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MG Midget and Sprite Technical - 5 speed box for race midget
|whats the best ratios and box to look for the 5 speed comversion|
|Does the race series you're entering allow a 5-speed box?|
|Anything Ford T9 based will take helical or straight cut gears. Quaife sequential or Caterham 6 speed (but 6th is 1:1).|
There is a book with this stuff in...
|It might not be too much of a problem in a race car but first gear on the standard type 9 is very low. What you find is that you rev it to the red line in first then when you change into second it drops right back to 4k revs (I can't remember exactly) and that's not ideal on an engine with a race cam. |
As I said that might not be too much of a problem unless you envisage using first on the track more than just for the start. I can't see it as using a 5 speed will mean you can keep the overall gearing low so first will be too low for event the tightest of circuit corners.
For hillclimbing though that jump was a a bit of a bind, especially if the start was on a hill so I had the 'Long 1st' kit fitted by BGH and it makes a massive difference. Now I can have a low overall ratio (4.55 diff) and 1st gear is nice and high with not such a big jump to 2nd.
I've only driven on a couple of full circuits (Cadwell and Anglesey) and using 5th with a 4.55 diff and 175/60x13 tyres is still only marginal. I can sometimes stick with 4th (depending on wind direction!) but it's hovering around 7.5k revs and I so I quite often stick it in 5th to give it a rest!
Of course there are a lot of other things to consider, if I had more power or was running without a windscreen I'm sure I'd have to use 5th a lot more on that gearing.
Reliability wise it's been great, it's a standard box from a 1.8 Sierra with the new first gear and reconditioned by BGH. I think BGH also do a full close ratio box as well, with 5th 1:1 or as an overdrive.
|just a thought|
I was told by the scrappy I bought my t9 from that they use the t9 fitted to certain transits...the reason being the ratios are best for stock car racing.
you may have a problem with the input shaft being longer
the man to talk to is 'first motion gearboxes'
does everything for t9
|Are you sure your allowed to use 5 speed, here in the states you have to lock out 5th under SCCA regs|
Personally... 1st gear on both the datsun and the ribby is just a jumper gear for me personally... I rarely use 1st unless im starting off on a huge incline from a dead stand still, I always start with 2nd 90% of the time... 1st is just a waste of energy and time
|Prop and the Blackhole Midget|
This thread was discussed between 11/08/2015 and 12/08/2015
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