joes mack Posted May 16, 2016 Share Posted May 16, 2016 what would cause our 87 CF with a Allison auto to jump and jerk in 1st gear when pulling out of the station or on a hill? it only does it in 1st gear it shifts fine and is smooth as silk in all other gears. it started doing this all of the sudden last week. fliud level is right on the full mark. thanks joe Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/ Share on other sites More sharing options...
fjh Posted May 16, 2016 Share Posted May 16, 2016 It may be the diff ! We had one that did this! if it has a Mack limited slip diff they tend to pop and bang in certain conditions! Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333502 Share on other sites More sharing options...
joes mack Posted May 16, 2016 Author Share Posted May 16, 2016 it feels like driving with tire chains on when it is doing it Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333522 Share on other sites More sharing options...
CF600 Posted May 16, 2016 Share Posted May 16, 2016 I had the same condition, added a bottle of Lucas trans additive and it made the pull outs and shifts a lot smoother. The vibration might be as simple as a dry U joint. I try cheap and simple first. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333527 Share on other sites More sharing options...
joes mack Posted May 16, 2016 Author Share Posted May 16, 2016 we have our weekly meeting in a couple of hours so I personally will climb under it and check the u joints (they were supposed to be greased 2 weeks ago ) if that don't help I will try and get some of the lucas and put in it and hope that does it. thanks Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333557 Share on other sites More sharing options...
joes mack Posted May 19, 2016 Author Share Posted May 19, 2016 thanks for the help on things to look for I found the front u joint between the trans and transfer case is bad( the pump packing leaking aint helping things as water is dripping down on it ) so I will hopefully get it changed tomorrow thanks again for the ideas of things to look for I never thought about a u joint doing that but ive not seen everything either lol thanks again joe Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333790 Share on other sites More sharing options...
1958 F.W.D. Posted May 19, 2016 Share Posted May 19, 2016 20 minutes ago, joes mack said: the pump packing leaking aint helping things as water is dripping down on it Remember, not only is it normal and acceptable for leaking at the packing. Now get your minds out of the gutter you pigs. Quote TWO STROKES ARE FOR GARDEN TOOLS Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333794 Share on other sites More sharing options...
joes mack Posted May 20, 2016 Author Share Posted May 20, 2016 hellllllllllllllp I have another question what is the easiest way to change the u joint on this damed thing on the transmission side it has the big 8 bolt flange and on the transfer case side it has a regular yoke and the driveshaft is only 7 inches long is it easier to take the rear u joint out too and put it back with just the crosses and then install the cups or would it be easier to loosen the transfer case and slide it back about 1/2 inch to get the clearance it needs just to put the front one in. I'm about to pull my hair out Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333919 Share on other sites More sharing options...
kevink1955 Posted May 21, 2016 Share Posted May 21, 2016 I have not worked on a CF in Years but I think you need to remove the flange and also the cups from the rear joint. Sliding the transfer case aint gona happen as it's part of the pump casting and you would be moving the entire pump, plumbing and all. That's assuming it is Waterous or Hale, never seen anything else in a CF but I do not know it all. Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-333988 Share on other sites More sharing options...
fjh Posted May 21, 2016 Share Posted May 21, 2016 Take It at the flange Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-334020 Share on other sites More sharing options...
joes mack Posted May 21, 2016 Author Share Posted May 21, 2016 I am going to have to get out my torches and cut the u joint out of the rear of the driveshaft we have beat and heated and beat some more on this thing and it will not move I am guessing that the cups are rusted in the yoke and will not move so I guess she will get 2 new u joints and the pump re packed before I put her back in service. I was going to wait on the pump re packing for a bit but it is leaking pretty good and the adjusting collars are run up as tight as they can be so I guess now is as good of a time as any to replace it so be prepared to answer a few more questions on that as well. thank you all for your help joe Quote Link to comment https://www.bigmacktrucks.com/topic/45230-fire-truck-transmission/#findComment-334046 Share on other sites More sharing options...
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