re: Juddering rear end (lets talk about CARS,eh?)
On Tue, 03 Jun 2008 13:47:51 -0700, N8N wrote:

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


Ah,so! *THAT'S* what it is!!!
Author:
Date:
Subject:
 Steve
 2008-06-03 16:03:10
 Re: Juddering rear end (lets talk about CARS,eh?)
hachiroku wrote:
> 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
> http://tinyurl.com/cwpvp
>
> LS (Limited Slip) grade. Juddering

Shuddering, perhaps?


> from the rear of the car got WORSE.

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.
Author:
Date:
Subject:
 Mike
 2008-06-03 22:20:32
 Re: Juddering rear end (lets talk about CARS,eh?)
"hachiroku" <[email protected]> wrote in message
news:KVh1k.2172$Yx.1249@trndny08...
> 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
> http://tinyurl.com/cwpvp
>
> LS (Limited Slip) grade. Juddering from the rear of the car got WORSE.
> These are the circumstances:

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.




>
> 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.
>
> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=16
> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=49
> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=56
>
Author:
Date:
Subject:
 None4You
 2008-06-04 00:02:34
 Re: Juddering rear end (lets talk about CARS,eh?)
"Mike" <[email protected]> wrote in message news:4sn1k.8$_n.0@fe95...
>
> "hachiroku" <[email protected]> wrote in message
> news:KVh1k.2172$Yx.1249@trndny08...
>> 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
>> http://tinyurl.com/cwpvp
>>
>> LS (Limited Slip) grade. Juddering from the rear of the car got WORSE.
>> These are the circumstances:
>
> 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.
>
>
>
>
>>
>> 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.
>>
>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=16
>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=49
>> http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=RA&P=56
>>
>Wrong oil