What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

1986 K30 6.2 Diesel Truggy Build - "The Mule"

Overview Gallery Discussion
Quick update. I got my 6 degree shims for the front springs. Picked up some new U bolts as well. Have not had a chance to install them yet. Hopefully next week. Once I get the shims in and the extended brake lines in I will be able to cycle the front suspension and see how much fender I will have to remove.

I did talk to Tom Woods about driveshafts. They agreed one of their superflex U joints would help get a few more degrees out of the front shaft. They also said I should be able to grind the yoke on the axle side to accommodate a few degrees more.

I did grind a bit on the yoke and was able to get rid of the majority of the binding (I was in a pinch and needed my lift bay to do a brake line repair). I was able to move it around now without the fear of ripping the front driveshaft out. I think with the 6 degree shims and the superflex joint I might be ok.

As soon as I get a chance to cycle the rear suspension and measure for a driveshaft I was given the ok to order one. Planning on a 1350 CV with the thicker .120 wall tubing. It will be nice to have rear wheel drive again.
 
So it has been a while. No real progress but I hope to make some tomorrow. Hopefully I will get the 6 degree shims in tomorrow and put the longer brake lines up front. Then move to working on the rear brake lines.

Work has been crazy but is slowing down a bit. I also was distracted by working on a "new" tractor that a family friend gave us (me and my dad collect antique tractors too. This makes 6 yeah we have a problem). It is a 1951 Allis Chalmers WD. Tractor had been sitting for 2 years and needed a new rear rim and tube. Got her tuned up, new manifold gaskets, and a new muffler. Cleaned up nice and runs great we will probably use it to mow pastures.



I also did some late night welding on Nick's (newoldscottsdale77) truck so he could make the Rausch Creek Ride last weekend. Me welding up new rear shock mounting tabs for his shock in boarding. We wanted to get pics of the two trucks together but it did not happen.



 
lloydrage said:
Love this build !!!

Keep it going
Click to expand...

Thanks Lloyd!

Actually made some progress today. Got the pinion shims in and longer brake lines in. Probably will get them bled tomorrow. Also got my rear brake lines all laid out and made a list of what I need to buy. On to the pics.​

So this is what the ORD 6 degree shims look like. (I painted them black)​

​

​

They come with new centering pins. The factory springs had a 0.500" diameter centering pin. The new ORD springs had a 9/16" diameter center pin and I drilled out the spring perches to fit. The centering pins supplied with the shims measured .606" in diameter. I called Chris at ORD and he confirmed this and noted that the Ford axles use larger centering pins and he told me to grind them down to fit.

I devised and excellent way to do this. I chucked the centering pin in my drill and took it over to the bench grinder. I spun the bolt using the drill against the bench grinding wheel and in no time it was the correct 9/16" diameter.

Ground pin on the left, unground in the middle, ORD springs center pin on the right.



Driver's side installed



Passenger's side installed. Note this side uses 2 shims because of the studs in the cast part of the axle.



Used my sweet new Porta-band to trim off the center pins. Bought this last weekend for $65 at a flea market and it works great.



Also installed new U bolts from ORD. Note the fully threaded studs and tall nuts.



Final install with new brake lines. Just need to get them bled out.



Pinion angle looks much better and caster is about 7 or so degrees. Pinion angle issues seems to be solved!
 
So Past few nights after work I finished running the rear brake lines. Started from the coupler right under the rear of the cab. Ran a piece of hard line to the upper link mount. Then a piece of SS flex line to the upper link to a piece of hard line and then to a SS flex T. Then I was able to run the hard line inside of the truss to short pieces of flex to the calipers.



The big braided lines are the fuel lines that need to be tied up.



Wife helped me bleed everything out and they seem to work well. This afternoon I got the tires back on it and for the first time I was able to drive it around the yard with the big tires on it. It rides pretty well. Made a few laps around the yard. With the factory push pull steering I can barely turn left at all because of the lift but the full hydro will solve that.

after a few laps I backed the rear up on a dirt pile.







Note all the flex is in the rear the front has barely moved. I noticed the rear axle seemed to be "steering" left and right as it flexed. Very noticeable in the next few pics.









The front wheels are straight in those pics for reference. The wheel that droops out steers right because the effective length gets shorter. Not the easiest thing to see in the pics but I bet the rear axles is "steering" 10 degrees or so.

I know the lower link mounting points need to be moved down because of the steep angle. Using a 4 link calculator I also get anti-squat numbers of like 200% which is way too high. I was planning on just moving the lower link mount bracket down like 4.5 inches which nets me a 90% anti-squat number.

Is moving the lower mount down going to fix the "rear steer" issue I have? I am afraid I need a longer lower link and then I could move the lower mount forward more.

Any 4 link experts out there? I will post the 4 link calculator numbers later.
 
Last edited:
Ok did some 4 link calculating

Existing 4 link as is



Anti squat is 173%. I roughly figured total travel of 14 inches +/- 7 inches. Using the calculator the pinion angle change sucks from bump to droop (13 degrees!). I then used the calculator to see how far the axles moves. At droop it moves 3.91 inches forward and at bump 2.16 rear ward so at max articulation the axle moves 6.07 inches! Or left wheel at droop moves 3.91 forward and right wheel at bump moves 2.16 back.

I was already planning on moving the lower link frame mounts down to help with the anti squat. So next calculation is moving the lower frame links down 4 inches. (Z lower link frame end)



Anti-squat is now a much more acceptable 92%. Same 14 inch total travel. Pinion angle change is much better at 3.04 degrees. Axle movement dropped almost 2 inches as well to total of 4.35 (2.98 forward, 1.37 backward) so this is better but still not great.

From what I understand the reason for the movement is the fairly steep angle of the links at ride height. Now I understand why the links should be as level as possible at ride height. But to do this the frame end link brackets would be hanging way down. I played around with lengthening the lower links and mounting more forward on the frame but I was only able to reduce the axle movement by a half inch or so.

I am open to suggestions and opinions. Is moving the mounts down going to be enough? Do these numbers seem acceptable?
 
Anti-squat has to do with how the suspension reacts to the torque of the drivetrain, 92% is more like it.

The axle steer that you see is based on the roll axis angle, you ideally want that as close to zero as possible. 22 degrees is crazy high.
 
38377k5 said:
The axle steer that you see is based on the roll axis angle, you ideally want that as close to zero as possible. 22 degrees is crazy high.
Click to expand...

Yeah the guy who built the links clearly did not run any numbers on this setup and now I am sort of stuck. I already was planning on moving my frame side lower link mount down. That will not be hard to do but playing with the calculator it seems like I would have to change the whole setup to bring the roll axis angle down much more.

Do you think I can live with the 16 degrees of roll axis angle? This will be mostly off-road only but I will still tag it and would like to occasionally street it (Think Peterson's Ultimate Adventure or in reality a trip to Home Depot)
 
The problem with roll oversteer is that as the truck leans in a corner, the rear end steers even more. Then that causes the truck to steer more, which means more lean. It can be difficult to drive.

It's already together, I would give it a shot and see what you think.

But unfortunately I think you're in for a re-do on the frame side.
 
So I took the Mule on a field trip today. This was the first time that I hauled it on my trailer with the big tires. It BARELY fits as you can see and it does hang over a bit. I plan to get a bigger trailer soon. Looks good behind my Duramax.







That amount of tire overhang makes me uncomfortable but I was not going far. I took it for a short ride over to my local off-road shop Appalachian Off Road in Westminster MD. I have bought tube and dealt with him before very knowledgeable.

I wanted a second opinion on the 4 link setup. His conclusion was that it is not good. He is going to help me get it straightened out. We will be lowering the frame side lower link mounts and making them longer and moving them further under the frame. Then the upper mounts will be moved lower as well and inboard of the frame.

So we hope to save the axle mounts for the most part but make new frame mounts for the uppers and lowers. Going to be a little bit before we get started but it will happen eventually.

I am going to look at possibly adding a rear sway bar to let the front leaf springs do more work. I need to have a discussion with Currie to see what Antirock bar they recommend for a large truck like mine.
 
I have been working on the rear filler panel where the tail lights and license plate will be. Tail lights are Optronics Glow lights 4". The outer ring is the tail light and the clear center has red LEDs for stop and turn. The top two license plate bolts are LED tag lights. Panel is just clamped there need to get the tabs welded on still.

Pic of running lights lit.



Pic not lit.

 
Man this thing is badddd..

Gonna be awesome when you get the rear links all figured out.


And fyi, I would not be worried about the overhang of your tires on the trailer personally. Over half of the tire is on the trailer. I wouldn't worry.
 
Do you have any better shots of the frame side rear mount area? You could solve a lot of your design issues by getting those mounts lowered. They seem to be unnecessarily high.... But I can't really tell how they are mounted from the pics.

22* of roll oversteer is rediculous. The whole purpose of a linked suspension is to give you precise control over the axle's position under all operating modes (bump, droop and articulation).... Keep working that calculator, there is a better solution than what you've got and it may not even involve too much effort to rework your mounts.

-G
 
Greg72 said:
Do you have any better shots of the frame side rear mount area? You could solve a lot of your design issues by getting those mounts lowered.

-G
Click to expand...

You can see the frame side mounts just behind the cab behind the main hoop. Not the best pic but I will get a better one.



I agree the mounts are too high. I have been working with a guy locally who is knowledgeable on 4 links. The frame mounts will be lowered with the uppers moved inside the frame rails and the lowers beneath the frame and forward. All frame mounts will be moved down like 6 inches. On the axle side the lowers will be moved further outboard for better triangulation. Doing this results in a much more acceptable 7 degrees of oversteer. This is the best scenario we have worked up so far but I am still playing with the calculator.

I am just a little bitter that pretty much all the mounts have to get ground off when a "professional" shop set up the 4 link in the first place.
 
Not a whole lot of progress to report on. Waiting to take truck over to the new shop to re-do the rear 4 link (hopefully end of the month). I did get the rear filler panel finished and mounted on the truck. I also finished all the wiring. I used a flat four trailer connector to make the rear panel removable. I like how it turned out. I still need to mount backup lights some where. I am playing around with adding some more tubing (the blue tape you see).



Nick (newoldscottsdale 77) was over this morning to measure for a new driveshaft on my lift so it was a good time to get some pics of the trucks together. On to the pics!











For reference his truck is sitting on 39.5 Pitbulls and I am on 42s. They are close to the same height and pretty much the same wheelbase. Can't wait to go wheelin but still going to be a while.
 
good looking rigs you guys have there!! i learned all i know about 4 link from building RC cars, before i read the details i saw your links and thought "too steep." glad to see you're figuring it out and making progress. i'd love to have a set of ORD springs, one day maybe. i'm looking forward to seeing those springs broken in and flexing.
 
You must log in or register to reply here.

Latest Posts

Top Bottom