GTi_Tom

iTrader: (1)

I currently have 2 gearboxes for my hillclimb car which is 725kg and 220bhp n/a

before I put a decent box in I need to know what would be best for competition

1 is a normal series 1 lsd box, the other is a ib5 with st150 gears and series 2 lsd

The series 1 is
1st 3.15:1
2nd 1.91:1
3rd 1.27:1
4th 0.95:1
5th 0.76:1
Final drive: 4.27:1

The other box is
1st 3.58:1
2nd 2.04:1
3rd 1.41:1
4th 1.11:1
5th 0.88:1
Final drive 3.82:1

Which would be the best box to use as they are? Or is it possible to strip both mainshafts down and fit the st150 2nd, 3rd, 4th and 5th gears on the series 1 mainshaft?

Which would give
1st 3.15:1
2nd 2.04:1
3rd 1.41:1
4th 1.11:1
5th 0.88:1
Final drive: 4.27:1

FocusWRC

Hi

1st is the real problem with the IB5 box it's so short. Ideally a nice 2.8:1 first gear would be spot on ( thats something I'm working on ) Just to show what a set of ideal ratios would be here are the raios that are homologated for the 06/07 Focus WRC and the Group N Fiesta ST:

Focus WRC Group N Fiesta
1st: 2.84:1 1st: 2.83:1
2nd: 2.06:1 2nd: 2.07:1
3rd: 1.52:1 3rd: 1.64:1
4th: 1.22:1 4th: 1.35:1
5th: 1.00:1 5th: 1.15:1

If it was me I would be using the ST ratios ( BTW I have some Fiesta ST gear sets being crack checked and shot peened if you are interested? ) as they are closer to ideal competition ratios.

Unfortunately you won't be able to mix and match layshafts and gears from both boxes as teeth profiles will be different, and unfortunately the gears on the layshaft are not removeable i.e the shaft and gears are all one piece.

Just to confuse matters for what you are using the car for the series 1 final drive will be better rather than the ST one. I'm sure there will be a final drive in an IB 5 box better than the 3.8:1.

If you can afford it, I would go with a plated diff as opposed to a stock RS Turbo ( I know money is probably an issue!! ) As this can be set to a known pre load and have suitable ramps fitted for your application. The Turbo diff isn't tuneable unless you have the break off point adjusted, but a plate diff would be miles better!!

GTi_Tom

iTrader: (1)

Ta for the reply

I just thought it might be possible as I treid an escort ib5 layshaft with a st150 mainshaft and they were fine even though some of the number of teeth were different.

Also afaik CTS(gearboxman) do custom ratio boxes with the standard synchro gears. How do they do that?

FocusWRC

You can have gears made, they will probably be straight cut as the cost of helical will be to expensive. The syncro part of the gear will more than likely fused to the gear afterwards. As for the layshaft, something would have to be made afterwards, all very expensive, unless you are talking about the Quaife kit??