A904 Leak...

[keenkeener]

I am trying to track down a heavy leak in my tranny. It looks like it is coming from where the speedometer cable goes in. Should I just replace the cable? is there an o-ring or seal that should be replaced also? Are there any other problem areas near the speedo cable? Thanks for all the help!

 

[mustangdart]

there is an o-ring on the speedo drive, the drive is held in place by a 5/16 bolt and bracket. ther will be some oil that will run out when you remove the drive and be sure to mark it so you put it back in the same place (so the speedo works again) there may also be an o-ring on the cable (losening the big nut on the cable will alow you to check that) the cooler lines are further forward and higher up check them also as they are a more common failure.

 

[slantscamp]

uh oh. that has to go back in the exact same way it came out. i didnt make note of that when i took mine out. maybe the manual will show how to put it back in right.

 

[fishy68]

Mustangdarts right except there isn't an O ring on the cable. Their is only one inside the cable adapter. It's held in by a snap ring. Also before you disassemble it clean things good and make note of the position of the adapter housing as it's clocked differently depending on which speedo gear is used. There are 3 sets of numbers on the adapter housing close to where the cable screws on that have a notch to match up to a notch on the extension housing. Put it back in the way it came out with what ever set of numbers aligned up that were originally aligned up or your speedo won't work.

 

[fishy68]

uh oh. that has to go back in the exact same way it came out. i didnt make note of that when i took mine out. maybe the manual will show how to put it back in right.

I was typing to watch for that just as you responded this. Just count the number of teeth on the speedo gear and if it's say 32 teeth for example clock the adapter housing where the set of numbers has 32 in it.

 

[slantscamp]

thanks. i learn something new every day.

 

[keenkeener]

Mustangdarts right except there isn't an O ring on the cable. Their is only one inside the cable adapter. It's held in by a snap ring. Also before you disassemble it clean things good and make note of the position of the adapter housing as it's clocked differently depending on which speedo gear is used. There are 3 sets of numbers on the adapter housing close to where the cable screws on that have a notch to match up to a notch on the extension housing. Put it back in the way it came out with what ever set of numbers aligned up that were originally aligned up or your speedo won't work.

Thanks for the reply. You seem to know alot about the transmissions - what do you think it is likely to be? Do the speedo cables leak often?

Thanks!

 

[fishy68]

Thanks for the reply. You seem to know alot about the transmissions - what do you think it is likely to be? Do the speedo cables leak often?

Thanks!

Your welcome and I have rebuilt numerous torqueflites (a few GM's too) over the past 25 yrs. so I know them pretty well. I can't say it's a real common problem but it does happen from time to time so if that's the area it's coming from that's most likely it. Not only can the internal seal leak (it's actually a small lip seal, not an O-ring) but there is a O-ring on the adapter housing that can leak also. From what I've seen the internal seal is what leaks more often because it's a wear item. If you need a picture of it just let me know and I can scan a pic from the service manual and post it.

 

[slantscamp]

does this only apply to later model 904's. my 1963 pushbutton 904 didnt have any markings on the speedo cable or bracket where it went in the transmission. mine is leaking where the pushbutton cable goes into the transmission.

 

[fishy68]

does this only apply to later model 904's. my 1963 pushbutton 904 didnt have any markings on the speedo cable or bracket where it went in the transmission. mine is leaking where the pushbutton cable goes into the transmission.

Sorry but I haven't ever done one earlier than 66 so I don't know but I'd guess if it didn't have the "clocked" type housing it doesn't apply. The reason for the clocked adapter is for different size speedometer gears. For example a 24 tooth gear is much smaller diameter than a 42 tooth. If the housing was concentric it would have to be specific for a speedo gear count. The 66 and up unit has the shaft hole offset (cam like) and with that you can install different size gears and rotate it so it engages into the output shaft gear properly.

 

[slantscamp]

i see. thanks for the info. mine just has a hole that the speedo cable assembly fits in, and then a retainer that bolts over to hold it on. if that makes any sense.

 

[keenkeener]

Your welcome and I have rebuilt numerous torqueflites (a few GM's too) over the past 25 yrs. so I know them pretty well. I can't say it's a real common problem but it does happen from time to time so if that's the area it's coming from that's most likely it. Not only can the internal seal leak (it's actually a small lip seal, not an O-ring) but there is a O-ring on the adapter housing that can leak also. From what I've seen the internal seal is what leaks more often because it's a wear item. If you need a picture of it just let me know and I can scan a pic from the service manual and post it.

By the internal seal - you mean the seal in the speedo cable end? If not - send me the picture so i know what you are talking about. I went ahead and ordered the speedo cable and the o-ring that goes on the adapter.

 

[fishy68]

By the internal seal - you mean the seal in the speedo cable end? If not - send me the picture so i know what you are talking about. I went ahead and ordered the speedo cable and the o-ring that goes on the adapter.

No. There's no seal in the cable itself. The seal that leaks most commonly is located inside the part of the adapter housing that the cable engages into and is held in by a small retainer ring. Here's a picture of it along with how the adapter housing is clocked. Make sure when you remove the housing you make note of the clocking and install it just like it was. The clocking is for different size speedometer gears.

Oh yeah, make sure and replace the outer seal also because even if it's not leaking now once you disturb it, it might start leaking.