Straight Cut Box nessesary?

[CTrickle]

Hi All,

I've just bought a 1992 Caterham with a 180BHP 1800 Zetec, It has a 'heavy duty box' in it which makes a right old racket! Does anyone have any experience of power levels vs standard box? It's ok but would prefer it to be running a standard box.

Oh and I do plan to do track days in it if that makes a difference? First one booked at Woodbridge on 21st Oct.

Thanks
Ed.

[mickrick]

A helical box will handle that no problen.
It's torque that kills boxes though, not hp.

[CTrickle]

Cheers for that, I have no idea of the torque figure but you have confirmed what I thought!

When you consider the weight of the car that makes sense!

Thanks again!

[NuisanceFactor]

CTrickle said:

I've just bought a 1992 Caterham with a 180BHP 1800 Zetec, It has a 'heavy duty box' in it which makes a right old racket! Does anyone have any experience of power levels vs standard box? It's ok but would prefer it to be running a standard box.

I think that you only need to worry if it's a 4-speed type 2 (Escort sport) gearbox. All 5-speeds should be ok.

[Red Seven]

The ratios of your existing gearbox are likely to match the character of the car well.
If you replace your existing gearbox with any old 5 speed gearbox, you're likely to find that the ratios are quite different to your existing 'box.
You're likely to find that first is way too low, and 5th becomes even taller, if you use a standard Sierra 'box.
Helical close ratio, or standard gearboxes with modified ratios, are available, but are not a cheap alternative.

[mickrick]

But he never mentioned ratio's. Of course that's a different subject.
Or do you know the car? In which case I'll

[Aeroscreens]

If it's of any use to you:

My 7 is running a 2.0l Zetec (190bhp and 167lbs/ft) on the standard 5-speed box, no problems to report so far and it get abused a lot when sprinting etc....

[CTrickle]

Hi,

Red - the current box has really long ratios, I don't knwo if this points to it being standard gearing or not. I've only just got the car and so i'm not used to it yet but closer ratios would be good.

Mick - your right I didn't and I'm not to worried about them as at the moment I'm happy to drive around any worry's likt that.... until the racing spirit comes into play!!

Aero - Cheers, is that a sierra box?

Thanks for your help! I think an LSD is the first real upgrade I need to worry about - ideas/options?!

Ed.

[Aeroscreens]

Ed,

Yep, Sierra Type 9 (from XR4i, I think). Currently on 78,000 miles, one refresh at 58k from 'Road & Race'. Converted from x/flow to Zetec around 72k. It really needs a longer 1st for sprinting though..., but 5th is great for touring.

[downsman]

CTrickle said:

Hi,

Red - the current box has really long ratios, I don't knwo if this points to it being standard gearing or not. I've only just got the car and so i'm not used to it yet but closer ratios would be good.

Ed.

That sounds like a close ratio box to me. With very little difference in ratio between the gears and top being 1:1 in a 4 speed, all the lower 3 gears will feel long.

Straight cut gears are stronger but I understand they wear out more quickly and the noise is unpleasant.
5 speed with helical gears and a longer 1st would be my choice

[CTrickle]

Aero,

I don’t suppose you know if that box is a Ford MT75 box? Bit specific but would like to buy a box before removing the old one!

Can't wait to lose that blooming noise!

Cheers
Ed,

[Aeroscreens]

Ed,

Sorry not to be able to answer your question directly, but the box was the Sierra XR4i close ratio 5-speed with the following ratios:

1st 3.36
2nd 1.81
3rd 1.26
4th 1:1
5th 0.82

HTH

[CTrickle]

Thank you!

I think I'll wait for the evenings to draw in then remove the current one.

That way I can check what is in there then buy one that will definitly bolt in!

Cheers
Ed.