I'm putting a rear spool in tomorrow and discovered something weird and was wondering if anyone else can tell me what's up.

I went through my three diffs sitting in the garage and found
Ring 41 / pinion 10
Ring 41 / pinion 10
Ring 37 / pinion 9
Numerically, they are the same ratios. I believe that the 37/9 is out of an 82, the 41/10's are out of an 85 and an 87. Anybody else ever notice this, and which gears combo would you run??

I would think the 37/9 would be a stronger, since each tooth would have more meat.

Originally posted by AMJ
I would think the 37/9 would be a stronger, since each tooth would have more meat. My thought also, anyone else??

Are you sure one isn't a 7.5"?

Originally posted by zags
Are you sure one isn't a 7.5"? Well, they're still in the chunk from a Toy straight axle. I'm pretty sure they're not from a 7.5" .

83-older 4.11 diff's are 37/9 and are 8in 4cyl style diff's, in 84 they switched th the 41/10 ratio, any time you have more teeth to a pinion the stronger the diff will be, reason being: more tooth contact/more teeth contacting the ring gear at one time.

this is the same reason 5.71's are very weak, 6 teeth, 5.29's have 7, 4.88's and 4.38's have 8, 4.56's have 9 and 411's have 9, 410's have 10, and 390's have 10

:D

Originally posted by zags
Are you sure one isn't a 7.5"?

my friend and i had to switch thirds in his 84, the tooth count that came out was 41/10 and the 83 we swapped in was 37/9 i thaught that the 41/10 was stronger, due to both the ring and the pinion being bigger. and whatch out on the flanges for the driveshaft, the 84 and the 83 that we swapped were different and we had to drill holes in the flange of the 83 to be able to bolt the driveshaft up.:eek:

Originally posted by pitter


my friend and i had to switch thirds in his 84, the tooth count that came out was 41/10 and the 83 we swapped in was 37/9 i thaught that the 41/10 was stronger, due to both the ring and the pinion being bigger. and whatch out on the flanges for the driveshaft, the 84 and the 83 that we swapped were different and we had to drill holes in the flange of the 83 to be able to bolt the driveshaft up.:eek: I haven't looked at the flange, but it shouldn't be a big deal.

Originally posted by Todd
I haven't looked at the flange, but it shouldn't be a big deal.


yeah its not to big of a deal. all we did was drill new holes. but we din't replace the crush sleeve that we whould have:rolleyes:

Originally posted by pitter



yeah its not to big of a deal. all we did was drill new holes. but we din't replace the crush sleeve that we whould have:rolleyes:


why did you pull it off to drill it?? it can be done on teh diff IN the truck easily!

Originally posted by DSI



why did you pull it off to drill it?? it can be done on teh diff IN the truck easily!


well we pulled it first to see if the 84 flange would go onto the 83, but the tooth count and size difference off the teeth holding the flange was totaly different, so we had it off already, so might as well use the drillpress, we didn't change the crush sleeve nor set backlash and its still fine after about 10 000 miles and no signs of it leaking.