Working Out The Ratio

[Rogue Trooper]

Hi Guys

Could anyone please tell me how to calculate the diff ratio by spinning the wheels please? I know it's been posted a thousand times (mainly by Ben  ) but do you think I can find the damn thing. Search just isn't working for me today.

My diff with the Cresta innards is out of the van and sitting in my carport irritating me so I want to get rid of it. Would be nice to be sure of the ratio before I advertise it.

Ta very much.

[obsession]

mark a point on the wheel drum and backing plate, mark the diff yoke to housing slowly turn the wheel around once and count how many times the center shaft turns tip-ex or a white out marker is good to use.

[Rogue Trooper]

Thanks Craig. That's what I thought but the yoke turns about 1.9 times for every turn of the drum and that's not right.

[hunterbynature]

take the backing plate of rogue, ratio is stamped on the crown wheel

[Gordon]

Hi Rogue

I did the exercise this weekend. Looked up one of Ben's earlier posts to double check the process first. My axle is still in the van, but I used the following process. Jacked up one back wheel. Marked a position on this wheel using a strip of masking tape and a similar piece of tape on my back fender. Marked a vertical line on both bits of tape using a pen and a spirit level to make sure the both pen lines were 100% aligned.

Then climbed under the van and used two bits of tape to mark a point on the diff housing and on the drive shaft flange. I turned the drive shaft by hand whilst my missus watched the wheel. The wheel had to make two rotations. Ben made the point in his posting that you need to make sure that the jacked up wheel makes 2 rotations as it is essentially doing the work of two wheels (hope this makes sense). For 2 rotations of the wheelthe drive shaft rotated 3.45 tunrs, so I worked out my ratio at 3.45:1. Using the same logic for your findings it yours would equate to a ratio of around 3.8:1. I think the Crestas came in two ratios being 3.54:1 or 3.9:1, but others with more experience should be able to comment. Hope this helps

[hunterbynature]

also came in 3.7, i have a 3.45,  3.7 and 3.9

[Rogue Trooper]

take the backing plate of rogue, ratio is stamped on the crown wheel

Thanks Steve. I found your earlier post regarding that but I really don't want to have to find something to seal up the rear end again.

The wheel had to make two rotations. Ben made the point in his posting that you need to make sure that the jacked up wheel makes 2 rotations as it is essentially doing the work of two wheels (hope this makes sense). For 2 rotations of the wheelthe drive shaft rotated 3.45 tunrs, so I worked out my ratio at 3.45:1. Using the same logic for your findings it yours would equate to a ratio of around 3.8:1. I think the Crestas came in two ratios being 3.54:1 or 3.9:1, but others with more experience should be able to comment. Hope this helps

Aha, that did the trick I got 3.45 as well which is one of the ratios available so that makes sense. Thanks very much guys!

[ben]

could we make this post a sticky post in the diff section shane? so its easier for people to find in future.. its always gunna be something that people are gunna be asking.

cheers
ben

[Warren]

Stickied for you Benny Boy

Warren