Michigan 75A no forward travel

[Burnt.Fingers]

Michigan 75A no forward travel.
Waukesha 190 gasoline
75-AG - 1CA-3560
T75A3 transmission
C272-2 torque converter

Moves excellent in reverse.
140psi at the top cover.
Forward clutch drum heats up real quick and it wont move in forward at all.
Input shaft spinning fast all the while in forward.
Input shaft slows to travel speed in reverse.
Reverse works perfectly all the time.
Does anyone know if you can service the forward drum (clutches) without dropping the transmission? Looks real tight up in there ?
Doug Benedetto, Vienna NY

 

[DMiller]

Trans needs to come out. If going to do clutches and seals on Forward Pack may as well do Reverse while out, save a return trip.

 

[kshansen]

If this round thing is what you are calling the forward drum and it is getting hotter than other parts of the transmission I'd say there is a problem in there for sure. How long does it take for it to get hot?

To get that cover off you need at least as much space in front of it as the thing is long. That is more or less a pan that just cover the actaul clutch in side and would have to come all the way off to be able to do any real work. Like DMiller says if the seals or clutch plate in there are bad the chance everything else is perfect is about zero.

Kind of the "Pay me now or Pay me later" story! Who remembers that slogan?

 

[Burnt.Fingers]

If this round thing is what you are calling the forward drum

It's the forward clutch cover to be precise.
I agree rebuilding clutch packs on the bench will be a more controlled environment
However, I'm going to explore doing it in the frame, as I mentioned in the initial post reverse is working perfect and strong in every speed and so replacing those clutches is not needed at this point.

I just acquired this machine with no fwd, it has 7500 hrs on the clock, the fellow I bought it from purchased it in the late 70s in this same condition with little to no forward travel and never used it much or attempted to repair it.

I bought my first Michigan 75A serial 9xxx in 1980, that machine is almost identical to the 1CA3560 above and it's still running strong and used almost daily, I've got 40 years of operating these loaders under my belt.
I was also fortunate early on when I bought that first loader to meet a guy named DJ Smith Marcellus, NY who called himself "The Michigan Man"
And rightfully so, I dont believe there was anyone who knew more about these loaders or had more of them stacked up on shelves and out on his property then Don Smith.

Don taught me alot about maintaining my 75A loader but regrettably I never had transmission trouble and hes passed on now and too late to have that conversation with him.
RIP DJ

 

[kshansen]

I'm guessing that D.J. Smith you knew is related to the David Smith that lives just over the hill from me and has his own small trucking company and gravel bed.

Like I said the first thing I would be looking into is if there was a chance you could remove hoses and such to have clearance to slid that cover off. To be honest never worked on a 75A but did rebuilt a transmission in a 475IIIA once, a bit bigger machine, you could probably park this 75A in the bucket of that machine! And that one was done in frame. It's all a case of if you can remove the covers to gain access to the clutches.

Not sure where or how the control valve for this one is located and how it is connected to the clutch packs. There might be a problem in the connection from that valve to the clutch and not the clutch itself.

Do you have any access to a service manual on the transmission? Is there a tag on the transmission giving a model number? That would be a very good place to start.

Well a quick Google search on Michigan 75A found a manual that includes the rebuilding of the transmission:
http://www.tractorparts.com/PDFs/MICHIGAN75AOperatorsManual.pdf

It says "Operators Manual" but scroll down far enough and it goes step by step on rebuilding the transmission! Some good reading to get started! Start at page 39 and have fun, even gives some trouble shooting ideas!

 

[Burnt.Fingers]

Thanks KS,
The control valve is under the top cover and could very well be stuck or leaking.
I'll check that out first that's a great suggestion.

If I remove the battery tray, master cylinder, brake pedal ,floor boards and the connecting pipe that goes across the frame feeding both boom lift cylinders.
I'll have free access to the forward clutches from above and while standing on the right side plenty of room to get the cover off once those items have been removed.
I've got her cleaned up, took the cab off and inside my shop now...let the fun begin!

 

[kshansen]

Looks good place to be working!

One of the first things I would do if not already done would be to drain oil and see if there is anything on the suction strainer.

Then maybe pull the cover off the top and see what the valves look like. There has to be some passages from the control valve to the clutch shafts. I'd be trying to see if you could get the clutches to actuate with air pressure. They should make noise like a thump when applied and build up back-pressure on the port you are blowing the air into. I'd try them all so as to get a feel how a good one works and sounds compare to the one that you think is not working.

If while putting air in to the forward clutch you hear a lot of air escaping the next step would be to remove that cover and see if you can narrow down where it is leaking. Then take off whatever is needed to get access to that point. The pages I looked at in the online manual do not make it clear if the passages from the control valve to the shaft are tubing pressed into case or they are passages drilled in the case.

Be sure to take pictures and post them here I know I'm interested in knowing what the problem is, hope it's something fixable with out too much effort or maney!

 

[Burnt.Fingers]

That IS a great strategy KS.
I've used air plumbed with a regulator in the past to diagnose leaky intake/exhaust valves in heads and especially on 2cyl harley intakes for leaks to avoid a lean condition.
But, It never crossed my mind to check the clutches this way, should work perfectly, thank you very much for reminding me of that little gem.
with a 0-500psi gauge installed in the test port on the control valve cover, its at 140-145 in neutral, the spec is 150-200psi
When you apply the brake the pressure drops and then rebounds right back to the initial reading properly like the manual states it should.
Shift into reverse the pressure drops to 20psi that surprised me as I thought it would build pressure and be nearer the 140?
And then shift in fwd it drops and stays at zero no surprise there.
I'm planning to drop the fluid, pan & filter in the morning and see what it all looks like.
Thanks again for your input! Much appreciated.

 

[Burnt.Fingers]

Trans fluid drained 18qrts was a reddish dextron type and dirty brown.
Filter looks like an old original.
screen in the pan very clean with the exception of 10-12 steel fragments that resemble a spring.

 

[Burnt.Fingers]

Took readings off my other almost identical 75A loader for comparison.
That machine moves good in both directions and will fill the bucket with ease.
Idling pressure at the control valve test port =120psi
Shift forward it drops to 80psi
Shift reverse drops to 60psi.

 

[kshansen]

Those spring parts do not look good! As if you didn't know that already!

A quick look at parts breakdown does not seem to show springs like that connected to the clutches themselves. So I would be looking close at the valves in the top of the transmission case or possible the converter and pump areas.

All it would take is for one of those bits to get caught in the wrong area to hold a valve open or closed to block of vent pressure from getting to the clutches.

As for the air pressure being used to test clutches it is a very common and good way to check clutches like this transmission. We used it on all the different transmissions, Allison, Cat, Rockford, Clark and others. Some work a bit sluggish or need a bit of oil squirted it to help the seal rings but if air even makes them work noticeably at 120 psi then you can be confident that oil at 120 psi or higher will work fine.

If you manage to find and fix this transmission without major tear down I would suggest finding a large magnet, say something like they mount a CB antenna to the roof of a car and put it inside the transmission case to grab any bits you might miss while cleaning in there. Just make sure it's not going to damage the suction screen or get into the gears. Many transmissions have magnets in them for that purpose.

 

[Burnt.Fingers]

Trans needs to come out.

That's where I'm at. But you were here first!
3 out of the 4 clutch packs wont pressurize.

After removing the top cover, I used shop air to load up each of the 4 clutch packs threw the ports that mate to the control valve cover.

The fwd clutch pack pressure blew right threw.
On the reverse clutch pack a majority of air is escaping at the clutches.
1st-3rd majority of air escaping.
2nd & 4th however I could hear the pack lock up and it will pressurize.
I'm going to make a couple small steel plates that will bolt to the cover at the 2 o-rings to allow me to dead head the control valve and test it for leakage.
I've got a beam slung across the boom with a hoist hung there to gently lower the transmission, it looks like it should angle out towards the front and slide out the side between the wheels once it's on the floor.

 

[DMiller]

It sucks but key was heat up
Fluid bypassing with clutches trying to engage but not.
Good luck on rebuild, most hydraulic shops can match seals
Clutch plates could lead many directions and pray no large hard parts destroyed.

 

[DMiller]

These people supply SOME of the old oddball stuff I need, they also have parts manuals under OEM Manuals for Michigans.

https://www.minnpar.com/

 

[Burnt.Fingers]

Almost have it ready to drop out.
Looks like if I jack up the right front 2" , remove the parking brake cable and right front wheel the trans can be lowered onto the floor & then slide it out upright on the pan enough to where I can pick it with a rolling hoist.

 

[kshansen]

Back when we did a lot of work on the old Hough loaders like the 560's and H-400's we had a place out back of the shop were we had large 3 foot square blocks lined up to back the loaders on to sort of like an above ground pit. Drive or tow as needed the sick machine on to it drop trany out the bottom and drag it out the open end. Same thing in reverse to put them back in.

At least the "little 75A" trany will be a bit easier to handle that the trany in an H-400! If you have access to a sheet of say 1/4 inch steel you could lower it on to that and have an eye welded to it to help it slid out.

Be very interested when you figure out where the bits came from. could even be an oil injury that was not completely cleaned up. seen things like that over the years and can cause lots of head scratching!

good luck and waiting on the next group of pictures!

 

[Burnt.Fingers]

Needed to drop the steering linkage out of the way and unbolt & raise the hydraulic pipe that connects the 2 lift arms for the boom across the frame.
And then do a mess of juggling fwd,back side to side while lowering it.
The rear driveshaft yoke was tough getting over the lower boom support.
Got lucky the strap rigging couldnt have been balanced any better, the trans stayed perfectly upright on the way down.

Smooth steel plate to slide it on is a great idea, thanks KS, I think the front wheel might need to come off for the trans to clear coming out the side.

 

[DMiller]

Getting it out is easy, slinging it back IN is not!!

 

[kshansen]

Getting it out is easy, slinging it back IN is not!!

You want to talk about a fun transmission to remove and install get hold of a Mack off-highway M-30 with a direct mount CLBT 5640 Allison!

I think I wrote that project a while back. If anyone is interested I could search for it or write it up here!

 

[DMiller]

No Thanks!! Used to have to deal with Euc Dump trucks, no transmission jacks and dragging the old gearboxes out on plywood using come alongs to get them down and back up.