Rear seal in a PL320 transmission

[Rusty Dawg]

Howdy,

 

I need to replace the rear seal in my 4 speed column shift transmission in my PLG, but I am not certain how to go about it.  The seal isn't simply pressed into the rear of the transmission as it seems to have a sort of shell around it that covers the rear of the transmission where the driveline is inserted.  Is it just a matter of gently prying it out the entire piece and then placing a new seal inside of it?  From the photos attached, it seems that that seal was siliconed in the transmission cap prior to re-installation.

Edited July 7, 2021 by Rusty Dawg

[nicklp]

The parts book shows that seal as one piece, but I wonder if you could figure out a new seal and put it inside that shell. 

[Rusty Dawg]

On 7/8/2021 at 10:25 PM, nicklp said:

The parts book shows that seal as one piece, but I wonder if you could figure out a new seal and put it inside that shell. 

I removed the seal/shell and someone had taken a seal, cut the outer part which is metal and siliconed the rest into the shell.  I will send a photo when possible.  I have another transmission lying in my shop and it only has the old seal in it with no shell.  I was wondering if I took a punch and notched 4 areas on the inside of the trans casing where the seal goes if that would hold it in place.  Heck I haven't tried to place the new one in there yet, but it may be snug enough without the notches.  Do you think the casing is necessary?  I found the replacement seal from National Seals, but not sure I could find a seal with the casing for this trans.

Edited July 10, 2021 by Rusty Dawg

[datzenmike]

I checked and Nissan seems to use the same rear seal on all their Datsun standard transmissions. 32136-07200 I can't think of any car or truck from mid '60 through the 90s that are not the same. They are under $5

 

Try it first. denting the sealing surface will cause leaks. If not sure just the smallest dab of RTV smeared around the inside of the case and drive the seal in with a suitable size socket.

[Rusty Dawg]

On 7/10/2021 at 11:54 AM, datzenmike said:

I checked and Nissan seems to use the same rear seal on all their Datsun standard transmissions. 32136-07200 I can't think of any car or truck from mid '60 through the 90s that are not the same. They are under $5

 

Try it first. denting the sealing surface will cause leaks. If not sure just the smallest dab of RTV smeared around the inside of the case and drive the seal in with a suitable size socket.

So would you say there is no need for the casing/shell that was on it?  I have an extra transmission that has the old seal still in it with no casing and I have seen a photo of this transmission online that did not have the casing either.  I had picked up a seal, National 710324, so I will try to see if it crosses with this one.  If not, I'll buy the one you mention.

[datzenmike]

I don't see a picture of this 'shell' but probably what we call a dust shield. If so, it will work just fine without it. The seal should press into the transmission case. Maybe use a suitable size socket and drive home with a mallet.

[Rusty Dawg]

54 minutes ago, datzenmike said:

I don't see a picture of this 'shell' but probably what we call a dust shield. If so, it will work just fine without it. The seal should press into the transmission case. Maybe use a suitable size socket and drive home with a mallet.

I agree.  My very first pictures show this "shell" that houses the seal.  The shell or housing I pulled off of my trans had someone taking a seal, cutting the outer metal portion to fit in the shell so as to just have the inner part of the seal and siliconed it to the inside of the shell to be installed on the end of the transmission.

[datzenmike]

I see it now. Maybe it helps hold the seal in? I think I would rub the inside with some RTV then press the seal in.

[Rusty Dawg]

Unfortunately the seal I purchased is too big for the opening.  Even if the OD was correct, the seal was much thicker than the recession inside the housing of the transmission and thus it would've stuck out about 1/8" to 3/16" of an inch.  I got the part number for a seal from someone who passed along the parts manual for a PL320 transmission.  It's obviously not what I have for a transmission.  I think nicklp is correct in that it's a one piece unit that I will now go searching for.  If I cannot find one, I might have to do what the previous owner did to make it work, which makes me a bit sick to my stomach.

[Charlie69]

Get the OD and ID measurement and call a good bearing shop and they should be able to source one from measurements.

[Stoffregen Motorsports]

The seal in the Austin Healey/MG Midget ribcase transmission looks identical to that seal, dust cover and all. They need to be chiseled off and cannot be reused.

 

Given the strong connection between Datsun and Austin, I bet this is the seal you need - https://www.spridgetmania.com/part/9G204/Seal-Rear-Trans-All--Ribcase--Sprite--Midget

Edited July 14, 2021 by Stoffregen Motorsports

[Stoffregen Motorsports]

There is another neat part that Mini Mania offers for the Sprite transmission. It's a front cover machined for an actual lip seal. There are four different varieties to choose from here - https://www.spridgetmania.com/ss/ENGINE,GEARBOXES,GE_SEALS

 

If the Datsun trans does not use a seal on the input shaft, I bet one of those covers would work, or you could even machine the cover you have and use one of the seals from Mini Mania.

[datzenmike]

 

32136-07200 used in the 520/521/510 the 240z 4 speed and automatic, 620 early 4 speed not used after '73 with this number. Everything after was 32136-E0100 and pretty sure just a superseded number.

 

 

I think someone couldn't find the correct one and 'RTV glued' something in. Probably former chev owner.

 

 

 

This is the E0100 which supersedes the 07200 and should work. This is the inner transmission side and the outer mating surface is rubber covered metal.

[difrangia]

Mike, I saw what you did there !! with that former-Chevy-owner thingie; but it absolutely has to be red RTV  and way more than needed for full effect !!

Edited July 14, 2021 by difrangia

[Rusty Dawg]

7 hours ago, Stoffregen Motorsports said:

There is another neat part that Mini Mania offers for the Sprite transmission. It's a front cover machined for an actual lip seal. There are four different varieties to choose from here - https://www.spridgetmania.com/ss/ENGINE,GEARBOXES,GE_SEALS

 

If the Datsun trans does not use a seal on the input shaft, I bet one of those covers would work, or you could even machine the cover you have and use one of the seals from Mini Mania.

I wondered this myself last night and tried to look online for any validation, but I could not find anything that this was the case.

[datzenmike]

They are less than $10 US... used to be $5 Canadian and now $13. Try one, nothing to loose. The old ones were metal on metal, put a block of wood over it and hammer in. The latest ones have a thin rubbery coating.

 

Metal one on left and rubber coated on the right.

 

[nicklp]

I did a bunch of looking around last night and found that the Spridget seal measures 29.5 x 51.78 x 28, so too small. But an MGA 1500 seal measures  35 x 56.3 x 28.6,  which appears to be right ID and OD, but longer by 5 mm. Don’t know if that 5 mm matters with the driveline installed. Sure would like to be able to measure/look at both side by side. Now late for work

[Stoffregen Motorsports]

1 hour ago, nicklp said:

I did a bunch of looking around last night and found that the Spridget seal measures 29.5 x 51.78 x 28, so too small. But an MGA 1500 seal measures  35 x 56.3 x 28.6,  which appears to be right ID and OD, but longer by 5 mm. Don’t know if that 5 mm matters with the driveline installed. Sure would like to be able to measure/look at both side by side. Now late for work

5mm seems like nothing. I'd give it a shot.

[datzenmike]

The longer one will place the rubber seal against a virgin part of the driveshaft flange that has no wear or rust pitting from the old seal. Some GM front crank seals are this way.

[nicklp]

Looks like it was used in : MGA 1500 of 1955-1956; Nash Metropolitan 1953-1961; MG Magnette 1953-1955; Austin A40 Devon, Dorset, Somerset 1947-1954; Austin A50 1954-1957; Austin A55 MK1 1957-1962; Austin A60 1961-1965

Part numbers: NA314; 1H3339; 35x56.3x28.6; 1G3419; 11G3417

It looks like the extra length is because it also has a felt seal outside of the rubber seal. I messed around with the driveshaft and trans which are both out of my truck, it looks like the extra 5mm won’t be a problem, so the only thing is to try it and see if works. Can’t wait to see how it works out 

PS Hey Stoffregen- do you know about the all British show that’s supposed to happen September 19th (Sunday) at the Dixon,CA fairgrounds? Google “Dixon British car” -should come up

Edited July 16, 2021 by nicklp
Actual info included

[Stoffregen Motorsports]

Yes, I have been meaning to hit up that show. My dad and brother go every year with my dad's 4AGE 20V swapped Sunbeam Alpine and his '52 MGTD. I suppose I could bring my road Sprite, but it leaks oil like the freakin Valdez...

 

So on that extra length of the seal, are you sure there's enough room for the driveshaft to move into the tail housing under suspension compression? It's still worth a shot, but it's something you'd have to keep an eye on. Worst case, the driveshaft compresses to far and binds up on the seal and twists it on the aluminum tail housing. That could actually be bad.

[nicklp]

Stoffregen, it sounds like you come from an admirable gene pool!

Yes, it’s a little weird discussing a risk for someone else to take. With my trans and driveline on the ground, and the driveline fully bottomed out, it appears that there is 2 or maybe 3 millimeters of clearance between the seal and the front of the driveline (which has a cup that goes over the tail shaft housing, so I had to stick a bent probe in there to measure). It also looks, from the dirt on the outside of the tail shaft housing, that bottomed out is at least 10 and maybe 20 millimeters farther in that that driveshaft got in normal driving. I rarely put much weight in the truck. I don’t know how much extra room Datsun would have left in there. Since Rustydawg still has that trans in his truck, I hope he will take some measurements, maybe with the driveline in and four or five of his closest friends standing in the bed. At the same time, he could check for play in the tailshaft bushing….

[Stoffregen Motorsports]

Cars are, and always have been, a huge part of my life! The love of them came from my dad and his dad. My mom's side of the family was afraid to get their hands dirty. I always felt they looked down their noses at us for liking greasy things.

 

If there is that much showing on the slip yoke, there will likely not be a problem.

[Rusty Dawg]

On 7/16/2021 at 7:13 PM, nicklp said:

Stoffregen, it sounds like you come from an admirable gene pool!

Yes, it’s a little weird discussing a risk for someone else to take. With my trans and driveline on the ground, and the driveline fully bottomed out, it appears that there is 2 or maybe 3 millimeters of clearance between the seal and the front of the driveline (which has a cup that goes over the tail shaft housing, so I had to stick a bent probe in there to measure). It also looks, from the dirt on the outside of the tail shaft housing, that bottomed out is at least 10 and maybe 20 millimeters farther in that that driveshaft got in normal driving. I rarely put much weight in the truck. I don’t know how much extra room Datsun would have left in there. Since Rustydawg still has that trans in his truck, I hope he will take some measurements, maybe with the driveline in and four or five of his closest friends standing in the bed. At the same time, he could check for play in the tailshaft bushing….

The most I will carry in the back of my truck will be a bag of compost from Lowe's.  I have other trucks that can handle the heavy stuff, so point taken.  Seal sent to the wrong Napa, so now waiting for it to get to my local Napa.  No hurry since it is as hot as the devil's ass crack around here the past 2 months, so not sure when I will give it a try.