MTFCA Forum

Last week, I overhauled my transmission.
Engine back in place, I started it few times, drove maximum 20 miles but rapidly had difficulties to maneuver in reverse.
Bad sounds, and eventually engine stalling.
I had to dismount again the transmission.

And then, horror show !!! After reading the forum, the adjustment must have been too tight (.002).
But how do you explain the bushing coming out ?

The bushings melted and flowed ?

The bushings were turning in the triple gears is my guess. Maybe the bushings were too tight? Never seen one like that before. There is a tendency to get all the tolerances good and “snug” when we rebuild a T.

Never seen bushings melt. Thats one nasty fail.
Lots of contributing factors. .002 way to tight. I like a .0045 clearance (thats honed or precision bored) Oil cant get in if tight.
No oil slingers. The subject is debatable, But I add slingers if no magnets. Not enough oil in the area to feed the bushings.

Other factors.
Did you chamfer the bushing bores & clear the oil groves after machining the base for proper clearance? Can limit lubrication.
Did you assemble with grease? That can prevent oiling until the grease washes out.

Look up ball sizing triple gears.

John kuehn wrote: ↑

Fri Apr 21, 2023 4:28 pm

The bushings were turning in the triple gears is my guess. Maybe the bushings were too tight? Never seen one like that before. There is a tendency to get all the tolerances good and “snug” when we rebuild a T.

Snug is a recepie for failure.
A better route is to add in racing clearance. Thats going to the upper limit of the clearance range. Serves me well.
Harley was a master @ this in the 20's

speedytinc wrote: ↑

Fri Apr 21, 2023 4:48 pm

Never seen bushings melt. Thats one nasty fail.
Lots of contributing factors. .002 way to tight. I like a .0045 clearance (thats honed or precision bored) Oil cant get in if tight.
No oil slingers. The subject is debatable, But I add slingers if no magnets. Not enough oil in the area to feed the bushings.

Other factors.
Did you chamfer the bushing bores & clear the oil groves after machining the base for proper clearance? Can limit lubrication.
Did you assemble with grease? That can prevent oiling until the grease washes out.

I did add oil slingers (on the other side).
No chamfer
I assemble with oil ....BUT I had another problem with the differential. It was assembled with grease, and one gear seized on the spider. Certainly what you said.

Sorry, slingers arent visible in the pictures.
Bushing clearance would appear to be the primary issue.
Do chamfer & clean the oil groves well on the next set also.

I’d suggest that you revisit where you got the bushings? My hunch is that what you show is someone’s homemade mix? You see…the tin apparently melted…yet what stayed behind was bright yellow??? ( which also might suggest ‘other’ brass as the remaining copper should have a pink cast to it.) Smelting bronze is not for the feint of heart and not like baking a cake. It is not just piling up on shavings of the individual components and tossing all in a super hot furnace. There is a trick as when and how to add the ingredients…and also a finite time in seconds to kill the smelt.

Tin alone will melt at about 230C. Copper will melt at about 1100C. The alloy ‘might not’ melt out until close to the highest temp component. I suspect you had clumps of tin and veins of tin in your bushes??? (Not supposed to be)

As to the 002…sorry you never got the notice! That is way too tight and the life of the rebuild is measured in minutes and hours when set that close. As others point out, 0035 has been deemed to be about the minimum that works even for someone skilled with the tools.

IF what melted out was tin…that happens about 230C (450F) so is plausible if there was no place for oil to go. But it would have to be free tin and not tin atomically locked to copper as alloy.

.002 would be the running fit, or .002 clearance all the way around not just on one side.

Just confirms my policy of almost NEVER replacing the triple gear bushings. I always replace the pins!

Did you "face" off the bushing flanges for .008 - .012 clearance between the flange & edge of the gear ?

My bushings didn't melt but they did seize on the pins and twist the pins out of the flywheel. My understanding is that most failures are due to installing gears without enough clearance.

I'm glad to see George Mills chimed in.

When I look at that, I do not see bronze; I see something else but don't know what it is, that's for sure. It didn't melt so much as it flowed under heat and pressure. You're looking at 1900F to melt bronze, and you cannot convince me that those parts got that hot - in fact, I'd say it was impossible.

Try to imagine a scenario where metal is 1900F and the oil remains liquid and does not flash into combustion leaving black sooty char everywhere...things sure got hot, but not 1900F hot...what a mess!

I'm going to say it is likely two issues. Bushing clearance was set to tight AND tripple gears were not properly aligned with the drum gears when reinstalled. The slight binding of the gears put a substantial strain on the bushings which caused the gross deformation under low speed engagement.

Another area of concern are the bolts used to hold the starter ring gear. I'm sure the bendix gear collar took a beating by those bolt heads protruding from the rear surface of the flywheel. Not the case when the stock brass screws are utilized.

Where the triple gears timed when installed?

Pierre did you replace the pins that the triple gears go on? What I’m trying to wrap my mind around is the shoulders had to be twisted off for the bushing to walk up off the pins and out of the triple gears. I’m not sure how that happens. To Scott C.’s remarks on the temp. I agree if it got that hot to melt the brass/bronze coupled with oils & some gas residue there would have been a fire, the temps on motor oils flashpoint is around 420F mixed with a little gas residue I’d guess it’d be even lower. I asked about pin replacement because the only thing I can think of that would cause that calamity is a combination of too little tolerance, loose pins or pins driven in with an angle. I guess it pins were not replaced they were probably worn so much that the triple gear could rock & bind multiple times with the rotation of the engine at speed. I’d also check reverse drum especially for cracks might not be a bad idea to check them all. I could also see that the transmission being dramatically out of alignment that it would create a lot of stress on the triple gears & drums rotating in an elliptical pattern. A real mystery with not enough info so according to William of Ockham the simplest answer with the fewest variables most likely is the correct one.

Here is a link to old post that might help.
https://mtfca.com/phpBB3/viewtopic.php?t=2114

George Mills wrote: ↑

Fri Apr 21, 2023 5:28 pm

I’d suggest that you revisit where you got the bushings? My hunch is that what you show is someone’s homemade mix?

I got them from the classical vendors (Snyders, Mac or Lang). I agree that they look more brass than bronze.

Les Schubert wrote: ↑

Fri Apr 21, 2023 7:59 pm

Just confirms my policy of almost NEVER replacing the triple gear bushings. I always replace the pins!

Can you elaborate on that ? You want to keep the original bronze ? I would immagine the bushing to wear more than the pin.

RajoRacer wrote: ↑

Fri Apr 21, 2023 8:09 pm

Did you "face" off the bushing flanges for .008 - .012 clearance between the flange & edge of the gear ?

Yes I did. This was my first concern before opening the transmission. .01 look quite small. Is there a maximum limit ?

Scott_Conger wrote: ↑

Fri Apr 21, 2023 8:48 pm

When I look at that, I do not see bronze; I see something else but don't know what it is, that's for sure. It didn't melt so much as it flowed under heat and pressure. You're looking at 1900F to melt bronze, and you cannot convince me that those parts got that hot - in fact, I'd say it was impossible.

Try to imagine a scenario where metal is 1900F and the oil remains liquid and does not flash into combustion leaving black sooty char everywhere...things sure got hot, but not 1900F hot...what a mess!

Fully agree. But how the bushings became what they are ? The answer must be "flow under pressure". There was no smell of hot oil, or hot material.

havnfun wrote: ↑

Fri Apr 21, 2023 10:27 pm

Where the triple gears timed when installed?

The triple gears were timed, and I put the drums with the gears easily.

Mark Chaffin wrote: ↑

Fri Apr 21, 2023 9:44 pm

I'm going to say it is likely two issues. Bushing clearance was set to tight AND tripple gears were not properly aligned with the drum gears when reinstalled. The slight binding of the gears put a substantial strain on the bushings which caused the gross deformation under low speed engagement.

Properly aligned, if you mean timed, yes. But I did not checked if the pin were square to the flywheel.

JTT3 wrote: ↑

Fri Apr 21, 2023 10:28 pm

Pierre did you replace the pins that the triple gears go on? What I’m trying to wrap my mind around is the shoulders had to be twisted off for the bushing to walk up off the pins and out of the triple gears. ...
I asked about pin replacement because the only thing I can think of that would cause that calamity is a combination of too little tolerance, loose pins or pins driven in with an angle. I guess it pins were not replaced they were probably worn so much that the triple gear could rock & bind multiple times with the rotation of the engine at speed. I’d also check reverse drum especially for cracks might not be a bad idea to check them all. I could also see that the transmission being dramatically out of alignment that it would create a lot of stress on the triple gears & drums rotating in an elliptical pattern. A real mystery with not enough info so according to William of Ockham the simplest answer with the fewest variables most likely is the correct one.

The pins were not replaced. They looked in good shape. Solidely attached to the flywheel. No play at all. And they are still firmly in place after this mess !!
How do you check the angle ? With a small simple machinist square ?
The shoulders have not been twisted off (you see it on the first picture). And the bushing did not walk up off the pins and out of the triple gears.
It just flowed !!

Dan Hatch wrote: ↑

Sat Apr 22, 2023 5:28 am

Here is a link to old post that might help.
https://mtfca.com/phpBB3/viewtopic.php?t=2114

Thanks Dan, very interesting post indeed !

Hello Pierre:
I have never seen this before. most likely you're victim of bad parts."Bushings"
The triple gear pins have to be perfect to fit the new bushings , If there is any wear as they always wear on one side.
They need to be replaced from just overheating them alone.
If you'd like to contact us as i can send pictures of how to size bushings.
You can follow the link that others have suggested.

What kind of motor oil are you using?

Pierre
In my experience the ORIGINAL bushings typically have very little wear and are made with a good quality material. The pins are typically worn quite badly on the inside surface where all the load is applied. The pins are usually quite easy to simply drive out the old ones and drive in the new ones from the magnet side. The new pins I have bought are usually “stepped” slightly in diameter so most of the pin drives through easily (might almost just slip through) and then the slightly larger part holds it in place.
Just my way of doing it.

OK I'm lost,
I was under the impression that if the triple gears were assembled out of time that low & reverse would bind up giving you 3 brakes & high.
So I'm thinking I need to be educated on this? But that doe's seem to make sence.
I have never seen a starter gear bolted on like that, what else do I not know?? I'm thinking that was a dumb question you can fill a 55 Gal.
drum with what I don't know about model T's.
Craig.

How can you put on the triple gears out of time unless you force them on. And if you did I don’t think you could spin the drums easily. They should spin freely without the drum and plates installed. That’s always the test for me.

Pierre
How was the car running and driving before you worked on the transmission. Was it making noise or??

From an examination of the photos posted, I’m concluding this is a likely scenario:

The pins were pressed too far thru the flywheel.

The flanges grabbed and galled at the area of the pin that was too wide.

The bushings then spun in the gears and the flanges broke off.

What looks like “melted ends” sticking out of the gears is where the ends of the bushings bent & smeared when they worked far enough out to contact the reverse drum.

It is quite likely that the first three things happened and there was nothing noticeably wrong until the spun bushings worked far enough back to hit the reverse drum.

Another thing I noticed is that it looks like your flywheel may be an earlier non-starter flywheel that was machined to accept a ring gear. If there is a combination of early and late parts in this trans, perhaps there are also potential issues with incorrect combinations of disc-drum, brake drum, and clutch plate spacers you are contending with as well.

He stated that he DID NOT replace the pins Adam.

John kuehn wrote: ↑

Sat Apr 22, 2023 4:06 pm

How can you put on the triple gears out of time unless you force them on. And if you did I don’t think you could spin the drums easily. They should spin freely without the drum and plates installed. That’s always the test for me.

Pierre
How was the car running and driving before you worked on the transmission. Was it making noise or??

The drums were spining freely when installed. As I said, I put them very easily, so I assume they were correctly timed.
Before working on the transmission, I drove few hundred miles with pleasure.
I got the car a year ago, and spent some time adjusting the engine.
Then, I decided to check the rear axle. Good idea, it was still equiped with the babbit thrust washers.
Before puting the axle back on the car, I looked at the play of the 4th main bearing. There was NO 4th main !!!
That's why I decided to dig further in the transmission and engine.
I have to say it's a Montier car, equiped with a overhead valve head, very much like a Frontenac head.
The flywheel is specific, not machined for magnets.
I have added some sort of slingers when rebuilding the transmission. What is a good idea ?

RajoRacer wrote: ↑

Sat Apr 22, 2023 5:26 pm

He stated that he DID NOT replace the pins Adam.

Okay... It doesn’t mean the last guy that replaced triple gear pins did it right. Look at the picture…

Unless the picture is showing a really exaggerated view of what is actually there, that pin is pressed too far thru the flywheel and there is a definite shoulder exposed to the bushing…

Also, by the surface finish on the end of that triple gear pin, it isn’t a FORD pin. There was a small run of Substandard TG pins that were an issue a couple years ago, as well as a larger issue about 30 years ago.
AND, it’s a non-standard, aftermarket, specialty flywheel with no counterbore on the back side to help the average mechanic properly set pin depths…

I would not trust those oil slingers not to fatigue and break in service.

Pat is correct, those slingers are way too light.

Adam wrote: ↑

Sat Apr 22, 2023 10:30 pm

Unless the picture is showing a really exaggerated view of what is actually there, that pin is pressed too far thru the flywheel and there is a definite shoulder exposed to the bushing…

Also, by the surface finish on the end of that triple gear pin, it isn’t a FORD pin. There was a small run of Substandard TG pins that were an issue a couple years ago, as well as a larger issue about 30 years ago.

AND, it’s a non-standard, aftermarket, specialty flywheel with no counterbore on the back side to help the average mechanic properly set pin depths…

No counterbore on the backside, you mean a way to press the pin flush ?
You idea is that the diameter of 0.681" which is pressed in the flywheels is exposed to the bushing. I don't think so, but I will check the diameter/length of the pin when I will take them off. They have certainly not been replaced a couple years ago. But 30 years ago, who knows ???
They look quite robust as they are still in place after this mess. I would really think if something was poor quality, it was the bushing.
The flanges of the bushings did not brake. That's why I said the bushings flew. I cannot take them off.
What you see of the picture is the rest of the flange at the back of the TG.
download/file.php?id=160660&mode=view

TXGOAT2 wrote: ↑

Sun Apr 23, 2023 7:04 am

I would not trust those oil slingers not to fatigue and break in service.

Jerry VanOoteghem wrote: ↑

Sun Apr 23, 2023 7:34 am

Pat is correct, those slingers are way too light.

OK, I will change them.....or put a standard flywheel with slingers from the vendors.

The sheet metal slingers offered in the past were prone to failure. Cracks & breaking.
I dont know if the current offering has improved.
Personally, I make my own from 1" X 1/8" 90 degree extruded aluminum T6.

Dan McEachern manufactures a good oil slinger set !

Dan McEachern manufactures a good oil slinger set !

and he makes triple gears with needle bearings and the mating pins which they need...quite a few years of testing/service and rave reviews...might be just what you need!

He also makes the best triple gear pins. His are the only ones with the shoulder like Ford pins.

im with les find the best original gears and bushings with new pins. philip

My observation is that the original bronze bushings wear very little. The pins always wear

That's a new one on me too. Strange - is that brass not oilite bronze?
IDK if this helps but I just did a video on transmissions and I touched briefly on "not too tight" in it. https://youtu.be/S1khArmLN2Q

I second the slingers - replace them and get it re-balanced before you go forward. I would probably replace the pins too after that much trauma.

Several years ago when I rebuilt the transmission in one of my cars, the vendors sold two different qualities of bushings. The better quality ones were over twice the price of the cheaper ones. I went with the better quality ones and have not had a problem. Good chance the previous builder used those cheaper bushings and too tight of clearences. I do not believe they are being sold today.

There is still 2 qualities on Lang's website :
660 bronze : https://www.modeltford.com/item/3314-1/2.aspx
“close to ZBronze” : https://www.modeltford.com/item/3314-1/2BQ.aspx

When you order the full set, I guess you get the 660 bronze.
This is what I had. I don't remember if it was from Snyders or Lang's.

Pierre,
The oil slingers shown are too thin and will break. I have seen a setup like what you show last for about 20 minutes before breaking. Also they are not needed, The teeth on the flywheel ring sear will move lots of oil. I have a Scat crankshaft in my car with no slingers and have run it hard for many miles without any problems.
What is important is getting the proper oil grooves and dippers added to the rod bearings.
I have become a fan of using yellow Timesaver lapping compound to fit the bearings. It is a slow process but when finished the engine bearings are already broken in and ready to have full power applied.