farmermann Posted October 1, 2009 Share Posted October 1, 2009 1989 Mack R688 with 1070B-12speed.Everything worked fine until driving at low speed tran. lockup, killing motor. Seems to be air problem-going into two ranges or reverse at same time. Dealer replaced o-ring kit in selector head and is now telling me must be inside so want to put in rebuilt {BIG$$$} I still think air problem, any help??? Quote Link to comment https://www.bigmacktrucks.com/topic/10886-tranny-problem-1070b/ Share on other sites More sharing options...
fjh Posted October 1, 2009 Share Posted October 1, 2009 Its likly inside, common failures broken snapring on the tail shaft broken shift rails in the back section.The shift lid prevents air type failures it has a lock out pin inside that will not let the trans be in rev and forward at the same time unless somthig is broke. Quote Link to comment https://www.bigmacktrucks.com/topic/10886-tranny-problem-1070b/#findComment-41225 Share on other sites More sharing options...
farmermann Posted October 1, 2009 Author Share Posted October 1, 2009 Its likly inside, common failures broken snapring on the tail shaft broken shift rails in the back section.The shift lid prevents air type failures it has a lock out pin inside that will not let the trans be in rev and forward at the same time unless somthig is broke.IF you work air shifter trans will unlock, driveable(slow) some noise like trying to change ranges.Is it possible to see anything through PTO hole? Also is back section removable or do I have to drop complete trans.?? Quote Link to comment https://www.bigmacktrucks.com/topic/10886-tranny-problem-1070b/#findComment-41229 Share on other sites More sharing options...
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