Hi all. According to the manual the ID codes for my axle is supposed to be next to the diff but as you can see from these images there is none (click image to enlarge it): <a href="http://picasaweb.google.com/lh/photo/tlG-abQWMxL_M0JRlr2qRA?feat=embedwebsite"><img src="http://lh4.ggpht.com/_qIfzkfjR_Nw/S7zOqe5OFcI/AAAAAAAAC8w/sx2FOilGfEo/s400/IMG_3495.JPG" /></a> <a href="http://picasaweb.google.com/lh/photo/AuEE9UJsCzhFjc3wluhR4w?feat=embedwebsite"><img src="http://lh6.ggpht.com/_qIfzkfjR_Nw/S7zOpDNFIaI/AAAAAAAAC8s/8J0pKMpBXMk/s400/IMG_3493.JPG" /></a> Am I looking in the wrong place? Is it possible to identify what kind of axle this is by this picture? <a href="http://picasaweb.google.com/lh/photo/CrFFUvmbXYlLzNSYpHYzqg?feat=embedwebsite"><img src="http://lh4.ggpht.com/_qIfzkfjR_Nw/S7zOr4FIlII/AAAAAAAAC80/FIVOzshu5W0/s400/IMG_3497.JPG" /></a> Thanks!
Thanks! Is there any way to figure out gear ratio, diff slip, etc w/o the ID code? How strong is this type of axle considered to be? I know 12-bolt is the "real deal" but I only have a mildly tuned 455 so I'm thinking it should be strong enough.
As far as I'm concerned, the 8.5 10 bolt is just as strong as a 12 bolt, especially if you upgrade the parts in it. The pinion shaft and pinion support is the same as a 12 bolt. The Buick 8.5's from 71-72 use bolt in axles, the 12 bolt is a C clip rear, advantage, Buick. I have a 1971 8.5 10 bolt Buick rear in my car. It has 30 spline Moser axles, matching Eaton Posi, and 3.73 gears. The 8.5 will handle a mild 455 with no problem whatsoever. If you want to know if it is posi, and the ratio, remove the cover and look at the ring gear. There will be 2 numbers stamped into it. Divide the smaller number into the larger, and you will have the ratio. Post a picture of the guts and we will tell you if it is a posi or not. You should pull the cover anyway to inspect things and change the oil.
It is indeed an 8.5 as it has the two stubs on the bottom.. just something to think about..if it came out of a g-body or s10-/s15 the azle tube is the same diameter as a 7.5 rearend which is 2 5/8...unlike the typical 3in tube diameter of the other 8.5 rears!
Another way to tell if you have a posi is by turning the axle on one side and see which way the other side turns. If they turn in the same direction it should be a posi. Bob H.
Buick suffix codes are usually facing down to the ground. NOT the front or back...That is pontiac and chevy. Check the bottom of the tube between the spring perch and the cast center on both the driver and passenger side. KEEP looking it will be there. Jim
Easiest way to check the ratio is to open the diff cover and wipe the edge of the ring gear while spining the ring gear. There will be a part number then the pinion tooth count number then next the ring gear tooth count and finally a date code. Just list all the numbers and will decode it. Jim It is a 8.5 1971 1972 rear for GM a-body cars.
Thanks for all the replies! I have confirmed that it is a posi. The reason I took the axle out of the car is because I want to change ratio so the current ratio isn't all that important right now although I need to know it sooner or later. The guy who I had planned to help me change gears isn't able to help me for another 6 weeks so I'll do it on my own. I have the factory manual (Detroit Iron CD) and the guy has quite a few guides on his web site. Can you point me to other resources for restoring a rear axle (not just change gears but going over the rest as well)? Is there anything in particular I should be concerned with (besides being thorough)?
www.jdrace.com free help just ask and send pictures will walk you through it as long as you have the patients. Jim
The ID code for the axle is LA B070 2. There's a number of numbers on the ring: <a href="http://picasaweb.google.com/lh/photo/KMLC6eDSR0f62082BJPhWg?feat=embedwebsite"><img src="http://lh3.ggpht.com/_qIfzkfjR_Nw/S8SyGOFWOKI/AAAAAAAAC88/oXo-nbPRYXU/s400/IMG_3534.JPG" /></a> Not sure what to divide with what...
Why change the 3:42 that is very nice gear for crusin and with a 455 it should have enough low end.I got 3:73 in my car with a 430 and it runs about 3000 to 3100 on the highway.Just my 2 cents
Not to question Larrys knowledge but I was told by the seller that it should be a 4.10 and it certainly runs like one as the revs are almost unbearable at highway speeds. Anyway - the parts are ordered and I've never changed gears before so I don't mind learning something new. :TU:
I'm only going by what I can see. I see what looks like a 41, 12, and then another number that I can't make out.
The gear pictured is an original gear and is 3.42 NOT 4.10 AS far as RPMs go at 60 3.42 will run close to 3000 rpms on the highway It is the ORIGINAL 1972 gear set part number then 12 - 41 (3.42 as larry stated) then 12 that would be the month December then finally 72 which is the year 1972. What gears did you order? Ratio that is?
@Larry: As I said, I didn't mean to question you, I was just confused as I had been told differently by the seller (who had no reason to lie). I guess he did anyhow. @Jim: I've ordered a 3.08. I guess that my mufflers makes it sound like the engine is working harder than it should as 60 mph feels very taxing on the engine (my tach is broken so I don't know the revs). In my world a big V8 chugs along at low revs (up to ~2500) at highway speeds but I've never driven an old V8 car before so my ignorance certainly helped fuel the belief that this was a 4.10 gear. Good thing I'm going to replace my mufflers as well then.
Can you put a 2004R or 700R4 in your GS? That gear ratio would match up very well with one of those trannys.... with the 700 in 4th and the lockup engaged it would be like having a 2.40 gear set...the 200 would be slightly less:3gears:
