XJ S3 Gearbox in Mk2 : Gearbox Support &kick down

Hi all,
I puttend an ex S3 , BW66 Gearbox in my „new“ Mk2 . Not the straight forward job I was told. A small test drive brought up a heavy resonance when start driving, disappearing at higher speed. It seems that the support of the box is to low at the back , spring fully compressed. I was wondering how others solved the support issue.
Another thing is where / how to connect the kick down cable of the bw66 ?
Thanks for your help,

I can’t answer either question.

But don’t drive it with the cable disconnected. It isn’t merely a kick down cable. It actually controls a valve in the transmission which determines internal operating pressure.


How about the driveshaft, did you replace the bearings?
And do you still have the engine stabilizer bar on top of the bellhousing.
You should indeed never drive without the kickdown cable, it also regulates the oil pressure inside the box, or you will burn the clutch plates.

Its advisable to connect a transmission pressure gauge if the bw66 has a port,

I made one from 6ft of hydraulic hose and an inexpensive gauge from Ebay

fabricate a kickdown bracket, and adjust accordingly

failure to have your trans operate at correct pressure will be very undesirable

(this info refers to a BW8, but is appropriate for any transmission

same goes for the angle of output flanges relative to driveshaft, must be within tolerance

a shorter spring or packing shims (depending on which problem you have) sounds like it is needed


Hi All,
Sorry for the long time between, a few health problems and the cold workshop delayed the project .
I now got some help at a warmer place so continued. We replaced the old spring by one of a series 3 and now the stuff is in line. It reduced the resonance mainly, but its still there at the start. will try to remount the engine stabilizer as Peter Jan suggested.
For the kick down cable : We mounted a bracket by and a pick up at the throttle rod down the carburetors . It works , but we have to check or the stroke length is good .
keep you updated , regards Roger

Rome, sounds like tailshaft pinion angle adjustment. Are you running the 2 piece shaft? If so, the height shoould be set such that the first shorter shaft is parrallel to the engine… i,e. an extension of the gear box. Use an angle finder to measure these either on the tailshaft flange with the shaft out, or on the flat part of the uni. Then the second part (longer) needs to be set so that the angle of the engine and first part are the same as the diff pinion. You achieve that but adding and removing spacers to both the rear engine mount and mid joint to raise or lower that entire assembly. If you have a one piece shaft, then ignore the stuff about the short shaft and just adjust as per the long shaft. All this needs to be done with full vehicle weight on the wheels at ride height. cheers

Is your engine mounted at the front or just ahead of the oil filter? Could be that the spring still is too weak. That might alter the driveshaft alignment. Don’t hang the engine by the stabilizer. Don’t rely on shift points and instead look at the pressure; the bracket should replicate the torque of the enginE, at least you should be at the correct pressure at idle and do the 2nd kickdown click at full throttle.
Slight deviations do not matter but leave the cable off or too soft and you will lose the bands quickly.

Hi Roger, It’s been a year, did you finally resolve this issue and have you kept the series 3 spring in place at the rear?

Hi Pierre,
Thanks for your message . Yes its already a year further in time. I resolved the issue of the bumping and resonance , but the box still doesn’t shift to the 3trd gear.
Its the first time in 45 years DIY in cars that I stuck with it , just because I thought to buy a ready to drive car. I spent the time to the other cars
Got meanwhile some tips and I ordered just last week some gaskets for the box and will dismantle the back of the box directly after 2 weeks holiday that starts this thursday.
I understand that you intend/ startd the same swap ?
Kind regards,
Roger Meeuwissen

Hi Roger, do you have a photo of the kick-down cable bracket you used & mounted at the carburettor? Was it off a MK2 S type?

Are you sure you are in 2e drive?
Often 1-2 is not noticeable, and 2-3 is.
How many Revs are you doing at 50Kph, and what is your end drive ( 3.54 is standard for a 3.4/3.8 automatic). Or is this a 2.4?

Hi Pierre,
Sorry I don’t have good pics at the moment , best I take them when the car is on/at (?) a ramp. That will be next month as I need first make progress with my other project ( XK 150 DHC)
Last week I just improved the Kick down mechanism :I welded an extra flat iron of so 10 cm with holes at the lever under the carbs . In this way could I realize de necessary stroke of so 50 mm of the cable. It resulted in shifting to the 3e !

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Hi Peter Jan,
Thanks for overthinking the problem. Yes I was sure that it sticked in the 2nd . To be honest I was so disappointed due to the test drives that I only know that the revs were over 4000 at so 90 km/hr . Left the car for long time. Ordered seals for the gearbox in order to have a look at the govenor .
Then 2 weeks ago at the day I would start to dismantle I called during the drive to the workshop an experienced Jaguar Engineer ( may be familiar for you: CRS ) he advised absolutely fix the good shifting and the kick down cable adjustment . As I thought I need for sure do this anytime I started herewith . Made new kick down lever, see above , readjusted shifting . Result: shifted to 3rd !! .
Next is to adjust the kick down cable in detail now, as when I gave full throttle during driving the box went to the first gear … Further when I shift from N to D or D to R there is a very hard grip . Advise was to readjust the brake bands. Will be continued. regards out of Apeldoorn ( NL)

Does CRS stand for Component Rebuilt Services? If so, they were the New Jersey based factory approved rebuild center for the Borg Warner Model 66 and others in the 1980s and 1990s.