What rear end gear do i have?

[chev74]

WHile cruising down the road at 2700 rpm, going 65mph with 32" tires behind an SM465 tranny?

i know there is a formula for all this, so even a link to the correct site would help. My rear end has no markings on it, I have looked.

Thanks in advance

[LONGHAIR]

It is probably 3.73 but could also be 4.10...it depends upon the accuracy of your speedometer and the actual (measured) diameter of the tire, not just the size marked on them.

[larry may]

[QUOTE=chev74;2673254]WHile cruising down the road at 2700 rpm, going 65mph with 32" tires behind an SM465 tranny?

i know there is a formula for all this, so even a link to the correct site would help. My rear end has no markings on it, I have looked.

Thanks in advance[/QUOTE

http://www.csgnetwork.com/multirpmcalc.html Could be this may help

[OrangeCrush1970]

I just figured this out yesterday. I thought I had a 4.11 but NOPE! It's a 3.07. Im turning 3k rpm at 65 mph.

check out this post and scroll down to #6
http://67-72chevytrucks.com/vboard/s...d.php?t=286975

Post #6

Find the ID stamp and then go to americanclassic.com and use their VIN decoder to find your stamp ID.

That fail safe way though is to pop your rear cover off and look at the stamp on your ring.

[LockDoc]

Try this link, post #6:

http://67-72chevytrucks.com/vboard/s...d.php?t=286975

LockDoc

[OrangeCrush1970]

Originally Posted by LockDoc

Try this link, post #6:

http://67-72chevytrucks.com/vboard/s...d.php?t=286975

LockDoc

That stamp was right where you showed me Leon!

[LockDoc]

Originally Posted by OrangeCrush1970

That stamp was right where you showed me Leon!

Sounds good. They can be hard to see if you not sure where it's located. Glad you found it.

LockDoc

[67ChevyRedneck]

Originally Posted by LockDoc

Sounds good. They can be hard to see if you not sure where it's located. Glad you found it.

LockDoc

Looked mine up a couple years ago too, that's how I found out for sure it was a 3.73.

[lukecp]

Originally Posted by OrangeCrush1970

I just figured this out yesterday. I thought I had a 4.11 but NOPE! It's a 3.07. Im turning 3k rpm at 65 mph.

check out this post and scroll down to #6
http://67-72chevytrucks.com/vboard/s...d.php?t=286975

Post #6

Find the ID stamp and then go to americanclassic.com and use their VIN decoder to find your stamp ID.

That fail safe way though is to pop your rear cover off and look at the stamp on your ring.

Unless you have some really, really short tires, or your tach or speedometer is off, you have lower gears than 3.07. With 3.07 gears and a 28" tire you should be about 2500 or so RPM at 65.

Best way to know what gears you have for sure is to pop the cover and have a look. The number of teeth on the ring and pinion will be stamped on the outer edge of the ring gear. For example, if it has 41 10 stamped, 41/10 = 4.10 gears. The fluid probably needs to be changed anyway.

[OrangeCrush1970]

Originally Posted by lukecp

Unless you have some really, really short tires, or your tach or speedometer is off, you have lower gears than 3.07. With 3.07 gears and a 28" tire you should be about 2500 or so RPM at 65.

Best way to know what gears you have for sure is to pop the cover and have a look. The number of teeth on the ring and pinion will be stamped on the outer edge of the ring gear. For example, if it has 41 10 stamped, 41/10 = 4.10 gears. The fluid probably needs to be changed anyway.

At this point, nothing much will surprise me. I do know that my spedometer is off as Im running 31" tires, I hope that my tach is off but the rev's of my engine seem to be in the neighbor hood of what my tach is showing. The axle housing doesnt look like it'll hold 4.11 gears either and we've had several eyes on it (my rear end). The next step will certainly be to pop the cover off, but it's full of fresh purple juice so Im reluctant, but it's gonna happen.

[chev74]

thanks fellas! ill see what i can do...