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  #1  
Old 10-02-2006, 05:02 AM
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Default trouble shifting a mack 10 speed

Hi there, so im new to truck driving(1 month) i decided to change careers after 15 years in construction. Its great and Im loving it. My problem is with the truck Im driving. Its a 2002 granite mack dump truck, with a 10 speed transmission. It goes Lo 1-2-3-4-5 low range select high range 6-7-8-9-10. The problem is when I have a full load with a pony trailer. I can shift through all the gears from 1 up to 10 on any hill no problem as long as the hill will allow me to start in 1st. When the hill is to steep and I need to start in low I cant get it to shift from lo to 1st. In all the other gears I take it up to 1800rpm shift slide it in at 1600rpm. Now the only way I can do it from lo to first is to take it up to 1800 shift(with the jake on) so it drops down to 1000rpm and it goes in to gear, but now the rpm and the steepness of the hill, and the weight of the load are too much for 1st gear and the truck either almost stalls or I have to stop and start off in low gear again. This is very frustrating when your only a few car lengths back from a light and it takes 2 lights to get through the intersection(not to mention it sure makes the people behind you mad) So what am I doing wrong? please help a newbie out :cry:
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  #2  
Old 10-02-2006, 07:29 AM
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Location: Redneckistan
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Sounds to me like the rpm are WAY to high and the truck is almost back to a dead stop when you try for 1st? You should try a little progressive shifting and keep the rpm in the low gears a lot lower. the key to this is to get the truck rolling and really shifting QUICKLY when the rpm are falling. You need the clutch and VERY little rpm to shift from low to 1st, but you really have to get into gear quickly.

The problem with raising the rpms that high at that low a road speed is that all of your momentum (road speed) dies while you are waiting for the rpms to drop.

Hope this helps and I hope I'm not misdiagnosing this
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  #3  
Old 10-02-2006, 03:04 PM
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Thanks for the reply, I do progressive shift, and I dont shift at 1800 all the time. I should have said i bring it up to 1800 for steep hills. If I shift at 1800 on a hill by the time im done my shift and im into full throttle the rpm is down to 1400 which for this truck is just borderline for pulling itself backup to 1800. Any lower than 1400 and it wont pull. Thats where my problem is with the lo to 1st on a hill, but i will try not bringing the rpms up so high on a hill in lo, like you said. See all the other trucks we have are 15 speeds, so they have 5 deep reduction gears which are perfect for getting the truck rolling on a hill. My truck only has 1 deep reduction gear, so like you said the shift has to be at quite low rpms which the truck will almost be at a dead stop but maybe faster than when I was waiting for the split second of the jake bringing the rpm down to 1000 from 1800. I also heard that a 10 speed with mack engines after 2002 are not a good design as the older macks had more horsepower, and a 10 speed was not an issue. If the lower rpm shift doesnt help, maybe I will try switching trucks, so I dont end up being the one tearing the driveline out. :lol:
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  #4  
Old 10-03-2006, 12:17 AM
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Join Date: Aug 2005
Location: Southern Ontario Canada
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I have the same problem with my truck, but it has a 9LL it says.
It is almost impossible to shift from low gear into first with it. It just refuses to shift and just grinds. There is just too big of a jump between gears, low is barely moving and first is too fast.

I have driven lots of 8LL and they work just fine. This 9LL is just stupid.

But i do have deep reduction, so most time i just flip into deep reduction and start off in first deep reduction.

Whoever ordered a 10 speed in a a dump truck must have been stupid, a 15 speed or a 8LL is a way better tranny for a small HP dump truck.

A 13 speed is also no good in a small hp dump, low gear just isn't low enough, when you get into the deep soft ground.

We have some 500 hp trucks with 18 speed's and they do just fine. Gotta love 500 hp and not even pulling a pony.
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  #5  
Old 10-04-2006, 09:40 PM
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I wouldn't shift with the jakes on it makes the rpm's drop way too fast. 1800 rpms is just right you just need to shift quicker.
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  #6  
Old 10-04-2006, 11:44 PM
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Location: Hobbs, New Mexico
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macks are a pain in the butt on shifting they lose rpms way fast I used to shift at 1800-2000 in my granite with an 10 speed maxi torque low low multireverse tranny even pulling a float with 70,000 pounds it wouldnt stall in first on a hill. maybe they got the littlest motor they could for that truck :twisted:
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  #7  
Old 10-05-2006, 04:33 AM
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Thats the tranny I have paystar. I believe the motor is a 460 or 460 horse(not sure if thats correct) Our loads are generally around 85-90, 000lbs. So whats the trick with the shift from Lo to first. I tried shifting from Lo to first at about 1400, letting it drop to 1000 and it didnt do too bad, mind you the hills werent that extreme, but when I made the shift it tourqed the cab up pretty good. Still doesnt seem right to me maybe its because I had my foot right into the throttle but if you dont it just dies right off. Once its moving in first the rest of the shifts are easy and the truck pulls nice. Its almost like it should have 2 low gears. The only time I was using the jake for shifting is the Lo to first shift just to get the rpm's to drop faster so it would go into gear without losing my momentum. So tell me how you used to do this shift paystar on a fairly steep hill say where you had to take off in Lo? Thanks
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  #8  
Old 10-05-2006, 01:55 PM
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hmm i never really had to take off on a hill but climbing one on a lease road or something id just downshift to second and run 1600 rpm all the way up it the only time I used low is when i got stuck in a sandy or muddy situation. I would say try avoid stopping on a steep incline. but if it cant be avoided then I guess practice going from low to first on flat ground then try it climbing
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  #9  
Old 10-06-2006, 03:16 AM
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Ya I guess I will just keep practicing. Where I am is all mountainous so a good portion of intersections are on fairly steep hills. Ive been trying to time the lights by leaving some room creeping up to the light but theres always idiots pulling in front and then your stopped. Oh well sooner or later it will end up working or the truck will get a new clutch. It seems like this truck would be much more suited for highway driving. thanks for the help.
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  #10  
Old 10-07-2006, 03:16 AM
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Im a rookie to fellas..So heres my question....I drive a century with a 60 series regular 10 speed detroit 430hp engine...I pull a 53ft van and my problem is that when i get a load about 38,000-44,000 on board and soon as i get to the mountain areas and im doing about 30mph when my rpms get to about 18000 and its time to shit, by the time i get to shift as fast as i can it doesnt pop into gear i gotta drop it right back to where it was...Do i just leave it where its at even though im at high rpms? Or just wait till i come to a leveled part of the mountain to shift into the next gear
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