latest on oil leak, found an MA6 clutch

[Jack O.]

I pulled my tranny to get a better look to find my oil leak. Everything on the back of the engine is dry but the front of the trans is a mess. It has to be the trans even though it doesn't smell like gear oil.

The real interesting thing though is that the car (a '69 427/435) has the MA6 heavy duty dual disk clutch. I don't know if its original equipment - probably not. I have the tank sticker and its not on their but I've read that this option often didn't appear on the standard documentation. The pressure plate is stamped in yellow ink with 3187797 which doesn't cross to any numbers I saw in the archives about the MA6. I haven't found a number on the fly wheel. My car is an early '69, Nov '68 build date. In fact, the latest NCRS judging manual for '69's was changed regarding the earliest sidepipe car found after my car was inspected by Chuck Berge and the paperwork verified. I thought that was pretty cool so it's possible it came with the MA6 but I don't know how to verify. I'll probably go to a standard fly wheel and clutch setup.

[roy braatz]

Re: latest on oil leak, found an MA6 clutch

There is a seal in the Trans front cover that the throw out bearing rids on and it also has a gasket for the cover, easy to take off and check.

[Joe L.]

Re: latest on oil leak, found an MA6 clutch

Jack-----

If it's actually the transmission that is leaking, there are really only 3 likely culprits from the front of the transmission.

1) Oil drain back hole under front bearing retainer is plugged or otherwise occluded. Remove the bearing retainer and check this. Also, make sure that the oil return groove in the bearing retainer aligns with the oil return hole in the case. It should since the bearing retainer mounting bolt pattern is offset to ensure correct installation. Check it anyway. Make sure that no gasket material or sealer gets into the oil return hole. This is VERY, VERY common when folks foolishly use silicone sealer on the front bearing retainer-to-case gasket;

2) Check the bearing retainer bolt holes in the case. These often get "loose" (even though the bolts will tighten up to torque value). When this occurs, transmission oil will seep by the threads and cause leakage problems. The fix: install thread inserts with Permatex Red locking and sealing compound. You can also try just putting some silicone sealer on the threads (very sparingly; you don't want to create the excess to plug the oil return hole). This method may or may not work;

3) Check the transmission cluster shaft fit in the front case. This hole often becomes worn from repeated rebuilds of the transmission or becomes "egg-shaped" from long service. If either of these things happen, it will leak fluid at this point. The fix: have a bushing installed in the case by someone that has experience in this fix. Contact Ed Hartnett in Lansdowne, PA for info on a source. Alternatively, one can "peen" the inner surface of the hole with a center punch to upset enough material to re-establish a tight fit and then apply silicone sealer to the hole perimeter before re-installing the cluster shaft. This may or may not be effective in curtailing the leak.

As far as the MA-6 clutch goes, it's unlikely that the car was originally fitted with this piece. I don't think that this unit was available in early production 1969. In fact, I have a Corvette order form for a friend of mine's original owner, early 69. The form is dated 9/29/68 and his car was built in early Novemeber. The form doesn't even have a check-box for the MA-6 clutch. Of course, this could have been one of the "secret" options that had to be added in the space marked "other options and special instructions" (the L-88 option had to be added here). However, somehow I seem to recall that the MA-6 was on later versions of the order form.

On the other hand, it would be unusual for someone to have added this later. Plus, the 1969 L-71 was the only Corvette engine that the MA-6 clutch could ever be optionally ordered in conjunction with (it was standard on manual transmission 1971 LS-6, though). So, who knows? Maybe yours was one of the first 69s to get it. The number that you mentioned is not likely a GM number that would have been used for a clutch piece. However, it could be a Borg and Beck number. Borg and Beck manufcatured this unit for GM.

The big problem today with the MA-6 clutch is the availability of spare parts. All of the GM parts are long-since discontinued and extremely difficult to locate. There is no reproduction or replacement source for these parts, either, that I am aware of.

[Craig S.]

Re: latest on oil leak, found an MA6 clutch

Jack/Roy - the Muncie transmissions do have the gasket on the flange of the throwout bearing support, but there is no internal oil seal at all on Muncies. When I took a class on rebuiling these at Bloomingon, the biggest leak issue on the front case is the countershaft bore in the transmission itself, and to fix this correctly requires a careful rebushing of this coutershaft bore in the case. Ed Hartnett who taught the class does this, and it would be the way I would approach this problem. Silicone seal etc is a bandaid and short lived fix....Craig

[Joe L.]

Re: latest on oil leak, found an MA6 clutch

Roy----

Muncie 4 speed transmissions do not use a seal on the front bearing retainer. The only seal present on the transmision front is the bearing retainer-to-case gasket.

[Wayne M.]

Zone Newsletter re availability on N14 & MA6

This was the picture as of Aug 20th '68:

"RPO N14 will not be available for production until approximately Nov 1st"
"Current indications are that RPO MA6 will not be available for production until mid-October"

[from a reprint in Dec. '92 Vette Vues]

[roy braatz]

Re: latest on oil leak, found an MA6 clutch

Joe your right about the seal sorry . Could be that the trans vent is clogged causing pressure inside.

[John H.]

More On N-14 Availability

I have a Zone Letter dated 2/11/69 with more history on the N-14 issue; it quotes a wire sent on 12/11/68 which informed Regional Distribution Managers to continue to hold new orders for N-14, as "Difficulties currently being experienced are limiting production to only a few of this option daily; St. Louis has over 1,000 N-14 orders on hand, and current indications are that it will be late January before sufficient material is available to build orders now at the plant. To prevent problems arising at the plant due to the large number of N-14 orders being held, Processing Centers are requested to immediately accelerate transmittal of their remaining January allotment without N-14. Will advise later when the Stop Condition on Corvette orders with N-14 will be lifted, but it appears that it will be sometime in January, and will apply to February production. Advise Zones accordingly so they can answer dealer inquiries on Corvette orders delayed for N-14".

The letter goes on to say that another wire was sent on January 17th, stating that material was now being received at the plant at a rate which indicated that transmittal of additional orders with N-14 could be resumed on Tuesday, January 21st, and that present indications are that N-14 orders now being transmitted will be scheduled for production starting at the end of February.

This same letter also indicated that "Production of units specifying the L-88 Special 427 V-8 Engine Option are currently being delayed due to what appears to be a critical hood problem; since these are all "sold orders", we have instructed the plant to hold them pending more definite information on hood availability."

The same letter also indicates that "The Corvette Power Teams Chart has been revised to reflect the 350 cubic inch 350hp engine with 4-speed close-ratio transmission as not being available with RPO C-60 Air Conditioning due to inadequate cooling performance for city driving conditions".

Interesting history in these old Zone Letters