|John's Cars is the home of halfbreeds those
wonderfully English cars with American drivelines. While not everyone loves my V8
conversions, most loathe the Borg-Warner (BW) automatic transmission. Time for
another John's Cars exclusive retrofit:
Which Jaguars are compatible with this conversion?
XJ6 Quarterbreed kits are for all 68 to 87 XJ6 models (XJ6, XJ6C, XJ6L). Kits for
XJ12, XJS, Mark I, II, IX or X are available too. No kits for ETypes yet. The Jaguar
T400 from later V12 engines and the German ZF transmission on 1988-on XJ6's (XJ40) will
not bolt to a pre-88 Jaguar 6-cylinder nor to early V12s equipped with a Borg-Warner.
There's never been a GM trans behind a Jaguar 6-cylinder until John's Cars Quarterbreed.
Why should I put a GM Transmission in my XJ6?
|The archaic, light duty BW (derived from a 1962 Rambler
design) and its idiosyncrasies are expelled by a GM Turbo Hydra-matic (THM) transmission.
Prime benefits of the Quarterbreed conversion:
- Strong and reliable Jaguar uses a GM THM in their later V12 cars, Rolls-Royce has
used them since 1969.
- Quarterbreed cars are quicker less mass, better gear ratios and stall speeds.
They also have consistent upshift and downshift characteristics.
- Older Jaguars with a 3.08, 3.31 or 3.54 rear axle ratio really benefit from a GM
overdrive, relaxing a buzzy 3000 RPM cruising speed to a calming 2100+. Lower
RPM means better gas mileage and less engine wear and tear.
- Years later if your Quarterbreed needs tranny service in Bass Lake, CA., you can
have it repaired for a fraction of the BW price tag, not to mention the same day.
- Faster Starts the GM flywheel-starter combination creates more torque and
cranks faster... Plus you'll eliminate the death rattle flywheel and the
$$$ Lucas (Prince of Darkness) starter.
- Finally, when your cat finally uses up all 9 lives and its time for a V8
you will already have the transmission, starter and more. I will even allow you $200.00+
for the QB kit leftovers returned when you go Chevy V8.
The Jaguar twin cam 6-cylinder is retained without modification to it or the car.
The shifter retains its original appearance. Check out our Customer Testimonials.
Which transmission should I use?
- T350 for 1982 to 1987 Jags (with a 2.88 differential). Inexperienced drivers can lug the
Jag motor (258 CID) when combined with a T700 30% overdrive and a 2.88
- T700 overdrive for pre-1982 cars (with a 3.08, 3.31 or 3.54 differential) to reduce
- T400 is not recommended as it is more involved and not necessary for the
horsepower/torque of a 4.2L.
- Don't use a 4L60E or 4L80E on your Quarterbreed.
What is included in the kit?
ME, TELL ME
|If you want to know more, an abbreviated version
of the Quarterbreed installation instructions is available for
$25.00 (and Ill credit it to your kit purchase). Part
- block to transmission adapter
- crankshaft adapter
- transmission crossmember and mount
- automatic flywheel
- shifter linkage
- speedometer hookup and calibration
- transmission cooler lines
- all the hardware
- my infamous instructions!
- 100% bolt-in, of course.
You furnish the GM transmission with torque-converter and starter (see the checklist on
the next page). Modify your driveshaft or we have driveshafts ready to install.
Quarterbreed installation time is 5 to 10 hours you do not have to remove the
motor. All the particulars are supplied in the instructions. Check out the
particulars in the Quarterbreed Quick
|You may purchase via PayPal. But you will get better
customer service and sometimes lower prices by ordering via telephone
How much is an XJ6 Quarterbreed Kit?
Quarterbreed Conversion Kits
|1969 to 1982
|1982 to 1987
to install 1, 2
cells are suggested Jaguar Model & GM Transmission
ground freight. Hawaii freight: add $35.00 for kits,
$20.00 for driveshafts.
Overnite freight to all 50 states: add $40.00 for kits.
Call or email for freight overseas.
||Return your leftover
front driveshaft with yoke and flange for a $40.00 credit.
||On T700 applications,
manual low is not selectable because the XJ6 shifter
does not have enough travel - just like the newer XJ6,
GM police cars, and all Fords.
How To Order
|Please fill out the XJ6 Quarterbreed Conversion
Kit Order Sheet completely, sign it, and return it with a money order or
cashiers check (no personal checks and no company checks). We do not accept
credit cards on kits. We do not ship kits COD nor do we accept credit cards on
kits. No exceptions! Especially important are
the VIN, engine number on the driver's side of the bellhousing flange, and the year of the
GM transmission. KITS are in STOCK and shipped upon receipt of funds.
The XJ6 Quarterbreed Conversion Kit Order Sheet
is a JPEG image (about 185K) so it will take a minute or so to load. Print it out
from a Laser, LED or ink-jet printer only dot matrix printer will be useless.
Make sure your print margins are set to .50 inches or it may not fit on a page. If
you have any questions, please email them to firstname.lastname@example.org.
1969 to 1979 XJ6: Please call before ordering the T700 as
slight mods are necessary on some combinations.
Also, transmissions with a lock-up torque convertor require additional attention - see
Lockup Transmission opposite.
Note: Given the proprietary nature of my conversion kits, I do not allow the
return of a conversion kit for any reason.
Quarterbreed Quick Start
|Here is a detailed check list for the items you
furnish another 30 minutes now could save you hours later! Start gathering
what you need TODAY and order your Quarterbreed kit when youre ready to roll!!!
Preparation is the key to make things flow smoothly. Knowing what you are going to
get before ordering will make both our lives simpler. Note: John's Cars does
not sell GM transmissions they are readily available from your local
rebuilder. Hot rod transmissions are not needed or recommended in keeping with the
character of a luxury car. I do not recommend any kind of shift improver kits -- you
don't want slam shifts that spill your coffee -- Stock GM is the quality you want.
||Whether this is your first project or you are a seasoned professional, I wanted to
make sure you understand that you don't have to remove the motor to
install in your Quarterbreed. Many manuals say that pulling the motor is the only
way to change the transmission! It simply isn't true you can do a
Quarterbreed in 7 to 12 hours. No modifications/machining to the block or crankshaft
||GM Turbo Hydra-matic transmission brief ID course:
||Turbo Hydra-matic (THM)
||No separate tailhousing, light duty 3-speed, not
||No separate tailhousing, 4-speed overdrive
(.67:1), no modulator
||Four bolt tailhousing, 3-speed, vacuum
modulator at rear of case
||Six bolt tailhousing, super duty 3-speed, vacuum
modulator near filler tube
||Four bolt tailhousing, 4-speed overdrive
(.70:1), no modulator, AKA T700, 4L60 (not Corvette)
||Electric shift version of T700, must have a
computer to operate
||Six bolt tailhousing, super duty 4-speed (.75:1),
no speedo, computer required
||Remember that the transmission type must be the same as you originally
ordered or else the shifter, mounts, speedo, etc. are not going to work properly. The
adaptor plate is drilled for Chevrolet or BOP (Buick, Olds, Pontiac) transmission cases.
Inspect the GM bellhousing for cracks around bolt mounting holes and for damaged dowel pin
holes. Inspect shift shaft where the shift lever attaches (make sure you have the shift
shaft nut). Check the threads where the transmission mount bolts to the bottom of the case
for damage. Make sure the transmission oil cooler fittings are in the GM case and are
tight. Check case vent, modulator and modulator line as applicable. Note:
The T700/4L60 Corvette trans does not have a transmission mount on the case not
Lockup Transmissions: Transmissions that come with the
torque-convertor lockup feature must be hooked up to prevent damage to the transmission.
All T700 have torque-convertor lockup. Late model T350 transmissions were available with
lockup torque convertors and can be identified by a blue 2 terminal connector on the left
hand side of the case. John's Cars offers ELECTROLOCK, the simple
set-up to lock-up a T700 torque convertor for maximum fuel economy. Easy to install - no
drilling, tapping or machining required. For T700 trans 82 to 92 (not 4L60E). The kit can
be installed with the trans in the car. ELECTROLOCK is 85.00. If you are buying a
rebuilt transmission with torque convertor lockup, tell them you want the trans to lockup
on it own and they will do it (and you won't need Electrolock).
Tailhousing: Inspect your tailhousing for wear inside the speedo gear
hole it should be polished but it must not be grooved or the speedo gears will
fail. You'll need the matching speedo sleeve retainer.
T350 with 6" Tailhousing Notes: You must have the tailhousing
with the small (13/16") speedometer gear hole GM #464193 to use the speedometer gears
furnished in the kit. Exchange a tailhousing with large speedo hole for one with a small
hole when buying your transmission or I can supply a refurbished tailhousing with new
bushing and seal for $25.00, JCI Part #6"TAIL.
Torque-convertor and bolts: I recommend a torque-convertor with a
higher stall speed (from a fuel injected Camaro or Trans Am). The torque-convertor should
be a balanced unit when you buy a rebuilt. Not all companies balance them. Be sure! Get
the proper hardware (3 bolts) to attach the convertor to the flywheel bolts are
either 3/8 NC #3987930 or metric #1261968.
Misc: When buying your trans, make sure you get a speedo clip
(#6261781). If you use a T700, you also need a holddown yoke (#1254856).
||1) Buy the torque convertor from the same guy as your transmission. 2) If
you are buying a rebuilt transmission with torque convertor lockup, tell them you want the
transmission to lockup on its own. 3) When you buy a rebuilt transmission, you'll get the
case and guts only cables, bolts, etc. will be up to you. I've listed most items
here but I'm not there to know every detail. Most often they will give you things like the
speedo clip #6261781 or T700 holddown yoke #1254856, but you've got to ASK! Most 1980
trans are metric all T700 are metric.
|I recommend a torque-convertor with a higher stall speed (from a fuel
injected Camaro or Trans Am). The torque-convertor should be a balanced unit when
you buy a rebuilt. Not all companies balance them. Be sure! Get the proper
hardware to attach the convertor to flywheel 3/8 NC #3987930 or metric #1261968.
Back of GM Starter
Use a starter (with solenoid) for a 1982 Camaro 305 V8, S3502MS or Delco Metric
#1261968 it is 4" in diameter and has a straight across bolt pattern (not
staggered). Some people wont like this starter, but be assured it is more than
adequate to turn over a Jaguar six cylinder. A big case GM starter will not clear
the oil pan.
Starter Nose: Be sure the kit starter bolts fit the nose properly. Drill
or ream the holes in the nose if necessary. If you already have a metric starter but
it has a staggered nose, the correct nose is GM #1986096.
Starter Stud: The starter should have a stud extending from it (at the 4
oclock position) for the "L" brace to attach to. Part number for the
stud if it is missing or damaged is GM #1979441. The nut is supplied with the kit.
This brace is very important you cannot install the stud with the starter in
the car do it now! Verify the back of the starter has the bolt and stud at
the same locations as illustrated.
|You need a dipstick and matching tube. Universal tubes work in most
applications. For T350 use #K35999U, for T700 use #T44494U.
and four bolts:
|You need a flywheel cover and bolts. T350 use GM#14038632, T700 use
#15650700. Replacement plastic covers are quieter and easier to trim, universal
||These instructions use the following names interchangeably: Kickdown/KD,
downshift, throttle pressure, detent, and TV (throttle valve) cable. If you
dont have a cable:
|T350: GM cable #25507541 with Seal #1262475
T700: GM cable #25515598 with Seal #25518260
||matching bolt, either
1/4" NC x .5" or 6mm 1.00 x 10mm
|I prefer to modify the front half of the Jaguar 2 piece driveshaft
assembly and replace the Jaguar slip yoke with a GM one. Any driveshaft shop can do
this for you. Theyll cut off the STUB of the shaft and fit a new weld yoke at
the dimension specified. I suggest you use a Spicer slip yoke 2-3-6361X.
Length provided when you order the kit.
Quarterbreed Hardware List
Car Quest 03-846
Pep Boys 3602
|Torque Convertor Bolts
||3/8" NC #3987930 or metric
|Filler tube and stick
|Flywheel cover bolts
|Detent Cable Seal
|Speedo Sleeve Retainer
|Speedo gear clip
|Detent/Speedo Cable Hardware
||1/4" NC x .5" or 6mm 1.00
Other Look Fors
|Here are items you might find while doing the
Quarterbreed Conversion... better to check them out now than have them "find"
|The forward catalytic convertor (at the manifold) has a history of
cracking. Listen for exhaust leaks before you start it is no fun to have to
pull it off when you thought you were finished, besides the customer expecting you to PAY
FOR IT! We have replacements for $285.00.
|Series 3 cars have a history of shift cable failure. The cable was
downsized and will kink if forced. Parking against curb stops and on an incline are
the usual cause of kinking when pulling the transmission out of park. Use the hand
brake and dont force the shifter. The kink will occur inside the console at
the shift lever.
|On Series 3 models, take a drive (if the vehicle still drives) and test
the cruise control before you start about 50% of the units DO NOT work.
Cruise only functions in the "D" position.
|If you have time before starting this project, pry on the center support
bearing to see if it is shot. Usually 75,000 miles or that THUMP, THUMP on
acceleration is a sure sign. Jaguar Part # EBC9040 at $64.95 from JCI with the
purchase of your QB kit.
|Park, Reverse, and Neutral positions stay the same as before.
Overdrive position of the T700 will be the "D" (drive) position on the shifter,
direct drive is "2" (second) on the shifter, while second gear is 1 (first) on
the shifter. The shifter does not go far enough to "hold" 1st
gear. You can modify your shifter if this is a must for you. I do not offer a
modified shift mechanism nor a modified shift indicator plate.
Jaguar Parts and Spares
|John's Cars is more than Jaguar conversions, we
also stock a full line of Jaguar
Part and Spares (new, used, rebuilt and aftermarket), available on our on-line