Overdrive for V8s

[David C]

I just stumbled upon a web page for Cabmasters in Lancs advertising that they have 46RH transmissions in stock. No idea of price but they seem fairly hard to find now, particularly in the UK. My research suggests that these should be suitable for late 408 through 410 and both types of 603 - but please don't take my word for it. PATC in the US makes a kit to attach them to the big block engine in the 411 but there may be issues with balance of torque converter.

[Green411]

Hi David
Have just seen this, it's extremely useful - thanks. Such a swap is on my (long!) list of jobs to do on my car.
I've emailed them asking for a price and will report back.
Cheers
Mark

[David C]

I will be fascinated to hear. You should be able to buy a used transmission in the USA for between $500 and $1000. Easy to spend another $2000 on rebuild of torque converter and transmission. About another $1000 to crate, send within the USA and get it back to the UK. Add 20% import duty and you could be about $5000 in with loads of phone calls and emails to set it up. That should be a good starting point to assess the value of the option from Cabmasters that I think was advertised as rebuilt.

Alternatively, get a used transmission and ship back to run as is and you might get away with about $1500 but costs to rebuild will probably be higher in the UK. It will also be more difficult to find someone who knows what is required for the rebuild.

It's worth considering the stall speed of the torque converter. Many second hand units are likely to have been rebuilt by now and a good few people are likely to have gone for a higher stall speed to go behind a tuned engine. This may not be what you want in a Bristol. It's a fair chunk of cash to sort out so worth factoring in to the total.

[Green411]

Sorry for the slow reply, which you will correctly interpret as 'I thought I'd posted this but have just discovered I hadn't actually done so.....D'oh.....'
I emailed Cabmasters about the A518/64RH, their chap Brian says £2k + VAT, only 2 left, buyer collects from just north of Manchester. Their photos suggest it comes with a torque converter. Their replies were quick and friendly. They are buyers of surplus OEM stock so may not know the full ins & outs of all their items so I think that if you want one then do plenty of research to make sure it'll work with your engine, adaptor plate notwithstanding. They are advertising them as suitable for some diesel trucks plus Aston Martins. So are they a diesel trans or a petrol car trans? According to Herman at www.bigblockmopar.nl a diesel transmission has heavier duty internals which Herman thinks will be bad for economy in a petrol car.
Having said all that the photos show a part number of P52119161AB which when I searched on it comes up with Dodge Dakota/Ram 2wd truck transmission at www.2040-Parts.com in NY, USA. Allegedly brand new OEM, $777! It's so unfair.....

[David C]

At that price I would say it's a no brainer. According to my research the internals between petrol and diesel models are interchangeable, mainly the number and thickness of clutches.
I would imagine the benefit of the lockup would far outweigh any losses due to heavier duty internals.
My research suggests that the A and LA engines are internally balanced and should bolt up directly. The wide block engines will need an adapter and probably a different flexplate to balance the engine.
Please note that I'm not an expert on this and don't have a lot of practical experience but I have spent a good few hours on my own project so I think I'm qualified to suggest a few questions to ask those who are genuinely clued up on the subject.
For anyone seriously considering upgrade to overdrive the major considerations are cutting a chunk out of the crossmember on the car and making a new mount, shortening the prop shaft, upgrading transmission cooler pipes from 5/16 to 5/8 and probably fitting a new cooler or rebuilding the radiator to a higher spec. Also some work on the gearbox tunnel but I can't help with details of this as I found a smaller 42RH that I hope will not need any modification.
Control of the unit looks relatively straightforward with parts costing £100 to £200.

[David C]

I have just noticed that you say the Cabmasters unit is 64RH. This requires more investigation before rushing to buy.. 46RH seems fine but I don't know about the 64RH.

Edit - I have double checked and can't find any reference to 64RH so assume this was a typo.