Offroad-Express

I,m trying to decide what diff ratio to put in my 1990 VX 4.2 diesel turbo cruiser. I am currently running 35' tyres but the vehicle is very hard to get rolling and sits at about 1800rpm at 100kph. What rpm did these cruisers do at 100kpm on standard factory tyres.

Surely someone out there has still got their cruiser on standard wheels and can tell me what revs it does at 100km. It needs to be a standard 80 series 4.2 turbo diesel without the separate overdrive select.

Diorama wrote:Surely someone out there has still got their cruiser on standard wheels and can tell me what revs it does at 100km. It needs to be a standard 80 series 4.2 turbo diesel without the separate overdrive select.

will check my speedo/ rev counter on the way to work this morning

mine is manual on 33s, but have checked speedo with GPS and its spot on

let ya know later

r u auto or manual? .

4.56 will correct your gearing back to standard...close anyway.

hahahahahahahaha

wot a cock I am

drove to work and forgot to look at speedo

have put an alarm into cell to remind me on way home

my stock 80 series sat on 2150 at 100km on 31's which was pretty acurate.

To find the correct ratio get new tyre size and divide by old tyre size x your old diff ratio should give you the new ratio you need EG 35(New size)divided by 29(old size?)x4.1=4.9 (so you'd need a 4.88 ratio)
Lots of formulas etc here
http://www.4lo.com/calc/geartable.htm

Did the same math H2o,, But used 31" as start point and assume 35" are 34.5" . = 4.56. If you are towing trailers etc then 4.88 is probly better . My 2c worth.

righto then

mine is a manual VX

4th gear 100kph was 2900 rpm
5th gear 100kph was 2500 rpm

and just to chuck another one in there

4th gear 50kph was 1600 rpm

these are not totally accurate as my speedo drive in the back of the dash is bloody noisy and the needle flickers quite a bit around 100kph, but it was very close.

hope this helps somewhat, although a manual may be completely different from an auto VX

SKID

skid wrote:righto then

mine is a manual VX

4th gear 100kph was 2900 rpm
5th gear 100kph was 2500 rpm

and just to chuck another one in there

4th gear 50kph was 1600 rpm

these are not totally accurate as my speedo drive in the back of the dash is bloody noisy and the needle flickers quite a bit around 100kph, but it was very close.

hope this helps somewhat, although a manual may be completely different from an auto VX

SKID

Like what he said, pretty much same same although I have 4.56 ratio and 35s http://www.4wdbits.co.nz/ProductDetails.aspx?productID=1

Diorama wrote:I,m trying to decide what diff ratio to put in my 1990 VX 4.2 diesel turbo cruiser. I am currently running 35' tyres but the vehicle is very hard to get rolling and sits at about 1800rpm at 100kph. What rpm did these cruisers do at 100kpm on standard factory tyres.

Manual 80 crusers are very low geared compaired with the auto's,my friend has a 80 manual on 35" Maxxis Bighorns and that spins 2200-2300 at 100kph with std gearing.

4.6 gears correct nissan safari's on 35's which has the same 4.1 ratio std,pretty much conforms what the other Boyz have said 4.56.

My safari auto on 35's is doing 1700 at 100kph,I know how you feel

Shane

Its an Auto. I had already done all the calcs and 4.56 should bring me back to standard. I do alot of towing so am considering 4.88 but I was concerned that it might start reving too high a 100kph. Currently it runs at about 1800 revs on 35's and feels as though its labouring at 100kph. When need to do a start on a hill with a load on the back it takes a long time to get moving and once i had to put it in low range. I have just had the whole gearbox rebuilt as I cooked it and I suspect that was due to trying to drive the big wheels. Just wanted to compare my calculations against what the stock standard revs would be to see how much extra it would be pulling.

Also what was the original standard tyre size on the 1990 80 series VX turbo diesel auto.

Diorama wrote:Also what was the original standard tyre size on the 1990 80 series VX turbo diesel auto.

open the drivers door and lookon the bottom of the B pillar for a sticker with the factory tyre size on it.

with my 33s and a car trailer and 40 series on the back, I have to stick mine in low range to move on a 30 degree slope, otherwise it will either stall or burn the clutch out