Cat 977L

[Mike-JCB]

Hey guys, My 977L now has a right final drive leak that has gotten significantly worse over night. It’s had a minor leak that’s gotten worse and I believe from looking at the sprocket and measuring both sides, I think the preload is loose, and the sprocket is slightly cock eyed.

Does anyone have a helpful set of instructions on how to check or set the preload?

My manual isn’t much help.

 

[Cat977]

I don't think you want to go to preload. That would be tight plus even tighter. I've never done it, but get all the load you can off the sprocket. Rear corner off the ground, track loose top and bottom. dial indicator setup out by rim. Use crowbar to move rim in and out. Tighten nut (it has a lock washer or a jam nut)( I'd guess O.B. location) till you get about.005 to .025 movement at the rim and that's a guess.

 

[tctractors]

By the sound of things you have a failed F/drive, if the sprocket needed a bit more pre-load it would not be Cock eyed just possibly wet around the seal groups, I am no expert and you might be on the correct path, the loading on the bearings allows for no movement so a dial indicator would be of little use, Chris U.K.s post might be of help as he took a good look at his casings. tctractors

 

[Nige]

Chris U.K.s post might be of help as he took a good look at his casings. tctractors

Here's a link the Chris's thread. You'll have to scroll through the pages to find the posts & photos relating to the final drive work that was done on his machine.
https://www.heavyequipmentforums.com/threads/cat-977l.87515/

 

[Cat977]

I really like measuring tools. They're a good reference for getting an idea of about where you are. Blue ox did have a good idea with doing it before putting the chain on. Much better feel that way. With the chain on and the indicator out on the rim it would be hard to feel any .005 movement might even feel tight. I would like to know it wasn't tight. I would also like to know the procedure.

The amount of preload applied is important. It must be sufficient to reduce the excess play, but care must be taken not to apply too much preload. Proper preload allows the rolling elements to freely rotate in the bearing races, while excessive preload could lead to skidding. This will increase friction and heat generation, which can ultimately lead to premature bearing failure.

(Preload) Does this mean set it up as if was already doing its job carrying a load or does it mean set it up so it will do the job properly?

Is there no way of measuring preload?

 

[Nige]

Is there no way of measuring preload?

Not AFAIK. Preload means the taper bearings have a load on them often achieved by using shims under an end plate (no bearing end play in other words) so how could anyone tell if the bearing preload is 0.001" or 0.010" because there is no movement to measure.

 

[Cat977]

Good answer Nige.

IMHO you have to find where any play stops (dial indicator). Then add crush. With out specs I wouldn't put on any crush. It maybe easy to add crush. Without having the sprocket free from the track I don't think you can have feel for it being set right.

When the tracks are off you could get a fairly good idea by spinning and pulling the sprocket, that would still be a subjective opinion and you could get it over tight, or loose. If there was a spec. for a spring scale it could be used on the rim to tell the amount of drag on a tight bearing set up.

On regular tapper bearing I normally used a dial indicator and a prybar . This would give the proper running clearance. As you push the inner races closer together it gets tighter. I believe that is impossible to do in this case and you have to go by feel and maybe a dial indicator.

 

[tctractors]

Good answer Nige.

IMHO you have to find where any play stops (dial indicator). Then add crush. With out specs I wouldn't put on any crush. It maybe easy to add crush. Without having the sprocket free from the track I don't think you can have feel for it being set right.

When the tracks are off you could get a fairly good idea by spinning and pulling the sprocket, that would still be a subjective opinion and you could get it over tight, or loose. If there was a spec. for a spring scale it could be used on the rim to tell the amount of drag on a tight bearing set up.

On regular tapper bearing I normally used a dial indicator and a prybar . This would give the proper running clearance. As you push the inner races closer together it gets tighter. I believe that is impossible to do in this case and you have to go by feel and maybe a dial indicator.

No DTI's needed on CAT F/Drives, there is only to types of adjustments used, the first type involves a C Spanner and a length of pipe pulled down hard, or shim stock added to give a turning load using a torque wrench as a gauge, no DTI is ever needed or used. tctractors p.s. the reason for this is the loading imposed by the Duo-Cone type seals that have an uncontrolled force on assembly, this would give an incorrect feel to any thought of trying to use a DTI, so the bearings are slammed up firm without any float or end play with the tightening adjustment being re- checked at Service points to ensure any wear on the bearings is managed by keeping them rim tight.

 

[Cat977]

Excellent explanation tc, well done, thanks for the explanation.
Shawn

 

[Mike-JCB]

Ugh, I’m definitely out of my depth on this one and will need to take it to a shop.

I read Chris’s thread which is awesome. I hope that it’s just bad bearings at this point and I don’t have anymore damage.

Any advice on sourcing parts should something really be wrong? Like replacement bull gears?

 

[Nige]

Any advice on sourcing parts should something really be wrong? Like replacement bull gears?

Offroad Equipment in TN get good reviews - www.offroadeq.com/

Really the first thing you need if you don't already have one is Cat Publication reference UEG0732S which is the Parts Manual covering machines between 11K5051-7762. Here's one - https://www.ebay.com/itm/143935465378

Then you can go searching places such as the Machinery Trader Parts section for OEM/aftermarket/used parts - https://www.machinerytrader.com/parts/search

 

[Mike-JCB]

I appreciate it guys. Setting up transport now to a shop and will keep you all posted on what we find.

 

[charles walton]

I appreciate it guys. Setting up transport now to a shop and will keep you all posted on what we find.

The best way to set your FD up is to buy a service manual for your machine and follow directions and like Nige said Offroadeq. parts in Alcoa Tn. can save you a lot on any parts you need.

 

[Mike-JCB]

Got the machine to a shop, the mechanic thinks it’s a bad bearing at best but needs to get her on the operating table to really see what’s going on. I’m curious if you all have any thoughts on the number of hours it should take to replace FD bearings if that’s indeed the only issue. Any thoughts?

 

[Nige]

No idea regarding your question but I have one. Does the mechanic have al lthe necessary information he needs to tear down and rebuild the final drive.? If not then please ask and it should be forthcoming.

 

[tctractors]

By myself I would often strip down both f/Drives on a D6C/D in a good day that is drop off the blade, split both tracks and push out the frames, pull off the rims and strip out both cases, sometimes a simple thing like removing worn drain plugs or case bolts can change the dynamic's but if you know all the moves it's not hard, the thing that changes the picture is the top pinion or a stuffed (Spun) D-Shaft. tctractors