On a 66 what color should the flywheel inspection color be, Black or orange.
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Re: Question on color of flywheel insp.
It can't be seen, but inspection dabs were usually lighter colors (white, yellow, orange, etc.). -
Re: Question on color of flywheel insp.
Assuming we're talking about the COLOR of the inspection COVER, here's a somewhat related question I've been wanting to ask, about slight differences on 2 earlier variations. The [3rd ?] latest one that we see on eBay (still avail. GM ?) has 2 'ears' or slots at each side of the rear main bearing area.
What I think is the older design [top] (unpainted on back) is completely straight along the top (block edge), except for a dip near each end.
The newer (?) [bottom] one has horizontal lips at each upper edge that act as limit stops against the block. Backside of this one is black, but obviously a service replacement, per GM tag # 3788422.
Anybody care to guess if both were production, and during which years ?Comment
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Re: Question on color of flywheel insp.
Jim -
I read your post as asking what color the flywheel inspection mark might be, as it didn't say "cover". On a 3 or 4-speed, it's orange (was in place when the engine was painted). On a Powerglide, the cover is semi-gloss black (installed at St. Louis).Comment
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Re: Question on color of flywheel insp.
Wayne----
As you know, the GM #3788422 was the bellhousing cover used in conjunction with bellhousings for 12-3/4" flywheels. It was first used for the 1962 model year for some Chevy II's with small blocks. As far as Corvettes go, it was first used for the 1963 model year for all small blocks with manual transmissions. It continued to be used for all Corvettes through the 1968 model year except 66-68 L-36, L-68, L-72, and L-71. After 1968 it was sparingly used for Corvettes and was limited to 1969 L-88/ ZL-1 and 70-72 ZR-1. The 3788422 was not used for any Corvette after 1972.
As you have noted, sometime during the years of its use in PRODUCTION, the design of the cover changed slightly. This must have been done via some change to the specifications for the part since the part number was not changed. When did it occur? I do not know. However, I suspect it occurred sometime in the 66 or later time frame. I feel pretty confident that the reason for the change was a first attempt at addressing the problem of in-service distortion of the cover causing contact with the crankshaft flange.
In January, 1976 the 3788422 was discontinued from SERVICE and replaced by the GM #354497. The latter piece was never used in PRODUCTION for any Corvette but may have been used for certain other Chevrolet models. This is the cover that has the "ears" you speak of. These were added as a second and more "aggressive" attempt at curing the crankshaft flange contact problem. The "ears" are designed to clip behind the oil pan real seal lip and positively prevent the crankshaft flange contact problem. From a FUNCTIONAL perspective, I recommend that all 1963-72 Corvettes originally equipped with the 3788422 convert to this cover. The GM #354497 remains available to this day.
The covers used for 14" flywheel bellhousings have a similar history. Cover GM #3843943, first used for 1964 passenger cars with 409 and manual transmission, and subsequently used for all 1966-74 Corvettes with 14" flywheels was originally designed without the "ears". This design continued at least until 1970 and I believe quite a bit later. There MAY also have been another earlier design that included a feature change similar to what was done for the 3788422.
At some point, and I believe that point was after 1972 and, possibly, after 1974, the "ears" were added to the 3843943. This change occurred without any change in part number. I do not know, for sure, if the "ear" version of the 3843943 was ever used on a PRODUCTION Corvette. I KNOW it was not used through, at least, 1969. Once again, I recommend that from a FUNCTIONAL perspective, anyone with a 1966+ Corvette with 14" flywheel and with a cover without the "ears" convert to that cover.
For 1975 another cover was released. This was GM #340252. This cover is similar to the 3843943 with one significant difference---the "ears" are much bigger and redesigned. That's because the 1975+ small block pans were designed with a larger rear seal oil lip to work in conjunction with the larger "ears" on the cover.
The photos below, from left to right, depict:
1) A GM #354497 ("third" design 12-3/4" flywheel cover);
2) A GM #3843943 and 340252 ("second" and "third" design 14" bellhousing cover );
3) A GM #340252 ("third" design 14" bellhousing cover)
4) A GM #3843943 ("second" design 14" bellhousing cover)In Appreciation of John HinckleyComment
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Re: Question on color of flywheel insp.
Yes, Jim
However, it is not completely painted.
The bellhousing and bolts would only have orange overspray near the engine.
Observed originals are devoid of paint on the bottom side.
HaNDComment
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Re: Question on color of flywheel insp.
Doesn't the amount of orange coverage on the bellhousing depend on the engine plant in mid-years? It does for C3s.TerryComment
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Re: Question on color of flywheel insp.
Joe;
I have an original 63 340 hp which has never had the transmission or clutch removed. However, I have considered this will be a natural course for my future maintenance - to replace the clutch and rebuild the 4-speed. At 44.5k miles I'm not quite there yet.
You recommend making the change to the inspection cover with the ears to prevent rubbing on the crankshaft flange. As I have not had any indication that such a problem may now exist, should I still plan on making this change at the time of my maintenance? What is the effect of such rubbing? Does the crank flange become damaged or is it just a source of noise, etc.?
Stu FoxComment
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Re: Question on color of flywheel insp.
Stu-----
Contact of the cover with the crankshaft flange causes no significant damage and, certainly, no damage to the flange. However, it produces a VERY loud and disturbing noise. The noise will not cease until the cover is pried away from the flange. Sometimes, this can be difficult since it resides so close to the flange and the distortion can be hard to correct with the cover mounted on the bellhousing. So, one often has to "live with it" until one can get under the car, remove the starter, remove the cover, and straighten it. Using the cover with the "ears" prevents all this from ever happening.
So, what causes the cover to distort and cause the problem? One very common cause is driving through large puddles of water. Of course, most of us probably don't do that sort of thing anymore. Another cause is striking road debris, including things that one wouldn't even think would be much of a problem (e.g. cardboard, small pieces of wood, etc.). I've even had it happen when there was no obvious reason for it; I have no idea what caused it then. I do know that the cover with the "ears" eliminates it, though. 100%. GM didn't modify the covers and add the "ears" because the previous designs worked just as well.In Appreciation of John HinckleyComment
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Re: Question on color of flywheel insp.
Joe;
Thanks for the information. I agree whole heartedly; Gm changed things for a reason. Granted, having worked there 22 years, I am aware that a lot of those changes/decisions are initiated by the bean counters, but a lot come from road experiences. I love to tell my fellow C-2 owners that they first designed my 63, then they took cost out of it for another 4 years, Ha!
I have had a few off road excursions over the course of 45 years (blew an on ramp once - ouch!) and have incurred a few dings as a result, including oil pan, rear spring, spindle and strut, etc., but I was fortunate to have never damaged a flywheel inspection cover (to the best of my knowledge). I once bounced between a telephone pole and a series of those white posts with black tops out on a country road. My only damage then was some white paint marks down the ridge on one side and a scuff mark on the other. It is amazing how much that fiberglas reinforced plastic will take from a glancing blow w/o cracking.
Thanks again for the info. I'll keep a watch on it.
Stu FoxComment
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