Mk1 diff question

[bulls in transit]

Got a mk1 Firevan with 5:8 diff,looking to change ratio to a 4:63.
Took a gamble on a c/w&p set off of eBay(just listed as mk1/2).
Arrived today(in Spain),reason took gamble was that in photo after part no(which I couldn't find to confirm),stamped on c/w is 8-37(thought might be last whole no.,divide by 8 becomes 1:4.625),so thought might be what I'm looking for.
Before I take diff apart to change just wondered if anyone would be able to confirm that I've got the right bit,what else I would need(read the ken b thread on later c/w&p)ie tools,parts etc.,or I'm wasting my time with wrong part,axle in vans silent,low miles,so was looking to change as little as poss.,know I need crush washer but was looking to reuse bearings etc.
Part no on c/w is72Vb-4210-CA. 8-37 C9.
Might even be the wrong bit,really just took gamble cos of the 8-37 stamp,thinking it would be a 4.63 c/w&p.
.

[bulls in transit]

Tried to get more info off of motomobil site,they list( but don't stock the one I need anymore) two c/w&p,one for 10 bolt diff,one for 12 bolt cover,10 bolt one has 25 splines to pinion flange,don't say how many for 12 bolt but counted one I've got it's got more than 25,so it's for a 12 bolt or another axle altogether.
Pics in manual and on motomobil site can't really make out pinion too clear(pics look generic),is the only way to see for sure to take apart what's on van?
Has anyone got a pinion for a 12 bolt twin wheel out of Van that they could post measurements of(total length,dia of two bearing surfaces) before I take apart,van is only transport,don't want if off road unessesarily here in Spain.

[Guy88]

if it helps in my A series (same axle as transit) i have a MK5 crown wheel and pinion fitted,

Pinion is different but only on the drive flange which was a lot bigger, i used a MK6 flange and nut (threads were the same)

crown wheel bolted strait to the original carrier and is all in and working

sounds like you may have a later set

[Guy88]

also to work out ratio, count the teeth on pinion and crown wheel,

Divide pinion teeth by crownwheel teeth to get ratio

[bulls in transit]

Thanks Guy,just counted teeth pinion 8 crown 37.
37div by 8 is 4.625,8div 37is .216(but that goes into one 4.629 times),so I'm thinking it's the ratio I was looking for.
Just thought,if I unbolt/drop prop at pinion flange,new one came with new nut,could see if thread matches first,if does undo existing nut(need to order seal first) and count splines on pinion,before taking rear cover/diff out,that way should be able to see if I need a different flange before changing.

[Guy88]

Thanks Guy,just counted teeth pinion 8 crown 37.
37div by 8 is 4.625,8div 37is .216(but that goes into one 4.629 times),so I'm thinking it's the ratio I was looking for.
Just thought,if I unbolt/drop prop at pinion flange,new one came with new nut,could see if thread matches first,if does undo existing nut(need to order seal first) and count splines on pinion,before taking rear cover/diff out,that way should be able to see if I need a different flange before changing.

Yep, and on the MK1 you wont need a new colapsable spacer as there isnt one

[Luke]

might be some help viewtopic.php?f=3&t=111158&p=936115