Have got a '95 FSR 500 na at a good price. However at 100 clicks she is doing 2600 rpm so I am looking for either a faster diff and/or an overdrive box. Is it better to go for the 6 or 5 speed overdrive? and any issues I should be aware of?
I have driven a few Isuzu's and they all seem to handle 2 to 3000 revs quite happily, but I have found that they are a bit thirsty when doing it. As jon-d has said, they are quite happy just chugging along. Maybe a higher diff is the go if you don't have too many hills.
1990NKR Isuzu&&1974 D1310 4x4&&195? Chamberlain Dere Backhoe&&743B Bobcat&am
It is all hills around here, and at 1000m altitude, which is part of the story behind upgrading from the Dyna = like stepping out of a Barina into a commodore . Admittedly with no tray but went all the way up Cunninghams Gap in top.
Mine has the later HE1 motor which has slightly lower rev rating
Did turns of the wheel and turns out I already have the fastest diff (4.333/1). Wreckers are wanting $3k plus for an overdrive box so might bide my time.
Has anyone put bigger wheels on, say 19.5 tubeless or even 8.25R20?
I have the Isuzu MBG6P overdrive box with 4.88 Eaton no 4 in our bus. I also have 10.00/20 tyres which gives me 100km/h at about 2000 rpm.
In direct I get 80km/h at 2000 rpm. Perhaps larger tyres with that diff might get you where you want.
There is a great calculator on the net. Go to "
" You need tyre diameter, gearbox and diff final ratio and you can then play around with the revs. This is what I used to get mine close to what I wanted.
Hope that helps