4020dt Posted July 9, 2006 Share Posted July 9, 2006 I just found this forum last week , the 9 speed was discussed a page or so back , I have a couple questions also . Here's my story : We have a 1988 R688 350hp 9sp 530,000+- mi , overall it is a pretty good old truck . Bought it in 2000 after our 1979 237 dropped a sleeve in the oil pan . We use it on the farm and son is now running it on construction . The range never shifted right to me or my son , would hang up going into hi once in a while and made too much noise to my estimation , course I was used to the old 2 stick 6sp .A year ago the 1st rev shift fork broke and due to timing I took it to my local Mack dealership . At the right time we could have fixed it or at least removed it and had it done . I have all the Mack manuals , in there it tells something about all the interlock settings etc . and all the updated parts for the trans . Anyway I told them to check all this out . They removed the trans , took the top off , put 3 new shift forks in , total parts was $800+ , labor $2000 . I thought that was pretty steep . They showed it to me , the clutches seemed to look ok to me and them too , they said that new clutch pack would be $2500+ . With only running 10-15,000mi/yr we thought we could get by with leaving it alone , just check the air cylinder and linkage . Well when we got it back it seemed to make more noise and hang up more often .Now what do we do? Is there an aftermarket source for these parts or are they available only through Mack?This winter when I have more time I can remove it and work on it .What does it take to convert to a 13sp Roadranger ? I have a line on one of them , neighbor has one that is behind a 400 Cummins , it is a RTO12513 , what else do I need to know about it ?I am pretty knowledgeable on John Deeres and other farm machinery but not really up to snuff on this stuff .I am open to all ideas , suggestions , other options or whatever . All replies will be greatly appreciated , Thanks in advance , Jim Quote Link to comment Share on other sites More sharing options...
David Posted July 10, 2006 Share Posted July 10, 2006 If you go to the 12513, your overdrive will go from .71 to .86. It's going to run slower. Quote Link to comment Share on other sites More sharing options...
HK Trucking Posted July 10, 2006 Share Posted July 10, 2006 If you go to the 12513, your overdrive will go from .71 to .86. It's going to run slower.Also, be aware that the 12513 will have to have the bellhousing with the provision for the Mack transmission mounts. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment Share on other sites More sharing options...
Joe Cummings Posted July 13, 2006 Share Posted July 13, 2006 The T2090 was a loser from day one, They were always problems.Look into a RTXF14609B the ratios are the same as the T2090. It has to be a B though to end up with the same amount of overdrive. Be prepared to get the right clutch housing, cut the driveshaft, and maybe change the shifter. Quote Link to comment Share on other sites More sharing options...
mudslut28 Posted July 29, 2006 Share Posted July 29, 2006 Joe is right..the 2090 is a good boat anchor. I had one in an RD800 and the clutch pack was a constant battle in it. Never would hardly go back to low range without going nuts. Quote Link to comment Share on other sites More sharing options...
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