progress report - 230 powered 1936 Plymouth

[n1gzd_plymouth]

I have been driving it a little while working on it.

rear drum problem fixed:

Last weekend I finally solved my rear brake problem (as you recall, previous owner separated the drums from the hubs and this resulted in making it impossible to adjust the brakes and keep the drum centered).

I succeeded in removing the old hubs and installing some NOS drum/hubs. My slow speed brake pulsing problem is now gone (brakes nicely now).

This was my first experience using a hub puller. I bought one that looks like most of the others that i have seen pics of on this board except that mine was very cheap (from China I suspect). At first I had a little trouble whacking it off until an old timer came by and gave me some advice (don't be afraid to hit it harder). That did the trick.

I did have one problem that I will need to fix correctly when I get a chance. When I went to install the new drum/hub using the old key the key did not fit in the hub key way (too tight). It was the same "size" as the old one but it was just slightly too snug. However the other side of the key fit just right in the key way. I ended up making new keys out of some key stock that I just happened to have lying around. I was able to install it easily with this new key. My new key is not tight enough though (teeny teeny bit of extra play). What I really need to do is make one that fits both the axle shaft and the hub keyway. I think that the ones that I have are ok for the summer (next winter I will do the bearings and can re-address this at the same time).

It took me longer than it should have to figure out that the key was not going to fit because I did not know how easy it should be to install the hub. The consequence of this was that I tried several times to push and bang it on (and then had to keep using the puller again and again to get it off again).

Eventually I saw the light and made a new almost good enough key. (learned a few things along the way).

Another thing, I could not find a torque in the book for the axle castle nut. I experimentally determined that you just have to make it as tight as you can without causing the wheel not to turn (and then put it in the nearest cotter pin hole. one person told me that it should be 100-200 ft lbs. Clearly this is not correct. I am sure that I ended up with significantly less than that. It is not very hard to crank it on too tight (and then the wheel can't turn). I also determined that the brunt of the torque is taken up by the key not the snugness of the taper on the axle shaft. This is why I am sure that I need to make yet another set of keys that are perfect.

By the way, I discovered that foam ear plugs make the perfect thing to block up threaded bolt holes (such as in drum) when during painting. I mean the kind that you squeeze before insertion and then they expand to fill the space.

More later.

Rebecca

[Young Ed]

The correct spec for the axle nut is 160lbs minimum. If its too loose the drum will move back and forth as you switch from forward to reverse. This will eventually elongate the keyway in your drum or axle. If putting the drum on this tight causes the wheel not to turn you have an issue with something else. Possibly the shims behind your backing plates or a lack of shims actually.

[eric wissing]

I want to see more pictures of your car. It is great. It sounds like you are plugging along and gaining ground. Keep it up. Eric

Edited July 7, 2009 by eric wissing
spelling

[n1gzd_plymouth]

Thanks for the info. I could not find a mention of that anywhere in the manual and I could not find it in the lockheed brakes section of motors either.

I will investigate this and fix it. Thanks for setting me straight.

Rebecca

[TodFitch]

Torque specifications can be found on my web site: http://www.ply33.com/Repair/torque

Rear axle shaft nuts are specified at 142 ft-lbs minimum.

[billwillard]

If you don't have the drum on the cone tight you are going to wind up with a bad axle and bad drum. The key is only there to stop the drum from turning on the axle. As the young one says you have some issues that you need to address NOW.

Bill

[TodFitch]

Hmmm. There was a big redesign of the rear axle between, IIRC, 1935 and 1936. And, if IIRC, there may have been a change in the taper. You mentioned that you got new drums because some PO had separated the hub from the drum. Are you absolutely sure that your new hub/drum assemblies are the correct ones for your axle?

[n1gzd_plymouth]

I was told that I have a 41 rear end. I have not proven that but there were left threads on the left side (36 Plymouth did not have that). The new drum/hub set is supposed to be ok for this setup.

visually it looks like my old parts (that had been separated). My plan was to punch out the old rivets, clean them up, and rivet them back together and use them as spares.

Clearly something is not quite right. One thing that baffles me is, how come with all the books that I have, am I not able to find one place in one of these books that lists the proper torque for this axle nut. I find that pretty strange.

I would agree that it sure makes sense that this should be torqued very tight.

I really need to understand this and fix it. I want to drive the car. last weekend I was so sure that I had it almost right. now it seems that I am wrong. I may need to get some local assistance (find someone who is an expert to advise me) since this is a safety issue. It does not seem to be slipping the way it is but I don't think that it is right.

Would you agree that no amount of torque should render the wheel unable to turn? (it should not be able to squish the bearing). Is that correct? If so, I don't understand why it does not turn if I make it really tight.

Thanks,

Rebecca

[n1gzd_plymouth]

Hmmm. There was a big redesign of the rear axle between, IIRC, 1935 and 1936. And, if IIRC, there may have been a change in the taper. You mentioned that you got new drums because some PO had separated the hub from the drum. Are you absolutely sure that your new hub/drum assemblies are the correct ones for your axle?

An incorrect taper would explain my problems completely.

Rebecca

[n1gzd_plymouth]

Torque specifications can be found on my web site: http://www.ply33.com/Repair/torque

Rear axle shaft nuts are specified at 142 ft-lbs minimum.

Thanks for this excellent info. This is an awesome site. I don't know why I failed to find this info in the books that I have. Thanks so much.

Rebecca

[n1gzd_plymouth]

I guess I need to figure out how to prove which axle shafts I have. Just because my car came with what appears to be post 1940 (because of the left threads on the left side) hubs and just because the person I got the car from thought it had a 41 rear end does not mean that this was so.

I need to figure out how to be sure which axle shafts I have.

Also, I have to find a way to figure out which years had the same axle shaft taper. I was under the impression that 1940-1942 had the same parts. How about 1936-1939?

I guess I need to find a parts interchange manual. Also, perhaps I need to pull off a new hub again and one more time compare it to the fit of the old ones. It took a lot of force to get it off so I think that it fit the taper correctly. I supspect that there might be some numbers stamped in the casting on both the old one and the new one. I should get those numbers. I should have written down what was on the new ones before installing them..

argh. I really want to drive this car this summer.

Rebecca

[RobertKB]

My parts book shows the same axles for '37 to '48 for Plymouth, Dodge, Desoto, and Chrysler.

Edited July 8, 2009 by RobertKB

[n1gzd_plymouth]

My parts book shows the same axles for '37 to '48 for Plymouth, Dodge, Desoto, and Chrysler.

Ok. That is a relief (the new hub that I have should fit if everything else is correct).

Next question: If I just press the hub on without the key how tightly should it fit on the shaft? I will get to the point. After I slide the hub on the shaft (with the key installed) am I supposed to tap the key in until it gets tight (as it is driven down towards the shallow part of the axle key way, it would get tighter). I did not do this (but I did tap it in a little - it is recessed about 1/4 inch in from the end - this is more than the original key which was tighter). Is it possible that my whole problem is simply that my key is not tapped in enough (of course it is very very very tiny bit too loose too but I don't think that is the problem).

Shall I go ahead and tap it in as far as it will go before it sticks? Is this possibly the reason why I cannot torque the axle nut as far as it should go. In other words, is it possible that if the key is not wedged the way it should be that the hub will press further down the axle than it should be and tightening the nut will cause to much squeezing on bearings further down.

The only other thing that I can think of is that it is shimmed incorrectly but if that is the case, how come the old hub was plenty tight (very hard to remove anyway).

Thanks again for helping me understand this. I guess there is no better way to learn about your car than to start with a car that needs everything.

Rebecca

[n1gzd_plymouth]

My parts book shows the same axles for '37 to '48 for Plymouth, Dodge, Desoto, and Chrysler.

One more thing. I have assumed that I don't have a 1936 axle because I was "told" by the guy who I bought the car from that I have a 1941 rear end and also the hubs that were on the axles had left hand threads on the left side (started in 1940 I think so this supports the presumption that I don't have a 1936 axle as I was told).

Thanks,

Rebecca

[RobertKB]

My '38 Chrysler 11" drums have left hand threads on the driver's side so I do not think it started in '40. I also had a set of '38 Dodge 10" drums that were left handed. As for the key, I would leave it where it is, about 1/4" from the end. I believe that is about where mine are on my three oldies. I find some keys slide in very easily and others need to be tapped. If you only have a very slight looseness with the key, I would not worry about it. The drum will not be hard to get off if you just slide it on without the key. It only really get sucked onto the tapered axle when you put on the correct amount of torque. I put it on loosely, then put in the key, and then torque it. I leave it loose enough when doing brakes that I can usually just tap it lightly to remove it or just pull it off by hand. If you have everything tightened up according to specks you should be able to turn the drum without a problem if your shoes are adjusted correctly. It should never bind and not turn unless you have another problem. Could be your backing plate is over-shimmed. You should not have more than 7 or 8/1000th inch play in the back axle. This can be measured with a mircrometer (not sure how I did mine but I did). Hope this helps. Others please chime in if you have other or different advice.

[n1gzd_plymouth]

I thought that Plymouth started in 40. Anyway, I am pretty sure that 37 is not left handed and since someone already said that the taper is standard starting in 37 I am going to stop considering that the taper is incorrect.

Back the backing plate shims. Now I need to understand this. In the exploded diagram I see shims behind the inner bearings (you have to pull everything apart to get to it). In the book they refer to these shims as the ones for adjusting axle end play (or adjusting the bearings).

I don't see any shims right behind the backing plate.

This could be the problem but it does not explain why I did not have this problem with the previous hub.

another question, when I was pulling off the hub (whacking on it), and when I was tightening the axle nut, I had to do something to prevent the axle from turning. I put the car in first gear for this. Is this the right thing to do? I was worried that I was going to put too much stress on the tranny.

Thanks again for sticking with me on this,

Rebecca

[Young Ed]

I would think tightness would be caused by undershimming. Wait a minute though. The drum doesn't push on the bearing. It pushes on the axle. The backing plate bolts push on the bearing. Perhaps its undershimmed and when the drum is tightened onto the axle its pulling the bearing out against the race? That could make it not turn.

[Young Ed]

When you are tightening it back on for the final I would think you'd do better with the tire back on and the car back on the ground.

[n1gzd_plymouth]

I would think tightness would be caused by undershimming. Wait a minute though. The drum doesn't push on the bearing. It pushes on the axle. The backing plate bolts push on the bearing. Perhaps its undershimmed and when the drum is tightened onto the axle its pulling the bearing out against the race? That could make it not turn.

I was thinking that if it was over shimmed (or the unlikely scenario that the taper is too little for the hub) that the hub would bottom out before it got tight on the axle thus effectively pushing on the bearing instead of the axle. That is what seems to be happening. However, I don't understand why it was not happening with the old hub.

I was tightening the axle nut with the wheel off so that I could easily test it to see if it turns. I could do that with the wheel on if I jack it up afterwards and try and turn it.

Clearly I need to understand everything about shims and where they are. Is it possible to measure whether the shims are correct without disassembling?

Rebecca

[Young Ed]

To check the shims you need both wheels and drums removed and both backing plates installed tight. Then you see how much each axle moves in and out. Without fancy measuring equipment available both my car and truck are setup with the smallest amount of movement I could feel.

[n1gzd_plymouth]

To check the shims you need both wheels and drums removed and both backing plates installed tight. Then you see how much each axle moves in and out. Without fancy measuring equipment available both my car and truck are setup with the smallest amount of movement I could feel.

Ok. I will check this on Friday. I assume that these shims are the ones that I see in the explosion diagram in the book. they are inside of the inner bearing grease seal (you have to pull both sets of bearings out in order to get to them?). It seems like you need yet another type of special puller for this (not the hub puller that I already have).

I would think that for the shims to be the cause of the problem that the endplay would have to be too tight (no movement detected). Would you agree with this?

Rebecca

[Young Ed]

The shims are or should be between the backing plate and the end of the axle housing. Lack of shims and axle freeplay are the only cause of a tight bearing I can come up with.

[n1gzd_plymouth]

The shims are or should be between the backing plate and the end of the axle housing. Lack of shims and axle freeplay are the only cause of a tight bearing I can come up with.

Ok. please help me to understand this (diagram not in front of me but I can kind of picture it).

Is this true?: Lack of shims, will cause too much axle end play (you can pull the axle in and out too much)? If this is the case then torquing down the axle nut could cause the backing plate to get pushed towards the bearing and press against it. If the shims are in there they permit the backing plate to press against the shim but not the bearing. Is that correct? If this shim is too large then (opposite problem from what I probably have) then it won't be possible to push the hub on far enough but the bearing won't get too tight (so this can't be my problem).

What I still lack, is a complete understanding of what comes apart to reach the shims, what tools are needed, and where you get these tools.

Do I have to remove inner and outer bearings to get to it? In the book that I have there is just one small paragraph about this. Is this a full day job or a couple of hours job. I guess I will need to disconnect the brake line to get the backing plate off (so I will need to bleed the brakes). Is this correct?

Does someone have pictures of this procedure?

Thanks and sorry for so many questions.

Rebecca

[billwillard]

Rebecca, You do not have to take anything apart to ck bearing end play. Just grab end of axle push and pull to see how far it moves in and out. Should be very slight movement. The key only needs to go in to where there is nothing sticking out but you do not want to push or drive it in any more. I think the first thing I would do is measure the hole in the old hub and the new one to see if they are the same. Also measure the depth. Never asume any thing. You will not hurt anything by putting the car in first gear while tighten. also pull your hand brake. I would retork to 175lbs after the car is back on the ground. If you have taken it out of gear and the hand brake is off the wheel should turn free.

Edited July 8, 2009 by billwillard

[n1gzd_plymouth]

Thanks. Yes. I understand that it is easy to check the end play just with the hub removed. I am thinking ahead, and assuming that I might need to change shims. I will check these things first and then think about the next step after that.

Thanks.

Rebecca