955L questions before i buy

[Nige]

With no idea of how familiar the shop that will do the pressing is with the task I just thought I'd throw it out there.
Of course I may be way off base and discover they've done the job before.

 

[cg3p0]

Im assuming they knew that, but not for sure. I can ask when i go get them, they already pulled the clutches off. Im just waiting for after the holiday to go get them. I do know they have the manual and they have done them before, the guy seemed fairly knowledgeable about the 955's.

 

[cg3p0]

Got the clutches back from the shop. Got a pic to show what broke. Was wondering why this part would have broke, i know its under pressure when the clutches engage but its not a moving part so i would have thought it should have been designed to withstand the pressure. Possibly someone tightened up too much? I can tell they replaced the yolk on that side so someone had been in there working at some point.

The manual gives specs for measuring the clutches to tell if they are still good. The measurement is 84.07mm +/- 1.02mm. My clutches measured (R) 86.5mm, (L) 88mm. Would have thought they would have measured under 84mm not over. Any thoughts on that? Clutches bad?

 

[Nige]

Aftermarket clutch plates and discs used in the previous rebuild..? Remember the spec in the manual only applies to OEM parts.

 

[cg3p0]

Ok thanks Nige, guess ill just figure on getting new ones while i got it apart.

 

[Nige]

It was only a thought, there could be other reasons. I don’t know if it’s possible for the friction material to swell if it is exposed to incorrect lubricants. Have a good look at the discs and try to find evidence of a Part Number. Also see if you can find a spec for a single disc or plate then measure the thickness of each one and compare it to spec.

 

[Nige]

Here's the info for individual discs/plates
Thickness of one new friction disc assembly ... .165 ± .005 in(4.19 ± 0.13 mm)
Thickness of one new separator plate ... .075 ± .006 in(1.91 ± 0.15 mm)

Also back to your photo in Post #63 above. That 1V-3242 bearing cage has been pretty hot at some time in the past. Look at how the paint is discoloured. Is the other side the same..? It may be nothing more than someone heating it up to install a replacement bearing sometime in the past but I thought I'd throw it out there.

 

[cg3p0]

Not sure about the bearing cage, all looks ok as far as i can tell. I can also see that they heated up the nut that holds on the bearing cage to get it off, i had to heat it up also to remove the nut. I dont have the most accurate measuring tools to check the thickness of the plates, but with my crude tool the numbers i came up with were ~0.164" on the friction disc and ~0.073" on the plates. Visually they look like they have a lot of material left on them to me. For some reason on the left clutch there was one extra separator plate, there was two back to back in the middle of the clutches. That does explain why that side measured about 2mm bigger than the other side. Guessing someone screwed up. Clutches good enough to run? New set of aftermarket discs and plates will run me about $800.

 

[Nige]

If all the plates look like the one in the photo above I'd reinstall them in a heartbeat, minus the extra separator plate in the LH clutch though......
Measurement-wise you're pretty well bang on with both friction discs and plates.

 

[cg3p0]

Well thats good news! Ive been in contact with offroadeq for the parts, they found most of them but looks like they have given up looking for some of the other parts so i just ordered a parts manual from servicemanualpro to hunt everything down.

 

[Nige]

Just a thought. Check the clutch springs against the spec in your service manual. They may be tired. Replace if they aren’t up to spec.

 

[Cmark]

To me, that extra plate looks too obvious to be an assembly mistake. More like a bodge to cover up a more fundamental problem, like a mismatch between used parts maybe?
A careful examination of parts and part numbers is warranted before reassembly, I think.

Edit.
That may be a sacrificial plate that should have gone on one end of the clutch pack and has been assembled in the wrong order.

Have you given the final drive input pinions a shake to see if there's any excess wear in the bearings?

 

[Nige]

It seems strange that the LH clutch pack measured approx. 1.5mm more than the RH one and that's pretty much bang on the measurement of a separator plate. I guess the $64k question is why..?
Like CM mentioned, it seems too odd to be an error but if somebody installed that extra plate deliberately what were they trying to cover up for because according to the OP all the individual plates & discs appear to be pretty close to specification..? It begs the question what else might be worn..?

 

[Nige]

Maybe the springs (post #71) are weak and the extra separator plate was put in there to compensate..?
Really to test the springs they need to be put in a compression tester, but I doubt the OP has the facility to do that. Check and report on the free length of the springs, outer 108.4mm, inner 83mm, as a first step.

Here's an interesting factoid........ in the 9K0714 Steering Clutch Gp. for machine Serial Number range 85J4672-4862 the Parts Manual calls out 14 friction discs and 13 plates. In the same Group for Serial Numbers 85J4863-Up the number of plates increases from 13 to 14. I can find no announcement explaining why this change was made, or even where the additional separator plate is supposed to be installed.
NOTE: The quantities of discs & plates listed below are for both sides of the machine (2 steering clutches).

 

[Nige]

Now I'm even more confused. Looking at an even higher Serial Number range of 85J the discs have now increased to 15 per clutch, but the specification of the overall thickness of a clutch pack under compression has stayed the same at 84.07 ± 1.02 mm ......!!

 

[kshansen]

Now I'm even more confused. Looking at an even higher Serial Number range of 85J the discs have now increased to 15 per clutch, but the specification of the overall thickness of a clutch pack under compression has stayed the same at 84.07 ± 1.02 mm ......!!

And then the description of how to measure clutch stack does not seem to make sense:
"Clutch pack dimension (measured across the teeth of the outer disc assemblies of an assembled clutch) ... 3.310 ± .040 in.(84.07 ± 1.02mm)"

I'm thinking the "disc assemblies" refers to the discs with friction material applied to them and all those I have seen the friction material is above the surface of the teeth, or am I reading that wrong?

 

[Nige]

OK, found a Service Mag article. Not that it makes things 100% clear but read on ........ and here's my 2c FWIW.

The specifications for measuring a clutch pack are with it assembled and compressed by the springs. So in the original build of 14 friction discs and 13 plates with a friction disc at each end you supposedly had to make a measurement over the outside of the friction material of the last disc at each end of the stack. Not exactly easy when it's assembled .......

So what it appears Cat did was change the measurement method to a much easier one where you simply measure from the outside of the teeth on the last friction disc at one end to the outside of the teeth on the last friction disc at the other end. You would not be measuring the thickness of friction material on the outside of the last friction disc at each end by doing it that way.

When the number of separator plates changed from 13 to 14 and then to 15 I am assuming that the additional plate(s) would be installed on the outer ends of the stack and therefore would not affect the "outside of tooth at one end to outside of tooth at the other end" specification, because the additional separator plates would be installed on the outside of that.

In summary - I have NO definite idea how many separator plates should go in that clutch. If I go by the book for the S/N it's 15, so in the absence of any information to the contrary that's what I'm going with. Looks like the OP might have to buy 3 separator plates......... I show them at $65 each for OEM.

Anyone have any opinions that maybe an lesser number (13 vs 14) of separator plates in the RH clutch might have had something to do with the failure in the operating mechanism..? Too little or too much movement maybe..?

 

[showrguy]

Any updates ??
I’ve really enjoyed following along with your project..

 

[baddboyy21]

I have been following on youtube! I really enjoy watching. I have a 955L also.

 

[cg3p0]

Oh wow, sorry guys i hadnt checked back here in a while, got busy on other stuff. Thanks for all the thoughts and information everyone. I have measured the inner and outer springs. Inners look good but a number of the outers are on the low side measuring around 106mm. The part where the clutches hook up to the final drive felt ok Cmark. Nige im thinking they must have made an error and mixed up the number of disc and plates, my parts catalog calls for 28 friction plates and 30 metal discs. That should be 30 friction plates and 28 metal discs imo. From an engineering standpoint i cant see any way they would design a metal disc to be on the end in contact with the metal of the hub, metal on metal slip contact = not correct imo unless there is something im not understanding here. Should be metal>friction>metal>friction.... all the way through imo, not metal>metal,>friction>metal... Must be a mistake. Im going to stick with 15 friction 14 metal per side unless someone can convince me otherwise. I guess I should get some new outer springs though.