Super M clutch

[PretendFarmer]

My 53 Super M is split and the clutch is out. But now there is a bit of mystery here. The clutch disk looks very usable. Its about .360" thick. I don't know what the spec is for clutch disk thickness, but this seems good.
The flywheel step is about 1.406".
The issue at hand is the clutch slips at tractor pulls. I went to pull a stone boat in 3rd gear. As I let the clutch out, the tractor barely started moving. The engine rpms dogged down a bit but then began to increase. Clutch slippage was obvious. Yet there seems to be nothing wrong.
Right now my best guess is the pressure plate springs are tired.

Visibly there are black marks on the pressure plate and flywheel which is obviously from when the clutch slipped too much and got real hot. The fly wheel is perfectly smooth to the touch.

There is a little chamfer here. The fact that the step is 1.406" and that I see this chamfer both tell me the flywheel has probably never been resurfaced before.

 

[David G]

My guess would be weak pressure plate.

 

[Janicholson]

A week pressure plate is a possibility. What engine mods have been done. It might require a stiffer PP to hold the torque. I
would not use a ceramic "puck" disk, they are hard on both the PP and FW. When mounted to the FW with the old driven disk, the
fingers should be nearly flat to each other. if not, the pins and levers may also be toast. Jim Good luck

 

[PretendFarmer]

Just your standard 4 1/8" overbore. Pistons looks like high compression pistons and compression was over 160. But Ive never had the head off. I actually measured from underneath.
I did put a 29/32 venturi in and enlarged the metering stem and main jet as well.
I cant imagine its pushing much more than 60hp.

 

[pete 23]

Do fingers of pressure plate lie parallel when bolted to flywheel. If not, you are not getting full compression pressure out of that plate. I have seen more than one rebuilt pressure plate that has been resurfaced too much and that loses your compression of the springs. I can't see a picture of the type of finger on that plate but normally a Super used the finger with little bolt on tip of finger so the finger itself cannot be adjusted to give false indication of proper clutch compression.

Had one pressure plate (rebuilt one) that had almost zero tension when bolted down. They cut them plates pretty thin sometimes.

 

[PretendFarmer]

(quoted from post at 19:16:18 06/04/17) Do fingers of pressure plate lie parallel when bolted to flywheel. If not, you are not getting full compression pressure out of that plate. I have seen more than one rebuilt pressure plate that has been resurfaced too much and that loses your compression of the springs. I can't see a picture of the type of finger on that plate but normally a Super used the finger with little bolt on tip of finger so the finger itself cannot be adjusted to give false indication of proper clutch compression.

Had one pressure plate (rebuilt one) that had almost zero tension when bolted down. They cut them plates pretty thin sometimes.

The pressure plate fingers looked even with each other. I actually looked up the belly pump housing and checked that before I did anything.

 

[randy hall]

you should be using a button clutch disc. much more holding power. me or any hy-capacity dealer can get you a pressure plate with stiffer than standard springs.

 

[used red MN]

Ok, yes the clutch should hold and kill the engine. Is this stone boat pull for a tractor pull
competition? Unless this is a timed event to cover a certain distance you should use 1st gear.
That is my opinion. Unless you're out in a field actually picking up rocks, if so question answered.
Don't get me wrong there is a problem with the clutch, just trying to get an understanding of what
you are doing.

 

[pete 23]

I don't mean even with each other, I mean parallel or flat, straight across plate. If they are tilted, slanted away, you don't have complete compression of the springs. As the disc wears the fingers move back, tilt back, don't lay parallel any more. Same thing happens if step on flywheel is wrong or too much material has been removed from clutch. Like I said, too many rebuilt clutches are machined too many times.

I have rejected clutches from hy capacity for that reason. Your disc measurement and the looks of it seem to be in good shape. A good clutch will spring back a considerable amount when unbolting it from the flywheel. A worn out one or over machined one will spring back very little.

I used to rebuild all the clutches I installed from new parts before the rebuilt crowd really kicked in. Lot of them with the heavy duty springs. Caught heck from one guy also as he did not like the clutch pedal effort but we left it in.

 

[robgIN]

I assume you checked / adjusted the free travel first, if so I would also say pressure plate bad.

 

[PretendFarmer]

(quoted from post at 00:29:12 06/05/17) I don't mean even with each other, I mean parallel or flat, straight across plate. If they are tilted, slanted away, you don't have complete compression of the springs. .

All the fingers were flat. I happen to take note of that. Another sign that they were flat is that when the clutch is engaged (pedal out) the throw out bearing wasn't touching the fingers either.
But yea they were flat.

 

[PretendFarmer]

(quoted from post at 00:29:20 06/05/17) I assume you checked / adjusted the free travel first, if so I would also say pressure plate bad.

Free travel seemed normal. From the clutch pedal it had about 1" of free travel.

 

[PretendFarmer]

(quoted from post at 20:39:46 06/04/17) you should be using a button clutch disc. much more holding power. me or any hy-capacity dealer can get you a pressure plate with stiffer than standard springs.

I would be interested in knowing the price of that. I went to the hy-capacity site but there are no prices. Why?

 

[PretendFarmer]

Heres a pic of the clutch assembled. I took this pic before I disassembled it. Fingers look normal to me.

 

[pete 23]

Not to keep harping on fingers, but your picture shows them as
definitely not parallel to plate which indicates disc wear or, like
I said before, improper flywheel step or excess removal of material
on pressure plate. This reduces clamping force on disc.

 

[randy hall]

you have to be a dealer to see the prices.

 

[PretendFarmer]

The step measures 1.406" which is the spec and I measured it a bunch of times to be sure. The disk itself measures .360" and clearly isn't very worn.
I have pulled out clutches before that had been worn almost down to the rivets and didn't slip.

 

[Janicholson]

Pete 23 is correct. The fingers need to be about 1/2" closer to the FW to be flat. New is needed. Kevin Meier can get high perf pressure plates. I do not recommend
ceramic Puck disks for this application. Jim

 

[ih560]

I'm amazed that you are able to run 3rd gear at a stone boat pull, with just an overbore kit. If the clutch wouldn't have slipped you would have surely killed the engine, unless you are running some pretty small tires.

I pulled my old M in many stone bolt pulls growing up (with an overbore kit, good gas head, modified carb and a few extra RPMs) and with 18.4x38's it was a first gear tractor unless it was a very slick track. With 15.5x38's I could run 2nd gear sometimes, but was still a first gear tractor at a stone boat pull unless it was just the first couple rounds.

 

[PretendFarmer]

I wouldn't exactly say it runs 3rd gear well. Its clear to me that if the clutch had good grab it would've stalled out immediately.
It does good with 2nd gear in 5500lbs and 6500lbs class.

 

[PretendFarmer]

So I have it back together. I elected to replace just the pressure plate. I couldn't get the measurements on what the thickness of a new clutch disk should be, but I think its about .370" and the one I have is .360". So with what else is going on around here, I elected to replace only the pressure plate. Throw out bearing and pilot are both tight. I know that means I will probably be into it again in 10 years but that's ok.

I don't have pictures of it, but someone in Earth's history put an extension in the clutch linkage to make it easier to push the clutch pedal down. Even with that on, with the new pressure plate in the clutch was at least twice as hard to push in. And the current adjustment was way off, no free play at all. So the old pressure plate was definitely the cause and was worn out.
I removed that extension because I don't like it. With the extension you don't get the "throw" I think it should have. So now the clutch is twice as hard as that to push in, but that's the way it should be.
I gave it a couple starts in 5th gear, the clutch brings the engine down real quick now. The way it should be.

This tractor was actually easy to split and put back together. Because it doesn't have a belly pump (stage 2 SM), I had easy access to the drive shaft to turn it and line up the splines and it went right together no problem. Having a helper was a big deal as I used an overhead hoist on the engine section with blocks of wood holding up the rest. So the helper could raise and lower the hoist as needed to line things up.
Overall I could probably split the tractor and have things back together in under 3 hours if I had to do it again.

 

[PretendFarmer]

Also, the spring coils on the new pressure plate from hy-capacity measure .170" and the old springs measure .140" so the new ones are considerably thicker.