Gearbox Choice For Track Work

[chipstick 382 1 Cars]

When I was 16v converting my 205 I decided I would like to go for a 1.6 box for better acceleration, yet sacrificing motorway driving pleasure - as this wasn't something I would be doing.

 

So I bought what I was lead to believe was a 1.6 box, but appears to actually be a 1.9 box. I have a very short first gear yet 70 mph is reasonable. Off the top of my head - it's been a while since I 'tested' it but I think it was either 3200 or 3400 at 70mph. There is a chance it could actually be a 1.6 box with a different final drive perhaps? It's the short 1st gear making wonder if it's been fiddled with.

 

While the car has been off the road for a little while I have been making various changes, and have changed the direction I wanted to go with the car. Gearbox thoughts came in to my mind and I thought that maybe now is the time to change the box over again for something different while it's off the road.

 

My main use of the car will be track and social after domestics. I don't need to use the car to nip to B&Q, or pop on the motorway.

 

Now, Combe is a circuit local to myself and after a day out there earlier in the year I am keen to spend a bit more time out there. Now I have a bit more power with ITB's and some better suspension, it dawned on me that a fairly fast track with 110mph+ sections may not be suited to a 1.6 gearbox. I would end up spending much more time at higher RPM than with a 1.9 gearbox. So now I am thinking, perhaps my current gearbox will be a better option to stick with.

 

While I may prefer the better acceleration from the 1.6 for B road driving, the top end of the 1.9 'box may suit the track better.

 

Just wondered what options and thoughts people went through when deciding on a gearbox for track use.

[Tom Fenton 1,526]

You seem to kind of go round in a circle with your question? When I drive my Mi car on any track, 90%+ of the time is spent between 4000 and 7000rpm as that is where the power is, so you keep stirring the box to keep the thing in the power band and singing. (1600 box) If your rev limit is 7500rpm then this is good for a real world 130-ish regardless of what the speedo says, this in my experience is pretty much enough for most circuits you will go to, and the other thing to consider is that in the event of an off, do you really want to be going any quicker in a 1980's French tin box?

[pug_ham 241 3 Cars]

It does sound like you have a 1.9 box fitted imo, can you remember what your approx max speed in second was?

 

Everyone has a different perspective on what they want from a track car, I've run a 1.6 box on mine (1.9 8v) without complaint (from me) after trying various different boxes when I first built the car, gradually working towards a lower final top speed & less suited to motorway use.

 

The only place I think a different box might be better is Cadwell Park on the park straight, from red lining in fourth, dropping to fifth & the car still pulls but not as enthusiastically but this is the only part of the track I'd like a different ratio due to the slight up hill climb towards the braking point.

 

Driving on track imo is much more about the best acceleration you can muster from the mix you have fitted, even if it means your car is less suited to any longer drives to a circuit you might take on.

 

g

[welshpug 1,626]

how much power is it running? IIRC the 106's in the Combe saloons run around 4.29 FD and they're over 200 bhp, that's about 125 @ 7k RPM on the 106 sport cluster and 185 55 14.

[chipstick 382 1 Cars]

I will look at testing the 2nd gear, but the car isn't mapped at the moment.

 

I suppose my sudden query was due to thinking a more constant higher RPM from a 1.6 'box may be more harsh than it needs to be on the engine than a lower RPM from the 1.9 in 70-110 region say for example.

 

I thought the acceleration benefits of the 1.6 unit was more lower down and say suited for sprinting on more intricate courses.

 

With Tom's comments RE the acceleration benefits continuing through the rev range, then this does make me think this would be well suited.

 

Power wise, until Sandy maps it when he returns from holiday I have no idea. The engine is standard apart from the Satchell inlet and GSXR bodies. Was RR'd at 172bhp a few months ago with just a filter and system, but I will take that with a pinch of salt.

[Baz 421]

4.4FD will do 130 at around 7200rpm, it's actually worryingly easy to be doing silly speeds very quickly! But it's soo suited to a 16v, really keeps the engine on song in it's power-band, i'd recommend this if you were hardcore and weren't going to drive it around any long distances on the road.

 

It'll be a realistic 180ish hp, but that's neither here nor there really. As said, you want to keep it in the power band so a longer box isn't going to help. A short first gear suggests 1.6 box, but then the other things you say don't.

 

I find the ideal is a 1.9 with a 1.6 FD for a track car that gets driven on the road, particularly a 16v, basically a 1.6 box with a less useless 1st gear!

 

If you want something a little more usable on the road, a longer fifth gear, Mi for example, can be fitted to give a slightly less frantic cruise gear, but then personally i don't mind a normal 1.6 box tbh! I have one i use for going to Europe etc, 1.9 with 1.6 FD & Mi 5th, can be a bit of a PITA on shorter UK circuits for the 4th-5th jump but it isn't terrible.

[pug_ham 241 3 Cars]

I thought the acceleration benefits of the 1.6 unit was more lower down and say suited for sprinting on more intricate courses.

A 1.6 box will be lower everywhere so better to keep the engine in the happier rev range imo, especially on a 16v motor imo which as standard has a lower still set of ratios for first thru third (Xsara VTS / Mi16. GTi-6 box is lower than 1.6 until 6th)

 

 

Supposedly the later CTI came with the 1.9 first & 1.6 ratios on a slightly longer final drive (3.93 iirc) but tbh the difference of <1mph in first between the 1.6 & 1.9/1.6 box isn't enough to worry about.

 

g

[rallyeash 155]

I run a vts gearbox which works well at Combe, rev limit is 7600 and I'm in 5th befor folly and pull 125 over Avon rise though I do have abit more power/torque than you.

[chipstick 382 1 Cars]

Some interesing points, Thanks

 

Looking at the chart Graham posted, I wouldn't say at a guess the '1.9' box I have is capable of 41mph in first. It was always a case of when pulling away you were almost instantly needing to change gear as the revs were soon increasing to say 4/5k- but then I have never been one for staying in 1st gear for much more than pulling away. For what it's worth, the indicated 110 going over Avon rise was in 4th gear. I didn't feel the need to touch 5th all day at Combe. Partially due to being my first outing. Going by the chart again RE 4th gear speeds, that indicates that it would be a 1.9 unit as I would need to be in 5th to carry that speed of 110mph with a 1.6 'box.

 

I am breaking a VTS shortly so that's another option, but before I drown myself in choices I think the 1.6 unit does sound more ideally suited out of the 1.6/1.9.

 

It's all about trying different setups and learning through experience. I'll put 1.6 'box on and see what I think and keep hold of the 1.9 one. Can always go back to it if needs be.

[petert 554]

I run a vts gearbox which works well at Combe, rev limit is 7600 and I'm in 5th befor folly and pull 125 over Avon rise though I do have abit more power/torque than you.

 

Ahhhhrrr, if only we could have the 205 Olympics.

[brumster 135 1 Cars]

Forgive me stating the obvious, but on the longest straight, you want to be just pipping the rev limiter in 5th before you need to stand on the brakes

 

Personally, I run what is effectively a 4.8 (it's actually a 4.4 but with shorter 3/4/5th gears, which gives me the joy of a slightly taller 1st/2nd from a 1.9 box but with the shorter ratios up the top) but I've got 8200 rpm's to play with, and I need 1st occassionally for hairpins/etc. For track use, you won't, so you're probably happy to sacrifice 1st gear as you'll only be using the other four. If you're 16 valve and have the revs to play with, surely a 1.9 box with a 4.4 final drive will give you all the top end you'd ever need?