mackr1989

sx 10 wheeler with 58 rears sags 2.5-3 inches when loaded or towing. everything in the rear was replaced 2 years ago except for the springs. trunnion, saddles, insulators, u bolts, etc. we were into the truck for way to much money to spend even more on the springs at the time which was when i was told they didn’t need to be replaced so i decided to hold off.

Don’t bother trying to split low range until you have figured out how to split high range. low range splitting is practically redundant, unless you are really heavy, because the half gears while in low are so close. as for general dump truck driving while loaded, start off in low if needed, shift L-4 while in underdrive, shift to fifth underdrive, then start splitting from there. fifth underdrive then split to direct. preselect up shifts while on throttle, throttle off to allow split to actuate then throttle on. i bring rpms up to around 1900 to up split and usually down split around 1400.

air compressor let go and leaked oil in the air system. how do you clean the oil out of the air system?

i do that also. sometimes i hit the splitter just before i move the shifter and have no problems with gears grabbing but i usually split passing through neutral. only gears that grind when splitting and shifting to the next gear are 3H-4L and 7H-8L. it doesn’t matter if i preselect or split going through neutral, it still grinds. i can smoothly split passing through neutral to the next gear or split just before i move the shifter with all of the other gears with no issuses.

i plan to. i just wanted opinions on the issue.

it has a 2 year warranty and it was installed a few months ago and i do split passing through neutral and the gears still grind.

had a reman 2180b installed and shifting from 3rd high to 4th low and 7th high to 8th low grinds. every other shift slides and clicks right into gear.

whenever i have to firmly and quickly use my brakes, i hear a loud thud sound and my truck pulls hard to the left. my mechanic cant find the issue. could this just be a bad brake chamber?

terminology was wrong when they were saying the synchros were bad. the clutches were worn amongst other things. $5200 was the cost of the reman.

the problem was the gears weren’t meshing together when splitting from underdrive to direct and direct to underdrive while in high range..no problem with gears in low range. splitting in high range would put the transmission in neutral and or neutralize then knock into gear. i was told that all of the synchros were worn and thats what was causing the problem. i put a reman in because it wasnt going to cost much more than repairing what i had. now it shifts fine in every position.

no grinding at all. i range shift, move the shifter, then split.

im going to call the company that did the transmission work and relay what you guys are telling me cause i was told much different. if my problem with this transmission was gear splits not meshing together causing neutralization and or rough engagement, what do you think happened to cause this? im now understanding what mach tech is talking about and didn’t at first due to what i was told previously by other people.

in an 18 speed? why do you think i was told that there is 6 and that they were all worn?

so just range as in high and low..not underdrive and direct?

so how many synchros are in this transmission for splitting gears? the only problem ive had is splitting from underdrive to direct and vice versa. never had a problem with high and low range.

well wont a bad synchro cause a a splitting problem? mack didnt come out with an updated synchro design? i was told there were multiple synchros that were worn out. im not disagreeing with what youre telling me. im just repeating what i was told and i dont know much about transmissions from a mechanical standpoint. also, the power divider was accidentally engaged while it was getting worked on. the switch label is worn and illegible and i couldn’t remember if it was supposed to be in the forward or backward position on the dash but did notice that i didnt think it was in the position it was in when i dropped the truck off. i switched the power divider from forward to backward as in “out” and now it shifts just fine. no problems with the transmission and luckily, the power divider still works.

so is the transmission going to stay this way unless it gets pulled apart again? or does it need to be broken in?

turned out that the synchros in the trans were worn out. i was told there was a recall on these and mack updated the synchros with harder metal. i wound up putting a reman in seeing that it wasn’t that much more expensive than rebuilding what i had. i am noticing that it can be difficult sometimes to move the shifter from gear to gear, as in its getting stuck and wont move. ive shifted a lot of different mack trannys and the only other transmission ive used that does this is a six speed low hole..2 stick.

air pressure in 2000 rd dump is always around 95-100 psi average while driving. it will build to 120 but rarely stays around the 120 range. no noticeable air leaks found.

ok so how exactly am i splitting incorrectly. i always kept my foot on the throttle and preselecting to direct for only a split second before releasing throttle, then id let the rpms come down then get right back on the throttle again. total time with this was fast and only took about a second. if this is incorrect, how should splits be done? release throttle entirely, split to direct and engage, then rethrottle?

but as far as repairs and parts?

hmm ok so what do you think is going on?

ive been told to always preselect splits but only just before or after getting on or off of throttle. the only time splits smoothly engage is by preselecting and slowly getting off of the theottle.

slipping under torque sounds more like it. quickly letting off of throttle after split then quickly getting back on it after rpms drop causes the shift to delay, grind and knock into gear or it just grinds and doesnt go into gear and i have to move the shifter to neutral to stop it.

could this problem be something like a synchro? im worried it could be. again, the trans does smoothly upshift when splitting very carefully by obviously preselecting direct, slowly taking presuure off throttle and keeping slight pressure and the shift slides right in.