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Turning Radius


BIGMAC

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Here's a question for you Mack experts, can you adjust those limiting stops on the front axle to improve turning radius ? I know the purpose of them is to stop the tire from rubbing on the frame but damn I need 3.5 parking lots to turn around, I had a guy turn the wheel all the way till it hit the stops & there not even close to the frame (12") at least...This is on a dump truck with only a 215" wb & 16' dump body, I haul with a guy that has a T-800 Kenworth 228" wb & 18.5' dump body & that baby turns in half the distance as the bull dog

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Here's a question for you Mack experts, can you adjust those limiting stops on the front axle to improve turning radius ? I know the purpose of them is to stop the tire from rubbing on the frame but damn I need 3.5 parking lots to turn around, I had a guy turn the wheel all the way till it hit the stops & there not even close to the frame (12") at least...This is on a dump truck with only a 215" wb & 16' dump body, I haul with a guy that has a T-800 Kenworth 228" wb & 18.5' dump body & that baby turns in half the distance as the bull dog

The turning radius is adjusted with the stop bolts as you said. The purpose of the stops is to stop the wheel from turning and hitting the chassis, however this must occur after the steering gear pressure relief poppets have relieved pressure (otherwise you run the risk of having hydraulic pressure from the steering system acting against the steering levers when they cannot move, resulting in broken and bent steering parts). There should be a minimum of 1" between the tire and any fixed chassis component when adjusted and 1/2" between the tire and any moving chassis components (such as the pitman arm). It sounds like maybe the steering gear has something wrong with it or has been tampered with previously.

"Mebbe I'm too ugly and stupid to give up!"

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How do you relieve the steering gear pressure poppets ?

They will only have to be reset. The procedure for resetting the poppets will depend upon the type of steering gear that you have. You will need to find out the make and model of the gear and then locate the manufacturers service information for that gear. This will need to be done before adjusting the stops, that way the poppets will be pushed to the proper location inside the gear on the first stop to stop turn you make after adjusting the stops.

"Mebbe I'm too ugly and stupid to give up!"

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They will only have to be reset. The procedure for resetting the poppets will depend upon the type of steering gear that you have. You will need to find out the make and model of the gear and then locate the manufacturers service information for that gear. This will need to be done before adjusting the stops, that way the poppets will be pushed to the proper location inside the gear on the first stop to stop turn you make after adjusting the stops.

This true and also some steer gears are self setting meaning you dont play with them after the box is installed unless you replace the screws with a serice tool.I always want to say the axle stops are made to keep the axle pressure off of the steer gear. I have seen many guys remove the axle stops and throw them away but some times a gear failure ocurs. This is not a good thing.I had a driver call me about 2 miles from work and ask me 6o come look at his steering box. It was sitting in a street blocking the road and it would not turn .The bottom of the box was broken out due to no axle stops.

glenn akers

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the pres relief popets are in the end caps of the steering box on the DM, R models, and the RD trucks that i have worked on they take a flat screwdriver to adjust they are 2 of them 1 on top and 1 on bottom of the boxes most times they are a pain in the butt to get to move because of the dirt/road grime will freeze them up if i remember right turn them out to increase wheel turn turn them in to decrease wheel turn. joe

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the pres relief popets are in the end caps of the steering box on the DM, R models, and the RD trucks that i have worked on they take a flat screwdriver to adjust they are 2 of them 1 on top and 1 on bottom of the boxes most times they are a pain in the butt to get to move because of the dirt/road grime will freeze them up if i remember right turn them out to increase wheel turn turn them in to decrease wheel turn. joe

That will be ok as long as you set your axle stops first then set the screws on the steer gear last.

glenn akers

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  • 8 months later...

What is the turning radius, front and back for a mack truck vision 2001 model. i want to build a 3 axle tank trailer for my truck. can anyone tell me asap? thank you

Not sure what you mean here- "front" and "back"? If you give us the wheelbase and maximum front wheel turn angle, we can pretty well calculate the turning radius. As for "rear" turning radius, do you mean off tracking? As for building your own tank trailer, you might run into a ton of legal hassles there- especially if you want to haul hazmat in it.

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Not sure what you mean here- "front" and "back"? If you give us the wheelbase and maximum front wheel turn angle, we can pretty well calculate the turning radius. As for "rear" turning radius, do you mean off tracking? As for building your own tank trailer, you might run into a ton of legal hassles there- especially if you want to haul hazmat in it.

Wheel base for the 460hp is 234 and wheel base for 427hp is 223. I do not have the maximum front wheel turn angle. Please use best guess estimate for this. Yes I mean off tracking for "rear". I am taking exporting the tank trailers to another country. Please reply asap. Thank you

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Wheel base for the 460hp is 234 and wheel base for 427hp is 223. I do not have the maximum front wheel turn angle. Please use best guess estimate for this. Yes I mean off tracking for "rear". I am taking exporting the tank trailers to another country. Please reply asap. Thank you

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Turning radius should be around 40 feet or so, assuming you haven't put super singles on the front to look "tough". To calculate offtracking I'd need to no the radius of the turn. And we're just talking about the truck- we need a whole bunch more info to calculate offtracking, etc. for the trailer. BTW, if you're sending this thing to a country that has offtracking regulations, I suspect they'll have dozens more regulations to comply with too.

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