1917 Transmission Broken Drum

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Model T Ford Forum: Forum 2012: 1917 Transmission Broken Drum
Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Saturday, June 30, 2012 - 05:41 pm:

As can be seen in the photos below, the brake drum from this 1917 transmission has separated from the gear/plate assembly. It was hard to diagnose while in the car as there was no LOW or REVERSE, but still the BRAKE worked. These early brake drums had very little material at the attachment point and should be replaced with the later style during a rebuild. Also, smaller oil passages for interior lubrication. Has anyone else experienced this type of separation?




Broken Drum


Pparted Brake Drum


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, June 30, 2012 - 05:55 pm:

No. I did open the lube holes when I did mine. The early ones are kinda small.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Ostbye on Sunday, July 01, 2012 - 12:07 am:

I have a question for you.. Did your bands chatter before it broke ? Looks like there was enough material but wonder if chatter made it break.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Sunday, July 01, 2012 - 12:19 pm:

Fortunately, (for me) the car belongs to a friend of mine who recently got it running. Initially, he was using cotton bands, and after many adjustments, converted to Kevlar. He never mentioned chattering bands, but being a new driver, perhaps he was a bit too aggressive with braking as he lives on a fairly steep hill. But also, this original drum may have been abused for the past 95 years and just finally came apart.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Sunday, July 01, 2012 - 01:04 pm:

Never seen one break like that. I bet it has been cracked a long time.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Sunday, July 01, 2012 - 01:53 pm:

Could you get some close-up pix of the break, all around? Or could you find someone to analyze the break?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Sunday, July 01, 2012 - 08:08 pm:

Ricks: I'll try to get and post some real close-ups of the break areas, but sorry, I don't know of any metal analysis guys that could do a scientific study. I kind of go with the chattering explaination which seem most plausible.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew David Maiers on Sunday, July 01, 2012 - 10:09 pm:

Cloth(or wood) bands are the weak point in the T trans, when you eliminate that "shear pin" the transmission is now the weak point.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willard Revaz on Tuesday, July 03, 2012 - 08:16 pm:

Here are some additional "BREAK" photos:








You might see some casting "voids" which could be contributors and I did notice that the "break" area was a bit thinner on one side than the other. The owner did NOT experience any "chatter" of the brake band in driving the car prior to the failure. Who knows, but makes for interesting speculation, Eh?


Top of pagePrevious messageNext messageBottom of page Link to this message  By J and M Machine Co Inc on Tuesday, July 03, 2012 - 09:07 pm:

Looking at the brake lugs I can tell that the drum doesn't have a lot of miles on it . Reasoning being they still are in good condition.
However this post makes a clear statement that the parts in an original Model T engine are nearing the end of their usable life.
If anyone is in doubt about using original parts without the need to magnaflux look no further than these photos.
Thank you Willard for posting these pictures.

This is one of the reasons we started making new drums due to lack of good available cores.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez-Templeton, CA on Tuesday, July 03, 2012 - 09:39 pm:

I am of the opinion that new transmission drums, new crank shafts and new wheels will be the future of the Model T. Rear ends are basically restore and replace Babbitt washers, the engine and the rest of the car can be rebuilt. These cars can last another 100 years if the replacements are made. But what do I know?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Cameron Whitaker on Tuesday, July 03, 2012 - 10:27 pm:

Just a little JB-Weld and it'll be good as new! :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Dallas TX on Tuesday, July 03, 2012 - 10:36 pm:

I think the drum failed due to a manufacturing flaw of some sort, either bad metallurgy or a huge crack. Very unusual failure, I can't see any amount of "chattering" that could cause a failure like that.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Matthew David Maiers on Wednesday, July 04, 2012 - 12:26 am:

casting void or not theres still alot of steel or cast iron that was freshly broken there, more than any normal braking situation can cause.

i wonder if the driver abruptly hit the brake, like stomped on it. could be enough?

either way high quality replacements are always welcome.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison on Wednesday, July 04, 2012 - 01:20 am:

Normally when an initial break occurs without the part failing and then fails later the original break will be discolored when compared to the new break. A lot of times the original break will actually show rust. Also, casting porosity is always a problem and casting design often dictates where the porosity shows up. The drums I've seen broken usually start in the web and never follow a common line between parts. This one is interesting because of the type of failure. Now all that being said, perhaps it's time for someone to setup their CNC machining center to start manufacturing transmission drums from material that isn't cast.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Craig Anderson, central Wisconsin on Wednesday, July 04, 2012 - 02:35 am:

Cast iron is king for that usage.
No other common, cheap, material will endure what cast iron has endured in similar applications for well over 100 years and still going strong in places where friction is involved.
Cars, trucks, steam engines, tractors and about anything else that moves moves because of the properties of cast iron.
Some beefing up maybe.......but not a different material.
Then again some broken drums out of over 15,000,000 (times 3 actually) isn't a bad track record either....... :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Wednesday, July 04, 2012 - 10:17 am:

Metal fatigue! For 100 years every time the car was put in high gear, it pulled in one direction on that drum and when the brake was applied it pulled in the opposite direction. Get a new drum and it will most likely last longer than the present owner of the car!
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Wednesday, July 04, 2012 - 10:41 am:

I would mail one or both of those parts to Jersey George for real expert analysis.


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