8 replies to this topic

[1275coopers]

Hi there. Im in the slow process( for me) of putting a jonspeed kit on my cooper s 1310 engine. The engine is out of the car as im tidying all my wiring up and just a general tidy up. anywho, I have a standard cooper s gearbox and standard diff. Will it last? I have looked into getting some straight cuts and an x-pin diff, but do i need it? I have only heard of it being recomended. So how much hp can a standard box take?

thanks in advance.

[Wil_h]

Standard helical box (treated carefully) will survive a suprising amount of power, it's as strong as a straight cut one in reality. The reason most people change them is for the better ratios.

The drop gears and diff are the weak points. I would advise a cross pin diff as a minimum, and it's the Minispares one you want, others have been shown to be weak.

If the drop gears have the end float set correctly and all the bearings are new or good condition, then they should hold up to 140+bhp, if treated with sympathy.

[1275coopers]

Standard helical box (treated carefully) will survive a suprising amount of power, it's as strong as a straight cut one in reality. The reason most people change them is for the better ratios.

The drop gears and diff are the weak points. I would advise a cross pin diff as a minimum, and it's the Minispares one you want, others have been shown to be weak.

If the drop gears have the end float set correctly and all the bearings are new or good condition, then they should hold up to 140+bhp, if treated with sympathy.

Ok, cool. Thanks for that. Is there any particular final drive you would recomend? Im pretty sure mine is something around a 3.7 and its got plenty of bottom end but revs high on a freeway. I was thinking of going a 2.95 or something. what do you think?
Also, what clutch would you suggest as mine needs replacing and i want something that can handle the extra power.

thanks

[mike.]

For a supercharged engine, i'd probably go for a 3.1 or maybe even a 2.95 final drive. You'll have the torque, so may aswell make the most of it. Depends what your using the car for though i suppose

For your clutch, i'd probably go for a bonded fibre plate, with a grey diaphragm.

[1275coopers]

For a supercharged engine, i'd probably go for a 3.1 or maybe even a 2.95 final drive. You'll have the torque, so may aswell make the most of it. Depends what your using the car for though i suppose

For your clutch, i'd probably go for a bonded fibre plate, with a grey diaphragm.

Great. thanks a lot for the help so far.

Does anybody have pictures of the breathers they have fitted? or what sort of breathing is required?

[mike.]

You will probably be fine with the 2 standard breathers (transfer cover and timing cover) and just have them plumbed either to a catch tank or to the air through a little filter.

If i were you though, i'd add another breather to the rocker cover; IMO you can never have enough breathers

[hustybusty]

You will probably be fine with the 2 standard breathers (transfer cover and timing cover) and just have them plumbed either to a catch tank or to the air through a little filter.

If i were you though, i'd add another breather to the rocker cover; IMO you can never have enough breathers

Timing cover breather has to go for the charger belt doesn't it?

[Prawn]

on the jonspeed suck through kit yes, the timing cover breather has to go.....

[mike.]

Well in that case, i'd certainly add a breather to the rocker cover.