Engine & gearbox dimensions

[Dunbreton]

Hi Folks, I’m looking for a little help with information please. I shipped an E-type Series 3 V12 2+2 back from the states last year and I’m starting my homework on some long-term projects for it. It’s currently running a 350 Chevy with a TH400 auto transmission and although this has a terrific sound and is likely to be a lot of fun, there’s a badge on the rear hatch that says it’s four cylinders short of the real thing. I have a 1994 XJ81 Daimler Double Six (6.0 litre) which I will use as an engine donor for the E-type with a manual box fitted. I’ve now been across many forums and threads looking at the various manual gearbox options to go behind the V12 and although the Getrag seems like a well tried and tested path, I’m put off by the likely age of a donor box and seemingly poor availability of replacement parts. An alternative route would appear to be one of the Tremec range of boxes. Where my difficulty lies is that I don’t have anything fitted to the car to serve as a reference point so I have no idea where the gear lever should be relative to the front face of the bellhousing and where this will exit the tunnel etc. Is there anyone that has a V12 and gearbox on a trolley that could give me some measurements please? Because of the replacement engine and planned steering swap, I’m not particularly precious about originality so if anyone has gearbox suggestions that may/may not involve tunnel alterations, I’d be pleased to hear them. Many thanks. Roderick

[abowie]

I can't answer your question directly.

Dellow in Australia (where I am) make a range of conversion bell housings for various gearboxes. I have one of them in my V12 XJS race car.

https://dellowconversions.com.au/?s=jag ... mit=Search

[dlpweb]

Like Abowie, I have a Dellow conversion setup.

Jeff is a super guy and loves to help

What I settled on is a Supra Turbo transmission behind a Dellow bellhousing. The Supra Turbo tranny is good up to about 600 HP; enough for most (stock V12 is only around 300); the gear ratios are spot on, and the size - gearshift location - is so close to the Jaguar clunkbox's location you simply cannot tell there is something nonstandard about the car w/o looking underneath. I might still have dimensions from when I did this 10 years ago. Will check. One thing i recall - Jeff Dellow had to fabricate a custom top cap for the tranny (where the shifter attaches) to move the location forward slightly so it appears where I wanted it. Of course, you will also need a custom drive shaft, though that's easy to obtain.

When you have it apart think about putting a Fidenza flywheel in.

Dellow has something like 10K castings to mate whatever engine to whatever tranny. But when you call on the phone you are as likely to get Jeff himself as one of the staff.

Oh - and his wife is as charming as a human can be (they visited the USA a couple of times & stopped by).

Have fun!

[lowact]

OEM, bellhousing length = 156mm. Gearbox length from bellhousing to vertical gear lever = 316 mm. Any other dimensions or photos req’d just list them.
As well as fit, consider torque and ratio.
XJ81 (6 litre HE) engine max torque > 460 Nm (340 ft-lb), gearbox may need to be rated at more than this if you want a warranty, would rule out Tremec T5’s. In practice the amount of torque you can apply is limited by wheelspin and diff ratio, higher diff ratio’s will cause the gearbox to be subjected to more of yr max engine torque before wheels spin occurs.
Gear ratios, a too low 1st gear ratio can be really, really, tedious, and very uncool. OEM, E-type 1st gear = 2.94, manual FD (diff) = 3.31 so overall = 2.94 x 3.31 = 9.7, imo less would be very much better (i.e. 9.0 with 3.07 FD). This would rule out Getrag (1st = 3.55) and Supra (1st > 3.29). Supra box with a 2.88 diff should have bearable ratios, but u would need to check that it is strong enough, some variants not as strong as others, torque rather than power …

[Dunbreton]

Wow! Thank you for the swift response folks.
I am aware of Dellow, from this forum but it’s great to have your personal recommendations Abowie and dlpweb and I’ll read up on the Fidenza f/w. Thank you Iowact for the precise measurements, I’ll likely take up your offer for a couple more when I have done some more reading on your ratio suggestions – very sound advice and much appreciated. I haven’t physically checked the differential yet but the speedo reference digits indicate a 3:31 and I have no reason to believe it has been changed. Thanks again. Roderick.

[mgcjag]

Hi.....are you intending to use this as road car and register it as such in the UK...if so then i would suggest you look at the DVLA regs for registering an imported vehicle......i think you could run into problems ..the normal procedure now is that dvla will inspect a car prior to giving it a registration...they look for originality......Steve

[Dunbreton]

Hi Folks,

firstly, thanks mgcjag for the DVLA heads up. I managed to register it when I brought it back to the UK a year ago. I’m fitting new seatbelts and changing the rear indicator lights from red to yellow and then it’s ready to be MOT’d. It’s MOT exempt of course but I’m getting it done for my own peace of mind. After that it should be road safe and legal.

Iowact, your measurements were just what I needed and I’ve been able to confirm that the Tremec T56 Magnum 6 speed manual has three possible lever locations, the first of which aligns within 20mm of the standard lever position according to your information. Can I just double check, in case I’ve misunderstood you, the 316mm measure is from the front face of the gearbox to the gear lever. And with the bellhousing at 156mm deep, the back face of the engine block to the gear leaver is therefore 156mm + 316mm = 472mm?

I’ve looked at the ratios and they seem to work well too at 2.66/1.78/1.30/1.00/0.80/0.63. Again, thanks for your thoughts here Iowact. Combined with the 3:31 diff, I should have a respectable first, spirited acceleration in 2nd and 3rd, capable overtaking in 4th/3rd complemented by responsive motorway cruising in 5th and almost some form of economy in 6th. Economy is perhaps too strong a word but we can always use my wife’s VW Up! if real economy is required. Others may find this useful; Tremec have a neat little app which will work out speed or revs for various input parameters and will also calculate tyre height.

I’m aware that the big T56 box will carry extra weight and its size will mean tunnel modifications. Neither bothers me as the car lost its originality when the V12 engine was scrapped in Massachusetts. I’m in discussions now with Jeff at Dellow (thanks dlpweb & abowie) for one of his bell housings to suit and he has briefly told me that the floorpan modifications are fairly few. I’ll cross that bridge when I get to it, possibly by making some form of tunnel cover from a donor vehicle.

Sorry, this thread is morphing into another 5-speed options discussion. All in all, the T56 looks to be a good route to follow. It will easily handle the torque and although the upfront cost is chunky, the new gearbox avoids finding a rare s/hand unit of unknown history, potential wear issues or problems with parts sourcing. I’ve still to confirm it but I believe the release mechanism is hydraulic and therefore a good deal lighter than a typical Jaguar manual clutch. I slipped disc a few years ago and my left leg can give me discomfort now and again. Future proofing further, I may keep the 4-speed auto from the XJ81, just in case I ever need to go back to two pedals only.

I believe the T56 has electronic and mechanical speedo drives, again I’ deal with this in due course.
The only downside might be that the T56 is a modern box and seems to have a very short throw with a real snickety snick change and that may be slightly out of keeping with the character of the car. Does anyone have other Tremec boxes? How do you feel it suits?

On balance though, I think the advantages will outweigh the disadvantages.

I’d be delighted for your further thoughts please folks, particularly if there's something I've missed.

Roderick

[lowact]

That’s correct, sum gives you the position of the lever when it is vertical, i.e. a reference dimension to locate the lever in the cabin, not were it mounts to the gearbox which is offset (forward of this). On E-type the lever is as far back as it can go, zero opportunity for it to back any further without custom cover and console.

Don’t know how it works in UK but I imagine that your registration is invalid if there are changes made that have not had engineers certification accepted by MOT, onus may be on you to ensure this? Is the engine number on your registration the same as the number on the engine or is it the original number on the compliance plate? Any engine change, any transmission type change, any structural modifications, if not advised, certified and accepted, could invalidate your rego? You might have difficulty finding a competent and responsible engineer prepared to certify structural mods to an e-type floorpan , even if you did, and MOT accepted it, insurance companies may not cover it?

I like that my car is manual however if in your position I would be staying automatic, your XJ81 with GM4L80E (4 speed overdrive) transmission in an e-type would be joyous and valuable, likely quicker than any manual. Same dimensions as TH400 so it should fit without cutting, imo a drop-dead criterion?

[abowie]

Does anyone have other Tremec boxes? How do you feel it suits?

Roderick

I have one of Paul C's JT5 boxes in a 3.8 roadster. I can't comment on it in comparison to the T56 box but I really like it.

You've got me thinking about putting a 6 speed T56 in my XJS now. They're common over here and seem to be about £800 used... I'd probably get change from my Supra box.

[Dunbreton]

Does anyone have other Tremec boxes? How do you feel it suits?

Roderick

I have one of Paul C's JT5 boxes in a 3.8 roadster. I can't comment on it in comparison to the T56 box but I really like it.

Thanks Andrew, the feedback on these boxes seems to be positive.

[Dunbreton]

That’s correct, sum gives you the position of the lever when it is vertical, i.e. a reference dimension to locate the lever in the cabin, not were it mounts to the gearbox which is offset (forward of this). On E-type the lever is as far back as it can go, zero opportunity for it to back any further without custom cover and console.

Don’t know how it works in UK but I imagine that your registration is invalid if there are changes made that have not had engineers certification accepted by MOT, onus may be on you to ensure this? Is the engine number on your registration the same as the number on the engine or is it the original number on the compliance plate? Any engine change, any transmission type change, any structural modifications, if not advised, certified and accepted, could invalidate your rego? You might have difficulty finding a competent and responsible engineer prepared to certify structural mods to an e-type floorpan , even if you did, and MOT accepted it, insurance companies may not cover it?

I like that my car is manual however if in your position I would be staying automatic, your XJ81 with GM4L80E (4 speed overdrive) transmission in an e-type would be joyous and valuable, likely quicker than any manual. Same dimensions as TH400 so it should fit without cutting, imo a drop-dead criterion?

Thank for all your information and thoughts here Colin. Now that my car is UK registered, I'm not aware of any restrictions from the DVLA on modifications. On a previous project, I simply notified a change of engine number on the appropriate form and my registration document was updated accordingly and re-issued but I will look into it further. Typically it would be my insurance company that would be the stickler for change but I expect that modifications that return it closer to the original spec will be acceptable. Your thoughts on manual vs automatic did make me take to Daimler XJ81 out on a work related journey yesterday and whilst I agree that it is a capable and enjoyable gearbox to use, it's just not a manual. In terms of cutting - I'm not phased - I am working through a whole bigger thought process for possible body modification on the car which I'm not quite ready to share yet but I have no qualms about originality/value as I hope my sons will want to keep this car after I'm finished with it. I'll come back to the post when I have more to report but in the meantime, thanks to all for their input and help. Roderick

[mgcjag]

Hi Roderick.....interested to know how you car is UK registered....As your aware all E types are now Historic registeted......does your V5 have it as historic?....what engine is on the V5 the chevy......or are the V5 details as per the original car details........I know someone that fitted a very late XK engine to an E type......the dvla picked up on the engine number difference and he lost his "historic"....also a modified body could cause problems.....weather you actually notify the dvla is up to you but officially any engine change or body modification should be notified to them......far better you know this up front rather than doing the work and then finding out.....Steve

[Dunbreton]

far better you know this up front rather than doing the work and then finding out.....Steve

Good advice Steve, I'll certainly check this out.
Thanks
Roderick

[lowact]

These dimensions may also be useful:



This is showing Jag 4speed with the tunnel cover propped into correct position over.
Box is in 2nd gear, i.e. the lever is as far back as it goes, note the angle of the gear lever. Note also that the gear lever is almost touching the back of the opening thru the tunnel cover, this is why I said zero opportunity for the lever to be further back without modifying the tunnel cover and console.
The point where the lever is almost touching the top, back of the opening thru the tunnel cover is 515 mm back from the front of the bell housing and 170 mm above the centre-line of the gearbox shaft.

[Dunbreton]

That's really informative Colin, many thanks for sending this photo and the additional measurements. When you see it like this you can see how compact a gearbox the original is and how little room for manoeuvre there is. Quite thought provoking. It's fathers' day tomorrow so I'm to be allowed some time on the car so will have a look at what the current state of the gearbox cover is and get better acquainted with the set up in general. Can you tell me the widest point on the box please? From the photo it looks as if it is probably the knuckle on the split of the case, where there is a connecting bolt, at 1 o’clock from the piece of wood it is resting on. Thanks Again. Roderick

[Dunbreton]

Hi Roderick.....interested to know how you car is UK registered....As your aware all E types are now Historic registeted......does your V5 have it as historic?....what engine is on the V5 the chevy......or are the V5 details as per the original car details........I know someone that fitted a very late XK engine to an E type......the dvla picked up on the engine number difference and he lost his "historic"....also a modified body could cause problems.....weather you actually notify the dvla is up to you but officially any engine change or body modification should be notified to them......far better you know this up front rather than doing the work and then finding out.....Steve

Hi Steve, what's you interpretation of the DVLA Historic Vehicle Regs in relation to conversion from LH drive to RH drive? New to forum posting, I realise this is a separate topic and may have been addressed somewhere else, please feel free to redirect me. Thanks Roderick

[mgcjag]

Hi Roderick....all the info is on the DVlA website...many have registered after converting from lhd to rhd...however its becoming more likely for the dvla to want a vehicle inspected prior to registration.....personaly i would register as lhd then change after........or get it in writing from dvla that a conversion would not affect registration....Steve https://www.gov.uk/vehicle-registration ... c-vehicles