Gearbox Lotus 7 S4

[Gatsby]

I'm in the process of exchanging my pettyful standard 85 hp xflow to one twice the power. In that connection I am naturally wondering if I should consider some gearbox changes while the engine is out. I use the car for (spirited) road use - but NOT for racing or trackdays.

 

I have studied techtalk at length and understand that some seem to be using the standard type 2 Escort Sport box with a high spec engine without problems while others (maybe more hardcore) are dead set on costly exchanges and modifications.

 

I have 4 questions:

1) Will the standard box be OK for normal road use?

2) Can I upgrade or modify the exsisting box without having to exchange to many other parts?

3) In case of an exchange what box can be recommended bearing in mind that I prefer to keep the stick in the same position and would like to avoid complicated and expensive modifications or alterations (such as type 9 5-speed box).

 

In case I should make alterations what parts do I need (so I know what to put in the "Wanted" section of BlatChat). 😬

 

Any feed back or suggestions are greatly appreciated - so I can get the car back on the road and keep it there the rest of the season. *idea* ❗

 

Thomas

[Nic M]

My S4 was raced for a number of years at one time with a 175-185 bhp race twin cam. As far as I can tell from the records the gearbox is the original fitment and there are no bills for work on it. I am currently reinstalling engine and gearbox to a 150+BHP unit so we will have to see if it goes bang!

 

Not the best of help but a little I hope!

[Graham Perry]

With double the power, won't first gear seem very low ? You might find that either a diff ratio change or a few gear ratio changes might be needed. I am sure someone here could advise

[jpringle]

Hi, i have raced an S4 for twelve years now with the same standard gearbox without any problems, i have about 160BHP.

You could fit a straight cut box or fit the internals to your casing,

Other gearboxes do not fit without major modification, I have a road going S4 that I fitted a five speed box from the 2.8 i capri some years ago and that required modifying the gearbox crossmember on the chassis, prop shaft, clutch etc and the gear lever is further forward.

I use a 3.9 diff but if you have an all steel engine a 4.1 or 4.4 would suit better.

 

If you want any more help let me know< i have had S4 Sevens for over 20 years now and currently have three, one race, two road cars.

[Nigel Riches]

The Escort gearbox is OK, in it's stronger Sport type derivitive, but for some better ratios and a stronger mechanism the Mk2 Cortina 'box, type commonly known as the 2000E gearbox, (correct number, type 2300), would suit your requirements, the gearbox will sit slightly high, this can be changed by removing a suitable amount from the gearbox mounting point on the tail housing, the mounting bolt holes ( on the bungy support thing) will be found to be approx 0.5" to far rearward, make the holes in the bungy carrier into slots as necessary, the gearshift will need to be modified by drilling holes to accomadate the rearward position of the gearstick, about 1.5" difference, assuming you have the Caterham remote shift arrangement, and the propshaft will need to be shortened, can't remember if it needed a different nose, the ratios are daifferent to the Escort box so the speedo drive gear will need to be corrected also, but if your getting more power, this box would be a better type than the Escort one,

Escort ratios. 1=3.337, 2=1.995, 3=1.418, 4=1

Cortina ratios. 1=2.972, 2=2.010, 3=1.397, 4=1

Hope this has helped, I did this mod before changing to the type9 box, it was definately worth the time, chuck the Escort thing away, mail me direct if you want more info, regards Nigel.

 

1982. 5 speed, clamshells. B.R.G / Ali. The True Colours.