Hi all - new member / owner here. I recently bought a 5-speed converted 1986 V12 coupe. I love it - it has a tremec T5 and a 4.11 rear end with an outboard rear brake conversion as well. The car is quick - much quicker that I anticipated. I'm a serial Porsche 928 owner and the Jaguar is quicker than any of the (all manual transmission) 928s I've owned. I was also afraid the 4.11 rear would result is a car that was a bit high strung on the interstate but it's not bad at all - the 5th gear ratio in the transmission is 0.68 so at 80 m.p.h I am at ~2750 r.p.m. As I said, I love this thing - My first drive in it was a 970-mile trip home that I did in one day and it was just great the whole way.

Anyway - I have two questions:

First - are there many other members on here who have 5-speed converted V12s?

Second question is about local repair shops - I'm in west LA and am looking for someplace that knows these cars. I normally do all my own work but my current living situation doesn't really allow for a good place to do major disassembly work that would take me multiple days to finish - like dropping the front subframe. The previous owner (who did the 5-speed conversion) had the rear end all refreshed at the time the conversion was done but the front end could use a total rebuild and I would rather have an independent shop that knows what they are doing perform the work than just anyplace or the dealer. Anyone know of someplace around here (West Hollywood / Century City / Fairfax area of LA ideally) that they can recommend?

thanks!

 

Welcome fellow traveler. Lol... You are lucky to have such a great car. Most other v12 5 speed cars have a prancing horse on the hood.

I have a 928 too. Its a 1986 S3 5 speed. I also had until recently a T56 six speed XJS with the 6.0L v12. Jag should have built them this way. Totally diffrent car in a good way. The Jag v12 with a manual certainly feels quick but the Porsche 4 cam really pulls hard 4000 to 6000 RPM. The 6 litre Jag V12 is flat up there. I can tell you from experience up to 80MPH the Jag can keep pace with the 4 cam 928 but after that the 928 power walks away. So as I see it, Jag could have built the better GT. The never to be XJSS could have had stiffer Springs, stiffer sway bars, 16 inch wheels, and a manual transmission. It would have matched the 928 up to 100MPH and had a better quality ride. As you probably know 928"s are noisy by comparison.

I do love the 928 though. So many of the ergonomics are bang on. The pedal locations and clutch feel is ideal.

I also have a home brew XJC with 500 HP Chevy V8 and T56. I copied the pedal and shifter locations and dimensions from the 928 because they are so right for me. This 3700 lb Jag has lots of other upgrades and blows away even the 928 GTS in every way but its been years in the making. I've got to find a way to drop 150 lbs so it weighs the same as my 928S3. 1st world problems.

I have driven a friends XJS with a T5. It was great too but the work was suspect and had a far too heavy clutch. None of my cars were like that and the quality of conversions varies greatly. Good thing you got a T5 over a Getrag 260. These WC T5 and T56 transmsiisions are fantastic and my 1993 generation Borg Warner unit has no trouble coping with quick 7000 RPM shifts.

Congrats on a great buy. Its an XJS so it probably needs a few things. Outboard brakes too...lucky you. Another fantastic upgrade that transforms the XJS. Enjoy the journey. Search around a bit...there are lots of front suspension upgrades to be done.

 

The car looks assume, must be quite different to drive.
My dream... like when I win lotto.
Any more pictures?

 

 

I converted my 91 5.3 to a Tremec TKO 600 5sp around 7 years ago. I went with the 2.87first & 0.82 5th, & 3.54 diff 60mph = 1,800 rpm .. I also went with the aluminum flywheel, big clutch & AJ6 enhanced ECU . I can't imagine yours with 4.11's, any idea what your first gear ratio ?

 

Hi - no I am not completely sure - I am 99% sure it is a TKO 500 or 600 by looking at the transmission (the crossmember looks suspiciously like a driven man kit supplied one as well). If it's a 500 then supposedly the 1st ratio would be 3.27 which seems kind of ridiculously high - it's not like it is set up for pulling stumps out of the ground in 1st although it is pretty short. I have been pretty pleasantly surprised how well all of the ratios and final drive are suited to the car - it's not too tall or too short in any gear and the gaps between them are quite good - if one didn't know better one could almost believe it was designed this way by the factory.

I suppose I can go ahead and do the math to figure out what the ratios are, given that I am reasonably sure the rear is a 4.11 (no reason to doubt the seller) and I can measure the rear tire diameter. Maybe I will do that tonight when I get home...