doubleclutchinweasel Posted June 20, 2012 Share Posted June 20, 2012 Hey, everybody.Thinkin' real serious about the '70 R600 I found recently. Went and drove it today. More right than wrong with it.Planning to re-do all the brake system anyway, if I get it. Brake linings have a bunch of life left. Adjusted the fronts up so it would actually stop bob-tailing. Rears were fairly close to being right.Rear adjusters don't seem to want to co-operate. Some of the "collars" are frozen to the bolt. Others compress, but the bolt seems frozen. Checked prices. Not enough money to worry about. I'll just change them all.Most I've seen use snap-ring to retain the adjuster. These Macks units seem to be retained by a BIG hex-head bolt. Is that how you remove them? I read somewhere the macks were 1.50" X 28 spline. Does that sound right?I think, if I buy this, I'll start by replacing all the cans and slack adjusters...then the compressor...then all the lines. Then it needs a clutch. I just want to get my ducks in a row on these slack adjusters before I jump in over my head.Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/ Share on other sites More sharing options...
David Posted June 21, 2012 Share Posted June 21, 2012 Check the bushings and seals on the cam shafts when you have it apart. Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124799 Share on other sites More sharing options...
doubleclutchinweasel Posted June 21, 2012 Author Share Posted June 21, 2012 Check the bushings and seals on the cam shafts when you have it apart.Excellent suggestion.So, are these Mack adjusters as I described them, above? Or, are they still held on with the snap-ring? I didn't clean it up enough to see any details yesterday. I'm a little concerned about how much it might take to remove that lock-nut...if it is indeed a lock nut! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124863 Share on other sites More sharing options...
MACKS Posted June 21, 2012 Share Posted June 21, 2012 Excellent suggestion.So, are these Mack adjusters as I described them, above? Or, are they still held on with the snap-ring? I didn't clean it up enough to see any details yesterday. I'm a little concerned about how much it might take to remove that lock-nut...if it is indeed a lock nut!It is a bolt and when you remove it and the washer behind it the slack adj should slide off,to replace the bushings you will have to take the s cam out and to do that you have to remove the drums,I would leave the bushings till you replace the brake shoes.. Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124877 Share on other sites More sharing options...
39 Baby Mack Posted June 21, 2012 Share Posted June 21, 2012 The older Macks had the Mack corporate brakes on them.They used these at least through 1970 as far as my experience goes and again I'm used to single axles.The Mack corporate brake used a 1/2" bolt to retain the slack adjuster along with a thick (hat shaped) washer that actually went part way into the slack adjuster.These brakes are not what you're used to!They do not have rollers in the shoes but instead use a flat wear plate.They have square brake block rather than tapered brake block which is bolted on rather than riveted on.The anchor pins are greaseable.The "S" heads on the cams are a special contour an i believe the cams are 1-1/2" 10 spline.I'm not trying to scare you, but I don't know what the parts availability would be or if they can be converted to a later style.Ron Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124881 Share on other sites More sharing options...
doubleclutchinweasel Posted June 21, 2012 Author Share Posted June 21, 2012 The older Macks had the Mack corporate brakes on them.They used these at least through 1970 as far as my experience goes and again I'm used to single axles.The Mack corporate brake used a 1/2" bolt to retain the slack adjuster along with a thick (hat shaped) washer that actually went part way into the slack adjuster.These brakes are not what you're used to!They do not have rollers in the shoes but instead use a flat wear plate.They have square brake block rather than tapered brake block which is bolted on rather than riveted on.The anchor pins are greaseable.The "S" heads on the cams are a special contour an i believe the cams are 1-1/2" 10 spline.I'm not trying to scare you, but I don't know what the parts availability would be or if they can be converted to a later style.RonThe hex I can see on the back of the slack adjusters is not a small hex, like you would associate with a 1/2" bolt. This hex is 1-1/4 - 1-1/2 inches across. Not sure if that tells you anything. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124888 Share on other sites More sharing options...
doubleclutchinweasel Posted June 21, 2012 Author Share Posted June 21, 2012 It is a bolt and when you remove it and the washer behind it the slack adj should slide off,to replace the bushings you will have to take the s cam out and to do that you have to remove the drums,I would leave the bushings till you replace the brake shoes..Sounds like what it looks like. The other post, above, mentioned a fairly small bolt on a Mack-specific adjuster. But, as I said there, this hex is HUGE. It is almost as large as the shaft itself. Any way I can identify what we have here by looking? The adjuster collar/bolt looks exactly like the others I've seen, except for the lack of a snap-ring. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124889 Share on other sites More sharing options...
Vladislav Posted June 21, 2012 Share Posted June 21, 2012 Old fashion ajusters look so.The only fixing nut is at the end of the shaft.But this one is of 1945.Vlad 1 Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124891 Share on other sites More sharing options...
doubleclutchinweasel Posted June 21, 2012 Author Share Posted June 21, 2012 Old fashion ajusters look so.The only fixing nut is at the end of the shaft.But this one is of 1945.VladActually, what I saw doesn' look anything like that. I'll check when I get home this evening; I MAY have a picture that shows one of the adjusters. I took several in that area, so MAYBE I got lucky and caught a glimpse of one!Thanks,More to come...Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-124892 Share on other sites More sharing options...
39 Baby Mack Posted June 24, 2012 Share Posted June 24, 2012 Kent Waiting to see pictures---don't remember seeing one like that or one like Vlad sent pictures of.I'm curious??Ron Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-125405 Share on other sites More sharing options...
Maddog13407 Posted July 2, 2012 Share Posted July 2, 2012 when i put my B613T together, we changed the S cams, backin plates and brake shoes over to the new style. the backin plates will bolt right up the axle housin and you will be happier with parts availability. think i scavenged the backin plates and s cams with the big C clip for the slack adjusters off a 1980 U model, YES Vinny my B model has a U model ring and pinion and backin plates and S cams. Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-126481 Share on other sites More sharing options...
doubleclutchinweasel Posted July 2, 2012 Author Share Posted July 2, 2012 I took one slack adjuster loose to see what was in there. The center bolt and washer do indeed hold a more-or-less standard adjuster in place.The cam shaft is 1-1/2" X 10 splines, which is fairly standard. The adjuster length is 7", and is offset about 5/8".The Bendix numbers I found in the book are 279946N and 279947N. These look right. Now, all I have to do is find some "in-stock" somewhere! Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-126538 Share on other sites More sharing options...
doubleclutchinweasel Posted July 11, 2012 Author Share Posted July 11, 2012 I found a mail-order outfit that can get these. So, I ordered 2 left and 2 right pieces. Should be here in a couple of weeks.As soon as it quits raining, isn't 120 degrees, and my shoulder and elbow quit killing me, I'm going to pressure wash 4 decades of crud off the steering knuckles, and see what kind of shape the kingpins, bushings, and thrust bearings are in. I plan to replace them all anyway, but it would be nice to find tha it didn't have to be done right now. I'd really like to finish all the air system first, THEN work on the front end. Oh, and I do have 1 broken leaf on the left front spring. I'll need to fix that pretty soon, too.Got my North Carolina "Weighted Antique Auto" tag today! Those guys sure know how to make money!More to come...Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-128284 Share on other sites More sharing options...
39 Baby Mack Posted July 12, 2012 Share Posted July 12, 2012 KentWhat size did the bolts end up being???Ron Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-128395 Share on other sites More sharing options...
doubleclutchinweasel Posted July 12, 2012 Author Share Posted July 12, 2012 KentWhat size did the bolts end up being???RonWow! I forgot to look! They were smaller than I originally thought. Seems like the heads may have only been about 3/4"-7/8". And, with the bolt out, I cold easily slide the adjuster on the shaft. That's how I got a decent measurement on the shaft; by pulling the adjuster out and measuring the shaft "behind" it.Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-128419 Share on other sites More sharing options...
doubleclutchinweasel Posted July 21, 2012 Author Share Posted July 21, 2012 The slack adjusters have now arrived at the parts house. They should ship out on Monday, and be here by Thursday or Friday. I should have the front spring back in by then, so I can put these on next weekend, maybe. Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-129804 Share on other sites More sharing options...
doubleclutchinweasel Posted August 25, 2012 Author Share Posted August 25, 2012 Just a couple of shots of the new slack adjusters and spring brakes on the old Dog. Notice the bolt-on retention instead of snap rings... Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-134900 Share on other sites More sharing options...
39 Baby Mack Posted August 29, 2012 Share Posted August 29, 2012 KentLooks like a new one !Ron Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135498 Share on other sites More sharing options...
doubleclutchinweasel Posted August 29, 2012 Author Share Posted August 29, 2012 KentLooks like a new one !RonThanks, Ron.Stops like a new one, too! And, leaks a lot less!You know, everything I'm doing on this truck turns into an "education". Nothing is simple! Everything reqires research, study, planning, and (finally) execution. And, the big parts are not usually the problem. Usually it's the little 1/4" bolts that hold the wires up out of the way that cause all the sweatin' and cussin'. Makes me feel old! I was out there last night, with the flashlight in my mouth (again) finishing up a couple of more air lines. Ten minutes to run the air lines, but two hours to get the old ones off.Wait a minute... That's what we love about workin' on these old trucks, isn't it?!!!More to come...Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135503 Share on other sites More sharing options...
miro Posted August 29, 2012 Share Posted August 29, 2012 You said it needed a clutch. If this has the push style clutch you might not have to change it. Mack used to put L shaped spacers between the pressure plate and flywheel, held down by the bolts. If you have this all you have to do is one by one remove those spacers and re-tighten the pressure plate.Hang on to those spacers you'll need them if ever you do need to put in a new clutch. Also a word of warning those old clutches and brake blocks are made of asbestos, do not breathe the dust! Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135505 Share on other sites More sharing options...
39 Baby Mack Posted August 29, 2012 Share Posted August 29, 2012 Thanks, Ron.Stops like a new one, too! And, leaks a lot less!You know, everything I'm doing on this truck turns into an "education". Nothing is simple! Everything reqires research, study, planning, and (finally) execution. And, the big parts are not usually the problem. Usually it's the little 1/4" bolts that hold the wires up out of the way that cause all the sweatin' and cussin'. Makes me feel old! I was out there last night, with the flashlight in my mouth (again) finishing up a couple of more air lines. Ten minutes to run the air lines, but two hours to get the old ones off.Wait a minute... That's what we love about workin' on these old trucks, isn't it?!!!More to come...KentIf you say so!!Ron Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135509 Share on other sites More sharing options...
41chevy Posted August 30, 2012 Share Posted August 30, 2012 If you say so!!RonMines 40 something years older... think of how much "fun" I have. Wouldn't trade it for anything! Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135581 Share on other sites More sharing options...
David Posted August 30, 2012 Share Posted August 30, 2012 Thanks, Ron.Stops like a new one, too! And, leaks a lot less!You know, everything I'm doing on this truck turns into an "education". Nothing is simple! Everything reqires research, study, planning, and (finally) execution. And, the big parts are not usually the problem. Usually it's the little 1/4" bolts that hold the wires up out of the way that cause all the sweatin' and cussin'. Makes me feel old! I was out there last night, with the flashlight in my mouth (again) finishing up a couple of more air lines. Ten minutes to run the air lines, but two hours to get the old ones off.Wait a minute... That's what we love about workin' on these old trucks, isn't it?!!!More to come...KentGo to Lowes and get LED lights that hook on your glasses or are on the brim of a hat. Quote Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135583 Share on other sites More sharing options...
doubleclutchinweasel Posted August 31, 2012 Author Share Posted August 31, 2012 You said it needed a clutch. If this has the push style clutch you might not have to change it. Mack used to put L shaped spacers between the pressure plate and flywheel, held down by the bolts. If you have this all you have to do is one by one remove those spacers and re-tighten the pressure plate.Hang on to those spacers you'll need them if ever you do need to put in a new clutch. Also a word of warning those old clutches and brake blocks are made of asbestos, do not breathe the dust!This one does not have the spacers. It is a cable-operated two-disc pull-style clutch. The only reason I need to change it is because the t/o bearing is pretty noisy. Discs have life left in them, but the t/o bearing only comes with the pressure plate. Bummer, huh? Besides, I'd hate to tear it down that far and NOT replace everything in there!Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135679 Share on other sites More sharing options...
doubleclutchinweasel Posted August 31, 2012 Author Share Posted August 31, 2012 You said it needed a clutch. If this has the push style clutch you might not have to change it. Mack used to put L shaped spacers between the pressure plate and flywheel, held down by the bolts. If you have this all you have to do is one by one remove those spacers and re-tighten the pressure plate.Hang on to those spacers you'll need them if ever you do need to put in a new clutch. Also a word of warning those old clutches and brake blocks are made of asbestos, do not breathe the dust!Yeah, different clutch. Cable-operated, twin-disc, pull-style. Has noisy t/o bearing, which only comes with the pressure plate.Kent Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment https://www.bigmacktrucks.com/topic/25771-replacing-slack-adjusters/#findComment-135681 Share on other sites More sharing options...
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