BW-66 Auto Box Repair

BW-66 Delayed Upshifts Solved
Dan Jensen

I had previously mentioned that the BW-66 in my '81 XJ6 would not upshift from 1st to 2nd when cold. Only after driving ~1/2 mile would it finally shift, and then almost immediately into 3rd and would then not downshift without the use of the shift lever. After the engine/transmission warmed up, the transmission operated as expected. These symptons seemed to indicate a sticky governor.

I pulled the governor last night to examine and clean it. [NOTE: there is a right way and wrong way to install the governor on the ourput shaft (learned this the hard way last year). Carefully note which side is rearward, i.e., the side with the opening faces to the rear.] There was no significant wear, but the flyweight action was sticky, requiring that it be pushed lightly by hand to get it to move. I disassembled all components of the governor, carefully cleaned them with clean Type FA ATF and a lint-free rag, and reassembled them. After assembly, gravity at ~45o was sufficent to cause the flyweight to move. After reinstalling, the transmission now shifts normally. The clearances on the governor sliding surfaces are very tight and an essentially imperceptible piece of grit most likely was retarding the free movement of the flyweight.

The task took about 3 hours, but I have done related transmission work on all my Jags so I am perhaps a bit faster than the usual shade tree mechanic. The only special tools I used were my self-designed wood beam engine support and a short wood 2" x 4" with a hole drilled in the middle to allow easy removal and installation of the rear motor mount with my floor jack.

B. J. Kroppe says:

Great post. Did you have to undo the spring tension on the rear transmission mount? When I installed my rear mount on the transmission (out of the car) last summer, it was a bear, and not fun.

Any good tips on how to wrestle with this?

The following is a description I have sent to two other interested parties re my governor repair. As far a replacing the rear mount, it is very easy if you use a floor jack and a short 2x4 with a hole in the center to raise the mount to the underbody. This way it is a breeze. I have tried it the other, i.e., manual, way and yes it is a bear. Peter Hamel wanted to know if he could do this job in the street. My response includes this question.

Let me start off with a recommendation. Ignore this if it does not apply to you. Buy a copy of (1) the factory repair manual, (2) factory parts manual, and (3) factory wiring diagrams. If you own a Jag and plan to do much of your own work, you will use all of these many times. Each can be purchased from the aftermarket. Total cost might be $100-150, but you will save that many times over. The Haynes manual is definitely not a substitute for any of these. In fact, I never open my Haynes manual. The reasons you should buy these are (1) the factory manual describes how to remove the governor (and many other useful things), if somewhat cryptically, (2) the parts book shows a blowup of the governor, how it should be positioned, accompanying bolts, seals, etc., and (3) well, this is a Lucas-equipped car. But on to your question. The following is my recollection of last night's work and the 4 or 5 other times I have worked on transmissions in my Jags, but use your eyes and judgment as you proceed since I may have missed a step. 

1. You need to jack the car up high enough to crawl around underneath. I use four tall jack stands and a good size floor jack to raise the car about a foot. Sometimes it is a bit tough to roll a floor jack on street surfaces, but you will have to be the judge of that.
2. You need to perform the following steps once the car is up on jack stands
   
   • a. Put the transmission in neutral. Loosen dipstick tube upper retaining bolt near dipstick and exhaust manifold.
   • b. Loosen disptick tube at pan and drain the fluid. This will be ~2-3 quarts. In theory, it may be possible to avoid this step if the front of the car is lower than the rear, but it is so easy to drain, I suggest you drain it. Besides, you will want to get as much of the old fluid out as possible and several fill and drain cycles will be required to get down to <~15% old fluid.
   • c. Remove three bolts securing exhaust pipe to catalyst.
   • d. Remove exhaust pipe heat shield on left-hand side of car (Phillips-head screws)
   • e. Remove 3/4 in. nut holding rear bracket to rear mount.
   • f. Remove two nuts securing rear bracket to transmission case
   • g. Remove the nut securing the shift lever to the transmission manual valve adjuster. Remove bolt securing shift cable to transmission bracket.
   • h. Support engine, either by a support in the engine compartment (you might as well make one of these for $20. Believe me, you'll use it again) or by putting a second jack and 2x4 beneath engine pan.
   • i. Remove four bolts securing rear mount. The mount is spring loaded so it is best to support it with your floor jack and lower it after all the bolts are loose.
   • j. Remove the eight bolts securing the rear motor mount support plate to the body.
   • k. Remove the four bolts/nuts holding the propeller shaft to the transmission output shaft.
   • l. Put the transmission in park by using a adjustable jaw wrench to turn the manual valve adjsuter. Remove the 3/4" bolt from output shaft and remove the output shaft flange.
   • m. Disconnect the speedometer cable and remove the drive gear bracket and drive gear.
   • n. Lower the engine somewhat at the engine support or jack, and start removing bolts from transmission tail housing. Note that some of the bolts are 9/16 and some are 12 mm (I think these are the correct sizes). The 12 mm bolts require a 12-point socket. A 6-point socket will not work. Note the location of each bolt since there are three different types of bolts securing the tail housing.
   • o. When all bolts are loose, tap housing. It should pop free. Once it is off, you will see the governor.
   • p. Note it's position (as mentioned earlier, it can go on backwards and I guarantee your car won't shift out of first, ever - guess how I found out?) and loosen the large bolt on top a few turns to slide the governor off.
   • q. If working o.k., the flyweight should easily slide back and forth in the sleeve as you tip the governor. If there is any binding, you need to dissassemble the governor and clean it carefully. This is easily done. Be careful. Even a slight bit of lint can land you right back where you are now.
3. As you may have inferred, a picture is worth a 1000 words. I personnally would hold off on this until you had (1) and (2) above. On a scale of 1 (add fluid) to 10 (do your own transmission rebuild) this is about a 3-4.

From: www.jag-lovers.org