Front end sag with snow plow

Macs Garage

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I have a 1999 K2500 single cab long box 8600#.
It had a snow plow on it when I bought it and I use as a plow truck and daily driver. The truck didn't sag much when I bought it. I have replaced both upper and lower ball joints, tie rods, idler arm and bracket, pitman arm, bearing hubs, brake pads, rotors, and put on Bilstein shocks. I took it in for an alignment and they couldn't get it aligned until they lower the truck adjusting the torsion arms. Rides better and my wife can get in easier. However when I put the plow on it really sags now. I had to raise my plow mounts up all the way, otherwise I had about 4" clearance. I plan on putting about 600# of weight in the back which should help. Question is- are my torsion bars worn out? Would aftermarket torsion keys ruin my alignment? Do I need something like a Timbren installed? The shop I took it to warned me they had to lower it. I should go talk to them, but I am not sure I trust them. Small town and only one that does alignments.
 

thinger2

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Ask them if they set the "Z Height" before they tried to align it.
That is a measurement between the lower control arm and the upper pivot in relation to the steering components.
That really needs to be set before they align it.
Look it up so you understand the basic concept.
Then go back to the shop in person and look the guy right in the eyeballs and ask him if he set the Z height first.
If he looks at you all shifty like?
Chances are he doesnt even know what that is.
I know youre kinda stuck because you only have one alignment shop in town.
But I will only take mine to a couple of different 4 wheel drive speciality shops.
It is more expensive for sure but not when you compare it to tire life and driveability.
Adjusting a gmt400 to compensate for weight distribution takes a little bit of screwing around to get it right but it can be done.
They even put sandbags on the drivers floor to compensate for my sasquatch size when they do it.
Basically, once youve replaced a bunch of front end components, they need to start from scratch and set it up properly.
I would take a drive elsewhere to have it done.
If you live in a land so cold that you need a snowplow
Somebody somewhere has a business that sets up snowplows
 

Supercharged111

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My dad bought a 92 K2500 8600# GVW a long time ago. The PO had run a snow plow, but removed it before my dad got it. The front end was cranked up pretty good on it, PO indicated that it was that way because with the plow the nose sagged too much. Every truck my dad hung a plow on sagged the front pretty good. Measure the fender height and put some crank back in those bars. You can always lower it back down in the Spring.
 

Schurkey

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Playing up 'n' down with the torsion bars will also affect toe, not to mention camber and caster. Nobody wants to have the vehicle aligned twice a year; or for that matter, re-set the torsion bar anchors.

I have a '97 K2500 8600GVW, with a Poly V-plow. It absolutely drops the front end when I lift the plow; and (with or) without the plow the truck doesn't ride as nice as my K1500--but I expected that.

I bought the truck with the plow on it--which is why I bought the truck. I found the installation manual on-line; there's instructions for how to set the mount height correctly. Might be worth checking out.

There's also the possibility of adding front overload springs on the shocks. Add some compression to the overload springs for Plow-Time, reduce the compression when the plow is removed. I haven't felt the need for this on my truck, but perhaps you would benefit. Be sure the diameter of your shocks is suitable for the springs and hardware in the kit.

www.oreillyauto.com/detail/c/rideeffex/accessories/truck---towing/trailer---towing/trailer-accessories/spring-helpers---shock-extenders/b3ec48504439/superior-rideeffex-load-control-springs/spr4/140490

 

Supercharged111

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Playing up 'n' down with the torsion bars will also affect toe, not to mention camber and caster. Nobody wants to have the vehicle aligned twice a year; or for that matter, re-set the torsion bar anchors.

I have a '97 K2500 8600GVW, with a Poly V-plow. It absolutely drops the front end when I lift the plow; and (with or) without the plow the truck doesn't ride as nice as my K1500--but I expected that.

I bought the truck with the plow on it--which is why I bought the truck. I found the installation manual on-line; there's instructions for how to set the mount height correctly. Might be worth checking out.

There's also the possibility of adding front overload springs on the shocks. Add some compression to the overload springs for Plow-Time, reduce the compression when the plow is removed. I haven't felt the need for this on my truck, but perhaps you would benefit. Be sure the diameter of your shocks is suitable for the springs and hardware in the kit.

www.oreillyauto.com/detail/c/rideeffex/accessories/truck---towing/trailer---towing/trailer-accessories/spring-helpers---shock-extenders/b3ec48504439/superior-rideeffex-load-control-springs/spr4/140490


If he had it aligned with no plow and he hangs a plow, his toe is off anyway.
 

Nad_Yvalhosert

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The issue is the ride height, right? So, OP... what do you want? Decent ride height when carrying the plow? Or correct ride height, sacrificing carry height?
 

Nad_Yvalhosert

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Here's the expectation: EVERY truck is gonna be nose low when carrying a snow plow. You cant have it any other way.

Cranking the torsion bars will affect caster mainly. Caster does not affect tire wear. Yes, toe is affected, depending on how much drop you encounter.
So how heavy is your plow, and how much of the winter do you have the plow on?
If you put on 3k miles all winter long, and 200 with the plow on, then set to factory spec.
If you put on 3k miles all winter long, and 2000 with the plow on, then set it to the positive (toe-in) end of the spec.

Here's my experience: 3/4 ton bars on my Yukon Denali. Western Unimount is already on, and will be till March. I cranked the bars, I leave them cranked. Caster is set as high as I can.
Camber is factory spec.
Lastly, I'm toed-out from spec (should be .24, I'm at .10)

Tires seem to wear well and that's what means most to me.
 
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Nad_Yvalhosert

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If they lowered the ride height, your bars are fine. (If they had to crank them to max, and it's still too low, then they're worn out)
Torsion keys will allow higher ride height without a harsher ride.
Timbren are good, got them on my Denali. Though they never touch, my bars are cranked too high.

Here's a dumb question. Did the "one and only alignment shop in town" remove the knockouts?
 
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Macs Garage

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Thank you all for your help. I don't think it would fit on the alignment rack with the plow on. I try not to take it out of town with the plow on, so most of my miles are with the plow off. I am going to put some weight in the box this weekend and see how it sits then. I guess I could accept it as is, raise the bars in the winter and lower in the summer, or invest in some Timbren bump stops. Thanks again!
 
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