Badfish70

I'm trying to decifer the build sheet but can't seem to find a match for number on build sheet, looks like G37 or G87. Been searching online all the vette sites but can't match it. Anyone know good site axle decoding site? Seller said car has 4:11 which seems accurate. Just wondering if they are original. 350/350hp with M21.

LeMans Pete

4.11 gears were the "performance" gear recommendation for the L46 w/ an M21. You can see the combinations on the GM Heritage Center's site for the Vehicle Information Kits. Here is the one for 1970. Page 133 will have your combinations.

http://gmheritagecenter.com/docs/gm-...t-Corvette.pdf

Iceaxe

If I'm not mistaken 3.35, 3.55 and 3.70 we the axle ratios available with the 350/350 option. The 3.70 was not available with AC.

Edit: And 4.11 could be ordered with the M-21 (but not the M-20).

forman

I think they came with 3.70 gears ... you can check it by jacking the rear ,, marking your tire with tape or chalk ..then you mark the drive shaft with tape or chalk then turn the drive shaft one turn 360,, the tire should move about a quarter of the way or 1/4 that would mean its 4.11 ,, sometimes its marked on the pumkin


youtube videos help its very easy and painless to do

gbvette62

Could the RPO be G81, which was the order code for the Positraction rear axle?

Looking at the list of RPO's found in the front of all Chevrolet parts books, there was no G31 RPO, and RPO G87 was an 8 1/2" ring gear.

LeMans Pete

The two gear offerings with the M21 were 3.70 as standard, and 4.11 as performance.

3.36 (standard) and 3.55 (performance) were available with the M20.

I believe your options were standard, economy, performance and special (there was no economy or special gear with the L46). Could you specify the rear gear ratio outside of those options? I wouldn't think so.

Badfish70

Thanks everyone for ur help, it definitely is an L46 350/350 M21 with no a/c and only power steering it's says posi G81 on sheet but below says axle ratio and looks like G87 or close to it, the 4:11 in it now may be original? As it was an option? Oh we'll. thanks again all

LeMans Pete

Mr. Fish,

Jack it up, climb on under and check the differential carrier housing. If original, your rear axle code will be stamped in the bottom followed by a date code and the W (for Warren assembly plant) and E (for the Eaton Positraction). CFB will be your 4.11 posi gear, CAO will be your 3.70 posi gear. If you find another code post it!

Easy Mike

G81 indicates an optional ratio for the Posi. G87 would indicate the actual ratio. If memory serves, Dr. Dobbins' book lists the ratios. I can check it this evening.


My hunch is that G87 would be on the Corvette order copy for 1970 if anyone happens to have an example handy.

SB64

That's right Pete I was going to suggest that he look at my thread where a chart is displayed showing the different codes, as you well know.
R

Badfish70

Thanks for the help guys, do you have a link for your axle thread?

69 Chevy

The hood, side exhaust cover and paint color are all incorrect for 1970.
What makes you think the drivetrain has not been molested?

I scanned this page from M. F. Dobbins Vette Vues Factbook 68-72, 3rd edition.

[IMG][/IMG]

Rowdy Rat

GS# and GV# called out specific rear axle ratios. Not all cars used them and I am also not sure as to what caused them to be used. I do know that I need to start researching this.

I can tell you that my old 1970 LT-1 had a GS4 code and had a 3.70 to 1 rear axle ratio. That is the standard power team for this combination, but the M-21 was an optional transmission so I am not sure if this had any impact on the code. I still have a 1970 LT-1 with an M-21/4.11 combo... I'll have to check and see what that is.

I can also tell you that GV7 for 1970 appears to be a 3.55 to 1 rear axle ratio, but I'm not sure how/if it has any relevance to what GS7 was.

Bottom line is, GS7 is going to specify a rear axle ratio... We just don't know why (yet!).

Regards,

Stan Falenski


Edit: The GV# appears to be for standard power teams. The LT-1 M-21/3.70 combination is standard too, but the M-21 is an optional transmission so I guess that is why it is listed as GS4.

Rowdy Rat

Well, so much for the theory that GV was a standard power team indicator... My current 1970 LT-1 with M-21/4.11 is GV8. Definitely not a standard power team.

Regard,

Stan

Badfish70

I already said the hood, obviously the color and the side exhaust are not original but it's what I wanted, and not looking for a concours accurate car, just want something I like and will drive hard as often as I can, I was just wondering if maybe the gears were original, but I don't care, I'm swapping the 4:11s anyway for 3:55s, thanks for your "help" it was just an inquiry. I love this car, sorry u don't, here another pic of my non accurate hood for your enjoyment