sexton Posted June 26, 2016 Author Share Posted June 26, 2016 Malcolm those steel disks are the friction material, page 390, para 5 of the manual states: " like the drive discs, the driven friction disks are steel with ground friction surfaces. The drive discs have external teeth and the driven discs have internal teeth" In our clutch that is it, there is no conventional friction material like you see on the clutch of a car or truck. Very interested once you get yours open to see if it is any different but I suspect it is not. In our clutch we have ten steel driving discs and nine steel driven discs for a total of 19 discs (up from the previous models which had 17). You can see why when the tank sits and there is moisture in the engine bay how the clutch plates can become frozen together, I realize that is not your issue but it can and does happen. John That's unusual. I've never come across steel-on-steel disks in a clutch. The driving and driven disks likely have significantly different hardnesses to prevent galling. We are planning on pulling the gearbox Wednesday. I was surprised to see that it has an aluminum housing. It only weighs ~1300 lb. Malcolm Quote Link to comment Share on other sites More sharing options...
David Herbert Posted June 26, 2016 Share Posted June 26, 2016 That's unusual. I've never come across steel-on-steel disks in a clutch. Malcolm There is a reasion for that - it doesn't work very well ! Hence this thread David Quote Link to comment Share on other sites More sharing options...
jdmcm Posted June 30, 2016 Share Posted June 30, 2016 And they sure don't like to slip, they like off and on...hence the lurch on start out! Quote Link to comment Share on other sites More sharing options...
sexton Posted June 30, 2016 Author Share Posted June 30, 2016 Gearbox and clutch is out. Probably won't have time until Friday to take the clutch apart. Malcolm Quote Link to comment Share on other sites More sharing options...
jdmcm Posted July 1, 2016 Share Posted July 1, 2016 Come on Malcolm the suspense is killing me!!!! Quote Link to comment Share on other sites More sharing options...
sexton Posted July 1, 2016 Author Share Posted July 1, 2016 Me too! That gearbox is a bit of a bitch to get out. A forklift, 3 chainfalls, and a big pry bar to finagle it out of the hull. In hindsight, we should have pulled the oil tank as well. Malcolm Quote Link to comment Share on other sites More sharing options...
robin craig Posted July 1, 2016 Share Posted July 1, 2016 Malcolm, I feel you pain when you stated "we should have pulled the oil tank as well". So many times I have been the junior member of a team and the proper ways have been ignored and shortcuts taken and then hours of forcing and pushing and prying have followed and the odd broken item made of unobtainium has resulted all for a perceived shortcut which wasn't in the end. I well understand in your circumstance things are different as the procedures etc are not well known, so no one should think I am being critical of you in any way, you are very talented and I am in awe of what you do. Quote Link to comment Share on other sites More sharing options...
jdmcm Posted July 1, 2016 Share Posted July 1, 2016 Malcolm Wouldn't hurt to pull the oil tank even now, when we cleaned ours out you wouldn't believe the mess that came out of it. You are in a great position now to do a bunch of chores that never get done due to the cramped quarters of the T-54 engine bay. I hope I can make it out your way and come see this beast in person...I am not sure how many of this type of tank are currently in Canada. Mark Flemming from North Vancouver sold his T-55 to a well heeled collector in the Fraser Valley, we have our Type 69 captured in Iraq, there is a turretless T72 in private hands in the Calgary area, being or been adapted for fire fighting, the T-54 sitting in front of KW Surplus also in Ontario and yours. Do you guys know of any others? Quote Link to comment Share on other sites More sharing options...
sexton Posted July 2, 2016 Author Share Posted July 2, 2016 (edited) We got the clutch disks out today. The cause of the clutch locking up was 3 of the driven disks (the ones with the teeth on the ID) were locked onto the clutch hub. In other words, when the pressure plate was removed, they would not slide off the hub like the other driven disks did. Their teeth were jammed in the hub "slots". For one of the stuck disks, the whole disk had shrunk onto the hub all the way round its circumference, binding it badly. For the other two, the binding was over about 1/4 of the circumference. The photos show why they locked. In the first photo, the disk teeth are binding on the left side of the hub teeth. The second photo, which is about 15 teeth further round the same disk, shows the disk teeth binding on the right side of the hub teeth. Assuming the plate wasn't like this when new, the plate has distorted. Localized overheating is the only thing I can see that would cause this. Some of the plates look blued (but not as blued as the pics show). But generally they are all in reasonable shape. A little galling but nothing serious. We haven't checked for thickness variations around the circumference or warping yet. This pic of the pressure plate may be more evidence of serious overheating. The white area around the OD could be oil ash. That's where the plates bear. The part inside the white area may be overheated oil, but just enough to coke it, not ash it. I don't know. Considering the difficulty getting access to this clutch, I suppose a new set of disks and pressure plates is the only sensible option. I wonder if an upgrade with proper friction disks was ever made for these tanks? John, yes, we will be pulling the oil tank and cleaning it before reinstalling the gearbox. No, I don't know of any other T-54's or variants. Thanks for the kind words, Robin. Malcolm Edited July 2, 2016 by sexton Quote Link to comment Share on other sites More sharing options...
jdmcm Posted July 4, 2016 Share Posted July 4, 2016 As far as I know there is no updated clutch except for the upgrade from 17 to 19 discs. Any idea what caused the overheating? The clutch is almost an off/on style clutch more reminiscent of a PTO clutch than anything seen in US or British tanks prior to them all going automatic Quote Link to comment Share on other sites More sharing options...
jdmcm Posted July 4, 2016 Share Posted July 4, 2016 Very nice of you to share all this information Malcolm, every little bit of knowledge helps keep these vehicles going and helps others avoid problems and or troubleshoot and repair problems which occur, very much appreciated Regards John Quote Link to comment Share on other sites More sharing options...
sexton Posted July 4, 2016 Author Share Posted July 4, 2016 Here are some more photos: Assembly Driving drum (long shaft is for direct drive of fan) Pressure plate Disks Driven hub Malcolm Quote Link to comment Share on other sites More sharing options...
sexton Posted July 4, 2016 Author Share Posted July 4, 2016 Any idea what caused the overheating? The clutch is almost an off/on style clutch more reminiscent of a PTO clutch than anything seen in US or British tanks prior to them all going automatic Don't know, but maybe from us treating it like a normal clutch and slipping it at low speeds? It started acting up when the tank was being finagled into a tight parking spot in sand on a very hot day. We know better now. We didn't see/feel any sign of it slipping under load. Malcolm Quote Link to comment Share on other sites More sharing options...
pkitson Posted July 8, 2016 Share Posted July 8, 2016 The Russians have been using steel as a medium for clutches since the BT series of vehicles. As with any clutch, it is always preferable to leave the clutch engaged. When sitting for any length of time, transmission in neutral, foot off the pedal. Would it be a good idea to check spring pressures in the clutch? Quote Link to comment Share on other sites More sharing options...
sexton Posted July 8, 2016 Author Share Posted July 8, 2016 Yes, I'd like to check spring pressures but I have no idea what they should be. John, your manual say anything? The clutch is all apart now. It's in good shape apart from the disks and pressure plate showing signs of overheating. We are trying to source a new clutch. Malcolm Quote Link to comment Share on other sites More sharing options...
sexton Posted July 8, 2016 Author Share Posted July 8, 2016 (edited) Some more photos: Inboard half of release bearing hub mounted on gearbox, showing sloped grooves balls ride in. Release bearing balls and return springs Outboard half of release bearing hub mounted on clutch, rotated by clutch actuating arm shown Spring assembly pushed along shaft by release bearing hub to disengage clutch Driven hub showing signs of running hot, based on baked oil. Driven hub, splined onto gearbox input shaft Driven hub mounted on gearbox input shaft Outboard clutch support bearing, mounts on gearbox input shaft. Piece of paper gasket for sealing bearing outer ring shown. Malcolm Edited July 8, 2016 by sexton Quote Link to comment Share on other sites More sharing options...
pkitson Posted July 8, 2016 Share Posted July 8, 2016 Checking for discrepancies in compression rates of the individual springs will give you an indication of general condition. Obviously the highest resistance would be the minimum spring rate you would want on all springs. Overheating could contribute to weaker springs. Anyone looked into the fuel leak or charging issue on the BMP yet? Perry Quote Link to comment Share on other sites More sharing options...
sexton Posted July 8, 2016 Author Share Posted July 8, 2016 Re BMP, it's a fitting on the injection pump leaking. The guy working on it is having a hard time removing the large castellated nut that holds the fitting on the pump. I don't think there is a problem with the charging system. I tested both 4D batteries with a conductance tester and it said they were both bad. Using a puny 100 amp load tester is no good for these big batteries. They need a much higher load to test them properly that way. Malcolm Quote Link to comment Share on other sites More sharing options...
sexton Posted July 8, 2016 Author Share Posted July 8, 2016 I checked a few of the clutch disks for warping and wear using a dial indicator on a granite surface table. Despite the evidence of overheating, they weren't that bad. Maybe 0.004" warping at most, and only a few thou wear. But when I overlaid a driven plate on another plate, I noticed differences in OD, ID, and teeth alignment caused by distortion. To show this, I put them all on a v-block and squared them to the v-block both ways so they all should have been centred to each other. (They are all machined on the OD so should be circular.) I lined up the teeth at the 6 o'clock position. The photos show the misalignments at the 3, 9, and 12 o'clock positions. Malcolm Quote Link to comment Share on other sites More sharing options...
jdmcm Posted July 9, 2016 Share Posted July 9, 2016 Hi Malcolm away for the weekend but will check the book when I get home for you. Do you know Dave Bane at the East Indiana Armor Collection? He has several soviet era tanks including T-54's. He may also have the spares you need John Quote Link to comment Share on other sites More sharing options...
pkitson Posted July 9, 2016 Share Posted July 9, 2016 Malcolm, Message sent regarding BMP. Perry Quote Link to comment Share on other sites More sharing options...
sexton Posted July 11, 2016 Author Share Posted July 11, 2016 Hi Malcolm away for the weekend but will check the book when I get home for you. Do you know Dave Bane at the East Indiana Armor Collection? He has several soviet era tanks including T-54's. He may also have the spares you need John OK, thanks, John. Quote Link to comment Share on other sites More sharing options...
sexton Posted July 11, 2016 Author Share Posted July 11, 2016 Malcolm, Message sent regarding BMP. Perry Haven't got it yet, Perry Quote Link to comment Share on other sites More sharing options...
pkitson Posted July 11, 2016 Share Posted July 11, 2016 Malcolm, First message was an email. I have just sent a PM. Perry Quote Link to comment Share on other sites More sharing options...
jdmcm Posted July 16, 2016 Share Posted July 16, 2016 Sorry Malcolm, book has no spec's on spring rates or pressures... How are things coming? Regards John Quote Link to comment Share on other sites More sharing options...
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