I find on youtube vidéo “TH400 pan repair and governor” the place of governor and how to removing of the gearbox. It’s on the same side as modulator, however is it really access on V12 setup ? may be because the exhaust
Simple things first!
Whright, so I will proceed in three steps : control vacuum modulator, control kickdown inhibitor switch and at last , if necessary, governor. So I try to have stock of these parts.
Thank you to all ! I will come back after my work.
Here’s an excerpt from Kirby Palms XJS Book:
"GOVERNOR DRIVE GEAR FAILURE: I’ll let George Balthrop explain both the problem and the solution: “PROBLEM: While cruising at 70, suddenly & without any noise or warning of any kind, the transmission kicked out of top gear, and when I pressed the throttle, the engine just revved as if in Neutral. I coasted to a stop on the shoulder and checked for transmission fluid leak – level OK and nothing under car – not wet. Got back in, and car would back up normally, and pull forward normally, it just wouldn’t upshift from 1st regardless of the selection: 1, 2 or D. It would freewheel in D or 2 when let off accelerator (no engine braking) so I limped back home via back roads. “CAUSE: Nylon gear on shaft of governor had worn away in the middle of its length, where it rides on the metal gear on the output shaft. This is believed to have been caused by rust buildup on the metal gear (above at-rest fluid level) from the car sitting unused for several years. If the governor does not turn, its spool valve which is operated by centrifugal force will never open to send fluid under pressure to the shift valves, so no upshift.
“FIX: The governor may be removed without getting under the car, accessed as follows:
- Slide the right seat fully rearward & remove the carpet from the Right footwell floor;
- Peel up the carpet & pad on the Right side of the transmission tunnel to expose the access cover, located just ahead of the seat and approximately even with the shift lever.
- Remove the access cover which is attached to the transmission tunnel sheet metal by 3 screws and 2 studs/nuts @ 1/2". The uppermost screw is at the top & hidden by the carpet just below the leather console cap, but may be removed with a #3 Phillips or Pozi-driv equivalent, without removing any part of the console.
- Place a drain pan on the ground (not in the car) under the access opening & remove the four 1/2" bolts securing the governor cover, on the right side of the transmission, above the right-rear corner of the transmission pan. All four bolts may be removed using a 1/4" socket set with U-joint via the access cover opening. Remove the cover, & some fluid may drain from the transmission case, but it shouldn’t gush into the car.
- The governor is the part just under the cover; grasp the top of this part and twist without pulling. If it turns, you have found your problem. Now remove it by gently pulling as you twist. The governor should pull straight out through the access hole. There is a nylon gear on the inboard end of the governor shaft. If this gear is worn so that the center is dished or smaller diameter than either end to such an extent that the teeth are nearly gone in the center, then the governor is not being turned by the output shaft gear and the shift valves never get pressure via the spool valve in the governor.
- Replace the nylon gear. I found a transmission parts & repair facility (County Transmissions in Vienna, VA) where very nice & experienced personnel replaced my worn gear for $5 (no labor charge) took several minutes to explain how the wear probably occurred (rust on output shaft gear) and even explained how to replace the gear again if this one goes bad, and gave me a second replacement gear for another $5. Now that’s service!
- Remove nylon gear by tapping out retaining split pin. Clean spool valve beneath & entire assembly. Fit new gear to shaft, driving it fully home against the shaft end. Using a 1/8" drill bit, drill a hole for the split pin, half way through the shaft of the new gear, then rotate and drill from the other side to meet the 1st half and finish the hole – this to avoid the shaft breaking. Tap in the new split pin and peen the ends to prevent slipping out. 8) Replace and top up with fluid as necessary, and smile when it upshifts. Carry that spare gear though, because there are several possible causes for the original gear wearing, and the cause may still be present and do the same thing to the new one. I figure several nylon gears ought to clean the rust off the metal output shaft gear though ;-)”
Balthrop advises that if your car won’t shift out of 1st, “It takes less than an hour to get to the governor (the first time you do it–maybe 20 minutes once you’ve been there), so rather than mess with other tests, I would advise just pull it & check it out.”
1 Like
Hello. After control kickdown inhibitor switch which was ok, I examined the modulator and found that the rubber elbow allowed air to pass. So as a precaution I changed the modulator (I had one in good condition) and the fitting. Everything works fine now ! However I’ll buy a new modulator just in case of new failure. The information of Jon about Kirby Palms is very interesting because, otherwise, I think it would be necessary to remove exhaust and bring down gearbox about 30 cm. Very difficult and dangerous without hydraulic lift !
2 Likes
FYI, because its a th400, lot of choice in parts. I bought a B&M adjustable modulator, part #20324, for $38.
I adjusted for slightly sportier shifts, a huge difference in driving.
Before, i could only get it to downshift by flooring it, and it would upshift to 3rd gear by 15 mph. Too boring for me.
The jaguar oem setting was probably something like 1 inHg to downshift and 15inHg to upshift, LOL
Hi. thank you Greg ! According “kirby palm book”, I red “finding my governor” on this forum and, infortunately, it seems there’s no access for governor inside car on XJS 1990’s. Is there anyone another purpose ?
Assuming you have the TH400 like me on my 1988, I had to remove the rear tail housing. (My speedo plastic gear, which you don’t have on a 90s, broke off and fell into housing). Had to drop exhaust, remove driveshaft body panel, drop driveshaft, and remove tail housing. A lot of work. While in there, I could see my governor.
It’s frightening ! May be I could consider drilling a window into the passenger side console and installing an access plate as Kirby’s early model. I would still remove the exhaust screen and remove first part of exhaust but it would be a more practical solution ?..
I thought everything works fine, now that you fixed elbow to modulator?
No Greg, everything works well ! But it’s just an eventuality if I had to one day disassemble, in case of governor’s failure. May be someone has already done like this ?
Greg, you say there’s no speedo plastic gear on 90’s models. I didn’t know about this change, is it modification made by Jaguar or G.M. ?
I don’t think the governor gear is a high failure part, so i don’t worry.
Up thru 1988 the speedo sensor was a plastic gear at transmission. Afterwards, it was moved to differential, and probably not plastic.
On mine, governor is located at the right side of gearbox against rear of oil carter. Jaguar parts specify reference changing from 157115 number (EBC1536 and no more EAC3185). From 179737 models gear box ZF was mounted but reference governor didn’t change (EBC1536). No more information about plastic or steel pignon …
There ya go.
Friend of mine say that failure is often due to long inactivity or insufficient oil, but teflon or plastic wear could be also one reason, may be manufacturing quality…