'Oscillation' - RE: [modern] XJR-ing & the 4L80E Tranny @36,000 miles

Im serious when I said to call TRANSGO - this should be a pretty straight
forward problem to solve if you describe the problem to them - but, as I
said, used transmission cores are expensive - you’d be lucky to buy a core
for $1,000 - and an earlier one at that ( early ones somewhat less
desireable due to several subsequent updates from GM ) IE you dont want to
blow them up ! - Have you called the dealer or checked the service bulletins
??

Regards, BiggySmalls
“‘Timothy Sheehan’” timish@pacbell.net
miles

Hi Biggy:

By oscillation - I am attempting to describe the very slight ‘shudder’ /
grabbing or ‘friction-ing?’ that originally occurred between 1800 and 2300
RPM as the transmission ‘attempts’ to engage OD. It feels like its a very
slight wheel balance problem - which I thought it was until I began to
drive the car more frequently and sequentially (thanks to the
encouragement
of this list) - and discovered it was NOT there when I kept the car in 3rd
with the J gate (ruling out a wheel imbalance origin at the same road
speed). However- with ‘firm acceleration’ - it is now occurring beyond
2200
rpm - almost like a ‘clutch shudder’ in a manual tranny when the clutch is
beginning to slip. This is very mild, not felt by passengers, but I can
tell
its behavior is definitely not right.

I had what seemed like this XJR 4L80E tranny problem with my '95 Buick
Riviera (4L60E) between 1800 and 2200 rpm only; 46-52mph) - and was told
then by the Tranny techs (verified by test equipment), that it was a
computer sensing issue- not quite enough throttle to fully shift into OD
-and not enough ‘off throttle’ to keep the tranny in 3rd. Like the Jag-
when
I kept the car in 3rd manually - it went away.

I absolutely hated it and due to a few other issues worked out an 'upgrade
to a ‘97’, which had a different tranny programming, along with a few
other
significant engine & suspension improvements. So GM knew they had a
problem
with the 'engine computer ‘talking’ to the ‘Tranny computer’.

These computer controlled things work great when they actually work- but
I
have more and more liked my ‘old fashioned’ positive shifting '72 V-12 E
type with its BW tranny, my '74 Jensen Interceptor with the Chrysler
Torqueflite and even the old GM 3 speed in the XJS so much better than
the
4L80E. Now if this is finally a problem that we have identified and can
be
resolved- I might actually get the car I thought I bought two years ago.

However - your saying the ‘planetary gears can explode and come through
the
case’ -really scares me. With the increase in this oscillation - I’ve
just
parked the car and have been enjoying my XJS Convert- with its just
completely renewed cooling & A/C system!

Is this oscilation /shudder the symptoms of what causes the tranny to
explode?
Your making me feel I should have it ‘rollbacked’ to a tranny shop?

Sherman
Columbia MD

-----Original Message-----
From: BiggySmalls [mailto:@R_Mahoney]
Sent: Friday, June 01, 2001 9:00 AM
To: modern@jag-lovers.org; Taffel, Sherman
Subject: Re: [modern] XJR-ing & the 4L80E Tranny @36,000 miles

I dont really understand what you mean by oscillation - you better
clarify----- Original Message -----
From: “Taffel, Sherman” STaffel@bcps.k12.md.us
To: “‘BiggySmalls’” <@R_Mahoney>; modern@jag-lovers.org;
Sent: Friday, June 01, 2001 9:04 AM
Subject: ‘Oscillation’ - RE: [modern] XJR-ing & the 4L80E Tranny @36,000
that description before
you call transgo …

Biggy

Hello,

Regarding this thread, you might want to check out this link.

Pretty unbelievable!!

And the relevance to the original post is of Sherman has to get a new
transmission, he might want to go all out and look into the 5 speed 4L80E
mentioned in the article.

http://www.johnscars.com/home/bonn.htm

Tim
95 XJR