MTFCA Forum

I'm looking for a replacement low speed drum and was looking for help in what to look for.
Cracks across the band and across the ribs I've seen on videos but what about the outer surface condition?
And what if it has been turned in the past?

Thanks

The band surface should be very smooth & running concentric with the gear. A little waviness is no big deal. Band will wear to shape.
Standard size is 7.5"

If they have been turned then they would be thinner, more prone to cracking in the future. Also turned to a smaller diameter will require more pedal travel making the adjusted pedal very close to the floor boards.

I think I will try and find a reverse drum also if I can so I will have one on hand if I find a crack in my existing reverse.
I would need a caliper to pick up the difference below 7.5" I guess.
I fitted new Kevlar bands because low & reverse were slipping, fixed the reverse problem but low is still pathetic so looks like a major job.

Might take a bit of searching, does any year low/reverse fit?

When you say you had slipping issues and the new band as you say is still pathetic, the problem is more than likely the cams on the shaft.

First gear band should only have 1.5" of free travel between fully back and just engaging the drum. Any more than this indicates wear in the pedal and notch ramps. I am working on one at the moment where the freeplay is almost 3 ". There are no new pedals available, so the only alternative is to rebuild the spiral ramps with weld and hand work them back to spec.

The current trans I am working on has a replacement brake drum and it did not match the driven plate circumference, so the pair were bolted together and reground to conform. To compensate for the wear/material ground off, a sheet metal spacer was fitted between the band and the new linings. I have used this same technique on other drums, but there is a limit to the amount of wear,grinding to be done.

Grooves worn around the drums are tolerable in most cases. The bands will seat accordingly with little effect. Any faults across the drum, such as an area of deep rust pitting, will chew the linings up, although not as quickly as a cracked drum.

Hope this helps,
Allan, from across the ditch.

Even though you might not see any cracks if the drum has a bluish color it means it has been slipping and lost it's temper. Avoid any drum which has turned blue.
Norm

Do yourself a favor and get a new drum. I just replaced all 3 in my 16. New drums with new shafts. New triple gears with needle bearings. Nice and quiet, just like a car I worked on with all NOS drums and gears.
New drums are thicker than worn used drums.

Also detecting all the web cracks has to be done after a thorough cleaning, bead blast & solvent wash or magnafluzing.
Greasy/dirty swap meet found drums can & do look good until cleaned.

I agree with Dan. Should never have to worry about the transmission ever again!

If you install used drums, there is always the chance one may crack in use. It's happened to me and to a number of my friends. It seems more prevalent with Kevlar bands, but remember, these drums are a century old and may have seen a lot of abuse.

I would recommend buying new drums from Dave Nolting. If your gears are good, you can rivet them to the new drums or go with new gears. https://www.davesrestorationandmachine.com/

To my knowledge, no one has ever reported one of Dave's drums cracking. They've been trouble-free in my car for the last 5000+ miles.

Great feedback Guys thanks.
Plenty to think about.
It does seem strange that low band wont grip, looks like it is grabbing the drum but maybe the pedal setup is really worn and thats a contributor. With no load (a rear wheel jacked up) it grips the drum fine.
I'll do some measuring.
Daves restoration looks a good option, thanks for posting.

Thanks

One thing to be aware of --- sometimes a drum can crack in the web, which is invisible unless the drum is removed. A friend of mine recently installed a set of Dave's drums after his low drum cracked across the drum and started peeling away the kevlar lining....the kevlar fuzz damaged the coil ring so it had to be replaced too. When the drum was removed, a crack was found in the web 180° from the original crack. This happened 1600 miles after a total rebuild in which a cracked reverse drum was replaced but the low drum retained because it "looked fine". He ended up spending a lot more $$ than if he'd just put in new drums from the get-go.

All good points.
If I had only one T and not fleet of other brands of old cars (all roadworthy) the approach to spending might be different.
At this stage I will try a search for a sound a 2nd hand one, plus a reverse also then pull it apart. Maybe I will have to spend a fortune in the end but i will explore every option.
What you may not realize is when you buy a $500 drum it might costs you $530 landed.
When I buy a $500us drum it costs me over $800nz, then usually the same to ship it = $1600nz then 15% tax if its over $1,000 including shipping. So now the $500 drum costs me over $2,000nz. That's for one drum!

Kevin, I have some good low speed and reverse drums. If I can help let me know. I could have them cleaned and crack tested, and get a postage quote for you. Send me an email and we can work out some details.

Allan from down under.

Rata Road wrote: ↑

Thu Sep 05, 2024 10:07 pm

I'm looking for a replacement low speed drum and was looking for help in what to look for.
Cracks across the band and across the ribs I've seen on videos but what about the outer surface condition?
And what if it has been turned in the past?

Thanks

The low speed drums are the thinnest in the transmission.
That's why we made and continue to make new drums and gears.

Best thing is to have them crack inspected if you are to use an original and check its thickness around the drum.

I see 'Alan" has some i would contact him as he is alot closer than the rest of us.
https://www.jandm-machine.com/custom_works.html

Thanks guys and yes I will contact you Alan.