RATT7

Speedometer "O" ring replacement to tranny - How To ? I Noticed that the speedometer cable that goes to the tranny is leaking - I picked up the o ring today and wanted to know how to install this - I have a bit of seepage where the speedometer cable fits into the side of the tranny, is this a straight forward fix to replace the o ring ?
Thanks
:)

isosceles

it's very easy. On a TH 350 you unscrew the cable housing and pull off the tranny. Then there will be one bolt holding in a tab that retains a sleeve that the speedo gear rides in. Pull the whoe sleeve out. Some trannies have an o-ring on the cylinder and a seal at the bottom where the speedo gear shaft goes through. I had to do mine about 8 months ago.


[Modified by isosceles, 11:14 AM 5/9/2003]

Captain Morgan

yep, it's rather simple. There is a small tab that holds the connector in place. I think the head of the bolt is 3/8ths. Loosen the bolt, flip the tab out of the way, wiggle the connector out. There is a small plastic gear that will come out too. Pull the gear out of the connector, remove the O-ring, and put on the new one. It may help to disconnect the speedometer cable so you can hold the connector in your hand, but you may not have to. Either way, it's fairly simple. The hardest part is getting to it, depending on your exhaust setup.

RATT7

Thanks - everytime I start a project on my 1980, theirs always something that just never goes to plan :)

CHEESERAL

Just remember when you pull out that driven gear assembly you're gonna get a lot of trans fluid coming out of that hole unless you drain it first, if you have a drain, ask me how I know.

RATT7

How much tranny fluid would I loose removing that speedometer cable ? I noticed that the cable assembly is quite high compared to the pan itself, would I loose alot ? Last week I redid the gasket for the tranny pan and want to avoid the pita again. :)

jimvette999

You will lose about a pint or so. There is an inner and outer seal associated with that speedometer. Replace both and look for groove in speedo driven gear. Inspect speedo drive gear for dished out wear while you are at it. I use two inner speedo seals.
Jim

CHEESERAL

A pint is about right, it looks like a lot more when it comes out at you and goes all over the floor.

Chuck

Captain Morgan

If you're worried about losing fluid, get a tapered rubber stopper about the size of that O-ring and plug it into the hole as soon as you pull out the connector. Just make sure the stopper doesn't go so far into the tranny that you can't get it back out.

Calm Screamer2

When I had to replace my speedometer cable I found that it was seized to the tranny (I couldn't unscrew it). There wasn't any room to get pliers in there, so I had to take the flange off the tranny (the thing you're gonna have to remove). That wasn't so bad, but putting it back on was. Need to insert the bolt (with the retaining tab dangling on the end of the bolt using a universal joint and a long extension while holding a flashlight so I could see where it was going. Took me about 30mins to get that bolt in (stupid bolt). Good luck.

Captain Morgan

Hmm, I didn't have any problems at all. I had the car up on jackstands and could access the bolt without a problem with a wrench. Took less than 10 minutes to get the housing out, install a new speedo gear and get everything bolted back in place. I didn't have to change the o-ring, but I've changed enough o-rings on other things to know that it's fairly simple. I also didn't even need to disconnect the speedo cable to remove the housing, but I imagine he'll need to disconnect it since he's changing the o-ring, if for nothing more than easy handling.

RATT7

Thanks for the advice - I will user some form of a stopper to prevent the oil from making a big mess when removing the o ring, at least it should be a little cleaner then the tranny gasket I did last week.

jimvette999

By the time you get the stopper in the fluid will be 90% leaked out. Comes out in a bit of a gush because of the size of the opening. No big deal...just let car cool down. You'll lose even more than a pint if front only is elevated. Just catch it in a pan and let er' trickle. There are 2 different size o-rings for those outer speedo housings...get the wrong one and it will still leak.
Jim

dogr74

I have a post on the forum looking for why I'm on my 2nd speedo gear in a couple of months. When I pull out the o-ring assembly, I don't leak any oil!!! Maybe my oil is too low causing the speedo gears to run dry and wear out. Is that possible? In any case, sounds like I need to check the fluid level.

jimvette999

SORRY....I was thinking of the larger style Olds/Pontiac speedometer housing . The Chevy has the small diameter one as you all know.
:conehead