Rear Diff gearing

[thorpey69]

What is the rear diff from and has anybody on here played with the gearing?,im pretty sure i dont need a theoretical 160+ mph road car,i figure that 130-140 would be quick enough,and the benefit of improved accelaration would be more to my liking,also probably a much cheaper way of tuning your 0-60 times and low down drivability than other expensive tuning methods.

[GreenV8S]

If you just dropped the gearing, your 0-60 times would go out the window because you'd need more gear changes. A close ratio box is what you really want, because this can give you a tall first and then stack the other gears close together.

[spend]

Try smaller tyres/wheels?

[slideways]

surely your car does 150+ standard??

[steve-V8s]

There were at least two types of DIF used GKN and BTR, with the later BTR one at least two different ratios were used, have tried both of them. The lower geared version ( which gives an overall higher geared car) makes for more relaxed driving and a theoretical higher top speed. It moves the revs in 3rd slightly too low for smooth 30mph use (at least with the cam I have) and 2nd is too low. Fitting the higher geared one (lower overall gearing) gives a more shove in 2nd and 3rd and eases the 30mph issue but does not help with acceleration from a sanding start. The lower 1st making control of wheel spin even more difficult which comes back to the real problem which is traction not power or gearing.

[Del 203]

steve-V8s said:

It moves the revs in 3rd slightly too low for smooth 30mph use (at least with the cam I have)

you can only use 3rd for thirty !!!!


So glad i'm happy with my set up

[Uncle Fester]

It seems that this is yet another example of secondary benefits from a mapped ECU.

Like you, I had to hold lower gears and thirty was a third gear speed. I have changed cam, but the old one was Kent 234 and the new is H404.

When I fitted the Emerald I was still on the 234 cam. Since then I have been able to pull cleanly in top from 1100 RPM. It will pull from 900 RPM in top, but feels less happy.

This alteration to the usable rev range would allow you to rethink the ratios you use.

That said, I agree that traction is the real problem. Perhaps what is needed is to choose an ECU that provides the option of implementing launch control. It’s not really what I feel to be the TVR ethos of the driver doing it all, and probably not for me, but it may be for others.

The original question was would it be a cheap bit of extra acceleration compared to other tuning options? If you change the gearing as you suggested then the engine will be revving more all the time.

This will burn more fuel all the time and wear your engine faster. Both will cost you more money.

The ECU route will give you more power and better acceleration anyway. It will also save fuel; you can change up sooner when driving normally, and allow you to use 95 octane petrol, providing a further saving. I think you will find it a more cost effective way of improving things.

[thorpey69]

Thanks for the replies chaps,the engine management upgrade is an interesting proposition,at the moment there are some noticeable areas of the rev range that could be improved,the car was fitted with a replacement standard cam just over a year ago so wear shouldnt be an issue affecting the drivability.The only issue with aftermarket management is the cost of some of the packages,i have considered mega squirt as an option,does anyone have a system fitted?