No 350? than...

I just finished the quarterbreed mod on my 84 XJ6. The GM 700R4 transforms the car. It has much better performance off the line and the overdrive makes for a very refined cruising experience. I've run it for years with the original BW66 and I must say, the GM700 is at a whole new level of smoothness. Very civilized, very Jaguaresque.

I got the kit from John's Cars (http://johnscars.com). He's already figured out all the details and the kit's worth the money in my opinion. It includes the adapter plate to mount the trans to the engine, a new rear cross member and trans mount, a crankshaft to torque converter spacer, trans cooler lines, shifter mods for the neutral safety switch and back-up lights, TV cable bracket and and all the hardware you'll need. If you use a 700R4, you'll need some way to lock up the torque converter in 4th gear to prevent it slipping at low RPM. Electronic lock-up kits are available for the 700s from many aftermarket sources for around $100. John's sell them and I just bought his. I needed to do a little engine work so I pulled the engine and did the job out of the car but you could do the whole thing under the car with the engine in situ.

You can get the trans from several sources. Check out Bowtie Overdrives(www.700r4.com). There are also lots of places selling them which advertise in HotRod, Rod and Custom, Street Rodder, etc. I bought a factory rebuilt crate from my local Chevy dealer. You can also get one from a local rebuilder. You'll need to have the front drive shaft altered and a new Spicer slip yoke welded onto it. John's instruction booklet gives you all the details for that. I found a local driveshaft shop which did a nice job or you can buy a modified driveshaft form John's for about $200. I think 1990 was the last year for the 700R4,aka4L60 before GM switched to the 4L80e which has electronic control. You can run the newer electronic trans on your XJ but you need an onboard controller and programming interface for a laptop computer to set it up for your application. That stuff is available (hot rodders are putting them into everything now) but it's just a lot easier, in my opinion, to use a pre-1991 TV cable controlled 700 and skip the electronics.

Some have reported that the 700 emits more noise than the BW. I haven't experienced that. Maybe because I got a factory reman. Maybe I'm just deaf. As stated on this forum, the shifter plate doesn't match up perfectly. P,R, and N are in the right spot. D is now Overdrive. 2 is now Drive, and 1 is now 2nd. John says you won't be able to get the 700 into manual 1st, but mine will with the shifter all the way back. It will slip into overdrive at around 45 mph on light throttle. It might lug a bit if you then slow down or climp a hill and the revs drop down below 1500. Of course, the trans will downshift back to third eventually, but sometimes I just leave the shifter in drive (formerly 2) around town and move it one notch into overdrive on the highway.

It took me about a week working slowly and doing it myself and the installation is nice and neat. Everything is reversable if you ever want to put it back the way Sir William built it.

John Testrake
Jaguar Association of Greater St. Louis
84XJ6/700R4,76XJ12L

whoa thx for the replies... i admit that BW tranny is very good and reliable... still i need to improve my fuel comsumption...
that 700 tranny conversion sounds good... so where is this tranny from?
and is there anyplace where i can buy the kit and/or info?

and i just realized that the trasmission mount is gone in my car... instead there is block of wood... wtf?!?!?

anyway thx for teh help... i really appreciate it.

thanks Doug, "Lug" is what I was trying to say, although I still don't know what it means in real driving conditions, but I'm starting to understand that it has to do with the final drive. Yes, that 'ol BW is a reliable horse, in my 12 years of driving the XJ, I've only given it one service. I hate to let go.

BTW: do you know if Beecham Jaguar (Dr. Greg Beecham) is still in business ? I can't find a website.

"But I do agree that a 4th gear/speed is needed in the Series 3 XJ-6 because the engine would relax at 80 mph."

In my opinion, for what it's worth, the real advantage of the 700 trans is the very low first gear ratio.....not so sluggish off the mark as with the BW trans.

"I have had zero problems with the Borg Wagner, it has been reliable and consistent."

No doubt about it, the old Borg Warner may be an antique, but it holds up well with just a bit of care.

" Also, I have been told that the XJ-6 with GM 4-speed tranny conversion ends up with a tendency to stall in 4th gear due to Torque curves."

Stall may be the wrong word as it implies the engine dies out. It may well "lug" a bit due to the overdriven fourth gear combined with the tall 2.88 final drive.

"I stopped doubting Sir William Lyons a long time ago, there must be a reason for the 3-speed tranny."

Yeah, there's a reason all right. Money and availabilty. The old BW was cheap and on hand. Four speed automatics were not commonplace at the time.

I have a 700 waiting to go into my XJ6 but the old BW just doesn't seem to want to give up the ghost....128K miles and still works fine :-)

Cheers
Doug Dwyer
JDRC

Gene,

You might want to consider a 5-speed manual transmission. Keisler Automotive offers one that is meant for the Series 3 XJ6. The 4.2XK engine is a whole 'nuther animal with a stick shift! (Just ask any of us who drive manual E-Types.) Of course you will have to install a pedal box as well, but Keisler can probably help you out with that too. Check out the particulars at www.keislerauto.com

Warren Hansen
70 E-Type FHC "Silver Bolide"
96 X300

re: Series 3 XJ-6 1984 (build date 1983):

I have zero experience with converting to the GM tranny, and I decided against it after finding out from John's Cars that he doesn't provide a replacement update for the illuminated Selector plate on the console if you install the GM tranny kit; I was told that "4th gear falls somewhere between D and R and that 1st gear will not match the 1 position on the original selector plate", and frankly, that's a half job by my definition. But I do agree that a 4th gear/speed is needed in the Series 3 XJ-6 because the engine would relax at 80 mph. In my car, I get 80 mph at 3,000 rpm with the original Borg Wagner, which means higher fuel consumption. But I have owned my XJ-6 since 1991 and I have had zero problems with the Borg Wagner, it has been reliable and consistent. It did develop a leak from the car being parked 9 months at a time, (I only drive it in Thanksgiving Day or other Holidays, or when my fiance asks). I fixed the leak using a product called 'LUCAS", (really!) sold at Auto Zone, it is almost like red gelatin, pours very slowly, but by golly it stopped the leak to zero. not even one drop since. It was recommended to me by a mechanic I trust. He said, "if Lucas won't cure the leak, nothing will, time to overhaul". I have asked many people and companies if there is an Electronic Overdrive Kit that can be adapted to my XJ-6, (the 1970's Volvo 1800-E CoupÚ and the 1800-ES Sportwagen have an electronic overdrive which makes those cars fly after 80 mph). I was hoping for a kit like the Volvo overdrive but no luck so far. By the way, this Borg Wagner transmission is a transplant from the 1957-on Studebakers I have been told. Also, I have been told that the XJ-6 with GM 4-speed tranny conversion ends up with a tendency to stall in 4th gear due to Torque curves. I stopped doubting Sir William Lyons a long time ago, there must be a reason for the 3-speed tranny. There is a Dr. Beecham in Australia (Beecham Jaguar) who installs the 4-speed ZF transmissions in older Saloons, and I understand he does it with the proper Shifter-position indicator plate. I'm going to find out if he sells any kits for the Series 3 XJ-6.

Gene,

Don't throw out the 4.2! It's a great engine and not the real cause of your problem. What you really need is a new transmission! Yes, a conversion from the BW so-called "slushbox" to a more modern GM 700 turbo 4-speed w/overdrive will cure your ills. I've made the conversion several years ago in my Series I XJ6 and it made a whale of a difference - a whole new driving experience!

The transmission is sourced from an old Camaro/Firebird and mounted with a mounting plate from John's Cars (Dallas, TX). John Call's it his "Quarterbreed" conversion.

Not only does the low end performance improve, but the top end noise levels and mileage improves as well. Instead of galloping along at 70 MPH and 3000 rpm, you switch to about 2100 rpm at the same speed in OD, and it makes for a much quieter and fluid ride.

And what's best, is you've maintained that stock Jaguar look in the engine bay - no obvious differences - the Trans dip-stick is in a slightly difference place, but otherwise it's hard to tell!

Keep on JAGIN'