Hi All, I've hoping to get to the bottom of my diff ratio query ,no pun intended. I now believe I have a Salisbury Axle (drums) fitted to my mk1 escort project. What i can't figure out is why and where does a diff ratio of 2.1 derive from and why fit that to a mk1 escort ?? Yes ive checked and double checked!! Any thoughts!!? Ronnie

 

2.1 seems rather unlikely.

 

Hi, yes it does but thats what it is..im now just curious and determined to find out what ive got or have been landed with. Its just a Learning curve for, I enjoy the knowledge . It'll obviously be getting changed .

 

Just how exactly are you determining this ratio ?

 

I'm jacking up one side of Rear axle, no prop connected. I then mark bottom of tyre at 6 o'clock that's off ground. I do the same on diff flange accept I have that marked 1 to 10 for an accurate reading. I then rotate the flange till the tyre has completed 1 full 360 rotation ...it only takes just over 2 full turns on the flange to complete one full turn of the tyre. Is that correct ? Ronnie

 

So you're turning only one wheel ? Which will likely result in a 2x wrong reading ?

So it's more likely you have a 4.2 or thereabouts ?

Most diffs have an ID tag on them to indicate ratio. Or if you can open it you can count the teeth on both.

Or if you want to test via the method you describe...both wheels must be in the air and free to rotate, and ideally you'll turn the input flange on the diff and count rotations until a single full rotation of both wheels.
Both wheels must be free to rotate.

 

steve, yes your right mate.. Not tried it but I suspected that can only be that. I was going to post a pic of the msg from my " mate" telling me to only jack up one wheel but what the he'll...maybe he thought he was being funny . Any cheers for that, solved even though I feel like an idiot lol. Regards Ronnie

 

On an old school Mk1 Escort a 3.9 diff ratio would be my guess.

 

Hi..,👍⚙️🛠..after one wheel aff the ground... Diff ratio 2.1? Then both wheels of the ground not much help either, so opened her up 4.1 not what im after but least I know now. Cheers for the posts

 

4.1 diff ratio is ok should give a pretty good top speed.