AzconaInc Posted December 5, 2008 Share Posted December 5, 2008 (edited) I just want to know the proper way to switch gears in this transmission..Sometime they go right in to gear and sometimes grind into gear.My mechanic told me it a 5 Speed mack Tranmission. with Lo Gears to..But he told me always to start in High becuase low gears are irrational for this transmission is this true..The second problem I have is when I'm in 4th gear and i go to slow down and try to put it in 3rd gear to start moving again I got caught in neutral and it won't go into the 3 rd gear or any other gear the only way it will go into gear is if I come to a complete stop and start all over again..Could some1 please help me this problem I wold appreciate this i'm pretty hands on but Im new to these kind of trucks thank you.. Edited December 5, 2008 by Manny Quote Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/ Share on other sites More sharing options...
Noid93 Posted December 5, 2008 Share Posted December 5, 2008 (edited) Manny, these trannys require very high and very low rpm shifts. Usually run the rpms up to 1800 in 1st gear pull it out of gear, and start pushing it into 2nd about 1300 rpm and it should fall in about 1250. You can damn near smoke an entire cigarette between gears. For down shifting, just the opposite. Run it down to 1200 and pull out of 5, rev it up to bout 1800, and slide it into 4. Best of luck. Edited December 5, 2008 by Noid93 Quote There Is No Replacement, For Displacement!!!!! Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26057 Share on other sites More sharing options...
AzconaInc Posted December 5, 2008 Author Share Posted December 5, 2008 Alright I'm going to try that cause i just had the tranny rebuilt and I thought something was wrong and everyone keeps telling me no you gotta learn how to drive these trucks..sometimes I shift into higher gears with no problems and then sometimes I get a little grind is this normal...So if I'm pulling up to a light in 4 th gear and going to slow down and then the light turns green if I have to go to 3 rd gear I put it in Neutral and rev it up to about 1800 and I throw it into 3rd gear is this correct...thank you very much and I appreciate the help and other tips you or anyone could help me with... Quote Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26089 Share on other sites More sharing options...
HK Trucking Posted December 5, 2008 Share Posted December 5, 2008 Alright I'm going to try that cause i just had the tranny rebuilt and I thought something was wrong and everyone keeps telling me no you gotta learn how to drive these trucks..sometimes I shift into higher gears with no problems and then sometimes I get a little grind is this normal...So if I'm pulling up to a light in 4 th gear and going to slow down and then the light turns green if I have to go to 3 rd gear I put it in Neutral and rev it up to about 1800 and I throw it into 3rd gear is this correct...thank you very much and I appreciate the help and other tips you or anyone could help me with...The engine RPM's have to be at the point they would be at if you were already in the gear you're trying to shift into.Once you grasp that principle, it's easy.That goes for any unsynchronized transmission. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26090 Share on other sites More sharing options...
rustydog Posted December 6, 2008 Share Posted December 6, 2008 Manny, you're not alone!! It does take some getting used to. Good Luckrusty Quote Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26150 Share on other sites More sharing options...
AzconaInc Posted December 12, 2008 Author Share Posted December 12, 2008 The only other question I have is why did they put a high and low button in this transmission when all you use is the high gears you never use the low gears cause when you try to use the low gears and hit the switch to high it never goes in gear. what was the point in the first place in doing it... Quote Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26907 Share on other sites More sharing options...
theakerstwo Posted December 12, 2008 Share Posted December 12, 2008 The only other question I have is why did they put a high and low button in this transmission when all you use is the high gears you never use the low gears cause when you try to use the low gears and hit the switch to high it never goes in gear. what was the point in the first place in doing it... What you say? Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26924 Share on other sites More sharing options...
David Posted December 13, 2008 Share Posted December 13, 2008 You have 6, 7, or 8 speed. See if 2060, 2070, or 2080 are stamped on the drivers side of the transmission. Quote Link to comment https://www.bigmacktrucks.com/topic/6482-1991-mack-690s-5-speed-transmission/#findComment-26967 Share on other sites More sharing options...
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