Fabri-cobbling a Autocross Chevelle

[chevelletiger]

I will keep those companies in mind for sure. I decided to put a LOT more spring in the car front and rear before opening the sway bar can of worms. So I'm going to a 950lb front and a 550lb rear.....I'm almost debating on keeping putting stiffer springs in it til i can back off sway bar stiffness, but I'll have to run another autoX event before I made that decision.

Couple things in regards to 3 link fab stuff:

--I personally would HIGHLY recommend a Ford 9" if you're doing to do a 3 link because the entire axle housing is able to be welded and that alone just opens up the possibilities for all sorts of different mount positions, etc. Because cast iron isn't weldable, mainly though I personally didn't like the idea of bolts holding the control arm mounts in place because they allow some movement. But if you can't do a 9" I get it, FWIW I did initially intended on using the factory 12 bolt ears for a 3rd link bracket back before I scrapped my watts link idea (ended up using it for welding practice after buying the 9 inch).

--I also personally recommend cutting out the factory stamped control arm crossmember and making one out of a universal ladder-bar crossmember, but this obviously depends on your welding capability and confidence. Having the frame out from the car helps but isn't required.

--If you're going to do a 3rd link using the factory ears, I would utilize the torque arm axle mount from the speedtech kit you have (specifically the ring that bolts on the cover flange) and weld reinforcements/triangulation off of that so that the strength will be idiot proof basically

--My rig is a symmetrical 3 link so the 3rd link is centered on the axle side to side, and with the axle at 0 degrees pinion angle the link mount is right on the vertical centerline as well.
I don't recall the exact length but I designed the 3rd link length to be pretty close to as similar length as the side-view length of the stock suspension as I could, 1 or so inches longer because the front mount is pushed toward the floor as forward as possible. I wasn't entirely concerned with the geometry of my setup here because its decently close to factory, I just added a whole lot of vertical adjustment holes on the frame side crossmember to adjust the squat/antisquat characteristics.

The SpeedTech kit I have is for a Ford 9,the thing is I spent so much on the 12bolt with the ring gear set,and tru trac,and I set it up myself I really don't want to waste it.

The upper ear bracket I'm making is 1/4 and press brake formed the same angle as the ears,and will have the holes drilled and reamed for shoulder bolts,that go thru 2 steel bushings that come into the cover side of the ears.
As for welding,I do it for a living,and have about 20yr of experience in conventional lathe and mill work,my old career lol.

Funny,but more me being crazy,I cut out the old upper trailing arm plate mounts and made some adjustable ie extra hole going up on the new mount brackets, per tony g and abc performance,I guess I can never be happy!
I'm just going to make mock up parts.first for this 3 link,but try out what I have now.

The issue I had with the SpeedTech torque arm was even though I made a beefy front mount for it it would still flex if I pushed on it laying on the ground,and how dang heavy it all is,the 3 link seems to weigh less.
Thanks for answering, I post pictures of whatvi come up with.

[chevelletiger]

Picture of the bracket.
I'll have to machine the stepped parts that go into the upper ears too.
I'm not going to cut the crossmember just yet till I get the LS swap done and I'll see how it handles with the abc crossmember mod first.

I get bored so I fabled this up in my spare time,I'll probably make the panhard bar mout too while I'm at it!
The bushingbis from a bmw rear trailing arm,but needed the hole drilled out to .500 was .472. It's 2.250 wide need to machine housings for those also.

Let me know what you think,or if it's a waste,
The way I'm looking at it the aftermarket torque arms,and 3 links Rely on little quarter inch thick welded tabs to the 9 inch housing.

Which isn't that thick either so hey we'll see

[416velle]

Picture of the bracket.
I'll have to machine the stepped parts that go into the upper ears too.
I'm not going to cut the crossmember just yet till I get the LS swap done and I'll see how it handles with the abc crossmember mod first.

I get bored so I fabled this up in my spare time,I'll probably make the panhard bar mout too while I'm at it!
The bushingbis from a bmw rear trailing arm,but needed the hole drilled out to .500 was .472. It's 2.250 wide need to machine housings for those also.

Let me know what you think,or if it's a waste,
The way I'm looking at it the aftermarket torque arms,and 3 links Rely on little quarter inch thick welded tabs to the 9 inch housing.

Which isn't that thick either so hey we'll see

That definitely looks like a pretty beefy setup that won't bend.

The only think I would advise would be to be absolutely sure the bracket wouldn't rotate on the axis of the control arm eye holes under power; I would add some ears off the rear-most part of the bracket and tie them into the top 2 holes of the diff cover. This will make it a little annoying to pop the cover off and service the thing, but theres really no other way to do it without welding to the cast iron.
I could be completely wrong though, some beefy bolts and 90ft/lbs might be enough to keep it there. I'm no engineer, i dropped out of mechanical engineering in college

[416velle]

Found my bracket I made before going Ford 9". Very crude, not the greatest looking, its apparent why I was very happy to get rid of it (though it would've functioned just fine), but this is somewhat what I meant by saying you should have something tie into the diff cover.

Another thing I notice, not sure if that's a soft bushing on your bracket but I would NOT use polyurethane bushings for the 3rd link at all, it should be rod ends/roto joints. A soft bushing would introduce bind into the articulation equation much worse than the factory 4 link. And I say this because I can confirm from experience when the suspension wants to move through bind, it will wear the bushings until there is no bind anymore.
IMO there should be zero soft bushings on the rear suspension at all because "zero bind" is the boasting attribute that a 3 link does better than any other solid axle layout, but if ride quality is a concern then a poly-delrin combo arm SHOULD be used to maximize the benefits of your redesign.

The reason you don't want soft bushings for the 3rd link is because ALL the movement the 3rd link will see during body roll or axle articulation is a side-side motion. I'll try to explain myself as best I can here, bare with me lol

Think of a circle. The axle in this case is a circle. Theres a dot on the left edge, a dot on the right edge, and a dot on the top. Rotate the circle any direction (simulating axle articulation), and the dots on the left/right sides move vertically along the arc, whereas the dot on the top moves entirely horizontal on the arc. That horizontal movement

A polyurethane bushing allows free movement in the same axis as the securing bolt resists movement that's not on the same axis as the bolt, and articulation is NOT on the same axis as the bolts. This is why a rod end-style joint is needed, because it moves freely in all axis' of movement. Especially important with centered 3 link.

[TitanFox]

I really like your coil mounts. I cant decide between mounting on the side of my valve cover versus the firewall.

[416velle]

I really like your coil mounts. I cant decide between mounting on the side of my valve cover versus the firewall.

Thank you! Firewall all the way IMO, it always looks better. Just make sure to mount them straight, if they're not level itll ALWAYS be the first thing you see when you pop the hood lol

[chevelletiger]

That bushingis pretty much a ball joint it's used in bmw rear control arms,and has those rubber boots to keep dirt out my wifes 2020 camaro uses them in the rear toe links also.

detroit speed is using something similar in the mustang front lca.
On there new setup.
The b
ushings are just to hold the whole bracket up,I'll make those slugs out of billet steel.

[416velle]

Gotcha, good good, I'll be interested to follow your build along and see how it turns out!

[chevelletiger]

Gotcha, good good, I'll be interested to follow your build along and see how it turns out!

I appreciate your input, not a bunch of us that fab our own parts.
It will be some time till it's done,but I like making stuff like this in my spare time just like you.
I'm going to try to make the factory crossmember work with this 3 link bracket in case it's a flop and I can switch back to factory.
I'll think it over lol
BTW what state are you in?

[416velle]

I appreciate your input, not a bunch of us that fab our own parts.
It will be some time till it's done,but I like making stuff like this in my spare time just like you.
I'm going to try to make the factory crossmember work with this 3 link bracket in case it's a flop and I can switch back to factory.
I'll think it over lol
BTW what state are you in?

Derek Kiefer has a pretty good 3 link/watts link build in his 69, he used the factory crossmember. Offset 3 link but it its food for thought on ideas. Some pictures of it are post #42

https://www.pro-touring.com/threads/138236-Derek-Kiefer-s-69-Malibu-build/page3?

I’m in Kansas, Salina Region is closest to me but I live almost perfectly splitting the difference between Lincoln NE, Wichita KS, Hutchinson KS, and Kansas City.

I used to live in San Diego California, thats where i blew my motor up at and basically what started the snowball rolling down the hill for completely redoing my car.

[Mtrhd329]

Been watching this for a bit. You should like the results from the 3 link. I made two different setups similar one last builds. One is an offset 3 link which is in the build thread here:

https://www.pro-touring.com/threads/...PER-quot/page7

The other I built an under slung torque arm setup. Both rode and articulated very well. In each the key was the adjustable panhard bar. Being able to drop it way low to get the roll center where I wanted it was key. Frame side was a tube coming straight down and had a slider clamp for adjustment. The rear end side had a slider box similar to a leaf spring slider that the bolt could slide up and down to adjust height. Couple of tube ends and some tube makes the rest of it. Worked very well and is very tunable. I would suggest making the slider tube slightly above the scrub line. If you lose a wheel that becomes your low point.

[416velle]

Been watching this for a bit. You should like the results from the 3 link. I made two different setups similar one last builds. One is an offset 3 link which is in the build thread here:

https://www.pro-touring.com/threads/...PER-quot/page7

The other I built an under slung torque arm setup. Both rode and articulated very well. In each the key was the adjustable panhard bar. Being able to drop it way low to get the roll center where I wanted it was key. Frame side was a tube coming straight down and had a slider clamp for adjustment. The rear end side had a slider box similar to a leaf spring slider that the bolt could slide up and down to adjust height. Couple of tube ends and some tube makes the rest of it. Worked very well and is very tunable. I would suggest making the slider tube slightly above the scrub line. If you lose a wheel that becomes your low point.

Very freakin cool. Took a look at your build thread, its ALWAYS fascinating looking at how people accomplish a similar suspension layout, ESPECIALLY on a different platform.

On a different note, seeing the pictures of your events at Qualcomm gives me happy-sad feelings. It was ahead of my time and I never got to even do drags there before it they closed it, let alone demo-ed it (I'm 24) but EVERYONE i talked to in San Diego area who autocrossed had nothing but good things to say about that venue. Good times tailgating there as well at football games

[Mtrhd329]

Qualcomm was a great venue. The CAM guys were awesome also.

I will keep an eye on your build closely as I'm building a chevelle now also. I went with UMI suspension and a factory LS swap for now as I wrap up the frame off. A little farther down the road will be engine mods and then another 3 link build on this car also. Good luck sir.

[416velle]

Qualcomm was a great venue. The CAM guys were awesome also.

I will keep an eye on your build closely as I'm building a chevelle now also. I went with UMI suspension and a factory LS swap for now as I wrap up the frame off. A little farther down the road will be engine mods and then another 3 link build on this car also. Good luck sir.

Very cool, send your build thread for your chevelle if you have one started!
My only tip of advice for the frame is DEFINITELY box the c-channel portion under the rockers (preferrably with a roll bar if you can), flat-plate box from ABC Performance. The speedtech or HPI kits that add the tube down the center are unnecessary weight additions because they dont tie forward enough to prevent frontal frame flex, just under the firewall. I have video to corroborate this.

[Mtrhd329]

No build thread for the chevelle. I upgraded to a you tube channel.
https://www.youtube.com/@RecycledRacing

I added the speedtech frame brace kit to keep me from caging the car. I had front frame sag also but welding all of the factory seams and a couple triangles helped out a bit. I plan to run two tubes up front from the bottom of the crossmember to where the frame kicks out to the side rails later down the road. Frame is super solid now. A jack anywhere on one side will lift up the car almost level. I lucked out and started with a convertible frame so it was kinda boxed already.

[chevelletiger]

That definitely looks like a pretty beefy setup that won't bend.

The only think I would advise would be to be absolutely sure the bracket wouldn't rotate on the axis of the control arm eye holes under power; I would add some ears off the rear-most part of the bracket and tie them into the top 2 holes of the diff cover. This will make it a little annoying to pop the cover off and service the thing, but theres really no other way to do it without welding to the cast iron.
I could be completely wrong though, some beefy bolts and 90ft/lbs might be enough to keep it there. I'm no engineer, i dropped out of mechanical engineering in college

I spoke with my ex machinist coworker, that also has a mechanical engineering degree.

What he said is the bracket needed a pieces on the forward leading edge that hits on a part of the diff housing that would keep the bracket from rotating forward on acceleration, he said having the bracket mounted to the 2 upper bolts on the cover housing would not do very much,since the forward wheel movement moves those ears down.

[416velle]

FIRST RACE WEEKEND OF 2024 BABY

Off to a start. Decent start but not great. 4 seconds off the fastest time of the day on test and tune day, so that makes me happy. Buuut i ran into some significant issues as a result of pushing the car harder than ever. Off and on missfire at part throttle (clears up at wide open somehow), havent had it tuned properly yet so im not too worried about that. Whats concerning is the axle hop im experiencing on hard braking during a wide sweeping turn. Very dangerous. I played with shock settings enough to conclude with the rear shocks FULL LOOSE, it doesnt do it as bad, and straight line braking its a beast. The signs suggest that i was picking up the rear inside tire, and the clunking the rear diff was making seems to indicate this as well. So im going to play with rear sway bar stiffness and lower the roll center the last 3/4” tomorrow, and if neither of those are joyful then i think i need to back down a spring rate about 50 or 100lbs to a 400. Shame on me for building something one off and expecting it to work perfectly right out of the box! But i built it for adjustability, this is part of the process. Another post soon to come tomorrow with results of the changes!

[416velle]

Might've made a big oopsie.

Got to the event today and after starting the car again for tech, it developed a death rattle. I determined very quickly it is not a main/rod bearing going out because it didn't seize at idle, so i limped it home driving as fast as possible. Got pulled over, begged and pleaded in the guise of "this engine IS a ticking timebomb", and got home. Haven't taken it apart, but I think either a cam bearing is going away or a cam lobe is flat. Theres a LOT of valvetrain noise and slight screech/squeak from the back half of the engine. Unfortunate but that's racing. Haven't dove into it yet, I think the extent I'll look at today is pulling a valve cover and checking valvetrain clearances. Finding out what happened will be easy though, the difficult part will be determining WHY. Because I have a baffled pan, high volume/high pressure oil pump, billet oil dumbbell, the whole shabang. I think this engine is coming out regardless. Deep down, I'm hoping its unrebuildable so I have an excuse to toss an aluminum block in it. But don't tell my wallet that

[chevelletiger]

I actually just pushed out the cam bearings on the ly6 6.0 I'm working on.
I'm going to run the stock crank and pistons,and re ring and bearing it,and throw a stage 2 or 3 cam in it and send it.
Your running a stroker right?
Sorry to hear your having issues with it.