1937 120C Pinion & Trans rear seals

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Dwight Bedsole
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Joined: Mon Jan 20, 2020 4:01 pm

1937 120C Pinion & Trans rear seals

Post by Dwight Bedsole » Mon Nov 16, 2020 8:01 am

I want to replace the seal on the pinion shaft and the rear trans seal on my 1937 120C and am having a very difficult time removing the flange nuts. The trans has a castellated nut so I assume that it is a right hand thread on the shaft holding the universal flange/yoke. The rear universal flange nut on the pinion shaft is not castellated but assume it also is a right hand thread. Both are being extremely difficult to remove, I am really surprised with the difficulty with the rear pinion nut since it should have been adjusted to a bearing preload drag of 25-30 inch pounds - could it be a left hand thread? I have been applying a 50/50 mix of acetone and transmission fluid to both nuts but still cannot remove. Can I heat the nuts with a torch since I am replacing the seals? I also have a Bolt Buster that I can use versus a torch, any suggestions would be greatly appreciated.

Thanks
Dwight

Dave Czirr
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Re: 1937 120C Pinion & Trans rear seals

Post by Dave Czirr » Mon Nov 16, 2020 3:09 pm

It's a right-hand thread.

If you're not going to install a new crush sleeve, then (assuming the rear axle is quiet and without indications of problems), carefully mark the exact position of the nut before you remove it so you can reinstall it in exactly the same position, thus preserving the existing preload.

Dwight Bedsole
Posts: 57
Joined: Mon Jan 20, 2020 4:01 pm

Re: 1937 120C Pinion & Trans rear seals

Post by Dwight Bedsole » Wed Nov 18, 2020 7:13 am

Thanks Dave for the response.
I do not plan to replace the crush sleeve, only the seal. I have no idea as to the condition of the rear axle, or the engine. Since purchasing the car a few months back I have spent time getting "her ready to wake up". The car has been setting up for 15 years, I was told it might need a valve job. I have rebuilt the brakes, fuel system (tank/lines/pump, carb) distributor, generator, cleaned sludge from pan, etc. In addition to low levels of lubricant in the differential and trans, and obvious seal leaks and having to spend hours scrapping tons of sludge/grease from the exterior of differential and trans I assumed the seals need to be replaced.
I will follow your advice on marking the position of the nut in addition to checking the nut torque (25-30 inch pounds with wheels off the floor).

Adam
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Re: 1937 120C Pinion & Trans rear seals

Post by Adam » Thu Nov 19, 2020 6:04 am

You have obviously done a thorough job of fettling the car ready to run. Regarding a valve job, the concern here is if the valves that have been open all this time have rusted around the seats. It is also possible that some might be stuck off their seats, caused by solidified carbon and gunge in the valve guides. If it were a race engine, I would suggest replacing valve springs because some have been compressed for 15 years, but it isn`t, so I won`t.

I would suggest getting her running and see how the valves seem. After a short period of running, sticking valves may free off and compressions may return to something acceptable. So try it before you strip the head off.

For the pinion nut, it is most likely dry threads that are holding you. Do you have a 24" breaker bar? That should normally shift it. Or, you could heat the nut, given that you are replacing the seal anyway (usual precautions because you are working near the gas tank). If you have, or can borrow, or hire, an impact wrench, that should get it moving in seconds. The tyre fitters tend to have some brilliant cordless ones these days.

I am keen to hear how she goes.

Adam..
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

Dwight Bedsole
Posts: 57
Joined: Mon Jan 20, 2020 4:01 pm

Re: 1937 120C Pinion & Trans rear seals

Post by Dwight Bedsole » Thu Nov 19, 2020 8:45 am

Adam, thanks for the advice.
Before installing new sparkplugs I squirted PB Blaster in each cylinder and a week later squirted Marvel Mystery Oil in each cylinder, hopefully to do some lubrication of the top end. Even though the heat riser valve is rusted closed I am sure you are right that moisture has taken it's toll on the valve /guides.
I have a 24" breaker bar, impact wrench and a bolt buster/torch. Currently I am drenching the nuts (pinion/trans) with a 50/50 mix of ATF/Acetone and will attack the nuts again this weekend.
Thanks again for your advice, I will let you know how she wakes up.
Dwight

Dwight Bedsole
Posts: 57
Joined: Mon Jan 20, 2020 4:01 pm

Re: 1937 120C Pinion & Trans rear seals

Post by Dwight Bedsole » Wed Nov 25, 2020 11:44 am

Adam - an update - My Craftsman air driven impact wrench with a max pressure of 90 psig could not remove either the pinion nut or the trans. nut so I borrowed a friends IR, cranked the pressure up to 150 psig and was able to remove both nuts. I marked the pinion nut and counted 8 1/2 turns. I have removed the rear trans. seal but still working on the pinion seal, may have to use heat. I purchased both new seals from Kanter and the new trans seal does not have a lip to facilitate removal as does the original seal nor is it as thick and beefy.
Dwight

Adam
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Re: 1937 120C Pinion & Trans rear seals

Post by Adam » Fri Dec 11, 2020 3:19 am

Hello Dwight

Sorry for not checking back for ages. Great news that the nuts finally shifted. Must have been very tight!

I expect the new seals will be fine, if a different style. Check the housing and journal diameters and the thickness to see where the lip will run.

Hopefully you will have it running well for next season now!
"Do not underestimate the English cousin.....they are not as stupid as they look!" - Signor Altabani in The Italian Job.

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