Diff ratios again .....

[Gordon]

Hi All

I've spent a good few ours going through all of the diff related posts on the forum and eventually decided to start a new post as my mechanicals differ somewhat from the more common setups. So apologies up front to all those who are sick of diff postings

I'm running the factory standard 4 cylinder option - the Vauxhall Victor 2.3L slant motor behind a standard 4 speed manual Bedford gearbox. I don't have any plans to change this setup. The diff is the standard 4.1:1 factory option and I am suffering with the usual complaint. She pulls like a feight train but tops out at about 80km/h. You can push her a bit further but she is over revving at that stage. We have had a failed attempt at installing a Cresta diff centre and Murray from McQuoid Engineering is now suggesting that we look at modifying the axle to accept a Ford Falcon diff centre. This gives us plenty of spares going forward and also a great deal of choice in terms of the ratio.

So the question now is around the ultimate ratio for my setup. In terms of weight the van is factory standard with only some light carpeted wood panelling in the back and an aluminium framed double bed base. In terms of future use the van will mainly be used for cruising and camping and we also plan to tow a jet ski at some future stage. The ultimate setup would allow us to cruise happily at 100km/h on the open road and with just enough grunt to make driving around the suburbs pleasant. Improved fuel economy would be a bonus, but isn't essential.

Any advice  would be greatly appreciated.

[ben]

3.45:1 i dont think youd bother going 3.89 as its not enough difference to the 4.1 to worry about. 3.45 will be the ratio you want. wouldnt want to go any taller with a 4 cyl! good for driving at 100 althou still reving a bit will be ok for towing small stuff.


i have a question for you new zealand blokes. do you guys ever get holden 6's in your vans or were they are slant 4's? i recon the holden 6's are sluggish image a slant 4!

cheers
ben

[Merlin]

3.23  3.23  3.23  3.23  3.23  3.23  3.23  3.23  3.23  3.23  buga i'm repeatin myself  i have found this to be the best comprimise between torque & cruising speed  cheers neil

[Numnutz]

I agree with Ben, some thing around 3.4:1 or 3.5:1 would be you best option, she would still have some get up and go off of the line, but would also have a bit more top end  speed.

[BusyKiwi]

the ford option is the borg warner, which came out in ford and holden and others. fords mainly did the 2.xx and 4.xx while holden did the 3.xx  (the xx is various numbers).

I'm changing my ratio from 3.08 to 3.45 (down at murrays tomorrow)

Give steelie gears a call, sorry forgot his name, he is really good on ratios vs rev vs speed

[Bas NZ]

Sorry guys, 3.5 is to high for a 2.3 litre 4cl, great behind a six but a 4 I'm not sure, ok Gordon just pulling your leg, maybe what you want it for it maybe ok, just keep in mind those open roads in NZ with slight hills, as I said before you only have a 4 speed and 3rd gear is not a driving gear, so you can't stay in it forever David let me know how it dives when done, would be interested to find out.

Hay has anyone put a 5 speed behind a 2.3??

[Merlin]

welllll i dont agree with ben .....so there   3.5 will be to high were talking about a pizzly 4 cyl here its absolute max rpm would be 5000rpm i could sit here and work out the roadspeed/rpm but i cant be stuffed ...its been a long hot shit of a day and i need a drink!!!

[obsession]

have had most , best one for me was 3;23 with Holden 253 was very reliable combo

[Bas NZ]

Yes, someone thinks the way I do...................

[LS120]

I went the Holden 3.45 Diff with a 6cyl holden & 4 speed box & its a good combo. 3rd gear up hills but 2nd in the big ones..

100k plus at 2,200rpm 80km at 1700rpm thats pulling 2.4tone (camper )