8550 transmission help

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   Hi all new to the forum here, looking for some help and info on an 8550 Allis. 
Quick rundown on the situation: the tractor is sitting in our barn currently and has not been used for around 8 years. It is an 8550 with the original transmission and an 855 Cummins motor swap. I am looking to use the tractor again as we recently returned our planting tractor on lease and i now need to pull our roller tractor to do the planting tractors job, it would be nice if i could use the 8550 to pull the roller (40 ft Mandako). 
The current problem i'm having with the tractor is that it pops out of reverse gear. 

I was wondering if anyone has any info on these tractors transmissions, and if anyone could share some info on what the cause of this could be and how it can be fixed. Diagrams would also be very much appreciated. Currently were still doing harvest but i'm looking to get some preliminary ideas so that i can check for symptoms before i power wash the tractor and put it in our shop to work on it.

Any help would be much appreciated, thanks!

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Dakotab19 Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 01 Dec 2019 Location: Michigan Points: 4	Post Options Post Reply Quote Dakotab19 Report Post Thanks(0) Quote Reply Topic: 8550 transmission help Posted: 01 Dec 2019 at 10:49pm
	Hi all new to the forum here, looking for some help and info on an 8550 Allis. Quick rundown on the situation: the tractor is sitting in our barn currently and has not been used for around 8 years. It is an 8550 with the original transmission and an 855 Cummins motor swap. I am looking to use the tractor again as we recently returned our planting tractor on lease and i now need to pull our roller tractor to do the planting tractors job, it would be nice if i could use the 8550 to pull the roller (40 ft Mandako). The current problem i'm having with the tractor is that it pops out of reverse gear. I was wondering if anyone has any info on these tractors transmissions, and if anyone could share some info on what the cause of this could be and how it can be fixed. Diagrams would also be very much appreciated. Currently were still doing harvest but i'm looking to get some preliminary ideas so that i can check for symptoms before i power wash the tractor and put it in our shop to work on it. Any help would be much appreciated, thanks!

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DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 20780	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 02 Dec 2019 at 11:01am
	I'm not an 8550 guy, but it could be a bent reverse shifting fork, OR the fact that the shift lever linkage from the cab down to the transmission isn't adjusted properly or WORN/LOOSE and not getting it 100% into engagement. 2nd gear and reverse are the farthest throw/stroke gear selections for the shift linkage, and if things are out of adjustment and/or worn that might be all it is. Hopefully it hasn't jumped out of gear very many times, or the gear teeth could be damaged beyond being useable. Farm implements work best going forward. Using reverse (under any load) would be a low percentage thing for me.

Dakotab19 Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 01 Dec 2019 Location: Michigan Points: 4	Post Options Post Reply Quote Dakotab19 Report Post Thanks(0) Quote Reply Posted: 02 Dec 2019 at 5:59pm
	So it would probably pop out of 2nd if misadjusted then?

MACK Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 17 Nov 2009 Points: 7664	Post Options Post Reply Quote MACK Report Post Thanks(0) Quote Reply Posted: 02 Dec 2019 at 7:50pm
	AC made a tool for aligning transmission top. Never used it, but it hung on wall of special tool room since 1973. MACK

SteveM C/IL Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Shelbyville IL Points: 8300	Post Options Post Reply Quote SteveM C/IL Report Post Thanks(0) Quote Reply Posted: 02 Dec 2019 at 8:39pm
	So MACK,wing it or never work on that model?

DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 20780	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 03 Dec 2019 at 6:56am
	There is only so much stroke in the shift lever. So, if it isn't going into reverse all the way, it surely is going all the way into 2nd, unless the linkage is loose or worn.

MACK Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 17 Nov 2009 Points: 7664	Post Options Post Reply Quote MACK Report Post Thanks(0) Quote Reply Posted: 03 Dec 2019 at 9:09pm
	Just never needed the tool. 7000 series transmission (except a 7000) was almost bulletproof. MACK

Dakotab19 Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 01 Dec 2019 Location: Michigan Points: 4	Post Options Post Reply Quote Dakotab19 Report Post Thanks(0) Quote Reply Posted: 04 Dec 2019 at 10:57am
	Is there a procedure to check the linkage, also if i wanted to check the shifting forks can I do it through the cab floor or from the ground? Edited by Dakotab19 - 04 Dec 2019 at 10:57am

DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 20780	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 04 Dec 2019 at 12:13pm
	The shift lever must fully 'detent' in 2nd gear and reverse. Anything short of that means the linkage is loose/worn and not centered properly for neutral. The linkage parts that wear are external and not inside the transmission (as a rule).