74 rear end gearing

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Oct 23, 2016 | 08:52 PM

vmsns007

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Joined: Apr 2016

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From: Fishers Indiana

74 rear end gearing

Driven gear is bad. I understand that to replace I need to know my rear end gearing and tire diameter. My tire diameter is stock but what is the factory gearing on my base engine 74? Any way to tell from differential markings although mine is unchanged from stock

Oct 23, 2016 | 10:27 PM

cobrachuck

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Joined: Mar 2006

Posts: 539

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From: SW Ohio

Automatic or 4 speed car?
Stock rear gear for automatic is 3:08 I would need to search for a stick shift car.
Now the ratio numbers are found on the bottom of the rear end date codes as well.
My stock 75 L48 auto were
AW = 3:08
Good luck

Oct 23, 2016 | 10:32 PM

cobrachuck

Pro

Joined: Mar 2006

Posts: 539

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From: SW Ohio

Found it, from Vette.net. Sorry looks like I was mistaken,
Transmission

Automatic Manual
Type 3-Speed Automatic 4-Speed Manual
Gear Ratios
1st 2.48 2.52
2nd 1.48 1.88
3rd 1.00 1.46
4th NA 1.00
Reverse NA NA
Axle Ratio NA NA
Final Drive Ratio 2.73auto 3.55 manual

Oct 23, 2016 | 10:40 PM

vmsns007

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Joined: Apr 2016

Posts: 207

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From: Fishers Indiana

Thanks. Yes it's a 4 speed. Warner transmission I believe for a June 1974 car with base L 48 engine (198 HP).
So if I read this correctly my car is geared at 3.55?

Quote:

Originally Posted by cobrachuck

Oct 24, 2016 | 07:09 AM

BKarol

Melting Slicks

Joined: Sep 2004

Posts: 3,227

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From: Northeast

This is from the gm heritage center. It appears that you could have a 3.36 which is std or the econ 3.08. Page 34 or 49 .

https://www.gmheritagecenter.com/doc...t-Corvette.pdf

You might want to download this file for future reference.

Oct 24, 2016 | 09:38 AM

Grahamred70

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Joined: Sep 2015

Posts: 216

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From: Haverfordwest Pembrokeshire

Quote:

Originally Posted by vmsns007

Thanks. Yes it's a 4 speed. Warner transmission I believe for a June 1974 car with base L 48 engine (198 HP).
So if I read this correctly my car is geared at 3.55?

Only way to be sure is jack up the back with both wheels off the ground, turn the road wheel one turn and count how many turns the drive shaft does, I think mine came with a 3.55 or 3.36 but when I checked it was a 4.56 so no wonder it felt like I was in 2nd gear all the time!!
I'm changing for a 3.36 over the winter along with a new clutch and a gearbox overhaul so should be a lot more civilised.
Graham

Oct 24, 2016 | 02:05 PM

cardo0

Le Mans Master

Joined: Oct 2002

Posts: 7,098

Likes: 378

From: Las Vegas - Just stop perpetuating myths please.

If you have the differential cover off or the differential out of car counting the teeth is a definite way to find it. FWIW my '74 L48 w/4sp had 3.36 gearing when I took them out. Chevy offered nearly all the ratios as an option so you would need your options/build sheet to know what came with your car.

Oct 25, 2016 | 02:51 AM

Richard Daugird

Melting Slicks

Joined: Dec 2015

Posts: 3,181

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From: Texas City, TX Texas

Quote:

Originally Posted by Grahamred70

^This^ Who knows what has been done to that car in forty years.

P.S. What ya gonna do with them 4.56???

Last edited by Richard Daugird; Oct 25, 2016 at 02:52 AM.

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Oct 25, 2016 | 04:59 AM

Grahamred70

Instructor

Joined: Sep 2015

Posts: 216

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From: Haverfordwest Pembrokeshire

Quote:

Originally Posted by Richard Daugird

^This^ Who knows what has been done to that car in forty years.

P.S. What ya gonna do with them 4.56???

Haven't thought about it but if anybody wants it I'll sell it, after all I'll never use it, could work well with one of those fancy 6 speed trans? It seems to be in good nick, doesn't whine or anything so should be worth good money to somebody.
Graham