Gearbox Advice for 235 bhp VX engine

[Nobled Again]

So here I am with a nice modifed HPC, pulling 0 bhp due to a ventilated crankcase.

I had been having problems with the gearchange (sticking in gear when pushed to high revs, especially trying to change up from 3rd to 4th), so faced with an engine rebuild its time to consider reworking the gearbox options.

 

Does anyone have any experience/advice on gearboxes that have worked well or badly for you in this sort of setup ?

 

Thanks !

 

N777HPC

 

forgot to say its a standard T9 at present

 

Edited by - Nobled Again on 13 Apr 2005 17:45:54

[stevefoster]

SPC built me a Semi-heli cut, Quaife internals, close ratio box about 4 years ago.

Been bullet proof so far, touch wood.

BHG (Brian Hill Geraboxes) is good too I heard. He can do a helical CR, 5 speeder at a good price.

 

Others will be along to tell you that a 6speeder will work well and even a sequential one too.

 

Hants (North) and Berkshire Area club site here

My racing info site

here

 

 

 

[Lotus Boy]

Stick to a 5 speed 'box. The VX2.0 produces so much torque you don't need 6 gears, plus you would be buzzing at silly rpm at high speed in 6th. Mark Piper has a 6 speed in his HPC but I don't think he wants to keep it in, he's been muttering about switching to a 5 speed.

 

If you are custom building then go for a long first gear ratio, standard 1st is too short really.

[ECR]

Sorry to hear about your ventilated crankcase......

 

I have been through just about every iteration of the type 9/ Vx 2.0. The synchros are just not designed for fast changes (fine if you only use it on the road though or if you change gear more slowly than me !). It is a personal choice but I have ended up with a Quaiffe 5 speed straight cut dog box in an alloy case with alloy lid. I have now stopped cracking casings and the gear change is quite smooth once you get used to it.

 

This is towards the extreme end of boxes but you might just like to consider it.

 

It can also be upgraded to a sequential change if you want......

[EFA]

The only worthy statement on this thread is by ECR. The 5 speed is a totally inappropriate design for a high power VX.

 

"The VX2.0 produces so much torque you don't need 6 gears" is cobblers - I have a VX of close on 200ft/lbs and 300bhp. I use a 6 speed box because it makes the car apprecialbly quicker.

 

The 5 speed box eats synchros and cracks cases all the time if you are running over 7000rpm and around 220bhp.

 

The only option is a 5 speed dog box with the stronger alloy case and (obviously) no synchros, or a Caterham 6 speed - which will do the job perfectly well and can easily take power torque and rpm.

 

 

 

 

[rickslack]

Be careful buying a six speed box for a vx, depends what your final drive ratio is as i think 6th is 1 to 1 ratio. same as 4th in a t9 ford box. Unless you rev the bolx of your engine this will seriously limit top speed. Revs are what kill the standard t9, suffers from oil starvation on the main shaft at much over 7000 rpm. I'm running a close ratio straight cut box built by competition transmission services in luton. Go for the heavy duty quaife kit.

If you speak to bernie at cts he can advise you on exactly what you need and wont rip you off.

www.gearboxman.co.uk/

 

[EFA]

Revs are what kill the standard t9, suffers from oil starvation on the main shaft at much over 7000 rpm.

 

No-one would run a std mainshaft - we are at least assuming he has a Quaife HD kit with needle rollers. - All the CAterham supplied 235's came with such a gearbox.

 

 

[Nobled Again]

Thanks for all the comments; confirms my feelings that the standard box just isn't up to it.

I definitely buy the longer first recco, and want third shorter as well, so I'll do the numbers on the 6 speed and a custom build.

 

Cheers, Peter

 

N777HPC