- September 23, 2020 at 10:02 am #1880SumptnersKeymaster
I have been approached by an owner who wishes to install a 5 speed gearbox. Any advise such as type of gearbox, kits available etc. and cost would be helpful.
If any owner is willing to contact the owner direct please use the contact page to let me know and I will put you in touch.
Otherwise please reply on the forum.
StewartSeptember 23, 2020 at 7:08 pm #1882lauriej1sParticipant
Has the owner a gearbox in mind, be it a Borg Warner T5 or its derivatives: the Rover L 77 ‘box or the tried and tested NZ Toyota set-up?
LaurenceSeptember 23, 2020 at 7:14 pm #1887SumptnersKeymaster
I believe the owner has an open mind. Wants advice on the best way forward.
StewartOctober 16, 2020 at 10:36 pm #1909Ian flhParticipant
I don’t understand the 5 speed box route, you are playing about bastardising the car, for reasonable originality the the way to go is overdrive on the standard box or fitting the 4.2-1 crown and pinion the overdrive. However if the reason is for everyday use and protect the original box, then bearing in mind cost of the various conversions which aren’t cheap then the way to go is a ZF 8speed auto box as used by various manufactures of luxury cars from 2008, must be a few cars written off about for it to be a viable propositionOctober 20, 2020 at 5:07 pm #1911MajorursaParticipant
New Zealand now seem to be doing Tremec T5 conversion kit in place of the Toyota. Link is here:
Those who have seen it will know that this is the gearbox the Jay Leno raves over in his Dart restoration blog. Cost is about GBP 1,500 for the conversion kit (plus shipping and taxes) and a bit of googling found a T5 gearbox for about GBP 2,000.October 26, 2020 at 5:44 pm #1915lauriej1sParticipant
There is a more cost effective route and that is by fitting a higher back axle ratio at 3.31 vs the SP standard unit of 3.54
However, if the Borg Warner T5 is your preferred route the closest set of ratios comparable to the SP is 2:95 (2:933 SP) 1:94 (1:742 SP) 1:34 ( 1.232 SP ) and direct 1.1. then the 5th gear and as Borg Warner offered a number of options for the T5 you can opt for a 5th gear ratio of 0:.85 to 0:63 . The most common in the USA is that fitted to a Mustang from 2.95 to 0: 73.
Whilst here in the UK it’s best to source those fitted to the 4 litre V8 TVR Chimaera.
The other route is the Jaguar option either 4 speeds plus overdrive or the 5 speed unit. In this case you need to buy the bellhousing for a V8 Saloon then some minor welding as the starter motors are in different locations Daimler saloon vs the SP.
Don’t forget you may need a clutch driven plate that will fit those boxes.
All gearboxes can take the torque of a higher tuned SP engine – I think up to 400 BHP (Jaguar might be lower to be on the safe side)
Note Borg Warner develop the T5 then sold the rights to what is now Tremec
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