What do you all prefer for transmission pan gasket material? I'm getting ready to replace the pan (for a newer one with drain plug), gasket, filter and some o-rings here soon. I've found the cork and neoprene gasket available. I have no experience with the neoprene gaskets, anyone here use them with good results?

 

I changed the transmission fluid just last weekend on my '73 Custom Cruiser. I just used the $6.99 Felpro gasket from Autozone (their part number TOS18621 for the THM 400). It's neoprene (I'm assuming, as it certainly didn't appear to be cork), and it works just fine. I'd get that (or the one for the THM 350, if that's the transmission you have...it's $1.00 less).

 

Thanks for the input, I have been leaning toward the neoprene also.

I may use the one that comes with this filter if it doesn't look like garbage.

https://www.napaonline.com/Catalog/C...+50052+2052006

 

That looks just like the one I put on my car.

I wouldn't worry too much about this. It's not like these gaskets are under some undue stress under there. I've changed the transmission fluid several times on different cars over the last several decades, and I've never given a second thought to the gasket. I just buy the one at the store and put it on and be done with it. I've never had leaks that had anything to do with the quality of the gasket material. It's more likely to be improperly or unevenly tightened bolts or mating surfaces that were not cleaned enough of old residue before the new gasket was put on. Whenever I've taken the pan down and changed the fluid, it was only because enough miles and time had elapsed that it was time to change it.

In fact, even after 50,000 miles, I've removed gaskets that came off cleanly enough and were in good enough shape that they could have been reused, but given how cheap new ones are, I've always just put a new one on.

 

I prefer cork, but its getting harder to find them readily available. The fiber gaskets like above are ok, the rubber ones I have the most leakage problems with.

 

I just replaced the pan gasket on mine. Neoprene and cork leaked. Plain rubber (NAPA) leaked. I have a genuine GM coming that I hear is the way to go, we'll see. I just got my Lokar locking dispstick today. One thing I hate is leaks so three's a charm

 

I can't stand leaks either. Mine leaks pretty good right now, but not for much longer. I am going to try my luck with the Napa neoprene gasket.

The o-rings on the modulator and the kickdown electrical connector leak pretty good...

I'm not sure the size o-rings that are required so I will either buy a bulk variety pack of them or just take the two parts into the store with me to match up. Unless someone here knows the exact size...

 

I feel better now....I finished my resto and the stinkin' tranny was still dripping. I replaced the gasket twice and it still leaked. I had a friend of mine who does transmissions work on it and he got her buttoned down pretty good. He put in a new gasket and used some type of gasket sealer on the pan and the trans. So far no leaks.

 

I wonder about this. A gasket sealer should not be needed. I did not use any on either of my two old cars, both of which I changed the fluid on last weekend. Nor was there any sealer used by whoever did the jobs previously as the old gaskets came off with no effort, which would not have been the case had they been stuck down with something. As I said in the other thread, one of them came off so easily that it could have been reused if necessary.

The use of the sealant may very well stop the leak, but it addresses a symptom, not necessarily the cause. The sealing occurs as the result of proper compression of the gasket between the pan and the bottom of the transmission in the way that an o-ring seals. I would suspect a bent or warped pan or insufficiently or improperly tightened bolts as the cause of your leaks, not the lack of a sealant (or the choice of what material the gasket is made out of).

I pity whoever has to change your transmission fluid the next time. It'll likely be a bear to get the old gasket off.

 

I asked him about this too because I looked at that thread. My pan is old and most likely warped. I will be converting to a 4-speed automatic over the winter this is just to get me through the summer. I plan on changing the transmission and the rear end gear over the next winter.

 

I agree, it shouldn't leak or need sealer but mine leaked like a sieve. My neoprene/cork gasket was old so I'll give that a pass but the brand new NAPA one was no better. The GM ones are a rubber/fiber mix with kind of a pebbly texture. Almost looks like a fiber gasket coated in rubber. I was told not to use sealer on it and it will be gtg. Ratech also makes this type of gasket so we'll see.

 

The old th pans are fairly thin. The bolt holes like to pucker towards the sealing surface not giving the gasket the proper clamping force in-between the bolts. then they would get cranked down and eventually split the gasket at the bolt holes. Make sure the gasket flange of the pan is straight before reinstalling. (Or as I do, pucker the holes outward slightly)

 

http://ratech.stores.yahoo.net/reaxhoga.html

The link to Ratech. Trans pans are at the bottom.

 

The service manuals for both my '67 and my '73 give the torque specification for the transmission pan bolts at 13 foot-lbs. That's not much. Most of the time, the reason the pan is distorted is because the pan bolts have been overtightened after previous fluid changes. I agree that that's a hard thing to fix short of getting a new pan, and a sealer may be the only real solution to chronic leaks.

 

I set the flange on a piece of wood and set a small ballpeen on the bolt hole. Then tap the back of the ballpeen with a deadblow hammer. Do that with each hole and you can usually get more life out of your pan.

 

Anyone have any experience with a Lube Locker gasket? They are rubber gaskets with a steel core. Thay also have the orange beading on them on both sides. I had good luck with the rubber gasket on my 350 trans. I couldnt get no cheap gasket to seal. I always ripped the cork and other gaskets with sealers. So I used a rubber one no sealer . Torqued it using a torque wrench center out if I remeber right. 12 ft lbs. Sealed good. But I have a rebuilt 400 trans going in and I was going to use a Lube Locker on the pan gasket. I also have a Lube locker for the axle cover too I was going to try.

 

I'd love to know what they claim the point of this is. The steel is certainly not going to add to the ability of the gasket to seal. If anything, it sounds like a gimmick.

 

The steel is there to prevent the overtightening and subsequent crushing of the gasket. The neoprene lines are what gets squished to make a seal.

These are vastly better than the other options in this thread.

.02

 

Perhaps, but you can also avoid overtightening by just not overtightening!


Besides, all this does is add another layer of metal. What stops the neoprene on each side of the steel layer from being crushed by overtightening? In the end, it's the neoprene that does the sealing, and if it can be crushed, it can be crushed.

 

DURAPRENE - I get them from trans guys, don't know how to source them otherwise.

 

According to this site

http://www.ecoreintl.com/index.php?o...283&Itemid=157

"Duraprene" is just a brand of recycled neoprene.

 

Update: After reading some posts here I decided to get the LubeLocker gasket. It worked like advertised with no leaks. I also installed the new Lokar anchor tite dipstick and no leaks there either. Replacing the vacuum modulator today as it decided to leak after 40 years (you knew this was going to happen right?)
My only advice is if you have an old transmission lying around that you're finally going to use make sure you change every seal. o-ring, gasket, etc. before installing it. You'll save yourself a lot of hassle in the long run. Although I did replace the front and rear seals all the others decided to go. Karma

On a side note the old 330 now puts down rubber at will. 1st to 2nd shift put down 6-7 feet and that was at half to 3/4 throttle. I just love this manual TH400 S/P transmission!