5 Speed Gearbox Installation

[david sutton]

I thought I would send a post on my exploits to get a 5 speed gearbox fitted into 829 UXF. I have had the car nearly 6 years now and have tried to make sensible amendments to help with driving pleasure. So it has R&P steering, Luminition ignition system, Kenlowe fan, halogen lights, Evans coolant etc etc.

The existing gearbox was the standard 4 speed with overdrive. I had suffered a few annoyances with it, particularly the gear change locking up when friends or family tried to drive the car. Changing gear needed sympathy and a gentle approach. Those who have had this experience with their own SP will know the remedial action is to take apart the top of the gear lever mechanism, then refit it. It has been alleged that this can be done in 10 minutes, although my experience was somewhat longer than that and 10 minutes was required for the chuntering of profane language. Another issue for me was that when the gearbox got hot, it became less inclined to change gear smoothly in the lower registers. On the motorway in top, it was divine. The overdrive did a great job and aided consumption of miles with an acceptable fuel bill. In central London it was recalcitrant and grumpy

I was advised by those who know more than me about the SP250, that the car was fine. The gearbox locking up was a consequence of wear in the selector mechanism. Of course it would have moods when hot. After all, the car was built in 1962 and the gearbox was adapted from an older design. The SP250 specialists who drove the car said all was well and my expectations may be too high. Despite their best intentions, I was ready to change the gearbox.

The challenge with changing the gearbox revolved around the need for a bell housing with an alternate gearbox. This is a custom made item and required specialist engineering. I was aware that kits could be found in New Zealand and California for fitting Toyota gearboxes but was unsure if I wanted to fit a Toyota box in my beloved Daimler. This attitude has subsequently proven to be without merit.

One day, I watched the Jay Leno video about his SP250 and fitting the Tremec T5 box. My meagre research indicated that Tremec were an American specialist company that makes sports car gearboxes and that the T5 was suitable in terms of gear ratios and being lightweight. The video describes solving the bell housing issue by having one made on a 3D printer. I discussed this with my brother, who works in automotive engineering and he suggested that if I could buy a copy of the CAD file for the bell housing, he could get one made up for me.

So I started a search to find a contact at Jay Leno’s garage. This establishment seems to get plenty of coverage on the web. My search was unsuccessful. Indeed, my failure and determination, got me emailing Mr Leno’s agent, explaining what I wanted and asking for contact details of the garage. This yielded a reply asking for my phone number, which I duly sent. About 15 minutes later I was outside the house when I was called back in to take a call. It was Jay Leno, the man himself. He was most friendly and we discussed the car and the gearbox conversion. He also said he would help with the bell housing files and would speak again the next day. We were on the phone for about 30 minutes and I was pleasantly astonished by his charm and helpfulness. I also calculated that it was about 0400am in America when he made the call.

He called back later for a further chat and said he had his engineering team working on it. We then had a conference call with his team about the conversion. Everyone was very positive and helpful about the conversion and its results. However, it turned out that the 3D printing process had not gone as smoothly as I had expected from watching the video. There had been errors in the file preparation and the resulting bell housing was wrong, or back to front. Their solution had been to cut it up and weld it back together in the correct orientation. I was given no more detail than that, so I apologise if it does not make sense. They said that the final cost was substantial and the job required much machining and detailed engineering to work. They would happily send me the files, but warned it was not an easy solution.

I had a further call with Jay Leno, the next day, when he phoned to ask what I wanted to do. I politely declined the offer of the CAD files. He said he was coming over to UK in the coming days to buy a couple of motorbikes. I said I would enjoy the opportunity to meet him and show him my car. He politely declined the offer of a meeting. We left it at that, and I now owe him some pics of my final solution.

It turned out that the gearbox in the video was not a T5 after all, but a TKO. This had a cost and weight impact, but is apparently an easier fit with respect to the gearlever location.

I elected to go down the tried and tested Toyota W58 route and buy a kit from Steve Sanett from Penta Labs. This turned into a saga with the installation undertaken by Wraith Motors in New Barnet. Wraith Motors were recommended to me by Phil Glenister before he retired. They have experience of working on SP250s and their chief mechanic, Eddy Spiteri is a good chap. The Penta Labs kit was complete and Steve or his colleagues were available for advice over the phone.

Driving with the new gearbox is a joy. In no time at all, I was able to focus on the pleasure of my SP250 and not think about any potential anxiety with gear changes. I would strongly recommend this solution.

When I am ready, I will write about my experiences with Penta Labs and Wraith Motors. For now, I want to conclude that Jay Leno is a great man, and I was overwhelmed by his humility and willingness to try and assist me with this project.

Happy New Year

from
David

[tjt77]

enjoyable post .. always a good idea to upgrade the gearbox if you wish to enjoy the car as it was intended.. the gearbox is the weak link in MANY brit cars form this time period and adding a modern 5 speed with overdrive has so many positive practical aspects its seems crazy NOT to take this route. Im in an ongoing saga with my own daimlers .. mainly problems with sourcing decent quality engine parts, but Im in the midst of gearbox conversions using parts i have unhand ..the first conversion is to fit an GM 200R4 auto box with overdrive to one of the 2 1/2 litre saloons.. this required a special backplate, and adaptor for flywheel (to take a GM drive plate) so that all the GM parts can be utilized (starter, driveplate etc ..and so fir its all worked out just fine.. the gearbox mount has yet to be fabricated along with propshaft...and I still have to change the 'cocks comb' at top of steering column in order to get the shift pattern correct.
Another conversion underway (on 4 1/2 litre..also for a 2 12/ saloon) is fitting a 'tremec' style 5 speed manual gearbox.. for this we modified the daimler back plate to take the common GM bell housing, made a special flywheel, that takes the original 'bolt on' ringear and the original starter is replaced by a modern 'gear reduction' starter.. same unit as used on Austin healey and mk2 jaguar.. the actual gearbox will likely be either ford mustang or Chevrolet camaro..its basically the same 'T5' borg warner box.. the tremec version a little more costly than a rebuilt GM or Ford unit.. but still 'affordable' the 'other' 2 conversions Ive simply sourced original damiler/ jaguar parts to go with a factory style conversion.. I took this route for simplicity and I have never had any issue with the jaguar full synchro overdrive box that these cars were supplied with new.. the SP 250 is in many ways easier to convert than the saloon.. and given that the lever is WAY further back its far better to use one of the existing conversions as those who build these set ups have done it before and worked out most of the 'issues' that arise..
as regards 'quality' and ease of use.. Toyota gearboxes as brilliant compared to the origin equipment.. they are extremely tough and run for hundreds of thousands of miles with no issues and shift beautifully.. plus there are a number of different ratios available depending upon original application.. the downside to the toyota unit is that as some point ( as with the common UK ford T9 conversions offered for many brit sportscars) the supply with begin to dry up at some point, whereas the US made tremec and its variants are likely to remain in production for a good while yet .

[david sutton]

Thanks. It seems that your endeavours have been more adventurous than mine. I have resorted to getting help with my project due to available time and not having access to workshop facilities and suitable tools. I possibly have become completely cack handed with spanners, as I do not spend enough time doing car repairs. Like so many of us, when younger, there was no challenge on a car that I would not try to tackle.

The next project with the car, will be a new hood and interior carpets. The current carpets are not old but the trimmer who fitted them may not have been as careful as I would have hoped. As for the hood, it is an ancient vinyl contraption that does nothing but cause bad moods and damaged finger ends when I fight with its unwillingness to be fitted. My current record time for fitting it is about 20 minutes. This has encouraged me only to drive on dry days with no forecast of rain..... I got caught in a heavy summer shower on the M4 last year and tried the old story that if you drive fast enough, you stay dry. Not true. My misery was compounded by a leak into the cockpit from somewhere above my knees.

Best Wishes
from
David

[Vortex O'Plinth]

.......My misery was compounded by a leak into the cockpit from somewhere above my knees.

Ah - the classic SP wiper spindle leak. So common it's really a feature of the car rather than a fault.

[daimlersteve]

Yes ,a minor situation we (most) have suffered in the past.
On that very subject ( water) ,at a shed raid some years ago there was a short fun series of questions. One of them being -- When do you know its time to put the hood up ? My entry -- " When the Map Pockets overflow ".
To my recollection i won on that entry ! ,
Steve

[daimlersteve]

Thats good news , i'll email Steve Sanet re the kit.
steve

[david sutton]

Thanks Steve & Nick.

My solution to the wiper spindle issue is to drive in the dry.....
I am sure that Penta Labs will be pleased to hear my feedback.

David

[simonp]

For future reference the NZ SP250 Club which is blessed with some great engineers regularly fit Toyota Supra 5 speed boxes and have modified the bell housing to fit.

I understand the gearboxes are bullet proof and plenty has been written about the conversion in the past. Anyone interested can contact any of the NZ guys who will I am sure be helpful.

SimonP

[Sonus]

Nice story. Quite amazed that Mr. Leno would take the time.

Here is my solution for fitting the Borg Warner T5 to my Daimler V8 in my TVR Vixen

[daimlersteve]

hiya sonus,
The larger Saloon bell housing makes it tight in an SP. Fly wheel is bigger as well as the starter position. What was the donor car for that particular t5 Sonus ? The stick is quite forward ( tvr only position i think ) The majority of boxes down this way are aussi or usa orig. eqiptment. I've modded several SP bell housings with a plate welded to the rear to accomplish the same as you have there. Am fitting one up next week to an SP.
Just as an aside --- what was the cost of Steves' conversion? All that said , Colin Dray at "Five speed Conversions has been threatening to make up a conversion for the SP/T5.
steve