After rebuilding a 1968 340 engine for my Mk2 I am now looking to convert from the BW35 auto to the T5 manual gearbox.
i would like any and all info as to what will be needed to complete this conversion and any tips you can give me and problems that I may come across during this work. I have no manual parts to date and would like to put together a full list of parts I will require before I start ordering, I would like to have all part required before I start work on the transition. Also if anybody actually has any parts I may require that are surplus to your needs I could be the person your looking for, just let me know.
Many thanks in advance for any info you are able to provide. Jim.

 

maybe these companies can help

in the USA:
Jaguar 5 speed and 6 speed Transmission Conversion Kits

in the UK:
:: G. Whitehouse Autos Ltd ::

 

I spoke to a T5 supplier at a spares day. I think they were Elite Performance Transmissions. It was a few years ago so I'm a little uncertain on the name. However, the man I chatted with was knowledgeable, friendly and helpful. In addition, though not cheap, they weren't as expensive as most.

Why are you going for the T5 rather than Supra or Fairlady?

 

I have done a T5 conversion to my S Type. I used a Mustang T5, and I needed to make an adapter plate to a Jaguar bellhousing, a rear crossmember, and a custom friction disk to mate with a Jaguar clutch. I needed to cut the body to fit the shifter and fit a boot to keep the heat out. I also custom manufactured a speedometer cable to have one end a Ford fitting the other end fitting the Jaguar speedometer. You'll need a clutch master cylinder as well. Fortunately the pedal arm is already there, the brake pad of an automatic spans both pedal arms. You will need a clutch pedal pad and rubber, same with brake. You'll also need a clutch fluid reservoir, bracket, hose and line, slave cylinder and pushrod, hard line between slave and master cylinder, flywheel and clutch.

The driveshaft also needed adapting, and I needed to change from U joints to CV joints as the driveline angles were wrong.

If I was doing it again, I'd probably get one of the 5speeds.com kits that bolt in. If you do DIY it, use a version of the T5 with a shorter tailshaft than the Ford. I think an S10 might be closer. The Mustang T5 has a 0.63 overdrive ratio, and even with the automatic's 3.77 axle ratio that was too tall for anything under 80 mph. I was constantly shifting between 4th and 5th. I changed the OD to a 0.73 ratio and that's much better suited to the 3.8 engine. That makes an overall ratio of 2.75 (3.77 X 0.73), I wouldn't go any taller than that, so change the ratio depending on what rear axle you have.

 

Gone through my old leaflets and the company was Elite Racing Transmissions. They suggest a 0.8 or 0.72 fifth gear for Mk2s.

 

Hi Peter
No I’ve been looking on the net for a suitable gearbox and I came across the T5 in a number of websites and it seemed it had the most supporting parts for the conversion, I thought anything to make life easier. I did not see anything relating to the other gearboxes you have mentioned. If you can give me more info on these I could easily change my mind as nothing is set in stone yet. I have emailed Elite Transmissions twice and phoned twice with no response which is disappointing, but I will try again. Thank you for your input. Jim

 

Hi I was looking for a kit to make life easier and found on the internet the T5 has a number of companies selling it along with various other bits so this was my first thought. I have a 4.55 differential fitted but have a 3.77 in my garage which I thought I would use with my auto box before I changed my mind to a manual, so either could be used, the T5 is sold with a .63 top gear but you can for £150 have it changed to a .8 top gear, so 4.55 diff with .63 or 3.77 diff with .8 which would also of course need to be installed, decisions decisions, help 🤪

 

Jim, I'll begin as usual by saying that I'm no expert. I've a Mk2 with a Moss box and what happens in regard to any swaps is a long way off due to the amount of bodywork that I have to get through. It will also depend on what's available when/if I get to that stage and whether I can make the Moss box change better (I've spotted some possible improvements to the 'gate'). However, like anyone with a Moss, I take an interest in alternatives. With all the effort involved, I'd definitely want to make the work worthwhile and find something that has a very nice action. The Toyota Supra and Nissan Z change gear very smoothly.

For the Supra, there's Realm Engineering in the UK. As I understand it, they provide a re-con box and all (or most) of the necessary extras. There's a company called Dellow in New Zealand who I think might have been the first to use the Supra. If you go with the Supra, make sure to have one with a suitably high (numerically small) 5th. I'd say 0.7 to 0.8 with a 3.77 axle.

The Nissan is a nice box, but the only supplier that I've seen is in the US and called something like Xcessive Manufacturing. I think they have a racing XJ and supply parts they developed for it.

Also in the UK is Simply Performance, but I suspect they are mainly Getrag. I don't find it nearly as smooth a change as the Supra.

If I had a lottery win, I'd probably go for the 6R80 automatic from Motor Legends. But ££££.

It's worth doing a serious internet search as there are probably more suppliers that I don't know about.

 

The 4.55 /0.63 combination is a good overall ratio, but with that axle ratio I'd be concerned about the driveshaft (propshaft) getting close to it's critical speed. There are some online calculators by Dana that can calculate the critical speed, it depends on the shafts length, diameter, wall thickness and type of joints at each end. I'd want to verify that you're not getting close, as you will have vibration problems near critical speed.

 

Hi, no I hadn’t given a thought to the prop speed and balancing problems that may occur thanks for that. I have now contacted

REALM ENGINEERING LTD to see what they can offer me, I’ll await their response.

 

After a bit more research:

Of the non-turbo Supra transmissions, the W58 is supposed to be very strong and has the most suitable ratio 5th gear at 0.78, which is close to that of the old Jaguar Laycock overdrive. The other versions are not quite high enough (in my opinion). In fact, it would be nice a bit higher, but it should give good cruising, 3,000 rev/min at 80 m/h.

The R154 gearbox was fitted to the turbo Supra. It has a higher 5th. But I think it's less easy to find, bigger, heavier and probably more difficult to fit.

 

Hi Peter
he came back to me but didn’t give details of which gearbox just that it’s from a Toyota Supra, I’ve emailed him back asking what the ratios are. Thanks.

 

I used vintagejag.com to handle my auto to manual conversion with a TK500 5 speed. They shipped me everything I needed. They found my list was incomplete so I am glad I called them. You might ring them us in the US at 208-684-4767. He was very knowledgeable especially about what parts don't fit together.

 

This is the email I received back from my enquires, they haven’t got fed up with me yet 😂To cover your questions, new outright prop is offered with the 5 speed set, reason being is that supra box has a sliding spline prop fitment rather than the flange fitting favoured by Jaguar, on the subject of ratios and G/box model number, please find these following



W59



First Gear: 3.830:1
Second Gear: 2.062:1
Third Gear: 1.436:1
Fourth Gear: 1.00:1
Fifth Gear: 0.838:1


This box is normally supplied when the set is being fitted to a heavier 4 seater Saloon, also benefits from a steel divider plate which is deemed the strongest box set up.



W57



First Gear: 3.285:1
Second Gear: 1.894:1
Third Gear: 1.275:1
Fourth Gear: 1.00:1
Fifth Gear: 0.861:1
Reverse: -3.768:1


This box is used for the lighter sports Jaguars and specials 'Powered by Jaguar'



On prices these are as follows,



5 Speed Toyota conversion to suit Jaguar MK2 £2175.00

Prop to suit the above 225.00

Delivery to SM5 2LR 45.00

Goods total £2445.00

VAT @ 20% 489.00

Invoice Total £2934.00



I hope the above is of interest and look forward to your comments



Best regards



Adrian

 

Now I am a bit confused by the ratios they have listed as they don't coincide with numbers that I find in various sources on the internet.

I'm not sure that I'd classify a Mk2 as a heavier saloon (by modern standards) and the 3.83 first gear seems low to me combined with a 3.77 rear axle. For comparison, I think the old Jaguar four speeds had bottom gear ratios of 3.04 and 3.38 (according to my service manual and also Paul Skilleter's Jaguar Saloon Cars). I always felt with my Mk2 that the 3.38 of the Moss box with a 3.77 axle is a real stump puller ratio. The heavier 420 and series 1 XJ6 used the same ratios.

The fifth gear ratios don't coincide with the internet, but maybe Toyota used different ratios for different markets. For me, I'd have preferred a number less than 0.8. My 3.4 Mk2 comfortably pulled the Laycock OD ratio of 0.78 and would run at 80 m/h and 3,000 rev/min across Germany all the way between the Dutch and the Swiss borders (apart from fuel stops). I guess the 0.838 top gear would increase the 3,000 rev/min to 3,200, not a disaster I suppose.

Again 'from the internet', Toyota used the W57 mainly for the Celica and the Crown and the W59 for trucks (presumably that explains the low first).

If I were you, I'd do some more internet research, then get back to them and ask why their ratios seem to be different from the numbers on various web sites. I'd also ask if they can offer the W58 (or even R154) as it seems like a good compromise between the W57 and W 59. I appreciate that it's a bit uncomfortable keep asking questions, but if they really want to sell you something they should be happy to give you open and honest answers. After all, your questions show that your interest is a serious one.

It would help if there were someone who has actually installed one of these boxes and could better comment on their experience with the ratios. You might try the E type and classic XK sections of the forum (and also the Jag Lovers forum).

(I have driven Toyota Supras and Celicas and always found the gearboxes to change very nicely and to be generally good, which is why I suggested the Supra as an option. As I recall, all the Mustangs that I've driven have been automatics, so I've no experience of the Tremec/Borg-Warner options).

 

Agree, the first gear seems a real "stump puller" ratio. OD isn't well suited to motorway cruising either, at least with a 3.77 axle. My T5 has a 2.95 first, and combined with the 3.77 axle gives an overall ratio of 11.1. I've never wished for a lower first.

With the ratios of the Toyota gearboxes I'd want about a 3.31 axle ratio, or even a bit taller. That was an available ratio in XJ's from the 70's, not sure how available they are now. Ideally I think you want the overall overdrive ratio (axle ratio X fifth gear ratio) to be in the 2.7-2.8 range.

Another possible idea is change to the 2.88 ratio from a Series III XJ6. I had an E type with the standard 4 speed gearbox and with the 2.88 XJ axle ratio it made for a good highway cruiser.

 

This is the ratios, rpm, speed data that I have worked out, hopefully accurate but happy to be corrected if not. These speeds are worked out with 185-80-15 tyres.
I only have the low ratio 240 auto differential fitted at the moment although I do have a 3.77 axle ready to fit. Opinions please 👍👎

 

I think there is an error in your calculations somewhere. Looking at the left two datasets, it appears the only difference is the axle ratio from 3.54 to 3.77. The difference is 6% between them, yet the 70mph revs are more than 6% different.

The original sized tires are 26.5" diameter, which gives 790 revs per mile, or the 60mph revolutions. With a 3.54 axle that gives 2796 RPM in a 1:1 gear, and your chart shows 2244. The 3.77 numbers look about right.

My 3.8 S Type will happily do highway cruise at 2000 rpm, less than that and it will start to lug on hills and more isn't really necessary. With the W59 gearbox you are showing 2800 RPM at 70 MPH, you could probably lower than for less noise and fuel consumption. You're at a lower elevation than I am, that makes a very noticeable difference in the power the engine produces. You can get away with a taller gear ratio simply because the engine makes more power and torque near sea level.

 

Attached is spreadsheet (I hate spreadsheets, but ..) with my calculations based on the contents of my service manual.

 

My feeling is that W59 (with the ratios given by Realm) is just about OK with a 3.54 diff. I'd like it better with a 3.3 or higher. Swapping diffs/axles adds to the cost and the work. As I wrote before, the W58 would make life a lot easier.