Saginaw or Muncie 4-speed?

[starfire]

I've searched around the forum for a while and have done nothing but gotten myself more confused.

I have a rear gasket leak on my 4-speed manual transmission in my Starfire. I went on Rock Auto and in the 1978 Starfire section they list only one gasket kit, for the Saginaw. In the 1978 Monza section they list two gasket kits, one for the Saginaw and one for the Muncie.

Here's the Saginaw kit:



Here is the Muncie kit:



They are obviously different. Can I be reasonably assured that my trans is a Saginaw and needs the Saginaw kit? I don't trust the vendors to know these things.

Any insight is appreciated.

Thanks,

[cjbiagi]

The factory did not put Muncies in Monza's or Starfires , so I can say it's almost 100% a Saginaw. If you look at the trans it is very easy to tell, a Saginaw has all 3 shift arms on the side cover. A Muncie has only 2 on the side cover and the third is on the tail housing. If you are going to take the side cover off you also want to change the shift shaft seals, these consist of a couple of "O" rings and another seal that is tapped into place. If you need a complete seal kit with gaskets and O rings let me know, the kit also comes with a front and rear seal and speedo cable O ring, all which are very easy to change.

[starfire]

Thanks for the info Clyde. Now as I have been poking around the internet, I come up with more questions. Are all Saginaw 4-speeds the same? Can you swap one out of an H-body into an F-body of a different (or same) year?

[starfire]

My trans seems pretty tight except for a leak from the rear gasket. There may be a small weep from the front gasket, but it might be motor oil from a leaky DS valve cover gasket. I got my car up on a lift a couple of weeks ago and washed the underside pretty well (power washer and degreaser). Put it back up tonight and it was obvious where the biggest leak was. Unfortunately it seems I'll need to do the differential shaft seal too. The side cover, shift shafts, and speedo connection all are still nice and dry so I don't seem to have a leak problem there. I think I'll leave well enough alone with those.

[cjbiagi]

Saginaws for a H body have the mount for the torque arm cast into the tailshaft, so as long as whatever trans you use has that they will swap in. However, different cars may have different 1st, 2nd and 3rd gear ratios. Most important is 1st as this is what gets the car moving. Generally it is matched to the engine and rearend gear ratio. There are lines on the input shaft that identify the ratio's. Of course tailhousings can be swapped if you find one without the torque arm mount and you have your old trans.

SAGINAW 4-SPEEDS (CAST IRON)

0 LINE INPUT -2.84/2.01/1.35/1.00

1 LINE INPUT - 2.54/1.80/1.44/1.00

2 LINE INPUT - 3.11/2.20/1.47/1.00

3 LINE INPUT - 3.50/2.47/1.65/1.00

[spencerforhire]

As Clyde said, it's a pretty safe bet you have a Saginaw in your car, but he neglected to mention the easiest way to tell the difference; the Saginaw has a cast iron case while the Muncie(like a BW T-10) is aluminum.

[crawfw]

In order to change the rear gasket, the side cover has to come off to access a snap ring to completely remove the tailshaft.
I've thought about cutting the gasket on top so it can be put in place without completely removing the tailshaft. But that would make cleaning the mounting surface very difficult if not already cleaned recently.
Also removing the trans is your best bet due to the difficulty of accessing the snap ring from the side cover while the trans is installed.
So you prob will be replacing at least the side cover gasket as well

[starfire]

Very good info crawfw. The good news is it looks like the gasket set has the side cover gasket. I was hoping to not have to mess with it, but it is what it is.

[crawfw]

Make sure not to lose the reverse detent ball. lol
Make sure your side cover is completely flush before tightening the bolts. Don't ask me how I know.
You will need some very skinny long snap ring type pliers to get to the clip to remove the tailshaft
Once the bolts are removed, you can pull the tailshaft rearward about 1/3" to 1/2"
Once the tailshaft is loose by removing the bolts. you will have to rotate the tailshaft to find the access hole to get to the clip through the side cover access.
If you have trouble getting the clip back in place, let me know. I found a great trick provided the tans is out of the vehicle.

[crawfw]

If you do remove the trans, do yourself a favor and buy a plastic plug for the real seal. They are priceless as far as keeping gear lube from getting everywhere.

[cjbiagi]

If you remove the bottom bolt from the tailshaft you can drain most of the lub out of the trans. You can also remove the side cover to drain the lub. I am kind of surprised that gasket is leaking between the tailshaft and the trans, I assume you are positive that is where the leak is?
I just rebuilt my Saginaw trans this past spring, unfortunately I have a small leak from the 1st/2nd shift fork so I am going to pull the side cover off again and replace that O ring. I di replace EVERYTHING but for some reason it started to leak from the shift shaft. Good news is I don't have to pull the trans to replace it. Still not looking forward to it......Maybe the O ring got damaged somehow when I installed it.......we'll see.

[starfire]

Clyde, yes, absolutely positively leaking from that gasket. It's starting to sound like it would be easier to just let it leak

[cjbiagi]

Well, everybody has different abilities, not sure how much you want to put into this. To change that gasket it you are going to have to remove the tailhousing. If you are serious here is a excellent video you can rent for $2 for a 48 hour viewing session. I looked at this several times before I did my trans, it is well worth the couple bucks. It shows you how to disassemble the whole thing. You won't have to go that far but at least you will see how it goes together. This is just a short trailer, to see the entire 45 minute video it costs $2.
https://vimeo.com/ondemand/21403?utm_so ... MxMQ%3D%3D