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MG MGB GT V8 Factory Originals Technical - Jaguar XJS Gearbox


Some of you may remember that the Silver Lady's TR7 gearbox broke while on the way to MG2007. As it was stuck between 4th & 5th gear we diagnosed it as a broken selector. Now the same thing has happen to a fellow club member. The question is will a Jaguar XJS 5 speed manual fit on the Rover V8 bellhousing? He has been told that it will, I am not so sure.
Any help would be appreciated.
Mike Cook
Mike Cook


While I don't know for sure, I would be real surprised if it did. Isn't the Jag 5 sp. a rare option? I've not seen one.
Carl Floyd


although i am not sure and did not proof it, i read about the LT 77 having been used for all BL cars of this period, Jaguars included. May be the shifter and the bellhousing will not fit our cars, the rest should be O.K. for the B and it should have a better 5th. ratio for the use in the B than the old SD1 has.

A very professional guide for a rebuilt of the LT 77 is published by the Dutch Rover Friends and can be found on the site -> <-.
Just click the colume you want to reed in the top of the page.
BTW, how did the damage of your box happen? Have there been signes before? The LT 77 in my V8 is just working fine since 26 years now, but sees that sh*t happens one day.


Huh. From the site that Ralph mentioned:

The 77 mill. gearbox is found on the Rover SD1 series, 5 speed TR7s TR8 and the manual versions of the Jaguar and Daimler 3.4 and 4.2 models.

I read somewhere that Jaguar used Getrag 265 on XJS. Not sure what years, though.
Carl Floyd

Thank you for the Dutch web site, I will look at it for information. As regards to the warning when the gearbox broke, there was none. I had been driving on a very very bad surfaced road, in 5th doing 60 mph because of the roughness of the road when it jumped out of gear and was stuck between 5th and 4th. It was impossible to move the gear stick from then on. The box had been rebuilt about 4,000 miles ago and I had no problems. I use ATF oil and it was full when drained.
Mike Cook

Time for a T5, Mike.

rick ingram

The Main thing that crossed the Rover tranny off my list was that it has a fluid pump. Make sure it works. I am used to Muncies in my '68 Camaro that uses splash-only lubrication. I'm not used to manual trans that need a fluid pump. Glen Towery said that he puts in an extra quart of auto trans fuild & that it has saved him when the tranny pump failed.
Carl Floyd

Consider the Rover R380 which is a great improvement over the LT77.

I have had an R380 in my (230bhp) B GT V8 for over 10 years with no problems, including many tens of thousands of miles rallying in France & Spain.

I use the oil recommended by MG for this gearbox when installed in the RV8 - Texaco MTF94.

Previously I had an LT77, and prior to that the standard factory gearbox.

IMHO the R380 is preferably to the LT77 and well worth the additional cost.
Nigel Steward


The place to find a solution to your problem is:


Jean Guy Catford

The supra box is pretty well bullet proof.

First and foremost, your car is beautiful!
Food for thought. Read somewhere years ago
folks were using TH400 transmissions with no
adapters or modifications on Jaguar. The TH400,
TH350, muncie, super T-10, T-5 all have the
same bolt pattern as far as trans to engine.
T-5, muncie and super T-10 all interchange
between the same bellhousing. This same bell
will bolt onto the buick aluminum v-8. Seems
to me if the TH400 bolts onto a jaguar motor,
wouldn't the reverse be true, untested by me
to date, but seems logical. Lotsa rovers
running around with T-5's behind them and we
all know the rover v-8's relationship to the
buick v-8,correct?


This thread was discussed between 21/08/2007 and 25/08/2007

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