urgent 45 diff help

[Matt_88]

Well i have blown up my rear diff and am replacing it this week.

I have pulled out the smashed one but before i put in my new one i just want to make sure on the diff ratios.

How can i tell what the ratio is on the one originally in there just by looking at it??

cheers

also would it be a good idea to run a welded rear diff with a injected 304?

[vk7ybi]

Count the teeth on the crownwheel, count the teeth on the pinion and divide.. Likely youll have 37 and 9.. 37/9=4.11.. Most gears have the tooth count or ratio stamped onto the perimiter of the crownwheel somewhere..
If the diff is welded good, it will work.. Get a Detroit.. I wonder which bits are blown in it, maybe you can install a Lokka?

[DIRTY ROCK STAR]

almost all are 4.11:1

a welded rear will be ok for a while. but if i were you, i'd buy a lockrite from the states.
the welded centre will be tough for on road use and wear out your tyres fast if you use it onroad.

[Matt_88]

ok kewl, I was just wondering it being is a 77 model i originally had 3.7's but i changed front diff to one with disc brakes which had 4.1's. Me not knowing this blew a front diff and a transfer case and just cant remember what diff i changed.

[RAY185]

ok kewl, I was just wondering it being is a 77 model i originally had 3.7's but i changed front diff to one with disc brakes which had 4.1's. Me not knowing this blew a front diff and a transfer case and just cant remember what diff i changed.

DOH!

[Punchy]

Since the back one is easy to rip apart i'd start with that and go from there

If you get stuck for a center drop us a line here i might have something floating around cheap