Moparmike Posted January 20, 2019 Share Posted January 20, 2019 I have 3 ed mack 2 2000 and 1 2001 why do everyone of these trucks frame crack at the back by the rear end running the long way ..dot told me park it dont lif it back on the road its dangerous smh Quote Link to comment Share on other sites More sharing options...
terry Posted January 20, 2019 Share Posted January 20, 2019 If you are talking cracked at the frame flange bend, top or bottom it is generally rust spreading a double frame, or even on a single frame at the trunnion stand at the bottom. terry Quote Link to comment Share on other sites More sharing options...
JoeH Posted January 20, 2019 Share Posted January 20, 2019 (edited) +1 on the rust, gotta disassemble frame, sandblast and paint before it gets to cracking point. You could probably still take it apart and weld it back together if it's the horizontal flange crack by the trunion. Mack frames want 100,000 pound tensile welding rods, 3/32nds for frame repair. I think 10018 rod? Took my dad and I about a week and a bit to do our 95 rd. Well worth it, but we didn't have any cracks yet. Because the DOT caught you you might have to show them the truck to be put back on the road, or sign that it's been fixed. Once it's been welded, bring it so you can't tell it's been welded. Edited January 20, 2019 by JoeH Quote Link to comment Share on other sites More sharing options...
Rob Posted January 20, 2019 Share Posted January 20, 2019 (edited) 10018 rod is good but so is a gas shielded cored wire for the task in the proper rating. Either stick or wire, the frame should be temperature elevated in the weld zone with a torch to about 350 degrees or a bit better and welded up and allow a slow cooling to not set up stresses in the steel that cause cracking. Probably should add the crack needs to be "Vee" grooved out to get a full penetration weld also. Edited January 20, 2019 by Rob 2 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
MACKS Posted February 25, 2019 Share Posted February 25, 2019 On 1/20/2019 at 8:50 AM, JoeH said: +1 on the rust, gotta disassemble frame, sandblast and paint before it gets to cracking point. You could probably still take it apart and weld it back together if it's the horizontal flange crack by the trunion. Mack frames want 100,000 pound tensile welding rods, 3/32nds for frame repair. I think 10018 rod? Took my dad and I about a week and a bit to do our 95 rd. Well worth it, but we didn't have any cracks yet. Because the DOT caught you you might have to show them the truck to be put back on the road, or sign that it's been fixed. Once it's been welded, bring it so you can't tell it's been welded. If your gonna take it apart why not just install new rails? 2 Quote Link to comment Share on other sites More sharing options...
JoeH Posted February 25, 2019 Share Posted February 25, 2019 Note that I said gotta disassemble BEFORE it gets to cracking point. 3-5k per rail. So you're looking at 12-20k if it's a double frame, just in rails. Add in 1k in bolts, a few likely broken crossmembers, you're looking at 25k. If your rails are still good like ours were in the last one we did, why take on the extra expense? Our truck only gets 5-10k miles a year, never in salt, so we're going to get a few decades out of our rails. Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted February 26, 2019 Share Posted February 26, 2019 13 hours ago, JoeH said: Note that I said gotta disassemble BEFORE it gets to cracking point. 3-5k per rail. So you're looking at 12-20k if it's a double frame, just in rails. Add in 1k in bolts, a few likely broken crossmembers, you're looking at 25k. If your rails are still good like ours were in the last one we did, why take on the extra expense? Our truck only gets 5-10k miles a year, never in salt, so we're going to get a few decades out of our rails. A dumb question Im sure, why do you use new bolts ??? I just bung the..back in and so far therehas never been a drama Paul Quote Link to comment Share on other sites More sharing options...
MACKS Posted February 26, 2019 Share Posted February 26, 2019 52 minutes ago, mrsmackpaul said: A dumb question Im sure, why do you use new bolts ??? I just bung the..back in and so far therehas never been a drama Paul I didn't know they cost that much,shop that works on my truck said he could replace my rails for ten thousand installed,to late to take mine apart,23 years in NY and plowing snow takes its toll.. 1 Quote Link to comment Share on other sites More sharing options...
kscarbel2 Posted February 26, 2019 Share Posted February 26, 2019 (edited) I suggest you go back with Mack "body bound" bolts, reaming new holes accordingly, 0.652 (5/8" BB bolts) or 0.776 (3/4" BB bolts). From page 30...............https://www.macktrucks.com/-/media/files/body-builder/manuals/7-frame.pdf/ Edited February 26, 2019 by kscarbel2 1 Quote Link to comment Share on other sites More sharing options...
Rob Posted February 26, 2019 Share Posted February 26, 2019 While the "body bound" bolts are the best to use by far, I've used these for many years on both mine, and other's repairs when stretching or relocating frames/parts without issue. I do use a "Hougen" magnetic drill with the correct annular cutter for the fastener and it's much less expensive than the other fasteners: While it may not be right or the best way it's worked for a lot of years for me. 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment Share on other sites More sharing options...
mrsmackpaul Posted February 26, 2019 Share Posted February 26, 2019 Whilst Im not questioning how accurate the information is here at a quick glance at Mrs Mack I cant help but notice she only has normal grade 8 bolts at best on her chassis Quote Link to comment Share on other sites More sharing options...
h67st Posted February 26, 2019 Share Posted February 26, 2019 43 minutes ago, mrsmackpaul said: Whilst Im not questioning how accurate the information is here at a quick glance at Mrs Mack I cant help but notice she only has normal grade 8 bolts at best on her chassis Mrs. Mack....is that a truck? If the real Mrs. Mack has grade 8 bolts in her chassis you better not back-talk her. 2 Quote Link to comment Share on other sites More sharing options...
JoeH Posted February 27, 2019 Share Posted February 27, 2019 4 hours ago, mrsmackpaul said: Whilst Im not questioning how accurate the information is here at a quick glance at Mrs Mack I cant help but notice she only has normal grade 8 bolts at best on her chassis Grade 8 is right, but Mack frames are assembled at the factory with "body bound" fine thread bolts, which are an oversized bolt in an undersized hole. All suspension, crossmembers, steering, cab mounts, fuel tank brackets, etc etc should be body bound bolts. Air valves and relays etc can be whatever the heck you want. I had an 01 Mack tractor that used "Huck" bolts for the air ride suspension. They're an approved alternative in some cases I assume. Quote Link to comment Share on other sites More sharing options...
mrsmackpaul Posted February 27, 2019 Share Posted February 27, 2019 I wonder if Australian built Macks just used normal grade 8 bolts as Australian content was very high All spring hangers, fuel tank brackets, air tank brackets, bonnets (hoods in the US) were all made in Australia No doubt there was countless other bits as well At a guess thats why we dont use the flash bolts used over there Paul Quote Link to comment Share on other sites More sharing options...
Vladislav Posted April 9, 2019 Share Posted April 9, 2019 I took apart the most of Canadian assembled 1988 R-model with Neway airride. Found that all the big suspension brackets together with crossmembers were assembled with Grade 5 (not Grade 8 ) body bound bolts. Seemed like the chassis was assembled at the factory that way. The fuel tank hangers and many other attachment brackets were installed using common style grade 5 bolts. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment Share on other sites More sharing options...
steelman Posted April 9, 2019 Share Posted April 9, 2019 It is considered good practice to replace bolts that have been in high stress situations whether it be a truck frame, a building or whatever. The bolts have been torqued properly and were stretched slightly. The threads could be deformed ever so little, but enough to lead to a failure. Do you really want to bet your life or that of an innocent motorist on a fastner that costs a couple of bucks? 1 Quote Link to comment Share on other sites More sharing options...
Mack Technician Posted April 11, 2019 Share Posted April 11, 2019 Unless it was a temporary installation, like a seasonal push axle removed during frost-break road limits, it was expected everything was Huck fastened and no reused bolts. Quote Link to comment Share on other sites More sharing options...
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