i need a 3.7 diff for the standard sunny houseing because i race speed way and i need to get the right revs for my cam at the moment im running the 3.9 and second gear with 185/80/r13 tires and it is reving to hard at 8 grand which is to much so any one got one or knows were i can get one its urgent

Do you know your gear box ratios ?
I have a 6.2:1 [yes 6.2) ratio diff that fits inside a H145 sunny diff housing with the std axles .. Instead of using 2gear you now use 3rd gear ..which works out very close to 2nd gear with the 3.7 .. but still depends on the gearbox ratios you have.. it turns your std box into a closer ratio box by using 2gear as your start off gear and there is a less of a drop in revs to 3rd and also 4th .. but your top speed in 4 isnt very fast ,, but that is not a worry for speedway use .. 1st gear is not used any more as it is to low .. if you got your gearbox ratios ..can work out the ratios for you .. Cheers Cam

I've got a sunny B310 differential - 3.7 ratio. I'll take $50 for it. It's in Seattle, WA USA. Send me a PM or email if you are interested.

Hi cam would you be able to tell me what car the 6.2 diff came from please.I have a 1200 coupe speedway car.It runs on methanol and is very quick but i also have the problem of going to different tracks and have to change diffs or tyres to over come track lengths and runnig out of legs because of the jump between 2nd and 3rd.Any help would be great.Thank you. Fish

I used 4.9 in mine,3rd and 12in wheels. YANDENA and ARCHERFIELD was great only 6000rpm to 7000rpm before turning left.