NLC Posted June 28, 2020 Share Posted June 28, 2020 I am looking at a R 300 Mack dump truck. Is the R300 a lighter truck than say a R600. It has 18,000 front axle And 38,000 rears. Any information will be appropriated. Quote Link to comment Share on other sites More sharing options...
j hancock Posted June 29, 2020 Share Posted June 29, 2020 No such truck as a Mack R300. Is it an R model with a 300 engine? Need more details. Info off door tag. Picture of truck. Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
fjh Posted June 29, 2020 Share Posted June 29, 2020 (edited) Rd800? Maybe 18000 is a heavy axle! Flat metal fenders? Edited June 29, 2020 by fjh Quote Link to comment Share on other sites More sharing options...
j hancock Posted June 29, 2020 Share Posted June 29, 2020 8 hours ago, fjh said: Rd800? Maybe 18000 is a heavy axle! Flat metal fenders? Yup, got to find out more. 18 on the front and 38 on the rear??? 15 hours ago, NLC said: It has 18,000 front axle And 38,000 rears. Quote JimIt doesn't cost anything to pay attention. Link to comment Share on other sites More sharing options...
jettertrucks Posted June 30, 2020 Share Posted June 30, 2020 r 400 Quote Link to comment Share on other sites More sharing options...
NLC Posted July 5, 2020 Author Share Posted July 5, 2020 I got the information on this truck. It is a R686ST, has a 300 Mack motor, 6 speed Mack transmission, 4:17 rears. Would this combination be a good dump truck? Quote Link to comment Share on other sites More sharing options...
tjc transport Posted July 5, 2020 Share Posted July 5, 2020 many hundreds of thousands of them were made. very good local use dump trucks. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
Maxidyne Posted July 5, 2020 Share Posted July 5, 2020 26 minutes ago, NLC said: I got the information on this truck. It is a R686ST, has a 300 Mack motor, 6 speed Mack transmission, 4:17 rears. Would this combination be a good dump truck? ST means it was built as a semi-tractor, probably has 10.5 or 12k front axle and 34k or 38k rears. Won't have the capacity of an RD or DM with heavier axles, but the 6 speed has a low hole which is good, will make a fine dump truck if it's in good shape and has enough capacity for your needs. Quote Link to comment Share on other sites More sharing options...
Quickfarms Posted July 5, 2020 Share Posted July 5, 2020 ST means it was built as a semi-tractor, probably has 10.5 or 12k front axle and 34k or 38k rears. Won't have the capacity of an RD or DM with heavier axles, but the 6 speed has a low hole which is good, will make a fine dump truck if it's in good shape and has enough capacity for your needs.S means tandem drive axlesT means tractor trailer brake packageThe ST does not mean it was ever a tractor.Since Mack would build what ever the client requested so Maxidyne is just guessing what the specs are based on a generic model number.To get the asbuilt specs you need to contact the Mack museum.Keep in mind that this is at least a 30 year old truck that has probably been rebuilt and modified over its life so anything is possible now.Your best bet is to look over the truck and figure out what axles, suspension and frame are currently there. 1 Quote Link to comment Share on other sites More sharing options...
Maxidyne Posted July 5, 2020 Share Posted July 5, 2020 Seems most of the R685ST dump trucks I've seen were converted from tractors, which made sense because there were a lot of them and a dump truck would sell for a lot more than a used tractor. But it's entirely possibly that some tractors were converted to dumps before they even had a 5th wheel mounted on them. The opposite is certainly true- IIRC the Postal Service Macks often were noted as "MR688P" or "MR688S" with no "T" on the serial number plate but with Mack's full knowledge were delivered with 5th wheels and trailer connections. Quote Link to comment Share on other sites More sharing options...
Quickfarms Posted July 6, 2020 Share Posted July 6, 2020 I know of 19 RS685LST’s that the FS2, factory order form, lists them as straight trucks because they were ordered as dump trucks per Don SchumakerI currently have a RS685LT that was never a tractor it has always been a flatbed So thinking that a ST or any T that is currently a dump truck was converted from a tractor is incorrect I remember picking up brand new Mack r models in the mid 80’s from the dealer and taking them to have there bed, box or roll off rails installed Quote Link to comment Share on other sites More sharing options...
Maxidyne Posted July 6, 2020 Share Posted July 6, 2020 Perhaps the customer(s) ordered them as tractors to get the shorter frame that didn't extend far behind the rear wheels so the body installer didn't have to cut off the frame overhang beyond the rear axles? Another possibility is that if a customer wanted air and electrical hookups for a pup trailer, maybe it was cheaper or easier to order a tractor and extend the lines to the rear of the frame? And no doubt there were canceled orders for tractors that got dump bodies installed instead of fifth wheels when they were brand new. That said, there's ample evidence of a first life as tractors in thousands of Mack tractors now outfitted as dump trucks. Quote Link to comment Share on other sites More sharing options...
NLC Posted July 7, 2020 Author Share Posted July 7, 2020 The guy said it was a county truck. Really nice looking truck. Has 125,000 miles and 3000 hours. Not sure if this is actually true but it is a very clean straight looking truck. Thanks for the information. Quote Link to comment Share on other sites More sharing options...
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