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65 CDV speedo gear housing o-ring

Started by bctexas, February 15, 2020, 02:40:48 PM

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bctexas

Hi all,

The speedometer gear housing on my '65 CDV was leaking.  I was able to obtain the inner seal and outer o-ring from a local parts store.  The inner seal fits, but the overall diameter of the outer o-ring is too large.  I looked up the parts on Amazon, and it lists a seal/o-ring set for a TH-400.  The listing includes the o-ring sitting between the jaws of a digital caliper, and it is the same outer diameter as the one I already have - too large.  Any words of wisdom?  Is the '65 TH-400 different in this regard than other TH-400's?  Unfortunately all the local transmission shops are closed for the weekend, and the parts stores have no other info....

Thanks in advance!
1965 CDV
1970 SDV

Cadman-iac

#1
 By how much is it too large? It needs to be slightly larger in order to make a good seal.  It compresses when it goes into the transmission. Not too much, but some.
When installed in the groove,  you should be able to feel it bulging out just a little.


What size is the one that you need versus the one that you got? I have at least a dozen different TH400's here to look at. Just need to know what I'm looking for.

And just out of curiosity, what brand is the one you got?

I currently have one out of the transmission,  and I measure the ID on the housing at 1.915" , and the OD should be near 2.080" , give or take a few thousandths.

And now I see your problem.  I just dug up a gear sleeve I know for a fact came out of a TH400, and it has an ID on the "0"ring of 1.75", one and three quarters. The OD for this is supposed to be right at 1.940", and the GM part number in my book is a 6264904. That may be superceded to a newer number.  But give that number to your parts person and have them cross it over to whatever brand they have.

I hope that helps.
Rick

PS: and now I see what probably happened, they looked one up for a TH350 instead of the 400. The first one  I measured was not in a  transmission,  but a box of parts,  and I made the assumption that they were the same for both. My mistake,  and probably your parts person's as well.
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

bctexas

Hi Rick!

I started the search with the GM number 6264904 (obsolete I am told) - which crossed to "ATP" TO-33, which O'Reilly's crossed to "Pioneer" 762004-10.  The new ring is 1.86 ID and 2.07 OD.  The old o-ring is closer to 1.74 ID and 1.92 OD.  If you enlarge the pic, you can see daylight between the new o-ring ID and OD of the housing.  I don't think that will work. 

The OD of my housing is 1.935, the o-ring groove is 1.75 ID.  So you are seeing the same thing I am.  More research to come.

Thanks for the help!

Happy Motoring
Bernie

1965 CDV
1970 SDV

Cadman-iac

Well it's a consensus then! Two against one, the one being your parts person. lol!
I'm glad you found the right one finally. I had tried to locate a good aftermarket number from my receipts when I did a reseal on my Suburban.  It's also got a 400 in it. The problem with my method was the descriptions on the receipts were vague.
Good luck with your repairs.
Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

bctexas

Hi Rick!

Unfortunately, I don't have the right one yet!  I'll hit a transmission shop on Monday and see if they can come up with the right piece. 

Thanks!
Bernie
1965 CDV
1970 SDV

Cadman-iac

Now that you know what happened, you can be sure to  get the 400 seal this time. It should be a common piece that any transmission shop has in stock.
I'm sorry you have to wait until Monday though. Did you ask your local parts store to crossover the GM number? Even the quickie stores should be able to do that. By quickie I mean places like Auto Zone, Pep Boys,  and O'Reilly's.
Napa should definitely have it in stock. But anyway,  I hope it goes well. 
Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

bctexas

Hi Rick!

Yeah, O'Reilly is the source of the wrong part, and he had the GM number.  I called NAPA and the counter guy said that he has worked on TH-400s and know exactly what I need.  And he doesn't have it.  He did give me a lead to a fellow who runs a local  transmission shop that he said will very likely be able to take care of me on Monday. 

Ah the joys of working on a 55 year old car....    ;)

Happy Motoring!
Bernie

1965 CDV
1970 SDV

Cadman-iac

That was such a common part too not that long ago. I'm sorry it's been a problem locating it. I hope your trans shop stocks it.
As far as O'Reilly's goes,  the guy must have gotten the  lines crossed when he looked it up. Because the larger O-ring is for the TH350. Perhaps he only glanced at it and saw the TH part of it and didn't look further.
I have made that mistake myself a few times. And at least you now know what you need.
Good luck with your search, and the repair. Hope all goes well.
Rick
CLC# 32373
1956 Coupe Deville A/C car "Norma Jean"

Daryl Chesterman

Mr. Long, the GM number 6264904 interchanges in the NAPA system to ATP 13895.  This o-ring has an ID of
1.737" and a cross section of .103".  It is a really common o-ring and is in stock in a lot of stores.  You might call your local NAPA jobber and see if they have that number in stock.  If they do, take your speedometer gear housing with you and see how it fits--you might even want to take the old o-ring with you to compare sizes before trying it on the housing.

Daryl Chesterman

Glen

The standard measuring system of O rings uses the ID and cross section.  An O ring with an ID of 1 ¾” and a cross section of 3/16” has a dash number of 327.  The numbers before the dash refers to the type of material the O ring is made of.  The full number might be AS568-327 for example. 
Here is a size chart http://zork.info/O-ring
A lot more info about O rings too. 
Glen Houlton CLC #727 
CLCMRC benefactor #104

bctexas

Mr. Chesterman - Thanks, I talked with my local NAPA and was told they did not have it in stock.  Whether he found this cross reference or not I don't know, but he claimed to have personal experience with TH-400s and seemed to know what he was talking about.  I will call them again with that part number when they open tomorrow.

Glen - great document, thanks!  Saved for future study and reference.

Happy Motoring!
Bernie
1965 CDV
1970 SDV

bcroe

#11
I refresh my 400s regularly, and do not replace that O ring until
it leaks.  I do not expect an auto parts store to have many detail
level transmission parts in stock.  Let me know if I need to send
one of my extra. 
Bruce Roe

bctexas

Bruce,

Thanks so much for the kind offer!  But:

Mr. Chesterman, you nailed it!  Oddly enough, when I put 6264904 into the search on NAPA's page, it comes up with 13895, but with a note that it does not fit a '65 Cadillac!  On your advice, I called and they had one in stock.  My leaky speedo gear housing is now fixed!  (O'Reilly was able to get the seal for the gear shaft).   Looks like the governor cover is seeping though....

Anyway, thanks all for the advice and the solution!

Happy Motoring!
Bernie 
1965 CDV
1970 SDV

bcroe

Quote from: bctexasOddly enough, when I put 6264904 into the search on NAPA's page, it comes up with 13895, but with a note that it does not fit a '65 Cadillac!  Bernie

Huh, how is the part different from all 65 up TH400s with a
speedo output?  Bruce Roe