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Transmission shifter linkage shaft deal ('75 Eldo)

Started by benji808, February 03, 2023, 06:29:05 PM

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benji808

Hi all!

I'm being told I have a minor transmission fluid leak out of the shifter linkage shaft seal. I am not sure if that is the right terminology, and so far have not found anything helpful in the shop manual (may be user ignorance!)

I would like to see it myself to learn and assess. Does anyone know where this seal is located and/or how to replace it?

Thank you!

The Tassie Devil(le)

The seal is around the gear selector shaft that protrudes from the transmission case.

The seal can be replaced without removing the transmission, but, one needs the Shop Manual, or one for the FWD transmissions to perform the task.   No special tools are required.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

benji808

Thank you, Bruce! I've looked through the Eldorado transmission section of my '76 shop manual and haven't seen anything about it. Do you know section #, or have any advice on procedure to replace? I'm planning to get under it tomorrow and see what I can figure out.

TJ Hopland

Every one I have ever seen just has an O ring for the seal vs an actual lip seal that was most common on other THM transmissions.

I believe 73-78 officially it can't be done in the car but if you are a little creative you can do it.   I didn't do it myself but a shop did it on my 73.  They said it wasn't easy.  I suspect its loosing the mounts and trying to shift things as much as possible.  Also side note the repair didn't last very long in my case, there must be wear in the bore that is letting the shaft move and an O ring just doesn't have the range to maintain a seal. 

71/72 is a little different than 73-78 because the changed the frame and mounts a bit to accommodate the impact bumpers that were required starting in 73. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

The Tassie Devil(le)

I know that with the rear wheel drive transmission, the Trans has to be removed from the car.

In the 1974 Shop Manual it is listed on Section 7, page 77, Section 64 liste the operations that can be done with the transmission in the car, and (h) lists Detent Lever, Manual Shaft and Parking Linkage.   With a listing of Section 75 for the removal, and 93 for installation.

It lists Figure 7-137 in exploded view.

Sorry, I don't have the '75 Manual, but, the '75 will be the same.

I know all this because I had to replace mine.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

benji808

Thanks, Bruce- that is helpful! I think I found a section about the "manual linkage"- so I can start there.

benji808

#6
Final update for this thread- I found the section in the shop manual Bruce referred to (screenshot below for reference; I've also included a picture of the linkage on the car - it's driver's side immediately above the transmission pan). Looks relatively simple once the pan is dropped. That being said I'm seeing fluid around the edges of the pan on the opposite side so I'm inclined to think it's actually the pan gasket/seal that is leaking. Should be able to sort it out in short order either way.

Thanks again!




The Tassie Devil(le)

G'day Ben,

Don't forget to check on the Drive Chain housing.   If there is a leak there, the Trans has to come out to fix it.

Mine was leaking, and as I didn't have access to a replacement gasket, it is large, I used Loctite 5900 to seal it and it has never leaked since.   Unlike all the other silicone sealers, Loctite 5900 is not attacked by Transmission Fluid.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

TJ Hopland

Dipstick tube is another good place for leaks especially if they seem worse after the car sits. When the car sits for a while the level rises in the pan so that seal has to work harder.  From there it runs down around the edge of the pan and looks like a leaking pan.  Mine used to just be damp all summer when it was being used but then loose a couple quarts over the winter when it sat. IIRC its a slightly odd square cut O ring. 

I also replied twice earlier in this thread that seems to have disappeared now.  One of them I noted that I found in the 73 manual too where it says that shaft can come out in the car but mine hit the frame before it would clear the case.  I wondered if there were differences in these transmissions and maybe I don't have a 73 in my 73.  I know my engine has been changed so its quite possible the trans had been too.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

bcroe

My own experience is either the shifter shaft may
be pulled in either a TH400 RWD or a TH425 FWD
trans, might involve messing with mounts and
dropping it a bit.  The problem is usually rust
comes up to the seal and destroys it, so you may
need to condition or replace the shaft for a
fix that lasts.  New available for RWD. 

But as described above, there are many other points
that might leak worse than a shift shaft. 
good luck, Bruce Roe

skinny_tom

If I may hijack this thread a little bit... There seems to be a lot of knowledge and just today I ran into a question I thought I'd ask before taking things into my own hands...

I would like to reseal the "manual shaft" seal on a 65 TH400. Step 1 clearly states "remove the pin securing manual shaft to case." The pin is stamped on one end so that it won't pull through, and tops out on what appears to be a little cover on the forward side of the case. Do I have to remove the little metal cover to remove the pin? It looks like a piece of sheet metal that's shaped to fit in the case on a friction fit....




Top arrow is the retaining pin. Bottom arrow points to the "cover" I'm curious about.

- Tom -
1965 Eldorado

bcroe

The only problem is the NAIL retainer.  It was
put in before the front pump assembly was put
on, to clearance to get it out.

I pull the nail out as far as possible, then
bend it and remove it.  To replace it I use a
long cotter pin of the same dia.  Bruce Roe