Jump to content
mackinit

need a lot of insight on mack 18 speed

Recommended Posts

my company has a 2000 rd triaxle with a mack 18 speed in it and i think it has a 400 or 427. it is soon to be my truck. problem is, the previous driver left the company and i dont have anyone to teach me how to shift it. i had never shifted a splitter transmission until today and i did awful. the gears ground so bad when i was trying to split. at what rpms do you upsplit and down split.? what is the max rpm and minumum rpm you can split? going down hill at moderate speed, do you heel/toe to split down while throttling up or throttle off then split then throttle on? preselect splits. are there normal sounds i should be aware of that may have me wondering if i did something wrong? there are so many more questions i have and techniques i need to learn before i really get on the road. i need a lot of practice and im scared of damaging this transmission.

Share this post


Link to post
Share on other sites
1 hour ago, mackinit said:

my company has a 2000 rd triaxle with a mack 18 speed in it and i think it has a 400 or 427. it is soon to be my truck. problem is, the previous driver left the company and i dont have anyone to teach me how to shift it. i had never shifted a splitter transmission until today and i did awful. the gears ground so bad when i was trying to split. at what rpms do you upsplit and down split.? what is the max rpm and minumum rpm you can split? going down hill at moderate speed, do you heel/toe to split down while throttling up or throttle off then split then throttle on? preselect splits. are there normal sounds i should be aware of that may have me wondering if i did something wrong? there are so many more questions i have and techniques i need to learn before i really get on the road. i need a lot of practice and im scared of damaging this transmission.

Read operators manual; you can get it from google; Mack trans are different from Eaton 

Share this post


Link to post
Share on other sites

luckily i was able to find the owners manual and it explained a lot. what it doesn’t say is at what rpms to split at. say at 1600 rpms, i want to down split, do i hit the button down while on the throttle? or off then hit it? i tried a bunch of different ways and it didnt work either way for me. is 1600 to high or should i be down splitting around 1400? 

Share this post


Link to post
Share on other sites

Mack Nit

gudday m8

the easiest way to drive the mack 18

wen the engine is up to operate n temp

in each gear run it upto the govonor ...... then change up

take note of wot the rev counter sez after the change

this is the same rev U would change down @

if run n down hilld deduct a cupla hundred revs to allow for over run

 

cya

Share this post


Link to post
Share on other sites
4 hours ago, mackinit said:

luckily i was able to find the owners manual and it explained a lot. what it doesn’t say is at what rpms to split at. say at 1600 rpms, i want to down split, do i hit the button down while on the throttle? or off then hit it? i tried a bunch of different ways and it didnt work either way for me. is 1600 to high or should i be down splitting around 1400? 

200 rpms is either direction when splitting.  If at 1600 revs you want to split down: hit the button down, then you need to tap the throttle, let off to break torque, then throttle up to 1800.  I'd say that 1600 is a little high to be down splitting, but can't say for sure what you are trying to do.

  • Like 1

Share this post


Link to post
Share on other sites

1600 was just an example and thanks for clarifying thats to high to down split. but in that case, 1600 rpms, foot off throttle, hit the button down, then hit the throttle right after split? is that right? if so, what should the split shift sound like? under normal driving conditions while loaded, on/off highway for example, what rpms should split shifts be made in general..up and down? glad i found this site. a lot off good info on here. i did read about mackr1989’s problems and my issue seems to be the way im shifting, not a problem with the transmission. but i did notice that when i ran the split test while the truck is at full air pressure and not running, the splitter doesnt always actuate quickly splitting down. sometimes it’s immediate, sometimes its delayed, sometimes it doesnt seem to move at all. i hear an air sound and knock which i assume is normal when it does work immediately or delayed. what does the delay or no apparent response mean?

Share this post


Link to post
Share on other sites

forgot to mention that i did get some stick time today and this was the sequence inwas using while down splitting. foot on throttle and hit button down to split at1500 rpms, let off throttle and let split engage and quickly get back on throttle. it seemed to work but is this bad practice? ive tried splitting down while off of throttle, hitting the button down, then hitting the throttle again as fast as i can and it kinda sounds like its grinding and makes a sound that to me doesn’t seem right. doesnt sound very smooth. 

Share this post


Link to post
Share on other sites

I don't know if its "the right way", but when I split down, I slide it to neutral, split down, double clutch it back into gear. It is way smoother. A lot of times, you can just downshift by whole gears.

 

Share this post


Link to post
Share on other sites

ekennedy..how do you mean you double clutch when splitting? how is that procedure done exactly?

Share this post


Link to post
Share on other sites

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. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...