TH400 speedometer gear housing seals?

[Tom L.]

Anyone know a part number for these seals? Mine's leaking, it needs replacement and I'd like to be able to pick it up somewhere rather than having it shipped. Thanks!

[Edward J.]

Re: TH400 speedometer gear housing seals?

Tom have you tried the local Napa auto/ or if you have a tranny shop in town stop by and ask them.

[Tom L.]

Re: TH400 speedometer gear housing seals?

I haven't, mostly because our two "old school" auto parts stores have closed due to pressure of the Big Box national chains. I checked their web sites and the item is no where to be found. My experience with the staff in these stores is poor at best, 1972 is an era they can't comprehend. Matching a simple 3-hole exhaust gasket (when there are only a few sizes) ended up stressing them out without their computer. Just isn't worth the time. Almost hopeless.

[Edward J.]

Re: TH400 speedometer gear housing seals?

Tom, the Delco number is 1240382 for the speedo seal, the o-ring for the housing you should try and match -up at a auto parts. I bet a GM dealership can also get the parts you need.

[Richard G.]

Re: TH400 speedometer gear housing seals?

I would do like Ed recommended and just ask the local transmission shop. +
Typically they have a bunch laying around as they are not required when rebuilding a four wheel drive.
The seal also interchanges between a bunch of GM transmissions.
In all likely hood the nylon gear has a worn spot where the seal rides on the gear.
Don't confuse the circumferential groove with the spiral groves that return oil to the inside of the transmission.
New gears do not have the circular groove in them.

You have two good options:
1) Replace the seal and the gear. (gear tooth count and color are important)
2) Use an aftermarket seal. It relocates the lip part of the seal to an area on the nylon gear that isn't typically worn.

Only place I know to get these is through a transmission wholesaler.
Rick

[Tom L.]

Re: TH400 speedometer gear housing seals?

The gear isn't that old, 5-6k miles. Also, it's the O-ring on the housing that slips into the transmission, not around the shaft of the gear. Thanks for the leads so far!

[Joe L.]

Re: TH400 speedometer gear housing seals?

The gear isn't that old, 5-6k miles. Also, it's the O-ring on the housing that slips into the transmission, not around the shaft of the gear. Thanks for the leads so far!

Tom------


If I was home, I'd have all the part numbers in a few seconds. But, I'm in Italy so I have nothing but my memory and I just don't recall the part numbers for these seals.

[Tom L.]

Re: TH400 speedometer gear housing seals?

I dropped by the big box stores and the help pretty much drooled when I asked them to look the parts up. I was able to find the number elsewhere for the O-ring so I should be set. Armed with an actual part number I hope the local places will be able to help. If not I'll be waiting for them to arrive in the mail box. Thanks!!