I've been working off & on this winter trying to solve the low pressure problem I have with the steering clutches on my D6c. It's kind of turned into a quest to solve what appears to be a combination of problems. A couple of years ago I redid the steering clutch seals so I checked out as many other potential causes as I could before removing the clutches again, but found I was losing aprox. 100 psi between the steering clutch valve and the clutches (by comparing pressures with clutches blocked off or not) To be sure it is all good I replaced the seals (with Cat parts) and both the bearing cages and clutch hubs (aftermarket). The seals, which are a split ring type, had a fairly large end gap (nearly 1/8") which I didn't care much for. After reassembly I checked the pressures and leakage again. I did get some improvement but not as much as I was hoping for. I realize it's designed to be somewhat sloppy but would like to get a little better pressure readings. Here are results after the new seals are in: Video of leakage at clutch seals at low idle w/warm oil: https://www.youtube.com/watch?v=ArhkfCFQlGU No doubt the piston seals have similar bypass leaks but aren't visible. 2nd video: Lt & Rt clutch pressures (low idle, warm oil) https://www.youtube.com/watch?v=BKxzEcy1G8M Note sluggish pressure rise. Manual spec. is 315 psi min. pressure 3rd video: pressures @ high idle https://www.youtube.com/watch?v=ydkPK91lKVk First gauge is supply pressure to steering valve, then the two clutches. 4th video: bevel gear case showing oil flow from valve as clutch is operated: https://www.youtube.com/watch?v=j475kwoWYQM Stream at far side is overflow lube oil for bevel gear bearings Near stream is dump from steering clutch pistons 5th video showing sluggish pressure rise even with clutches blocked off at the bevel gear case (low idle, cold oil) https://www.youtube.com/watch?v=DZVHmTetxTw The slow pressure rise here makes me suspect a secondary problem....perhaps bypass at clutch valve or in trans relief valve (see my other youtube videos of trans valve) I real temped to pull the clutches again and make my own seals that don't have such a wide ring gap. They appear to be made of Delrin and wouldn't be difficult to make since I have a lathe & mill. First I wan't to eliminate the clutch valve as a problem. I have located a used valve that I may be able to try out temporarily to see it it makes a difference. Basically, I think it's a build up of leaks from wear on several different parts that's reducing the flow of oil. I did tear down the gear pump and found it to be in good condition and checks within manual specs. I can get an aftermarket pump for about $150 Anyway, thought I'd post these videos to get other opinions about what I'm seeing.
Hi D6C10k. I know when I had my bevel gear out of my D6D last year to rebearing the BG shaft The Teflon seals [cat] were tight and firm in the bearing housings. Certainly no 1/8 gap. If you tear it apart again id certainly do some measuring of the bearing cap bores where the seals run. My hubs had bored into the housings due to failed bearings. I just cleaned the hubs up and replaced the housings. I had bought classic cat housings. But I couldn,t get the bolt holes to line up and start. So rang up cat dealer and they swapped for 2 new genuine housings. I do have my doubts now about any of this classic cat stuff. Best only used in a easy to get at location, in case it fails. Anyhow my point being I never had any seal ring gap issues like you are having. Cheers :drinkup
Merv, I replaced the bearing cages so wear isn't an issue. I measured the bores and both old & new were very close to the same size. The hub seals I took out were aftermarket and had about the same end gap as the new Cat seals. (The hub seals have overlapping ends but the lap ends have a gap) The piston seals, which are just square-ended, had about the same gap too. Makes me wonder if Cat is buying there "genuine" parts from and aftermarket supplier and they're getting sloppy when making them. Not sure what to do next....Don't really expect that Cat could help with getting better fitting seals. I can get enough Teflon material to make a full set of seals for about $75, but I hate to go to all that trouble. Don't wan't to make them too tight and then find out there was a reason for them to be loose.