66-427 throwout bearing

[Richard E.]

I'm getting ready to install an AC Delco #15680264 (CT24RG) throwout bearing in my 66 big block and I noticed that the bearing collar which the fork retaining clips snap into is not perfectly round as on the bearing I removed. A portion of the circumference of the bearing collar has two relatively flat surfaces that form a rounded point. (This is hard to describe) I asume this "pointed" portion of the collar allows for easier attachment of the fork. Should the "point" face toward the fork or away from the fork?

I also note that the aft lip of the bearing collar (faces toward back of car)is quite thin, possibly 1/2 the material thickness (guessing) as compared to the old bearing, does this sound correct? Is it possible I have a defective "new" bearing?

Appreciate any thoughts from those having experience with these bearings. Thanks everyone for your ideas.

Rich

[Joe L.]

Re: 66-427 throwout bearing

Rich-----

What's important is that the fork ears and spring tang are completely within the groove on the bearing assembly. As far as the circumferential orientation on installation, it's not really important----the bearing collar on which the fork is installed will rotate and will not remain in the installation position.

From what you describe, I would say that your bearing is as it should be and is not defective.

[Richard E.]

Re: 66-427 throwout bearing

Thanks again Joe. Do you suppose there is a reason for the "pointed" style circumference to the bearing collar? Just curious.

[Joe L.]

Re: 66-427 throwout bearing

Rich-----

I don't know the exact reason for that configuration. However, I do think that it has something to do with the eccentric configuration of the new release bearings.

By the way, one can still purchase the old style bearings. These days, they're the "budget" pieces for folks wanting to get a job done as inexpensively as possible. The eccentric style bearings cost more. Only the eccentric style is available from GM, though.

[Richard E.]

Re: 66-427 throwout bearing

Thank you Joe.
Rich

[William B.]

Re: 66-427 throwout bearing, GM part #??

I also have a 66/427 that needs a throwout bearing. What is gm's correct part #? Also is this the best to use or do you have another recomendation? Thanks, Bill

[Joe L.]

Re: 66-427 throwout bearing, GM part #??

Bill----

The current GM part number is 15680264 which is also known as Delco CT24AG. This bearing is not manufactured by GM. In the old days, GM did manufacture these bearings in-house via their old New Departure-Hyatt operation. They no longer do, though, and all clutch release bearings are outsourced. I believe this particular one is made by BCA (Federal-Mogul) and is their number 614018. However, I don't know that for a fact. If the bearing in the GM/Delco box has the number 614018 on it, then the GM bearing and the BCA bearings are exactly the same. If the GM bearing does not have the 614018 number on it, then it may or may not be the same as the GM part. Until this is confirmed, I would use the GM part.

[Joe L.]

Re: 66-427 throwout bearing

Rich-----

If you haven't already installed the bearing yet, could you please check it for markings and report what you find. These may be small and they may be either stamped or laser-printed somewhere on the bearing.

[Joe L.]

Clarification

When I said that GM used to manufacture these bearings in-house, I did not mean that they used to manufacture the GM #15680264. I meant they generally used to manufacture clutch release bearings in-house and did, in fact, manufacture the predecessor part numbers for the 15680264. They never manufactured the 15680264 in-house, though.

[Richard E.]

Re: 66-427 throwout bearing

Joe,
I have not installed the bearing yet and I will try to inspect it tomorrow. It will probably be late before I can report back due to my schedule but I will let you know what I find. The bearing I have was purchased from my local GM parts dept. at a Chevrolet Dealership. I believe I ordered this bearing using the GM part number that you mentioned but what I received was the AC Delco part.

[Richard E.]

Re: 66-427 throwout bearing

Joe,
I forgot to mention that I plan to use a light coating of molybdenum disulfied grease on the fork pivot ball and on the bearing ID and on the collar that the fork rides in. This is consistent with the factory assembly manual lube listing. Looking up the characteristics of moly it makes sense to use this grease. Any thoughts? Thanks.

[Joe L.]

Re: 66-427 throwout bearing

Rich------

Yes, you can use a VERY light coat of moly grease on the bearing contact surface with the clutch fingers and on the inner portion of the bearing. There is no need to pack the inner groove with grease as shown in the service manual because on this bearing there is no inner groove. The groove was a characteristic of the old bearings but is not used on premium bearings of the current design.

As far as the bearing packaging goes, the GM clutch release bearings have been supplied in Delco boxes for many years, regardless of whether they are ordered through Delco or GM. However, you will note that the box displays BOTH a Delco "short number" (in this case, CT24AG) AND a GM "long number" AVAILABLE THROUGH THE GM PARTS SYSTEM (in this case, GM #15680264). This means the part is a GM parts system part and, usually, of OEM quality. In any event, it's the highest quality part you can purchase from GM.

However, if a box contains any of the following:

1) Only a Delco "short number" and no GM long number, or;

2) A Delco "short number" and a GM long number WHICH IS NOT AVAILABLE THROUGH THE GM PARTS SYSTEM, or;

3) A Delco parts system part with only a GM "long number" and which "long number" is NOT AVAILABLE THROUGH THE GM PARTS SYSTEM;

Then, the part will almost always be an aftermarket-type part and not the type of part that would ever be used on a PRODUCTION installation. I say "almost always" because there are exceptions to this rule that I have become aware of over the years. However, there are not many exceptions.

[Richard E.]

Re: 66-427 throwout bearing

Joe,
The bearing has #BCA614018 stamped in the forward flange of the collar that the fork sits in. The rubber bearing seal has BCA 57 cast into it. It appears that the ID of the bearing is pre coated with a thin coat of dark gray grease from the factory. Cold be "moly" by the color.

[Joe L.]

Re: 66-427 throwout bearing

Rich-----

OK, thanks. That confirms that the Delco CT24AG, aka GM #15680264, is exactly the same bearing as the BCA 614018. I just installed one of these bearings in my car several months ago, but I forgot to check for that.

This means, for sure, that one can purchase either the Delco or BCA bearing and get the same piece. The GM #15680264 GM lists for $45.82 and can be purchased for about $30. A smart Delco shopper can buy the CT24AG for $19.92. The BCA 614018 sells for about 27 bucks through aftermarket, discount parts houses. So, one can actually buy the Delco-boxed product for less than the BCA-boxed product.

I've found this to be very often the case and it's been "boiled down" to another one of my "rules-of-thumb". If you find a GM/Delco part that you can purchase for about the same price at common trade discount as an aftermarket piece at common trade discount, then the parts may very well be the same.

However, if you find a much lower price when comparing an aftermarket part to its Delco/GM equivalent, then the chances are VERY GREAT that the parts are NOT the same (even though they may APPEAR about the same). The notion that GM generally just buys aftermarket parts, packages them in GM or AC Delco boxes, and marks them up by huge margins is, in my experience, generally a false notion. Even when they come out of the same factories, they are not, necessarily, made the same.

[Richard E.]

Re: 66-427 throwout bearing

Very much appreciate your help again Joe. I hope this information will help Bill also.