How can you tell what gear ratio you're running?
02-27-2003, 03:11 PM
#1
Drifting
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How can you tell what gear ratio you're running?
Without having a build sheet available, how can I tell what gear ratio I'm running in my differential?
02-27-2003, 03:37 PM
#2
Re: How can you tell what gear ratio you're running? (RCB69L36)
Look at the bottom of the differential near the back of the unit where the plate attaches. There is a number stamped on there. Take that number and look it up in "Catalog of Corvette ID Numbers" and it will tell you what gear ratio was installed in that housing. Now, that doesn't take into account what someone else may have done in changing the internal gears... Here are some ideas on what the codes mean
1969 codes
AK - 3.36
AL - 3.08
AM - 3.36
AN - 3.55
AO - 3.70
AP - 4.11
1969 codes
AK - 3.36
AL - 3.08
AM - 3.36
AN - 3.55
AO - 3.70
AP - 4.11
02-27-2003, 03:41 PM
#3
Melting Slicks
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Re: How can you tell what gear ratio you're running? (RCB69L36)
That's super easy. Drive down the road in 4th gear for a standard or I believe 3rd in an automatic, not OD. (Need 1:1 gear ratio)
when you are doing 75 mph, look at the tack, if you are doing just a hair above 3000 rpm, you have 3.08s, if you are doing about 3300-3400 thats a 3.36, 3500 -3600=3.55, 3700=3.70, 4100=4.10
Got it?
when you are doing 75 mph, look at the tack, if you are doing just a hair above 3000 rpm, you have 3.08s, if you are doing about 3300-3400 thats a 3.36, 3500 -3600=3.55, 3700=3.70, 4100=4.10
Got it?
02-27-2003, 04:04 PM
#4
Re: How can you tell what gear ratio you're running? (Evan Ginsberg)
That's super easy. Drive down the road in 4th gear for a standard or I believe 3rd in an automatic, not OD. (Need 1:1 gear ratio)
when you are doing 75 mph, look at the tack, if you are doing just a hair above 3000 rpm, you have 3.08s, if you are doing about 3300-3400 thats a 3.36, 3500 -3600=3.55, 3700=3.70, 4100=4.10
Got it?
when you are doing 75 mph, look at the tack, if you are doing just a hair above 3000 rpm, you have 3.08s, if you are doing about 3300-3400 thats a 3.36, 3500 -3600=3.55, 3700=3.70, 4100=4.10
Got it?
02-27-2003, 04:23 PM
#5
Burning Brakes
Re: How can you tell what gear ratio you're running? (Evan Ginsberg)
Evan,
I can't vow your simple idea is 100% foul proof, but it sure works for mine. I have a '79 3-speed Autom. with a 3:08 rear (a prior owner changed it from the stock 3:55). I also have the optional 255/60/15 tires and at 75MPH I am almost exactly at 3000RPM. I figured that's why one of the prior owner's changed the gear. At 75MPH which is cruising speed on H-Ways these days, I would be at 3,600RPM instead, and I imagine that's a lot more strain on the engine plus a lot noiser.
I can't vow your simple idea is 100% foul proof, but it sure works for mine. I have a '79 3-speed Autom. with a 3:08 rear (a prior owner changed it from the stock 3:55). I also have the optional 255/60/15 tires and at 75MPH I am almost exactly at 3000RPM. I figured that's why one of the prior owner's changed the gear. At 75MPH which is cruising speed on H-Ways these days, I would be at 3,600RPM instead, and I imagine that's a lot more strain on the engine plus a lot noiser.