leversole Posted March 29, 2012 Share Posted March 29, 2012 Successfully purchased two new (to me) Mack Parts manuals....one a 1975 RS685LST, the other a 1978 DM686SX to go along with my '57 B53S and '69 DM685SX manuals...The two new ones are complete. but DO NOT have a picture of the front motor mount?!? Don't understand the mystery! Would like to see some different parts drawings of the front motor mount because mine only has room to fit a single pulley, and wanted to see some others...I have a picture of a 675 engine like mine that has room for a three belt pulley! Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/ Share on other sites More sharing options...
David Posted March 29, 2012 Share Posted March 29, 2012 Here ya go..............http://www.ebay.com/itm/Mack-Trucks-pulley-No-310G273-3-groove-REF-253-/300671521556?hash=item46016b5314&item=300671521556&pt=Other_Vehicle_Parts&vxp=mtr Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-110867 Share on other sites More sharing options...
Rob Posted March 29, 2012 Share Posted March 29, 2012 Here ya go..............http://www.ebay.com/...e_Parts&vxp=mtrI think he is looking for the crankshaft pulley David.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-110868 Share on other sites More sharing options...
David Posted March 29, 2012 Share Posted March 29, 2012 Hey, three is three. Get a big hammer and make it work. Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-110869 Share on other sites More sharing options...
leversole Posted March 29, 2012 Author Share Posted March 29, 2012 I dont have a pulley problem...I have a motor mount problem! Thats why I want to see other style of motor mounts to figure out why mine is different and if there is anything I can do to fix it! Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-110870 Share on other sites More sharing options...
Rob Posted March 29, 2012 Share Posted March 29, 2012 I dont have a pulley problem...I have a motor mount problem! Thats why I want to see other style of motor mounts to figure out why mine is different and if there is anything I can do to fix it!If you set the engine further back in the chassis with a different, or modified front mount, the transmission mounts will also need to be replaced/modified also. I can't tell from your photo if that is a Thermodyne, or Maxidyne balancer on the crank. The Thermodyne is smaller. Do the transmission mounts appear to be original to the truck?Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-110871 Share on other sites More sharing options...
Maddog13407 Posted March 30, 2012 Share Posted March 30, 2012 the front hub on the crank is different from thermodyne's to maxidyne's. looks like you have an early single 3/4 inch belt pulley on the crank from 53 to around 58 or so on the thermodyne. after that they changed to to a two hald inch belt pulley on the crank and the newer maxidynes had a 3 , 1/2 inch belt pulleys and a longer snout on the crank. most guys put the old thermodyne crank hub to put a maxidyne in a B model. it had nothin to do with the front engine mount. Matt Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-111000 Share on other sites More sharing options...
leversole Posted March 30, 2012 Author Share Posted March 30, 2012 I think I understand...so the length from the back of the snout trunnion to the block is the same between the first picture and the second...the later models added length to the crank bushing which pushed the pulley assembly forward? Shape of the motor mount "ears" is further forward on the first picture because the later trucks had a longer underhood length? Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-111005 Share on other sites More sharing options...
theakerstwo Posted March 30, 2012 Share Posted March 30, 2012 the front hub on the crank is different from thermodyne's to maxidyne's. looks like you have an early single 3/4 inch belt pulley on the crank from 53 to around 58 or so on the thermodyne. after that they changed to to a two hald inch belt pulley on the crank and the newer maxidynes had a 3 , 1/2 inch belt pulleys and a longer snout on the crank. most guys put the old thermodyne crank hub to put a maxidyne in a B model. it had nothin to do with the front engine mount. Matt just like i remeneber. and water pump was different also.differnt lenght on the shaft. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-111007 Share on other sites More sharing options...
Maddog13407 Posted March 31, 2012 Share Posted March 31, 2012 yes the hub was the same distance from the bolt flange back twards the block on all of them but the later ones were longer twards the front to accept more belts. the wrap around underneith mount in the first pic is from a r model or dm which bolted to the flat crossmember. b models used an i beam mount that was under the front of the engine not in front. and yes the water pumps are different with longer shafts along with some had more spacer blocks between the oil cooler and water pump. Matt Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-111267 Share on other sites More sharing options...
Lmackattack Posted March 31, 2012 Share Posted March 31, 2012 from what im told if you have a maxidyne and want to put it into a B model you need all the front pullys from the B model engine and put them on the maxidyne. the water pump may just swap onto the maxidyne. this is to get the pullys up as close to the engine as you can as there is little space between the rad and block. Never done it but so im told... Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-111275 Share on other sites More sharing options...
Olivetroad Posted March 31, 2012 Share Posted March 31, 2012 I went through all this when I put a 237 out of a firetruck into my 71 DM. I had to change the front mounts, use different pulleys, change the fan, change the water pump, even reroute the coolant hoses with brass pipes instead so that it would all fit between the radiator and the block - got pretty tight in there with those additional pulley grooves. Quote Link to comment https://www.bigmacktrucks.com/topic/24155-wtf-elusive-part/#findComment-111293 Share on other sites More sharing options...
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