Joe Black Posted August 7, 2011 Share Posted August 7, 2011 Greetings all! Newbie to the forum here so apologies if this info posted elsewhere as search didn't find me an answer. Basically I've got a couple Midliners, 1986 and 1992, but the '86 transmission won't stay in 5th gear as it will "pop out" as soon as you release pressure on the shifter. You could hold it in with some effort, sometimes a LOT of effort! The small linkage on the tranny, with rod ends both ends attaches shift linkage to tranny, I replaced with new parts as the original was deteriorated and sloppy, but this made no imporvement. Could this be adjustment? Even though this is an '86 it has just under 5000 miles (former state agency truck) and I'm building out as a tilt-tray for farm and hobby use. Thanks for any info y'all can provide! I'll see if I can post a couple pics of the tranny... Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/ Share on other sites More sharing options...
Rob Posted August 7, 2011 Share Posted August 7, 2011 Greetings all! Newbie to the forum here so apologies if this info posted elsewhere as search didn't find me an answer. Basically I've got a couple Midliners, 1986 and 1992, but the '86 transmission won't stay in 5th gear as it will "pop out" as soon as you release pressure on the shifter. You could hold it in with some effort, sometimes a LOT of effort! The small linkage on the tranny, with rod ends both ends attaches shift linkage to tranny, I replaced with new parts as the original was deteriorated and sloppy, but this made no imporvement. Could this be adjustment? Even though this is an '86 it has just under 5000 miles (former state agency truck) and I'm building out as a tilt-tray for farm and hobby use. Thanks for any info y'all can provide! I'll see if I can post a couple pics of the tranny...Probably going to need a rebuild. Sounds like either the shift fork is bent, or syncronizer struts have gone bad with the remote possibility of the syncronizer springs defective. The mainshaft, or countergear bearings could be bad such as run low or out of oil at some time.Rob 1 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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83302 Share on other sites More sharing options...
Joe Black Posted August 8, 2011 Author Share Posted August 8, 2011 Wow, they've must've really abused this garage queen in the few miles it managed to get on the road. Crap. Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83334 Share on other sites More sharing options...
Rob Posted August 8, 2011 Share Posted August 8, 2011 Wow, they've must've really abused this garage queen in the few miles it managed to get on the road. Crap. I think that truck has more miles upon it than thought. I had a couple of midliners and they were very good units but the paint wear in your photos suggests either a new odometer has been installed, or it doesn't read out past either 100,000, or a million miles. Not saying your truck has anywhere near this amount but the paint flaking experienced is representative of high usage.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83342 Share on other sites More sharing options...
Joe Black Posted August 8, 2011 Author Share Posted August 8, 2011 This was one of two trucks that literally sat idle almost since the day they were new until they were both sold for $250 each to a couple employees from a state agency, one of which is a friend who purchased just for the 26' box. I paid him what he paid for the truck and drove it home after helping get the box off for him to use as storage. I've had it a number of years without anything on the chassis parked in the open here in central FL, it used to look much better but the sun isn't kind over time. I've seen the other truck and it had about 7K miles on it, so neither saw much use at the agency. Kinda one of those deals where someone had a great idea, spent some taxpayer money on it and it never went anywhere and it became something of a boondoggle they got tired of being reminded about. Especially after a new transportation manager came along and had both trucks fully serviced before someone could fill him in! Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83385 Share on other sites More sharing options...
hatcity Posted August 8, 2011 Share Posted August 8, 2011 Ft. Meade. South of Lakeland on 17. Is Roosters in Zolfo Springs still there?Used to run down 17 from Lakeland, jump over to 27 after a delivery (Roosters) then make my way to StuartOh yeah, Welcome. Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83389 Share on other sites More sharing options...
mowerman Posted August 9, 2011 Share Posted August 9, 2011 sorry dont have better news,,,but like rob says,slipping outa gear is generally not a cheap fix,,,i would look for a used trans got a hell of a price on it,,can afford to drop a few bucks in it,,,midliners are cool...good luck bob Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83409 Share on other sites More sharing options...
Rob Posted August 9, 2011 Share Posted August 9, 2011 Those "CM" series transmissions are not expensive to overhaul if you do the work yourself. Probably about a buck and a quarter for parts including the brass and bearings. This is of course given no broken gears, or hard parts. I've done a couple of them on the kitchen table, (no kidding) when I was younger and "Momma" was gone, (hence the reason I still breath). You don't even really need special tools other than a general mechanics set.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83414 Share on other sites More sharing options...
Joe Black Posted August 9, 2011 Author Share Posted August 9, 2011 (edited) Ft. Meade. South of Lakeland on 17. Is Roosters in Zolfo Springs still there?Used to run down 17 from Lakeland, jump over to 27 after a delivery (Roosters) then make my way to StuartOh yeah, Welcome.Don't know about Roosters, usually just pass through Zolfo to Arcadia or cuttin' over to Sebring. I grew up between Winter Haven and Bartow and have mostly been in the area ever since, middle of everything lol!sorry dont have better news,,,but like rob says,slipping outa gear is generally not a cheap fix,,,i would look for a used trans got a hell of a price on it,,can afford to drop a few bucks in it,,,midliners are cool...good luck bobI've seen a few used trannies, no CM's yet, but started wondering what else would fit. Could get a sweet deal on an RT910, that'd be interesting with the 2-speed rear...Thanks for the rebuild info Rob, I also got all the original Mack service manuals with the truck too, 5 big Mack binders with all kinds of manuals including tranny. It just kills me that every gear shifts and works fine and smooth, except 5th. Grrrr... At least with the 2-speed rear I can still get down the road at 60MPH so I can at least get some use out of the truck until fixin' the 5th issue!Thanks all for the input, I'll keep y'all informed especially when I start fabbing up the tilt-tray!- Joe Edited August 9, 2011 by Joe Black Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83420 Share on other sites More sharing options...
Rob Posted August 9, 2011 Share Posted August 9, 2011 Don't know about Roosters, usually just pass through Zolfo to Arcadia or cuttin' over to Sebring. I grew up between Winter Haven and Bartow and have mostly been in the area ever since, middle of everything lol!I've seen a few used trannies, no CM's yet, but started wondering what else would fit. Could get a sweet deal on an RT910, that'd be interesting with the 2-speed rear...Thanks for the rebuild info Rob, I also got all the original Mack service manuals with the truck too, 5 big Mack binders with all kinds of manuals including tranny. It just kills me that every gear shifts and works fine and smooth, except 5th. Grrrr... At least with the 2-speed rear I can still get down the road at 60MPH so I can at least get some use out of the truck until fixin' the 5th issue!Thanks all for the input, I'll keep y'all informed especially when I start fabbing up the tilt-tray!- JoeThat was a common transmissiona and should be fairly easy to locate. Putting another trans in the truck will be a bit of a task getting the shifter linkage to align in the cab where you want it. An RT-910 was a very good transmission in it's day with 27% splits, (memory serves?) between each evenly spaced gear. The engines in the midliners would do well with it but fitment may be a problem. Most 910's I've seen use a pull style clutch and all midliners I've seen use a push style. That engine being French, (like everything else) may be hard to get a clutch setup to work that is different than original.Usually that "CM" series trans is a very good medium duty unit. Anybody can tear one up but a good driver will get many, many miles out of one before it needs work. Both Clark, and Spicer "CM's" were direct competitors in the medium duty market for many years with both serving well if taken care of. People trying to "power shift", or "float" the gear such as in an unsyncronized transmission usually did them in on a short timeframe. The trick to longevity here was to simply use the clutch on every shift.I'd rebuild what you have and go with it. Taken care of the unit should last you well.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83429 Share on other sites More sharing options...
Joe Black Posted August 10, 2011 Author Share Posted August 10, 2011 D'oh! I'm one of those gear floaters! Comes from learnin' on an RT915 I reckon... I'll, ummmm, try that clutchin' thing you suggest and see how it works out!If need be I guess I could pull the 6-speed outta the '92 Midliner and put it in the '86 until the rebuild is done, then again I might like that even more with the 2-speed rear! The '92 truck has about 500K on it though and is pretty sloppy. Coming down a long grade you'll get to the bottom and find it's come outta 6th, lol! So I learned to keep a hand on the shifter when going downhill.Thanks for all the great info, I'll keep y'all informed of progress!- Joe Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83452 Share on other sites More sharing options...
Rob Posted August 10, 2011 Share Posted August 10, 2011 D'oh! I'm one of those gear floaters! Comes from learnin' on an RT915 I reckon... I'll, ummmm, try that clutchin' thing you suggest and see how it works out!If need be I guess I could pull the 6-speed outta the '92 Midliner and put it in the '86 until the rebuild is done, then again I might like that even more with the 2-speed rear! The '92 truck has about 500K on it though and is pretty sloppy. Coming down a long grade you'll get to the bottom and find it's come outta 6th, lol! So I learned to keep a hand on the shifter when going downhill.Thanks for all the great info, I'll keep y'all informed of progress!- JoeIf the six speed is a Renault BDSL series don't even go about rebuilding it cause it's cost prohibitive. I had two of them and when in sound shape they are a very good unit. This is another you must use the clutch with to shift smoothly.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83454 Share on other sites More sharing options...
Joe Black Posted August 11, 2011 Author Share Posted August 11, 2011 Any suggestions for sourcing a rebuild kit? I found one but it covers CM 50 and 55, not sure if that's a series that includes the CM5852A or a different trans. I like to get all the pieces together before the mayhem begins! Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83510 Share on other sites More sharing options...
rhasler Posted August 11, 2011 Share Posted August 11, 2011 Should be a CM55, here/s a link to the illustrated parts list from TTC transmissionhttp://www.ttcautomotive.com/English/onlineorder/pdf/T210-CM55_32.pdf Quote "Mebbe I'm too ugly and stupid to give up!" Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83515 Share on other sites More sharing options...
Joe Black Posted August 18, 2011 Author Share Posted August 18, 2011 UPDATE: Drove the truck Monday about 150 miles and noted the following - Transmission shifts smoothly into 5th but will immediately "pop out" under acceleration, you can hold it in gear but the harder the acceleration the more difficult it is to hold. When coasting you can feel the shifter "pull" back into gear but as soon as you give it some pedal then out it comes. Made the run in 4th gear and the 2-speed rear in high which gave 55MPH and the pedal floored, approximately 3200 - 3300RPM on the tach. Did an oil and filter change before the run, now just need to finish servicing the rest of the fluids! While I have service manuals I do not have any owner/operator manuals so would appreciate suggestions as to what coolant and ration to use when servicing. There's also a coolant filter.Thanks!Joe Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83936 Share on other sites More sharing options...
Rob Posted August 18, 2011 Share Posted August 18, 2011 UPDATE: Drove the truck Monday about 150 miles and noted the following - Transmission shifts smoothly into 5th but will immediately "pop out" under acceleration, you can hold it in gear but the harder the acceleration the more difficult it is to hold. When coasting you can feel the shifter "pull" back into gear but as soon as you give it some pedal then out it comes. Made the run in 4th gear and the 2-speed rear in high which gave 55MPH and the pedal floored, approximately 3200 - 3300RPM on the tach. Did an oil and filter change before the run, now just need to finish servicing the rest of the fluids! While I have service manuals I do not have any owner/operator manuals so would appreciate suggestions as to what coolant and ration to use when servicing. There's also a coolant filter.Thanks!JoeThe countershaft is walking due to worn out bearings.Chances are the trans at some point was run without oil and the countergear walked fore and aft in the case chewing the bushings and shim packs to pieces.Hope the gear is quiet in operation or it can get expensive.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83946 Share on other sites More sharing options...
Joe Black Posted August 18, 2011 Author Share Posted August 18, 2011 This just keeps getting better and better. Was hoping to just be able to pull the top cover and find a shift fork in need of replacing. Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83951 Share on other sites More sharing options...
Rob Posted August 18, 2011 Share Posted August 18, 2011 This just keeps getting better and better. Was hoping to just be able to pull the top cover and find a shift fork in need of replacing.Seen my signature icon didn't you? LOL!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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83967 Share on other sites More sharing options...
Joe Black Posted August 18, 2011 Author Share Posted August 18, 2011 Thanks Rob, feelin' the love! As a collector of antique and unusual machinery it's pretty much par for the course, but just one of those things I'm not looking forward to as I've never torn into a tranny before. I know once I do it I'll be thinkin' "That's it? Easy!" but I just gotta first get motivated to pull it, lol. Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83971 Share on other sites More sharing options...
mowerman Posted August 18, 2011 Share Posted August 18, 2011 Thanks Rob, feelin' the love! As a collector of antique and unusual machinery it's pretty much par for the course, but just one of those things I'm not looking forward to as I've never torn into a tranny before. I know once I do it I'll be thinkin' "That's it? Easy!" but I just gotta first get motivated to pull it, lol.ya,,well pickup a sixer,,and jump on it.,,is 3200 ok on that motor,,i was supprized you didnt blow it out.good luck,bob Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83974 Share on other sites More sharing options...
Rob Posted August 18, 2011 Share Posted August 18, 2011 Thanks Rob, feelin' the love! As a collector of antique and unusual machinery it's pretty much par for the course, but just one of those things I'm not looking forward to as I've never torn into a tranny before. I know once I do it I'll be thinkin' "That's it? Easy!" but I just gotta first get motivated to pull it, lol.The single countershaft "Spicer" trannys are a really good one to learn on. Very simple in construction and easy to teach oneself the power flow of operation.Only drawback is they are heavy sons a bitches for no bigger than they are.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83975 Share on other sites More sharing options...
mowerman Posted August 18, 2011 Share Posted August 18, 2011 The single countershaft "Spicer" trannys are a really good one to learn on. Very simple in construction and easy to teach oneself the power flow of operation.Only drawback is they are heavy sons a bitches for no bigger than they are.Robthats how i learned automatic car transmissions,,had a 62 ford,,,no reverse gear,,just jumped right in and tore it down,,had alotta fun doing it,,but put the hillholder in backwards,,had to take apart tail shaft only,,and swap it around,,,done half a dozen since.bob Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-83980 Share on other sites More sharing options...
Joe Black Posted August 20, 2011 Author Share Posted August 20, 2011 Oops! I lied on RPM/MPH, turns out it's about 2700 - 2800 for 55MPH with the accelerator floored. Question on the tranny: Is it okay to keep driving it until I can do the rebuild? Put about another 100 miles on it today pulling my equipment trailer around and will put about 30 on it tomorrow, but don't want to make it worse than it already is. Also, if there are any suitable substitutes for the CM5852 let me know as I come across stuff all the time. Thanks all! Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-84081 Share on other sites More sharing options...
Rob Posted August 20, 2011 Share Posted August 20, 2011 That engine should have an SAE #2 housing on the back of it. I've seen several mid liners with Fuller transmissions of all varieties behind them. If it were me, I'd find a nice RTO-9509 Fuller trans, adapt it and the driveshaft and be done. Several of those cab styles by Magirus have the exact parts you need. I've seen several in yards over the years as the last one was built in the late 1980'sYou could go with a straight five speed Fuller, Clark, or Spicer and retain a syncronized transmission too, but I'd rather have the extra gears.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/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-84082 Share on other sites More sharing options...
Joe Black Posted August 22, 2011 Author Share Posted August 22, 2011 Thanks Rob, at least that gives me an alternative as I never know what I'll come across. Part of the fun of being in the antique equipment/tractor hobby is all the wonderful people you meet and all the junk they have to trade with, lol! Here's a shot from yesterday after our mowing day getting the Florida Flywheelers show grounds ready for the show season, and in the background is the other Midliner (1994) I got for title/parts. Quote Link to comment https://www.bigmacktrucks.com/topic/20070-1986-ms-midliner-wont-stay-in-5th-gear/#findComment-84209 Share on other sites More sharing options...
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