1969 350ci/300hp C3 Clutch Diameter

[Terry M.]

Re: 1969 350ci/300hp C3 Clutch Diameter

Joseph-----


As far as spline count, all 63-70 were 10 splines. No exceptions. 1971+ were 26 splines except 78-79 with L-48 and "Muncie" transmission.

As far as size goes, all 63-68 small block, 65 L-78, 67-69 L-88, 69 ZL-1, 70-72 ZR-1, and 78-79 L-48 with "Muncie" trans were 10-1/2 (10.4)". All others were 11".

I don't know why the parts books can't get this right. I suspect, though, that what they're doing is mixing things up with other Chevrolet applications. Some of those did differ from the above. For Corvette applications, the above is how it was.

Back in the mid-1970s I ordered a replacement disk and release bearing for my 1970 LT1 from my usual Chevrolet parts guys. These guys were and are among the best in the Chicago area for sorting out these kinds of inaccuracies. I didn't change the release bearing until a little more than a decade later and they sure enough got me the wrong release bearing. So even the best parts people "back in the day" sometimes got it wrong. Too bad I didn't know Joe Lucia back then.

[Joe L.]

Re: 1969 350ci/300hp C3 Clutch Diameter

Back in the mid-1970s I ordered a replacement disk and release bearing for my 1970 LT1 from my usual Chevrolet parts guys. These guys were and are among the best in the Chicago area for sorting out these kinds of inaccuracies. I didn't change the release bearing until a little more than a decade later and they sure enough got me the wrong release bearing. So even the best parts people "back in the day" sometimes got it wrong. Too bad I didn't know Joe Lucia back then.

Terry-----


The release bearing mix-up is VERY common, particularly in the "old days". Most Chevrolets prior to about 1965 used the 1-7/8" long release bearing. So, many parts countermen just assumed that ALL Chevrolets used this bearing. Some parts catalogs are incorrect, too, but GM parts catalogs usually had it right.

After about 1965, most Chevrolets went to the 1-7/32" long release bearing which was later changed to 1-1/4".

The only Corvette, though, that EVER used a 1-7/8" long clutch release bearing was early 1955 V-8. However, there were LOTS of folks with later Corvettes that were sold a 1-7/8" bearing, NONE of whom could ever make it work. I'll bet a lot of parts countermen that made this mistake suffered the wrath of a customer that installed one only to find after the whole job was done that it wouldn't work. Those were customers, of course, that didn't compare the old bearing to the new one before they installed it.

[Terry M.]

Re: 1969 350ci/300hp C3 Clutch Diameter

Bringing the original release bearing in with me was the solution to my issue -- all I remember was the one they originally gave me was too long. I think they may have mixed up the Sp H Per 370 with the HD 370. That terminology was always an issue until I got it straight, then I had to remind them each time I went in.

[Joe L.]

Re: 1969 350ci/300hp C3 Clutch Diameter

Bringing the original release bearing in with me was the solution to my issue -- all I remember was the one they originally gave me was too long. I think they may have mixed up the Sp H Per 370 with the HD 370. That terminology was always an issue until I got it straight, then I had to remind them each time I went in.

Terry-----


What's an "HD 370"?

[Terry M.]

Re: 1969 350ci/300hp C3 Clutch Diameter

Terry-----


What's an "HD 370"?

ZR1 What's the ZR1?

[Joe L.]

Re: 1969 350ci/300hp C3 Clutch Diameter

ZR1 What's the ZR1?

Terry------


The ZR-1 used the same clutch release bearing as other Corvettes from L1955 through 1981. This was the "short" bearing. Actually, there were 3 different "short" bearings (even more if one considers all the different part numbers used over the years). L1955-63 used a 1-9/32" short bearing. This was replaced for SERVICE in 1967 by a 1-1/4" short bearing. 1964-80 Corvettes originally used a 1-7/32" short bearing. This was replaced for SERVICE in 1981 by the 1-1/4" short bearing. 1981 used a 1-1/4" short bearing from the "get-go".

The other common bearing was the 1-7/8" often referred to as the "long" bearing. It remained at 1-7/8" over all the years, right to the present time. However, as I mentioned, as far as Corvettes go, this bearing was used only for early 1955 V-8.

[Terry M.]

Re: 1969 350ci/300hp C3 Clutch Diameter

Here for all these years I thought they gave me the release bearing for the ZR1. Oh well -- I guess there is no shortage of misinformation in this saga. Anyway, as I said -- I got what I needed by bringing the old one in and getting a new one of the same size. That works every time. Parts changing for dummies.