The 'E' Type Forum

Has anyone done this conversion?
I have an option on a standard gearbox or an overdrive box which appears to be dimensionally identical ,any thoughts or ideas,or spares ie. bellhousing,flywheel ,clutch pedal?
Thanks Rob Gill

I think you would be disappointed with the manual 4 speed box.
I had one in my car and in 4th it was revving too high for my liking at normal road speeds. In my case I didn't have the Overdrive box choice, so wound up fitting a Getrag 5 speed, which I like, but it did need an adaptor plate to mount it to the bellhousing.

I see several threads listed on the subject so the info is around.

The overdrive box would be my choice.

Cheers
Mark

Rob Wrote:

Has anyone done this conversion?
I have an option on a standard gearbox or an overdrive box which appears to be dimensionally identical ,any thoughts or ideas,or spares ie. bellhousing,flywheel ,clutch pedal?

Hello Rob,
By Overdrive Box, do you mean a Jaguar 4 speed with a Type A Laycock De Normanville OD (as fitted to some XJ6 cars), or 5 speed box where the 5th gear has an overdrive ratio?

If the Laycock De Normanville option and unless you were only ever going to drive the car very conservatively (tantamount to having a dog and barking for it), then when fitting to a V12 E type you would be well advised to upgrade the overdrive to competition spec - springs, pump. UDC/ clutch etc; that work will cost around £500.00 by Overdrive Spares in Ruby, England. Apart from that, a Jaguar 4 speed, all synchromesh box with OD will fit an S3 without any modification to the drive line, or bodywork. However, if the gearbox with overdrive that is available to you is from an XJ6 (most likely), then the position of the gear change lever will be wrong, approximately 60mm further back for the XJ6, and therefore you will have to either modify the centre console, or get a gearbox top cover from an E Type gearbox (not very likely).

Welsh Motorsports make aftermarket top covers and as you would also need the selector rods to go with it, its quite expensive.

Depending on the year model of your car and the original Country of delivery, it could be that the Final Drive ratio is 3.07:1. There should be a tag on the Diff Cover that will give you this information. If your car does have a 3.07:1 diff ratio, then the 4 speed box without OD should be OK (engine rev wise in top gear).

Weighing up the additional costs that may apply with fitting a Jag 4 speed with OD, a 5 speed Supra (or similar) may be your cheaper option. Dellow's in Australia make bell housings for a number of different gearboxes that, in my opinion, is a better option than fitting an adapter plate to your existing Automatic bell housing. The AUD/GBP exchange rate helps you a lot if going that way.

Regards,

Bill

Hi Rob,

I've had the dubious pleasure of personally having done both of these conversions on my Series 3 V12.

The good thing is if a UK car you are highly likely to already have a 3.07 Diff (as I did) so even a standard 4 speed would probably be bearable however if you have the option of an Overdrive then this is the one to go for every-time.

I initially fitted a Getrag 5 Speed (from a Manual 3.6 XJS) but lots of the parts were non original such as:- gearbox adaptor plate, bespoke clutch, shortened prop-shaft, bespoke gearbox mount, speedo drive & fabricated gear linkage & ultimately whilst it made the car far more pleasant to drive I personally didn't like the 'feel' of the gear selection & it seemed somewhat alien to be putting the car into 5th like a modern car.

I have since removed the Getrag & have fitted an XJ6 All Synchromesh 4 Speed Gearbox (with Laycock Type A Overdrive) & an E-Type Manual Gearbox Cover with the beauty of this conversion (for me) being that it uses a standard E-Type V12 Bell-housing, Standard V12 Clutch (although I chose to get a Fidanza Aluminium Flywheel), standard prop-shaft & standard V12 Gearbox mount.

For me the discreet ability to flick the overdrive switch whilst in 4th really feels like driving a classic car as so many others had this feature in the 70's.

As mentioned so accurately by Bill you do need to uprate the Over Drive Clutch & can either get this done professionally or as I did just buy the parts (Uprated Clutch Friction Cones & uprated Springs) & do it yourself.

Borg Warner BW12 Auto & Getrag 5 Speed below for comparison:-


Getrag 5 Speed & 4 Speed with Laycock Type A Overdrive below for comparison:-




Fitted in the car with lots of room to spare:-



If you need an specific advice feel free to ask, I'm happy to share my experience.


Best of luck, it's definitely worth it!


Dave

Thank you for the information guys ,the clutch,s on overdrive sound interesting i will be investigating them when i have the gearbox.
Rob Gill.

Hi.

As has been implied, the hardest part of this conversion is finding the suitable bell housing. I did a similar conversion some time back using a Getrag gearbox and a special bell housing. I had to fabricate a gear linkage to get the lever out in the correct location. The bell housing was (I think) originally manufactured for SNGB and is rare. I happened on it by chance, along with a gearbox, clutch and flywheel. I had to make my own linkage and modify the original auto box tunnel cover. SNGB still had stock of the rear mounting, which required modifications and I had a special prop shaft manufactured. I agree the gear change takes a little getting used to, being very precise and heavy, fortunately, I like the nature of it, it reminds me of the heavy cocking action of a rifle.

Most conversions require an adapter between the bell housing and ‘box, but if you have no manual bell housing to begin with, you have to source one and the only Jaguar to employ a manual gearbox with the V12 is the E-type, so very few unused manual bell housings are available.

My special bell housing did not (quite) fit; the clutch just fouled the sleeve which carried the clutch release bearing and I had to remove the gearbox to correct this, possibly a result of a mismatch of components, but now overcome. I would happily have fitted an overdrive unit with original Jaguar four speed. Indeed my research indcated the upgrade might not be required, particularly with careful driving, but I have no real evidence to support that and bow to others experience in that regard. From memory, several people had upgraded six cyl XK engines to V12 levels of torque and power, still using unmodified o/d Jaguar gearboxes with no problem, even in race applications. Caveat Emptor as they say.

So, without the bell housing, a Jaguar ‘box and o/d may not be much use, but a five speed is a wonderful thing with the torque of the V12.

Whatever you do decide, good luck.

Simon.

vee12eman wrote: ↑

Sat Jan 13, 2018 8:40 am

but a five speed is a wonderful thing with the torque of the V12.

Hallelujah!!

The Tremec TKO500 kit I purchased from Keisler Engineering many years ago has transformed my XJS. I'm often tempted to fit this transmission (it came with a suitable bell housing, alu flywheel, clutch kit and release bearing) to my current E.... and convert the XJS back to auto (using a 4-sp GM 4L60e transmission).

I'm not advocating that particular transmission (it whines in 1st -3rd) but the overdrive does wonders for the car!!! 1900rpm @ 120km/h (75mph).

The v12 does not SOUND like its got torque, but it does!

I did the same conversion as Dave, 4 sp w. OD from an XJ including a Fidanza flywheel. I was lucky to find an E-type cover and have the gear lever in the correct position. My recommendation will be to have both the manual box and OD inspected and if needed,rebuilt before installation. I had to take the engine/gearbox out after only 600 miles due to a malfunctioning OD and noisy gearbox. I am not aware of any race modification to the OD, but the people in Sheffield, UK that did mine, used parts from the 4.2 spec OD. An upgrade from my 3.6 spec OD.
I agree with the statement about just flicking a switch and you are in fifth.
I guess in my case, the total cost for the conversion was about $5K not including the cost of my time.