I like most I'm always on the quest to improve performance from my old Golfy. I have decided my next stage in the cars development it to build a gearbox with gearset and FD to help improve acceleration and try and strengthen up the old 020 grenade! The car the box will be built for is a Mk2 NA engine revving to 7500rpm. The useable power band is from around 5200 to 7000rpm. The box is going to be built for track. I'm starting of with a 2Y 020 16v box and want to keep this casing. I will strengthen the dif by using bolts instead of the dif rivits. The ratios I'm looking at are: 1st stock 2Y 3.45 2nd Looking at swopping for 1.94 3rd stock 2Y 1.44 4th stock 1.13 5th looking at swopping for 0.75 FD 4.25 I feel the second gear will be useful as it means the car will hit over 60 and it brings the gear closer to third so I should not find I'm needing to shift up mid corner. Fifth will be almost identical to standard 2Y that I have which is fine on the motorway but still pulls fine. Thoughts.
A Mk3 8v GTI box might be a good compromise - I think they have an 0.80 5th, as well as the higher 2nd. Also gives you the wider range of clutch options that are available for the bigger input shaft. Might not give the ideal combination, but it'll save pulling 3 different boxes apart to get the result you want. I'm planning to go for AUG type ratios with a 3.9 FD (has the taller 2nd and an 0.89 5th). I can live with the lower 5th for the amount of cruising miles I do in the car. Assume you're going for an ATB diff too?
I had a quick look for gearbox ratios but could not find it, do you know the code? I'll buy the FD new and have to source the gear sets I want. ATB will be kept simples - Quaife FTW. I did look hard at the wavetrack but it does have parts that wear and it was a few hundred more...
I wouldn't go for the longer 2nd. You get a large rev drop when changing from 1st to 2nd giving a bogging down feeling. Only a problem when 1/4 miling or at the traffic light grandprix. However, the longer 2nd gets the 3rd gear buzzing in at a higher RPM. The 16v gearset or equivalent is the shortest stack 5 speed 020 as far as I can remember. With the 4.25FD you will never use lower than 3rd gear apart from super short circuits like Curby. I'd honestly say go for the 16v set with the 4.25FD and hold out for a 6speed kit . Gurds
Get me, Aero drag Coff, Frontal area, Gear ratios and FD Tyre size, Weight, And the torque curve vs rpm. From this input the the optimum acceleration can be modelled As a check we then test the vehicle with with G meter and see if the dyno measurements or the weight are correct as the forward acceleration should match up with what was modelled
Just looked at those and with the 4.25 fitted the plots look abit like as a standard 2Y (spread), seems the MK3 4.25 would have slightly lower shift points but not by alot.
This is being done on a budget if i could find a 6 speed that was affordable then I would love to, any one know if you can add a sixth gear easily as a DIYer?
I agree and will using the infomation supplied to work out how hard the vehicle will accelerate to the redline as model "drives" the above data. Gear sets for better accels can only be entered from what is available and if the accel data is not acceptable then further engine modifications will have to be performed to increase torque or shift torque to a more favourable engine speed range. Understand where I am coming from now?
