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Road ranger question, trouble changing from high range to low range

Nick009

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Joined
Jul 22, 2012
Messages
142
Location
Western Australia
I just bought my first truck with a road ranger. I did my driving course with one but that was about 10 years and I haven't driven one since. I bought a 1980 ford louisville LNT8000 tipper and the previous owner told me he replaced the gearbox with a s/h one at some point. Its a fifteen speed with deep reduction and then low range and high range.

I'm having trouble changing down from high range to low range. If we forget about the deep reduction and call 1st gear in low range gear 1. I'm having trouble changing down from gear 7 (high range) to gear 5 (low range).

There is no problem changing up from 5 to 7. I flick the range switch to high when in gear and move the stick, no clutch, no problem.

Please correct me if I'm wrong, but as I understand it I should do the same procedure in reverse to get from 7 to 5. But something is not happening right because I can't get from 7 to 5 without crunching sounds coming from beneath me. I've been trying to use the clutch, so in gear 7 I flick the range switch down then put the clutch in, move the stick to neutral, but when I let the clutch out there is a crunching sound. and then I can't seem to find a gear without slowing right down to a walking pace.

Am I doing something wrong?

I haven't tried to engage the deep reduction while moving but it does seem to work while stationery. I live in a very hilly area and I think I will need it to get up these hills with a load. What is the procedure for changing into deep reduction while moving?

Thanks for your advice
 

Plant Fitter

Senior Member
Joined
Jul 14, 2012
Messages
336
Location
Australia
The range change unit on a road ranger has a syncromesh unit to engage high or low range. When the syncro rings are worn out you hear grinding noises as the range change is taking place. To repair the back section of the gearbox has to be pulled off and the syncro unit replaced.

Just in case, check that the air hoses for the air shift are not kinked or blocked restricting the flow of air to the range change unit. Some of them also had some sort of screen or filter on the transmission air lines.

Some of the drivers on the forum may be able to give some tips about whether it is possible to work with a worn out range change syncro by matching the engine revs somehow.
 

mitch504

Senior Member
Joined
Feb 27, 2010
Messages
5,776
Location
Andrews SC
I really hate to say this to anybody, but, I think you are describing bad synchronizers. To check, get the truck moving, shift up to high range, flip the switch down, then, without using the clutch, move the stick to neutral. Don't try to put the stick in a gear, just let the truck coast. If you get a grinding sound then, you are going to have to rebuild the rear section of your transmission. If you flip the switch back up, the grinding will probably stop.

If you find the tag on your trans. and post the model number, we will be able to give you a little more specific help. It should be a number something like RT14615a, or something similar. Make sure you get all the numbers and letters right.

Good Luck,
Mitch
 

Nick009

Well-Known Member
Joined
Jul 22, 2012
Messages
142
Location
Western Australia
Do I just follow the air lines from the stick to the box? they are all exposed so it shouldn't be a problem. if I find a filter should I pull it off and try to clean it out?
 

Plant Fitter

Senior Member
Joined
Jul 14, 2012
Messages
336
Location
Australia
The air lines from the gear lever will go to a relay valve and then bigger air hoses to the shift units.

I just thought it worth checking as a long shot, before declaring that it is a worn syncro unit and having to pull the back half of the transmission to bits. Its easy and cheap to check the simple things first.

I replaced a syncro unit several years ago on a road ranger in an Izusu truck and I think it cost around $1,000.

Mitch504 sounds like more of a specialist so he might be better for detailed info.

I would be interested if anyone knows of any way of driving to work with a worn out range change syncro, or if it is just not possible.
 

Nick009

Well-Known Member
Joined
Jul 22, 2012
Messages
142
Location
Western Australia
Thanks Plant Fitter, I would be very interested in information like that too.

I will try Mitch's test of moving the stick to neutral without the clutch on Sunday and see what happens.
 

2stickbill

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Nov 1, 2009
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677
Location
Romayor Texas
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Sniffin diesel fumes.
You can open the Range shift cylinder on the back of the tranny it has an O ring on the piston clean it and the cylinder walls.I did this a few times was having the same problems and this cleared it up.
 

Nick009

Well-Known Member
Joined
Jul 22, 2012
Messages
142
Location
Western Australia
Thanks 2stickbill, that sounds very promising. Is this cylinder hard to find? how big is it?

what should I clean it with? Methylated spirits or something like that?
 

mitch504

Senior Member
Joined
Feb 27, 2010
Messages
5,776
Location
Andrews SC
I don't ever remember seeing the filter,lines or cylinder causing a grinding noise, but, I'd sure never say my not remembering something means it couldn't happen.:beatsme Usually, the air system will produce a slow range shift, or none at all.

A quick way to check the air system is to build full air pressure, shut the truck off, put the stick in neutral, and simply flip the range selector back and forth. It should produce a quick, crisp, CLACK, CLACK, back and forth as it shifts. If it has a long lag time, or is mushy sounding, it is a problem in the air shift system.

If you believe you have an air problem, I would first build air pressure, shut the truck off and crawl under it. Listen first for any significant air leaks, then look at and feel the air lines associated with the transmission for crimps and melted spots. I would then wash the filter as it is a more common problem than the cylinder, and is supposed to be done once a year or so as a maintenance item anyway. If the filter is kept clean, it should protect the cylinder. (By the way, you have drained the air tanks since you got the truck, haven't you? If you didn't find 3 drain valves, look for a plug in the bottom of a tank where a valve was removed. Not all trucks have 3 drains, but most do.) Drain the tanks before removing the filter as it can go flying or tear o-rings if you don't.

If you look at the back of the transmission, you will see, usually at the upper right, a 4x4" or so cylinder sticking off the back of the transmission. It should have a bunch of lines connected to it. The air pressure regulator for the trans. is usually on the back cap of the cylinder. If you look at the regulator, you should see a hex plug on the top. It usually takes a 1.5" wrench. Unscrew that plug, and under it you will find a sintered brass filter, about 5/8" x 1.25". Pay attention to which end is up, as the filter is tapered.

I usually moisten a rag w/ some alcohol or light penetrating oil (WD-40 if y'all have that), and wipe out the inside of the filter housing. Then you can wash the filter w/ about anything. I usually put my finger in one end and run some water in the other, it should flow freely. When I find a clogged one, I wash it w/ whatever it takes to get it clean, then wash it w/ soap and water to keep from putting solvents into your air system, where they can harm o-rings.

I would put the filter back and try the test again before removing anything else. If the filter was clogged, you may have to flip the switch 10 or 12 twelve times w/ full air pressure and the stick in neutral to clear things out. If you get a good crisp clack, go drive the truck and see if things have changed.

The cylinder the filter/regulator was mounted on is the cylinder Bill was talking about.

Your transmission may be set up slightly differently, but most roadrangers are set up this way. That's why I wanted the model number, so I could look in a book before giving detailed answers.

Everytime I have heard a grinding noise when shifting ranges one way, but a good shift the other, it has been the synchronizers, but I learn things everyday. Please let us know what you find out.

Oh, by the way, for us flatlanders, it is possible to drive the truck by just never flipping the range selector down unless you are going very slowly. Be glad it is your low range synchronizers, and not the high range ones.

Good Luck,
Mitch
 

Birken Vogt

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Nov 30, 2003
Messages
5,305
Location
Grass Valley, Ca
This answer depends on what sort of gear ratios you have in the transmission and rear end.

We had one truck that would do what I think you are describing, grind horribly on the shift from high to low. It was a 10 speed with a 5.14 rear I think.

The point is, with this truck you typically started off in 4th gear and went immediately to high side so you never really needed to flip back to low while driving. I would just leave it in high range until the truck came almost to a dead stop and flip it to low just before the wheels stopped turning. (If you flipped it to low after stopping sometimes it would not fully engage low resulting in no movement once the light turned green, embarassing.)

This problem is now fixed. I speculate that the transmission may have had the wrong oil in it. I do not think it had any internal work done as I would have known about it, but its possible. We have an outside shop that is good about finding problems as they develop and fixing them for us.

Anyway, just an idea to maybe help you make money and not spend it until you get some more jobs completed.
 

Nick009

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Joined
Jul 22, 2012
Messages
142
Location
Western Australia
Thanks Mitch, sorry I haven't got back out there yet to get the model number. It's now looking like monday when I'll get back to look at it.

There is some very small air leaks so the tanks are usually drained by the morning. These leaks were too quiet to hear in the industrial yard where I bought the truck, I can just hear them ay my relatively quieter house. I've only found the release valve on one of the tanks. Thanks for the tip to drain the tanks first, I wouldn't have thought of that!

From memory it does click up and down in neutral with the truck off,perhaps there was a slight delay. but I will double check on monday.


Birken, I have no idea what sort of gear ratios I have. I know its a 15 speed and in the top gear it only gets up to 80km/h I guess that would be about 50mph. And thanks for the suggestion of making it instead of spending it, that exactly what I need!!
 

Birken Vogt

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If I remember correctly a 15 speed is like a 10 speed except it has an additional deep reduction on it. I reread Mitch's comments and he said the same thing before I did. So it seems to me that with that low of a gear ratio, you could probably easily just avoid shifting from high to low except when barely moving, and save your pennies up for a better repair later, so long as it has the right oil in it now.
 

Hendrik

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Mar 5, 2009
Messages
1,232
Location
Adelaide South Australia
It's been a while since I drove the old school 15 speeds but from memory I used to start in 2 deep and then shift to 2 low, to avoid going into 1st low, which was a bit uncomfortable to get into.
However the shift from 2 deep to 2 low was not 500 revs, more like 800, so if you are goona drive the truck using only deep and high you have to aware that the revs need to be altered when going from 5 deep to 1st high (in other words you want to go from 5th to 11th if you count all the gears) however deep reduction is not another range insofar that you go 1-5 deep and then 1-5 low and then 1-5 high. Deep reduction is more a half range, perhaps think of it in the way that you can shift 1,2,3 deep and then go to low to keep within the 500 rev range.
It's hard to explain in words, far easier to show in truck but going by a vague memory you would need to shift 1-5 deep, rev the guts out of the motor, which is no big deal on the V8's and then drop at least 800 revs to get into 1st high (in order to avoid low range). Going back down is going to be a bit easier, as you can slow the engine right down in 1st high and then give it a fair few revs to get into 5 deep.
This may be of help http://www.roadranger.com/rr/Produc...missions/OtherTransmissions/PCT_308982#tabs-2
 

Hendrik

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Mar 5, 2009
Messages
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Birken, I have no idea what sort of gear ratios I have. I know its a 15 speed and in the top gear it only gets up to 80km/h I guess that would be about 50mph. And thanks for the suggestion of making it instead of spending it, that exactly what I need!!
Far out, this truck must have been set up for some specialised job, like carting bitumen or water cart?
 

mitch504

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Feb 27, 2010
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Andrews SC
I have seen a few dump trucks set up this way, particularly w/ low horsepower engines.

The only problem w/ using the deep reduction as an alternative to low range is that you have to go into low range before you can get into the deep gears.

His original problem is that he can't get into low range while moving in high.
 

Plant Fitter

Senior Member
Joined
Jul 14, 2012
Messages
336
Location
Australia
Far out, this truck must have been set up for some specialised job, like carting bitumen or water cart?

LN8000 with Cat 3208 goes 80km/hr @ about 2400 rpm. LNT8000 is probably similar. 30 years ago, a lot of people were happy going that fast. LNT9000's go a bit faster.
 

Plant Fitter

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Joined
Jul 14, 2012
Messages
336
Location
Australia
Any roadrangers that I have driven, you change gears at 1500 rpm, which works fine if you have an engine which has plenty of power at relatively low rpm. How does a 3208 perform with a roadranger? Really to get any sense out of a 3208 you have to be running between about 1800rpm and 2500rpm. Does that make it hard to change gears? How do you do it? Do you have to run a gear to say 2500rpm and then when you change rev it up to 2000rpm to get the next gear?
 

2stickbill

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Nov 1, 2009
Messages
677
Location
Romayor Texas
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Sniffin diesel fumes.
The cylinder is on the back of tranny.Round has 4 bolts if I remember right.I used a spray cleaner and fine emory cloth.Piston has O ring that can be changed.Cheap fix if this is the problem.
You might want to get some one to show you where this cylinder is.Hard to explain on here.
 
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