Full Chassis Design for S10/Blazer W/ 3Link + PHB & 2WD conversion on 4WD front

[ArtosDracon]

This project has been a long time running, however is currently mostly :bsjerk: and theory, with an emphasis on the former.

The whole design started life as a means to fit Corvette/Camaro wheels on the front of a 2WD S10 without spacers. It slowly evolved into bettering handling at the same time. Originally everything was based on a 2WD S10 front frame, however after a lot of research I found that a 2WD spindle with custom arms and balljoints on a 2WD frame would negate the need for a tall spindle and possibly tall ball joints as well. That gave the added benefit of there being a lot of crap 4WD S10 blazers in AZ.

About that point I thought that while I was at it, I should design a linked suspension for the rear so that I would be able to better account for the handling of the whole truck while designing the front. That led me to Triaged's calculators and (very)eventually to my current 3-Link + PHB design.

With a basis for working on the whole vehicle dynamics I really began to realize just how much of a pig these trucks are, and how high the weight is in them. In researching lowering the COG I found that the trucks are relatively very easy to "stock floor body-drop"; in other words, at some point when designing the trucks GM decided that they weren't truck enough so they raised the body mounts of the frame to make it sit higher without actually changing the floorpan. That will allow for the body to be lowered over the frame ~3" at the cab, and that's nothing to sneeze at. I further found that another .5-.75" can be had by removing the weak stock C-channel frame at the firewall and replacing with 3x3 box, thus leading to a firewall back chassis replacement.

At this point in the design I had done a firewall-back and had to modify the front frame horns to accomodate the stock front end with the lowered cab, so there was about two feet of stock frame rails left and an engine crossmember that had been designed to house a differential that I no longer wanted. :smoke: Well, F-it may as well just make a completely custom frame.

Of course the requisite reccomendations of going with a different front suspension arragenment came up. I'll be the first to admit that sticking to the S10 4WD hard points is hard to justify at this point, but I've got my excuses all lined up, so lets suffice it to say that designing completey from scratch would probably yield better results, but make the whole thing more complicated and ultimately more expensive, so I've ruled it out.

Well, that's essentially where we are today, if you factor in the 100+ hours of designing and calculating done to date. I'm essentially here to introduce my project and hopefully get a few extra sets of eyes on the details of my design. I'm far from an expert but am certainly feeling like I've done a fair job to date of incorporating what I've managed to absorb. I have a full Sketchup 3D model of the chassis thus far as well as a demo of Suspension Analyzer V2.0 that I've been working on. Data sheets from SA2 are attached as images.

ALL CONSTRUCTIVE CRITICISMS HIGHLY WELCOMED.

[silver69camaro]

Can you post a larger image file? Too small to see.

[ArtosDracon]

Huh, just tried twice, the pictures are huge on my computer, must be because they're .pngs, I'll re-encode them as .jpgs and see if it helps.

EDIT: Yup, that fixed them, they're 10x as big file size and viewable size, how odd...

Thanks for looking!

[ArtosDracon]

Well, 100+ views and no comments, so it's picture time. This is the most recent Sketchup model I have of the frame. Wheels specced to 18x10 off the shelf pieces with a 26" tall tire on them on all four corners. Because this thing is so nose heavy and there's not much to be done about it(it's a freakin truck) plans are 275 or 285 up front and 295 out back.

You can get a pretty good view of the whole layout from this one pic, but let me know if you guys want any other information or zoomed pictures. The only thing that I know for sure will be changing is the front anti-roll bar location, it will be getting moved back and use shorter arms, and be thinner. It's currently shown as 1.5", though I found I liked the 1.25" rates better, but with the shorter arms I'm hoping to use a 1" just like the rear, just shorter overall bar and shorter arms will mean stiffer. Both bars have arms with four holes for adjustable stiffness.

The rack is a custom piece I slapped together, I'm going to have to either scrounge for a really short front steer rack(like thats gonna happen) or have one made. I do have the equipment to cut and re-thread the rack shafts, so a junkyard piece is not out of the question at all.

Frame itself is 3x3 box tube, wall thickness to be determined later, likely .1875 or .25, will depend on weights when I get the body mocked up on the stock frame with the driveline and some of the mods.

Any questions or comments highly appreciated.

[ArtosDracon]

Well, I suppose I'm forced to assume that one of two things has taken effect here. I'm either so blatantly F-ed(and long winded to boot) that no one is bothering, or that I'm so good no one can find anything remotely wrong with my design therefore the silence(yeah I'm sure that's it ).

I do appreciate all the views, and since I'm not getting berated, I think I'll keep updating and see if anyone decides to chime in.

I've fixed the design on the front anti-roll bar, it's now using a 1" drilled bar with arms that kick out at 30 degrees, with four holes for adjustability one .75" centers, the 3rd hole out being at 8.5". The front anti-roll bar has been the first major limiting factor for steering to date, and it limits steering to ~25 degrees, which equates to 2.9" at the steering arm, quite reasonable as best I can tell.

I've also finally conquered the steering complexities of trying to adapt a chassis for a different spindle. I did have to move the engine back 3" and up 1.5". I think this is an adequate compromise, I know moving the engine back is relatively minimal, however keeping it as low as possible remains a key goal for the project, and it remains 2.5"+ down from what would be the "stock" location in most swap kits. I've also had to change a hard-point for the first time on the front end, however it is simply moving the front LCA mount rearward approximately 2". On the fortunate side, or rather the only reason I'll accept having to do so, is that the initial design of the LCA was highly offset to the rear, so that this modification will actually just make the arm symmetrical front and rear of the ball joint, and the arm was designed at level front to back, so it will not effect suspension travel in any way. I'm forced to assume that the arm was designed this way to help handle the torque of being 4WD, which it no longer will be.

The steering will require a bump-steer kit to help locate the outer tie rod ends low enough to keep bump-steer to a minimum. I will have to narrow just about any rack I can find for it, but that's far from the worst thing to ever happen and I do have the machining capabilities, so long as I can find a center section small enough to accommodate the overall width I need.

I've also begun to settle on a cage design. I'm currently thinking an 8 point cage, tying into the frame just in front of the coil-over mounts in the front, at the firewall inside the cab, just behind the seat position, and on top of the rear notch, just inside and behind the rear coil-over mount would give me the best compromise of packaging and torsion rigidity to the chassis. The greatest challenge here will be where to do the bolt-through mounts in order to assure the body is still removable if it ever becomes necessary. Current thoughts are at the firewall and at the floorboards, with 1/4" plate, four bolts and a pin(tubular?) internally to remove sheer loads from the bolts.

As always, any input would be highly appreciated. If this amount of chassis design is believed outside the purview of the "Suspension" topic I would be happy to relocate if necessary.

Thanks,

AD