Ride height factory specs - '86 KC 4x4?

[MaddieCycle]

I am finishing up a suspension refresh and need to set my torsion bars.  I bought this truck basically as a barn find and have little prior history. It has 15 inch rims but non-standard tires, however the diameter of the tires is 28.5 inches, which is pretty close to stock.

The truck sits HIGH off the ground.  I measured 16 inches from the ground to the frame rail, and 19 inches from the ground to the welded body panel seam.  I want to make sure I set the proper ride height to maximize suspension and driveline life, handling, alignment, etc....  The stock bottle jack that came with the truck can not come close to jacking this truck up, when it is fully extended it does not even reach the frame rail.  

 

Did someone previously give this truck a massive raise?  Would explain why the entire front end was shot.  The tension screws for the torsion bars were maxed out.  Does anyone know what the distance from the ground to the frame rail/body seam/other landmark is for a stock 4x4?

[captain720]

Sounds like a 235/75r15? That tire should almost rub at stock height. Do you have blocks in the rear or aftermarket springs? Are there any body lift blocks?

[MaddieCycle]

4 hours ago, captain720 said:

Sounds like a 235/75r15? That tire should almost rub at stock height. Do you have blocks in the rear or aftermarket springs? Are there any body lift blocks?

Actually the tires are in light truck/inch sizes, I forget what they are but it is not in the usual metric format.  Rear looks stock. No body lift blocks.

[captain720]

I always use the rear leafs as my gauge for how tall a truck is. A lot of 720s are "leveled" so the front is raised about an inch. They are also taller than Toyotas just factory. I will try and get a transfer case cage to ground measurement for you later today. A 235/75r15 is almost 29 inches so that seems reasonable. A 720 front end that is leveled will happily live 200k without any work except maybe an alignment so I wouldn't worry about it if it isn't crazy, any amount of lift increases wear and I have all mine normal height but a small torsion lift isn't anything to worry about when done correctly. Just my thoughts, big tires are what really break things and 720 4wds have almost no angle in the drive shaft to begin with so adding some is ok just keep an eye on the slip yoke. If your slip yoke has travel at both extension and squish then you are A OK

[datzenmike]

The proper height adjustment is to adjust the torsion bars using a spirit level held horizontal against the steering stopper bracket and measure up to the lower link spindle center line (this is the front of the LCA in line with the torsion bar behind it) (hope that made sense)

 

4X4

King Cab....1/54" to 1.69

Reg Cab..... 1.73 to 1.89

 

Tire size is irrelevant. This places the truck at the optimal suspension and steering geometry point. If the front end is aligned.

 

[captain720]

I have 9 inches at the lowest point of the transfer case cage and 14 inches at the forwardmost cab mount at the frame rails on a 4wd KC

[captain720]

I have 16 inches at the forward leaf spring mount on the frame rail. 

[MaddieCycle]

Thanks!

[datzenmike]

22 hours ago, captain720 said:

I have 9 inches at the lowest point of the transfer case cage and 14 inches at the forwardmost cab mount at the frame rails on a 4wd KC

 

22 hours ago, captain720 said:

I have 16 inches at the forward leaf spring mount on the frame rail. 

 

If you both don't have the same wheel size this doesn't help. Transfer case skid plates are often bent up also.

[captain720]

1 hour ago, datzenmike said:

 

 

If you both don't have the same wheel size this doesn't help. Transfer case skid plates are often bent up also.

Same size wheel and almost same size tire. 28.5 vs 29 on 15s, and I measured from the only spot on the transfer case cage that hadn't been smashed in by me repeatedly setting the entire truck on it. 

[Madkaw]

I have 7” up front wheel travel and 10” in the rear. I don’t like the look or the ride . 

[datzenmike]

Put 400 pounds in the back and you'll love.

[Madkaw]

10 hours ago, datzenmike said:

Put 400 pounds in the back and you'll love.

I kind of considered making my spare a concrete or steel donut and leave it cranked up under the bed . The weight would be out if the way and I could attach a spare to my roll bar and look cool 😎. 

[captain720]

1 hour ago, Madkaw said:

I kind of considered making my spare a concrete or steel donut and leave it cranked up under the bed . The weight would be out if the way and I could attach a spare to my roll bar and look cool 😎. 

My Gramps used to carry a 40lb sandbag to smooth out his ride. But it was a 92 S10 so it only took 80lbs to put it on the bump stops 😜

[MaddieCycle]

Well I put the torsion bar back in and indexed it per the FSM measurements. I've got the tension bolt tightened up to specs and following FSM procedure.  Measuring using the FSM landmarks (steering stop and LCA pivot) the suspension appears 1-2" too LOW. So now I don't know what is going on. Fatigued bars perhaps? I am going to try and tighten up the tensioner some more.

 

Do people use an impact wrench to tighten the torsion rod tensioner?

[Charlie69]

Are you using 2 wheel drive specs?

[MaddieCycle]

Nope. 4x4

[datzenmike]

18 hours ago, MaddieCycle said:

Well I put the torsion bar back in and indexed it per the FSM measurements. I've got the tension bolt tightened up to specs and following FSM procedure.  Measuring using the FSM landmarks (steering stop and LCA pivot) the suspension appears 1-2" too LOW. So now I don't know what is going on. Fatigued bars perhaps? I am going to try and tighten up the tensioner some more.

 

Do people use an impact wrench to tighten the torsion rod tensioner?

 

Think about it. Even if t bars are made of rubber, if you have the bottom of the steering stop to the center line of the torsion bar vertical distance correct, THAT is the ride height. A soft torsion bar is irrelevant. It will look low if the rear is higher. Most trucks are 'raked' and higher at the back. Makes sense that it will run better if carrying a load.

[MaddieCycle]

well, I stepped away from this project for a few days to try and resent my brain. Just went out and set the height using a level, T square, and ruler and was able to easily get it to FSM specs. So who knows, maybe just needed to take a break. Thanks everyone for your input!

 

The spec for my '86 KC 4x4 is midpoint of the LCA bolt should be 2 - 2.25 inches higher than the bottom of the steering stop on the control arm, not the actual stop bolt on the spindle. I used a 4 foot long carpenter's level and a T square with a ruler while parked on flat ground.  After measuring and finding both sides low, I took weight off the front wheels and then torqued up the bar adjusters with an impact wrench after lubing the threads.  Let the truck down and then backed out the adjusters by half-turns or so then re-measuring until I got both sides within factory spec and within about 1/8 inch of each other. Don't forget to tighten down the jam nuts.  The front end rebuild on this truck was a brutal job and dealing with the torsion bars was by far the most awful part of it.  Truck rides like near new now, though, definitely worth it. Off to the alignment shop.

Edited August 19, 2020 by MaddieCycle