Last summer on a "one Car" tour with my wife I experienced what I thought to be a main bearing failure--heavy thumping under load, letting up when load removed. Rather than tear into it at the time I replaced it with my spare engine. Today I opened up the troubled engine--bearings are OK--but one triple gear bushing is seized to the pin and one gear is spinning on the bushing--the 3rd one is just fine. Two questions I have: (1) is it conceivable the triple gears could sound like a loose main bearing under these circumstances and (2) The .002 clearance recommended is that .002 total--ie with the feeler gauge on one side of the pin thats all there is or should it be .002 on both sides of the pin for a total of .004?? I always am so confused. My limited experience tells me loose is better than tight on these bushings. Any thoughts?? Thanks. Dewey
Arthur, you have the answer in your last sentence. On new pins I always give more clearance than less. You can't get into trouble with too much clearance, but too little and you can see the results.
This won't help now but hopefully others will benefit from your bad luck.
Allan from down under.
Arthur,When rebuilding a tranny I was told that a used bushing if it is.005 to leave it ..its good,
but no more than .
Lorenzo
.002 is right but you need to ensure your gears arent binding. You can use the hash marks on the gears as the manual describes to sychronize them but if that transmission had ever been rebuilt way back in the past and a set of gears or two replaced then you may not be able to get them to work.
Go ahead and ream to .002 clearance then with the flywheel up, try to slip on the drum assembly and gears as illustrated. Get one in then slip the second in but rotate it and try to find a spot the gear meshes freeliy. Third the same.
Same thing happened to me, but I kept driving it for years, until the gears jammed and tore the crankshaft flange off.
Here's the Dan McEachern solution I'm putting in the ol' brass picup.
No more soft pseudo Z bronze for me.
rdr
Triple gears should have .003 Minimum, and .003-50 Max. We set all at .003.
.002, to .002-50 will get you in trouble, a one half thousandths is a Mile.
I dunno, mines really quiet with .002
The correct gap is .002 on each side or .004 in total. As long as the bushings are properly fitted they will last for a long time with no problems.
Stephen
At .004, the gear tips to the out side, and starts eating into the flywheel, and teeth to its mated Gear.
Patrick, years ago we set the triples at .002, and they will work, for a while, but pull a long hill in low, on a hot day, and you are taking your chances.
The Ford service manual says up to .005 is acceptable. I have been running tripple gears with .004 for a few years now and use low a lot. I have had the transmission apart since replacing the tripple gear bushings. There is absolutely no damage to the flywheel or other gears.
Stephen
Ya, .006 on the crank shaft end play also, but that is worn, over haul Specs, in a worn engine. You don't fit new bushings that way.
Well I am running full synthetic too so that might help?
I believe the service book says to replace the bushings if they have .005" clearance.
Oh boy, here we go again.
That's NOT what the service manual says. The manual says that .005" is the wear limit (service limit). If it reaches .005", you are to replace the bushings.
Most home builders can't get within .002" tolerance on reamed bushings much less .0005". And there-in lies the problem with regurgitating specs. But here's the facts.
The problem with the repro bushings is that they are made from 660 bearing bronze. The 660 has a higher coefficient of expansion than the original Z-bronze so the 660 bushings need to be reamed about .001 - .0015" larger than the .002" spec given in the manual. This makes the clearance .003-.0035". This is TOTAL clearance NOT clearance on each side.
The downside is this eats into the service limit since it stays at .005".
Sorry Larry, I was responding to Stephen's post. You are indeed correct.
The debate about clearances is largely a waste of time unless you know the bronze that was used. Jersey George did a recent report on this, using my old bushings, among others. Ask him for it.
Dan said he has installed needle bearings in over 100 sets of gears, with zero failures. Of course, he uses his own special hardened pins.
I got all done having new repro pins and bushings fitted to .002, then changed my mind and went with Dan's deal. Maybe I'll use that flywheel, gears, pins and bushings, or maybe sell them for whatever I can get.
rdr
An "easy" way to check the material is to measure the length at room temperature. Then heat the material to +200 Delta and measure again. If it grew .002" per inch in length then it's probably 660.
Ricks, Just for curiosity, what does the bearing setup cost? Thanks Paul
With your gears, new bearings and pins are in the $200+ range.
If you're paying somebody to make sure the pins you buy are straight and round, and install and ream each bushing to each odd pin, your cost will be in the same league.
Is this the right way to measure the pin clearance????
When I reamed I measured both sides of the pin then when I installed the pins in the flywheel I measured and trimmed the heights. I put the .002 feeler gauge on one side of the pin so the total clearance (I assume) is .002.
When I assembled the transmission I meshed each gear one at a time so that once assembled each will wiggle loose and the whole assembly rotated like glass.
I havent really driven it that much but it is quiet and shifts smooth.
In my opinion properly machining Model T transmission bushings (not McEachern triple gear bearings) requires you index the gear or drum by the pitch circle of the gear teeth.
The Dearborn transmission reamer greatly facilitates the process. There are also other ways to accomplish that.
Ron the Coilman
quote:Is this the right way to measure the pin clearance????
Ron,
Will you ream my bushings?
Robbie
The book says "If there is more than .005 play between the bushing and shaft new bushings should be installed in the gears." Not if there is .005 or more play. The point of my post
is .004 is fine.
.005 is the point of no return, Wilson reamers will cut a hole .680, using a Stock pin sized at .677. that is .003, and that should be Min., that is for triple gears, other bushings are different clearances!
The main thing here is to have tools the will give a precise accurate reading, or you will never know what you have for sure.
Heck, I used a brake cylinder hone to get it to a tight fit, then finished it out with Timesaver. Been five years with no problems. Would I want to pay for a job done right and find they did it that way? Heck no! Would i do it again on one of my own? You betcha!
New triple gear bushings with a .005 clearance diameter difference can expand and seize in an over-heated transmission. The strange part of that situation is that when the transmission cools off, the bushing material does not shrink back to the previous size. Here is an example.
What ever broke that pin off James, was not from .005 thousandths clearance of bushing to shaft. A much smaller clearance, it would take, like .002.
If the teeth on the gears did not force them selves apart, and it was bushing to pin, it would have, and could have broke the pin from your heat when at the moment the bushing stuck on the shaft, and in the same time the bushing in the gear wouldn't break loose and spin, the low torque, and leverage, would have snapped the Pin, or Pins.
660 Bronze is the closest thing we have today to Z bronze, so learn to live with it. Ford said to give the bushings 0.002 in. running clearance. He didn't say clearance, he said running clearance which means 0.004 in. total clearance. He then said that if the bushing has 0.005 in. clearance it is too much. He said clearance, not running clearance which is total clearance. I have never heard of a bushing or pin failure using 0.004 in. total clearance. If you use anything less you are asking for problems. Experience speaks for itself and none of our transmission rebuilds have ever failed..
A little OT and yet related.
My 27 machined flywheel was damaged as the pins got loose.
Is there no salvage except as new flywheel in my HCCT when I restore it?
When I rebuild my tranny after my break down last summer I took flywheel and replacement drums from the 25 spare engine I have, but I would like to get it rebuild as complete spare engine and transmission for eventual backup should the need arise.
And Ron, I think too I'll have you do all the reaming - grin -
Hey Ralph, The Dan McEachern solution looks good, so when do you plan to get back on the road and running?
Soon, John, soon. Priorities include roofing and plumbing on the ol' house. I made a new firewall, refinished the spacer board, and am removing lacquer and polishing brass, as long as I have the firewall and w/s off.
Soon, John, soon. Priorities include roofing and plumbing on the ol' house. I made a new firewall, refinished the spacer board, and am removing lacquer and polishing brass, as long as I have the firewall and w/s off.
Oh, that's clever; it reposted 2 1/2 hours later... ?