All-Purpose Scout 80 build

MotoDave

Explorer
Sure doesn't look as tall when you're not 3' from it, huh?

Right now the front coilovers are sitting at 7"up/5" down, I designed the 3-link for the reverse (5" up/7" down). The rear is level with the front at that ride height, and I think it'll give me a decent balance between bump compliance and flex in the rocks. With some fender trimming there is room for the axle to move through its full range of travel.

The rear wheel opening is probably going to get enlarged a little more, which will make it look more balanced with the front and give me a bit more room for uptravel. Shooting for 50/50 travel on a 12" shock in the rear.

The rear springs are 56" long Chevy 3/4 ton springs with a few leafs taken out. I am planning to play with adding/removing leafs to get the rate I want. May end up getting a custom spring pack made up for the truck, or my inner nerd may take over and 4 link the rear. Some day.
 

cj7ox

New member
Just came across this thread, and read it through. Great looking rig! Makes me want to get my '64 80 going again. At present it's sitting dejected in the drive with two flat shoes.
 

MotoDave

Explorer
Minor update, nothing terribly exciting.

The rear axle is slightly narrower than the front, so I am running into similar shock mounting issues as I had with the front coilovers. I'd like to package the rear shocks outside of the frame in the wheel well, otherwise I'm severely length limited since I am not going to poke the shocks through the floor.

I spent some time pulling the leaf pack apart so that I can flex things out with just the main leaf in place, to see where the top of the tire really ends up at full stuff.

Wheel well clearance looks OK, I may need to cut a bit more to fit at full bump.
2014-11-02%252015.31.37.jpg

2014-11-02%252015.30.19.jpg


The idea is to try to run the shock behind the axle to see if I can avoid the top of the tire as it moves in under articulation. I should also get rid of what's left of the stock body mount - it looks like it would do some work to the sidewall of a tire :)
2014-11-02%252015.35.43.jpg


Mocked up shock mount, I'll tack all this in place and cycle again to see how it looks.
2014-11-02%252016.36.48.jpg


Backup plan is to run a 10" travel short body Bilstein 7100 shock under the floor. It'll have to be laid back at roughly a 30° angle, which is more than I would like, but is something I can work around if it comes to it.

I've also got all of the TBI sensors mounted, as well as the front accessory drive stuff. I think I have a radiator that will work (Camaro) and have been thinking over how to mount it. Looks like I can work with the stock mechanical fan so I'll stick with that, but I have room to go electric if I want to later on. Starting to think through plumbing and wiring.

Any suggestions for a fuel tank that will fit behind the rear axle? I'd like to find something around 20 gallons that doesn't hang down too far, ideally with an internal fuel pump that will work with the TBI system. My plan is to run the fuel system off of this primary tank, and use the 2 10 gallon saddle tanks as extra capacity for longer trips. They will have a transfer pump system to pump into the main tank.
 

superbuickguy

Explorer
how much space do you have? I built a tank for my Corvette... it was 12x16x29 (IIRC).... the biggest issue in tank building is not so much volume, but useable volume. Most tanks are sloped to the pickup so fuel doesn't slosh too far away - so a tank would, from the side, be 12" tall on the front and 9" on the back with a 12" front to back measurement.... if you can't slope, you lose about 4 gallons of usable capacity because the pickup keeps sucking air.

I've always wondered if using a pivot-style suspension could be made to work on a 4x4.... in other words, put a pivot and run the shock horizontally - and rather than a 50/50 pivot you could use a longer shock and shorter pivot to the axle.... I swear I should ask on Pirate just to spin them up (again)... some days, it's a lot of fun to poke them ;)
 
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KMW-NW

New member
Interesting idea. I bet it would take some experimenting to get the valving right. Seems like having linkage would change the forces.
 

MotoDave

Explorer
how much space do you have? I built a tank for my Corvette... it was 12x16x29 (IIRC).... the biggest issue in tank building is not so much volume, but useable volume. Most tanks are sloped to the pickup so fuel doesn't slosh too far away - so a tank would, from the side, be 12" tall on the front and 9" on the back with a 12" front to back measurement.... if you can't slope, you lose about 4 gallons of usable capacity because the pickup keeps sucking air.

I've always wondered if using a pivot-style suspension could be made to work on a 4x4.... in other words, put a pivot and run the shock horizontally - and rather than a 50/50 pivot you could use a longer shock and shorter pivot to the axle.... I swear I should ask on Pirate just to spin them up (again)... some days, it's a lot of fun to poke them ;)

Interesting idea. I bet it would take some experimenting to get the valving right. Seems like having linkage would change the forces.

You guys are referring to cantilever suspension designs, using a bellcrank with unequal length arms to gain (or reduce) motion ratio.

I've actually designed several before, one for our FSAE car in college, which used a 4" travel shock to get 2" of wheel travel, and one for my old Toyota T100 (which I never built). In a performance car application they are great, they let you package the shock better in terms of weight distribution, and in our case let us use a longer stroke shock for better damping control. The key is they work best when the bellcrank arm is as close to perpendicular to to the pushrod and shock as possible, and they are only consistent if the bellcrank isn't rotating through a large angle. The correct way (in my opinion) to design one is to never let the shock go over 90° to the bellcrank, which becomes a real challenge with a long travel offroad suspension.

If you look at the one commercially available kit for a J**p (that I know of) you can see how the shock is at a severe angle to the bellcrank at ride height, transitioning closer to perpendicular as the suspension bumps - this part is OK, but definitely not ideal. I'd be pretty worried about how much the motion ratio of the shock is changing over the range of travel. It also looks like the pushrod will cycle past 90 degrees, causing a decrease in motion ratio - this is pretty much exactly what not to do, from a lingake design perspective. http://www.fourwheeler.com/how-to/s...ler-evo-lever-suspension-system/photo-21.html

Anyways my conclusion is that I'd want the arms of the bellcrank to be 25-50% longer than the travel of the shock, meaning to fit 12" travel shocks under the scout (or T100) I'd be looking at 18" long arms - not any easier to package than what I'm dealing with now:)
 

superbuickguy

Explorer
You guys are referring to cantilever suspension designs, using a bellcrank with unequal length arms to gain (or reduce) motion ratio.

I've actually designed several before, one for our FSAE car in college, which used a 4" travel shock to get 2" of wheel travel, and one for my old Toyota T100 (which I never built). In a performance car application they are great, they let you package the shock better in terms of weight distribution, and in our case let us use a longer stroke shock for better damping control. The key is they work best when the bellcrank arm is as close to perpendicular to to the pushrod and shock as possible, and they are only consistent if the bellcrank isn't rotating through a large angle. The correct way (in my opinion) to design one is to never let the shock go over 90° to the bellcrank, which becomes a real challenge with a long travel offroad suspension.

If you look at the one commercially available kit for a J**p (that I know of) you can see how the shock is at a severe angle to the bellcrank at ride height, transitioning closer to perpendicular as the suspension bumps - this part is OK, but definitely not ideal. I'd be pretty worried about how much the motion ratio of the shock is changing over the range of travel. It also looks like the pushrod will cycle past 90 degrees, causing a decrease in motion ratio - this is pretty much exactly what not to do, from a lingake design perspective. http://www.fourwheeler.com/how-to/s...ler-evo-lever-suspension-system/photo-21.html

Anyways my conclusion is that I'd want the arms of the bellcrank to be 25-50% longer than the travel of the shock, meaning to fit 12" travel shocks under the scout (or T100) I'd be looking at 18" long arms - not any easier to package than what I'm dealing with now:)

Hmmmm... all I get from that is blah blah blah, I'm not saying no, blah blah blah :D
 

superbuickguy

Explorer
now, with all that said... I'm not just giving you crap.... several hood, hinge designs run the strut through the middle of the triangle to allow the hinge to fold flat when closed... there is little reason why that couldn't become a rear suspension - after all, it's accomplishing the same thing you're trying to do; that is, package a longer travel suspension in a smaller space.
 

MotoDave

Explorer
Ever notice how those hood hinges are easier to move when they're almost closed than when they're open? That's the effect of motion ratio i'm talking about, not ideal for suspension performance.

I'm a suspension dork, its what I studied in school (Mechanical Engineering with emphasis on mechanism design) and its my truck, so I get to be picky about things like this :)

Its also a hell of a lot easier to build normal shock mounts, and I would ideally like to actually drive this truck some time in the near future. But I totally think you should do a cantilever suspension on your H3 :)
 

superbuickguy

Explorer
Ever notice how those hood hinges are easier to move when they're almost closed than when they're open? That's the effect of motion ratio i'm talking about, not ideal for suspension performance.

I'm a suspension dork, its what I studied in school (Mechanical Engineering with emphasis on mechanism design) and its my truck, so I get to be picky about things like this :)

Its also a hell of a lot easier to build normal shock mounts, and I would ideally like to actually drive this truck some time in the near future. But I totally think you should do a cantilever suspension on your H3 :)

can't screw with the H3... it's my DD
 

superbuickguy

Explorer
while I do have a car for each weekday - the H3 has this other plan.... starts with a blown 6.0 LS motor... but that's wayyyyyy down the road.
Plus, I have room for vertical coil overs in the back of mine (see Rod Hall for how that would happen).
 

Ophex

New member
Any suggestions for a fuel tank that will fit behind the rear axle? I'd like to find something around 20 gallons that doesn't hang down too far, ideally with an internal fuel pump that will work with the TBI system. My plan is to run the fuel system off of this primary tank, and use the 2 10 gallon saddle tanks as extra capacity for longer trips. They will have a transfer pump system to pump into the main tank.

There is good info here:
http://www.justih.org/Binder-Bench/showthread.php?t=14082
http://www.binderplanet.com/forums/showthread.php?t=121017&highlight=Fuel+tank&page=2

If you look up the Extreme 4x4 build they went over it.
 

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