Cruiseliner Posted August 25, 2013 Share Posted August 25, 2013 Hi, I have a 90 model valueliner with a 18 speed Mack box, I think it's a T2018. When I go from low range to high it makes a big clonk noise.The box is only 3 years old with only a cupple of thousands Ks on it.Is there an adjustment or something to stop this.All help is a appreciated. Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/ Share on other sites More sharing options...
krismoriah Posted August 25, 2013 Share Posted August 25, 2013 Could be the air valve on the tranny not pushing enough air. Sometimes cleaning them helps. If that doesnt help then usually a synchronizer is going bad...so time for another rebuild..but maybe not a full rebuild. Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-201715 Share on other sites More sharing options...
fullfuel01 Posted August 25, 2013 Share Posted August 25, 2013 common issue. I would bet a six pack it's syncro problem. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-201760 Share on other sites More sharing options...
Brandt Posted October 4, 2013 Share Posted October 4, 2013 (edited) Usually a syncho - especially if it does it when the trans is cold. Edited October 4, 2013 by Brandt Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-210064 Share on other sites More sharing options...
Cruiseliner Posted October 5, 2013 Author Share Posted October 5, 2013 It only does it when it's hot. It's like a big thump when going from low to high but good going from high back to low.This was a brand new box not a rebuild. Can you replace the syncho without taking the box out ? Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-210161 Share on other sites More sharing options...
fullfuel01 Posted October 5, 2013 Share Posted October 5, 2013 Then it might no be syncro.. You can remive yhe rear part only but you need the tool that will jold the shaft. Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-210170 Share on other sites More sharing options...
Brandt Posted October 5, 2013 Share Posted October 5, 2013 Can you replace the syncho without taking the box out ? You can on an Eaton, I would assume you could on a Mack. Generally a shop will have bought or made a jig for keeping everything lined up going back in. Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-210193 Share on other sites More sharing options...
Challenger Posted October 5, 2013 Share Posted October 5, 2013 Could be a loose synchro fork pinch bolt and or a synchro failure. Mack has the tools to do a "inframe" synchronizer replacement. Every truck is different, it depends on how much room you have to work with. You can do an inframe synchro on a Granite in 6-8 hours. I did an inframe on a RD one time. The rear of the cab had to be unbolted and lifted up, it was a total waste of time. Pulling the trans would've been easier. The trans is a T2180 Quote Link to comment https://www.bigmacktrucks.com/topic/32468-18-speed-mack-range-change-noise/#findComment-210209 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.