My car is coming up for the 500 mile service on the rear end and I want to put on that fancy aftermarket W27 cover, I have a 65 8.2 rear end and the cover is advertised to fit 70-72 8.5 rear ends. I thought both these rear ends took the same cover anyone know for sure?

 

Fusick has 2 covers listed: one for 71-72 (10 bolt) and one for 70 (12 bolt) only.

If you asked Monzaz or 507OLDS they would know for sure. My guess is one of those covers will probably fit.

 

Different bolt patterns between the 64-67 8.2 10 bolt and the 71-up 8.5 10 bolt, so no, the the W-27 cover will not fit your 65.

 

500 mile rear end service??
Hope you meant 50,000!
Wow - that's worse than 3,000 mile oil changes!

 

I rebuilt the rear end and it's suppose to be serviced after 500 miles.

 

I've got a question that I'm sure a few of you around here will know the answer to......

I think I read somewhere that the last year for the 12 bolt rear ends for the 442/Cutlass was 1970, is that true?

 

i believe you can get a blank w-27 cover{no bolt holes drilled} through one of the venders.

 

That's what I understand. The Assembly manual for 71 shows a 10 bolt.

Charlie? I don't think so, that's why they make 2 different styles - 12 bolt cover and 10 bolt cover. Why would they ever leave drilling the holes to chance by selling a blank?

 

That's what I thought. I knew I read it somewhere. I have a guy who lives a few miles from my place who considers himself and expert on all muscle cars (he's a Chevy guy.....nuff said)

Anyways, he told me my car wasn't worth much because it had the 10 bolt rear end. To which I told him that the 12 bolt rear ends were discontinued after 1970 (in the Cutlass/442, not sure about the rest?) and he claimed I didn't know what I was talking about. I figured I'd ask some of you guys who really know your stuff!

 

Don't forget that the 12bolts were brought in during the 60's for the HP wars. More power needed stronger axles/carrier. By 1971 the HP wars were lost and GM amongst other manufacturers were forced by Insurance costs of all things to lower HP in order to sell product that was easily insured. If you're not building a street racer, the 10 bolt will be just perfect and there's a plentiful supply of parts for them, unlike the 12 bolt. Although 12bolts are stronger, you don't need that for most of the driving that these cars were designed for. Your friend probably thinks that what chevy supplied was universal to all GM brands. According to this link 10 bolts became the standard in 72. http://novaresource.org/axle.htm#1972
There may be other web links that can prove or disprove anything anyone wants to say.

If you want an interesting read and a source of good info (Jim - Monzaz and Brian - 507OLDS) take a look at this: https://classicoldsmobile.com/forums...lt-type-o.html

 

Actually my friend thinks he is the "be all/end all" to knowledge of muscle car parts. I'm always happy to prove him wrong. Although I always need written proof and then he conveniently gets amnesia and forgets that he made those comments.

I knew the 12 bolt was a stronger rear end. There used to be a 70 around here with a 350, factory 4 speed in it and the 12 bolt rear end. The car was drag raced with a 425 c.i. in it. But it was a factory 350 car according to the vin tag.

I'm gonna check out that thread when I'm done wrenching on the 455 tonight.

Oh and I keep forgetting to mention.....my name is Eddie, by the way. I'm used to being called Olds on other forums because they are Oldsmobile related, but being called Olds on an Oldsmobile forum can get confusing.

 

Yeah? Ask him about a Type O axle...

First, unless the car was built in Canada, Olds NEVER installed a "12 bolt" axle in the Cutlass line. The Chevy-style 12 bolt uses twelve bolts to hold an 8.875" ring gear to the carrier. The fact that the cover also has 12 bolts is coincidental. As I noted above, Canadian-built Cutlii DID get this Chevy 12 bolt from the factory.

For the 1967-1970 model years, Cutlii built in the US got the Type O axle. This has 12 bolts on the cover but only ten bolts holding an 8.5" ring gear. Note that the Chevy 10 bolt axle of the same period also used ten bolts to hold an 8.5" ring gear, however no parts interchange between the two. The Type O DID use bolt-in axles instead of the stupid C-clip retainers on the Chevy axles.

 

Charlie? I don't think so, that's why they make 2 different styles - 12 bolt cover and 10 bolt cover. Why would they ever leave drilling the holes to chance by selling a blank?[/QUOTE]

i only mentioned it as i saw 3 or 4 blank w-27 covers at the parts place last year sitting on the shelves.

 

Ahh, the rejects! or defective returned ones...

 

I definitely didn't know any of that! It could have been built in Canada, but I'm not sure. But......he's one of those guys who fill you full of crap then deny after you prove him wrong.

I like hearing these type of details about these cars because there's so many things I didn't know.

 

The 12 bolt Chevy rear is potentially stronger, but stock axles and C-clip axle retention are not great.

 

I guarantee you that a 71/72 8.5 is a stronger better rear than the 'O type' 12 bolt rear. The 8.5 axles have a larger diameter between the splines and the bearing surface than the Type O axles. I put the 8.5 on equal or better footing than the 12 bolt Chevy because with a Chevy,the lower the gear the smaller the pinion gear. The smaller the pinion gear,the more chance of failure. The 8.5 doesn't have that problem.The Chevy takes less HP to operate than any other rear but the pinion problem keeps it out of high HP drag cars. The 8.5 rears are plentiful and are as cheap to build as a Chevy. Ask Brian Trick-507Olds about the 8.5 rear,he'll tell you about them.

 

That is true. You can't get pro gears for the 8.5 or Type O, but you can for the 12 bolt Chevy. You just have to spend a good bit of money upgrading the Chevy to get the strength potential.

 

That's really easy to find out. Look at your cowl tag. The plant code for Oshawa is OS

But if it's truly a 442? They were all built at Lansing

 

The two that Fusick sells are repros of the factory style covers for the Type O "12-bolt" and the 71-72 10 bolt housings. Some vendors sell blank covers so you can drill them to fit a Chevy 12-bolt housing, though I believe Supercars sells them already drilled for that application.

 

They built 442's in Canada,only the W-30 cars were built in Lansing. All of the Canadian built 442's had 12 bolt Chevy rears. I don't know if that's what you meant or not,just sayin what I know about them.

 

As noted, 442s were built at all A-body assembly plants, including Oshawa. My first 442 (a 1968) was a Canadian-built car. In any case, the VIN will tell you exactly what you have and what assembly plant it came from.

 

No.......my car has the 10 bolt. It was built in Fremont California.

I was referring to a 70 350 car that had a 12 bolt rear end. It was sold a few years ago and I think it ended up in northern New Brunswick?

 

You said it better than I did; thanks eh? I was thinking about Olds 71 442 avatar pic when I was typing that comment. Yes, I do know that 442's were not exclusive to Lansing.