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Mack maxi torque problrm


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Have a 2002 mack 688 . When i load the truck and im driving im getting a noise / and a feeling like the transmission gear is skipping . Its hard to explain but it feels like a gear is trying to engage enen though im not hottibg the splicer . The truck runs great and was haul heavy loads up hills with no slipping . Any ideas

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I am assuming you have a transmission with some air shift, as in forward reverse, high and low

However it sounds like your loosing air pressure or theres crap in your gears no allowing them to slide fully in

I would change the transmission air filter first

Then if the problem is still there, check for air pressure on the gear box should be about 60 psi, anywhere from 45 to 75 is fine 

Then drop the transmission out and lift it apart for a look-see 

Or get us some more details on the transmission model, theres a few Maxitorque types

Paul

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Those damn peanut's.... they can fool you into thinking its tranny noise. the drive shaft is a tube, and carries the noise up to the tranny...  jojo

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Yeah I know a guy that had a driveline noise, pulled the tranny had it rebuilt, put it back together, and yes noise still there, noise was front rear end, talk about a unhappy camper!  Terry

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There was a thread on here a loooong time ago about a fella that had clunking noises coming through the drive train, It turned out he had put new tires on one axle only and the mis matched tires were causing a problem with the power divider . I don't think this is the case , just throwing it out there . 

Edited by 85snowdog
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Keith 

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1 minute ago, 85snowdog said:

There was a thread on here a loooong time ago about a fella that had clunking noises coming through the drive train, It turned out he had put new tires on one axle only and the mis matched tires were causing a problem with the power divider . I don't think this is the case , just throwing it out there . 

as stated Tire size plays a huge part!

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More then 1/2in difference in tire size is a huge no no on macks. Says so in the service manual.   

Edited by Onyx610
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22 minutes ago, theakerstwo said:

Years ago i installed a 4 speed aux trans behind a 6 speed for lower gears for a house mover.We did the ujoint angles like should be but a few days later he came in with a noise.His buddy say they did not install trans right.I sent him on his way but a month later the story comes out were he had taken it to another shop and had some more work done to it but no fix.He comes in having a fit over it and take it with him and drive some more and found the peanut knok.I looks at his tires and one is flat and its mate is low.I say go fit tires and get back.I never saw truck again.I have always said on a mack rear end 3/4" difference in tires is max.

yup First thing to look for if your running Mack rears! my belief is if you got to run miss match tires ( Don't recommend it how ever ) Run em kitty corner that spreads Some  of the wear thru out the diffs and power divider!

 

Just an opinion

Edited by fjh
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Yup. All the setup is in the front housing of the FR axle diff. Take away the prop shaft, drive yoke, front cover and you'll able to pull a cage out and see them wedges. Sure better to look at a cut or blow out view in a book and read a bit. The CRD92/93 maintenance manual may be found on the net.

Vlad

Никогда не бывает слишком много грузовиков! leversole 11.2012

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Be sure to check the cams while apart. If the peanuts are worn ( I have seen them chipped ) most likely the cams are worn also. The inner cam comes out with the assembly so easy to inspect but you need to look inside the carrier nose to inspect the outer cam. Replacing only the peanuts when the cams are worn only limits the new peanuts life. I have heard of the peanuts and inner cam being replaced successfully due to the drama/ complications of removing and pre loading the piñion bearing, not something I would do unless pressed by a customer. 

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replacing the outer cam requires the removal of the input/ bevel pinion housing. Pay attention to the shim pack thickness for the housing, and the shim for the outer cam.  if you attempt this, you will need to make a jig that holds the outer cam in place so it cant rotate, and it will be bolted to the housing as well. then the big nut inside is torqued to around 1300 lbft. if you get this apart, decide on bearing condition.  then when you put it back together, you have to press the outer cam in place, as a completed assembly. the pressure is 10,000 PSI..  wrap a string around the housing several times,  and pull the string and pull the string with a 'fish scale'  from youre tackle box.  reused bearing pull at 2-5 llbs, new bearing pulls at 3-6 lbs.  this will indicate proper bearing preload.  adjust the shim thickness as needed.. once that is done then you need to torque that skinny nut to around 1300lbft. once done then you put the assembly into the carrier housing with 2 bolts holding it in place, and check the tooth pattern for the bevel pinion and the bevel gear, use Prussian blue gel to set the 'root' good,  adjust the pattern using the thin shims for  the input housing. it is highly possible that the original shim pack will be correct.  if so,  put her together.. good luck to you, jojo

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23 minutes ago, Joey Mack said:

replacing the outer cam requires the removal of the input/ bevel pinion housing. Pay attention to the shim pack thickness for the housing, and the shim for the outer cam.  if you attempt this, you will need to make a jig that holds the outer cam in place so it cant rotate, and it will be bolted to the housing as well. then the big nut inside is torqued to around 1300 lbft. if you get this apart, decide on bearing condition.  then when you put it back together, you have to press the outer cam in place, as a completed assembly. the pressure is 10,000 PSI..  wrap a string around the housing several times,  and pull the string and pull the string with a 'fish scale'  from youre tackle box.  reused bearing pull at 2-5 llbs, new bearing pulls at 3-6 lbs.  this will indicate proper bearing preload.  adjust the shim thickness as needed.. once that is done then you need to torque that skinny nut to around 1300lbft. once done then you put the assembly into the carrier housing with 2 bolts holding it in place, and check the tooth pattern for the bevel pinion and the bevel gear, use Prussian blue gel to set the 'root' good,  adjust the pattern using the thin shims for  the input housing. it is highly possible that the original shim pack will be correct.  if so,  put her together.. good luck to you, jojo

Quite the procedure!   terry:MackLogo:

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yes Terry, it is..  of course it could just be torn down and stuck back together,  but how long will it live?  I posted that info so he could see what is involved before he takes it apart..  hope to see more comments for him,, jojo

Edited by Joey Mack
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