Hi all,

I've got a 1995 129 WB 5.2 B2500 van and wondered a few things please.

1. How can I tell what rear end ratio I have? I have the vin number, would that tell me? Or do I need to go under the van to read off a number on the rear end?
2. Has anyone reduced the ratio on their van and got an improvement in MPG? (I do a lot of highway with low payload so wouldn't worry about losing towing power etc)
3. Is it as simple as buying a new ring and pinion like this and having the mechanic swap it over or is there more to it than that?

https://www.autozone.com/drivetrain/...17_486916_6064

4. I've found a 2.76 ratio as the lowest so far, does anyone know if this is actually the lowest? My thinking is that the lowest number would give the best mpg seeing as I don't haul or tow etc

I don't have a tach on this van so can't tell what the revs are at 70mph but it feels high so wondered about the whole overall idea of the above.

Thanks very much guys

 

1. There should be a tag with the ratio under one of the bolts holding the differential cover on.

2. I haven't.

3. Yes, plus you have to have the speedometer calibrated to the new ratio.

4. I believe that's the lowest ratio you can go.

Some scan tools that read live data will display operating parameters including the current RPMs. That's one way to can find out what the RPMs are at a given speed.

 

The ratio might be stamped into the end of the pinion where the u-joint is located.

 

Hey all,

Found two little metal tags on separate bolts on the diff cover, both dirty so need to clean off and check again but it looked like one read 35 (I was hoping for another number there but seems to be only a 3 and a 5) and another something like 0932 which doesn't seem helpful.

Could the 35 mean 3.55 gear ratio maybe?

I will also check the this bit too "The ratio might be stamped into the end of the pinion where the u-joint is located."

Thanks

 

Probably 3.55's then.

 

It does sound like it would be, hopefully that's the case.

Thanks

 

Makes sense to me too.