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I agree. This is totally do-able, but measure twice and cut once. Mock up just seems critical to success. This appears like a weekend, rather than one night project.
The reason that I'm trying to make it an "I have everything lets bolt it on," project is that I have a friend that works at a dealership and his alignment guy has already agreed to align it to anything I want (he sees it as a challenge since I've had a local Firestone tell me "we can't do it."). If I can have everything made so it's a one day R&R operation then I can take it over there some night or a Sunday, the 2 of us can do it on a lift, and then I get it aligned the next day, all done. The problem is that I can't have it incapacitated on a lift the next morning (well my friend would probably say it's OK but I know what management is like over there and I don't want to put him in that position).
Otherwise, it's doing it in my driveway (there isn't even room near the garage, it would mean dragging stuff out about 30' away), where I can do it at my own pace and can make parts to EXACTLY the dimensions I need, but the driveway is steep making it sometimes tricky to work on heavy stuff that needs to be supported, lately I've been getting a lot of attention from the county (like a parking tickets for things like missing front tags), so car disassembled for a few days would be questionable, hood up worse, I lose having a helping hand to help guide the K-member in, and we've been having crazy weather where it's rained at some point almost every day for weeks, usually in the evening/afternoon which would be when I would be most likely to have time to work on it (this kind of thing can make this take weeks...).
This is totally doable, even though front suspensions are more complicated than rear this is nowhere near as big or difficult a project as my plastic gas tank/fuel system/rear axle/rear axle brackets/custom TA... or my top end redo/swap/convert LT1 heads/single plane efi conversion projects which were both done in the same parking space and both took a good part of the summer, but at the time I didn't have the county pressure and I had more time to work on it.
With the stock k-member still bolted up - I would drill a small pilot hole in the rail like I did. That will give you a reference of stock center, once you remove the stock k-member.
Just how you re-adjust the angle put into the UMI spring cup bracket is up to you. Just for knowledge gathering before doing, I would take some thick washers, grind an angle into them, put them between the bracket and k-member, and just see how much re-adjustment can be accomplished. If it gets you there, you could tack weld to bracket for final install. If you don't like it, you haven't wasted much while learning. Once you alter the bracket, there's no going back or have to re-purchase that part.
I'm not sure if I fully understand the washers part, just shimming it at an angle to see if it will fit?
Honestly, with the weight jack I've decided I don't trust the UMI part. Their spring cup is made out of 11ga steel (1/8"), and maybe it holds up to spring pressure fine with the spring pressure spread evenly across a 6" surface and with a round locator lip welded to the middle of it, but with the lip cut off and all the load transferred to the middle of the cup I see this thing flexing in action and bending and finally failing. The new part that I drew up would be made of 3/16" as it's modeled, and I might decide it needs to be 1/4". Either way the "stock" UMI part isn't strong enough and it would be more work making it strong enough than just making a new one.
The bolt through the rail does not have to be perfectly perpendicular - aesthetics only. Casual eyeball is fine.
Oh, I could care less about it being perpendicular. I care about it not poking through the side of the frame rail. Heck, if the engine was out of the car I could handle it poking through the side of the frame rail- I would cut it and then box it so it ended up just as strong, with a little body work you could even make something not perpendicular look good, just not anywhere near as easily with the engine in there.
You still need a plate welded to the spring cup, NOT the frame rail (very weak). Plate will have enough spring force to ensure no vertical movement, but the lateral/side-to-side movement is critical to prevent. That's different if you're wanting to weld a plate to the topmost portion of the spring cup (your blue line). I would suggest cutting down the vertical length of the spring cup (portion with the red X) and weld to the bottom of the remaining cup. That is always the way I've seen it done, but there's always a first.
I never had any intentions of getting the frame rail involved, it's not strong enough for any kind of point load and as far as I'm concerned it's just in the way and can't be significantly weekend at that point because the steering linkage attaches ahead of that point. The vertical portion of the UMI spring cup needs to be cut because it's preventing adjustment range, whether to weld to the top or bottom of the existing cup is up to how much of that range you want to keep and if there is space above the cup. Past that a proper weld on top will be as strong as below, I have 0 concerns over my welds.
The fact is that it's academic, since I don't believe that the UMI spring cup is strong enough to deal with the weight jack in the vertical direction, and I question if it's strong enough at all in the horizontal, specifically front and back where it has a gusset on one side and not the other and in torsion left and right. I believe that the UMI spring cup modified this way would bend and possibly tear. The additional advantage of making my own is that I could always put the originals in and some regular springs...
You seem married to that nut (no, not your wife - nut w/ zirk fitting). I see no benefit, and it's causing you design problem considerations. DSE doesn't use them, and their threads are much, much closer to the elements in the bottom of the a-arm .
I believe that is a failure point in your design, especially if someone is prone to just tinkering with the adjustment and/or runs it dry (I don't believe the zerk is necessary, just convinient)
I don't see any "design problem considerations," besides "can I put a big enough hole in the bottom of the frame rail without hitting the side and do I need to turn the nut down some to make that work."
Why is it a failure point? Well, general design and fabrication rule of thumb is that the tread depth should be at least equal to 1-1.5x the major diameter of the fastener for full thread strength at 70% thread engagement (what most cut and rolled threads have). That plate that you use has about half that at best (I'm guessing that the threaded sleeve welded into it is about 1/2" thick). Mechanical engineers will design as few as 4 threads with steel in steel threads, but in most cases, we're talking about hardened on both sides, and I know that these shafts are of questionable hardness/heat treat and I'm not even sure you have a full 4 threads engagement. Finally, all these ideas assume that you are tightening the fastener down, that there is no play/wobble in the threads, so technically for that to be the case we'd need to add a jamb nut to the assembly, and in that case the shorter the nut the more wobble you'll get and the faster the threads will wear (more movement + more load on each thread).
I don't believe that your setup will fall apart right away, but I don't believe that it will live for 10 years of regular driving also. I don't know how many of our cars are getting used for that kind of driving but I like to build mine so at any time it could be used as an insane daily driver, and occasionally I will drive it in DC Metro traffic for weeks at a time.
Your spring ideas seem fine.
Honestly, I'm thrilled the way that worked out. I'm sure someone is going to give me crap about using used springs, but I don't know of any new ones that will get me as close to perfect and I don't need to worry about the initial sag you get. I suppose that if I have a problem I have a new set of them in a box (Koni badged, Koni used to sell "matched" spring/shock kits with Eibach pro springs in them).
OK, Mark, I didn't mean to question your abilities. If you can do the spindle, you can do this. For those following along/will read in the future; bottom is better.
I, too, have driven my car in Metro DC traffic. Had an alternator fail in the parking lot at Colonial Williamsburg - the things we remember. My dream in '89 when I bought it new was to drive it in all the lower 48 states and on track at Road America - my friends just rolled their eyes, yeah sure. I figured I'd give up on Alaska and Hawaii. One evening while walking down the Champs Elysee, I saw a canary yellow ZR1 Corvette with Hawaii plates drive by (must have been someone in the military)! I have Arkansas, Mississippi, and Louisiana left - Delta trip; and everything north of Yankee stadium - New England trip - to go to finish that dream. While in France, I went down to Monaco and walked the Monaco Grand Prix circuit - that was a good time! I spotted this Ferrari dealer, walked right in the service garage from the street, and took this pic.
i am out of town so i am just reading your thread and trying to remember what everything looks like on my 3rd gens in regards to the stock k member and a arm and the UMI... one thing to keep in mind is as i am thinking about it is to check the relative overall inboard-outboard location of the spring cup, stock vs UMI... i believe UMI may have angled their top spring cup for the reason of better spring alignment to the cup in their a-arm as i am thinking it may be positioned a little more inboard on the top. again i am not measuring anything right now just going by memory and that picture i took of the atomic orange 3rd gen from the top down, ie i would check what you think about the position.
if you are making your own top piece you of course can adjust this if it is an issue.
if you look at my 1988 camaro thread in the engine swap section i think i have a pic of the suspension without the engine in that may give you again a view of the spring alignment
i may be not remembering right, but i am thinking that may be the reason for their angled top
i am out of town so i am just reading your thread and trying to remember what everything looks like on my 3rd gens in regards to the stock k member and a arm and the UMI... one thing to keep in mind is as i am thinking about it is to check the relative overall inboard-outboard location of the spring cup, stock vs UMI... i believe UMI may have angled their top spring cup for the reason of better spring alignment to the cup in their a-arm as i am thinking it may be positioned a little more inboard on the top. again i am not measuring anything right now just going by memory and that picture i took of the atomic orange 3rd gen from the top down, ie i would check what you think about the position.
if you are making your own top piece you of course can adjust this if it is an issue.
if you look at my 1988 camaro thread in the engine swap section i think i have a pic of the suspension without the engine in that may give you again a view of the spring alignment
i may be not remembering right, but i am thinking that may be the reason for their angled top
You have no idea how much time I've spent scouring the pics in your build threads looking for good info in the pics...
I wish so much of your stuff wasn't all black
Without having pieces in front of me to measure, I'm guessing that GM designed their parts with the stock early 3rd gen ride heights in mind (over 28" tall at the fenders) and UMI did their's with the typical somewhat lowered (or sagging) ride height that most people end up with and that the control arm spring pocket is slightly outboard of the cup in the K-member. At least I hope the reason was something like that rather than they outright mistakes I've found in 3 of their products the last few days.
Until this second I was thinking that having that upper spring cup right up against the frame is most likely the best thing, but just had the thought that it not touching and basically suspended between 2 points on the K-member probably has some NVH advantages...
Alan, this pic from one of your build threads makes it look like at least with some droop the angle of the stock UMI spring cup goes counter to where you want it to go (it makes it look like the spring is bowing outward rather that straight):
Assuming that is a pic of the stock K with just one of the weight jacks in it those were just the second most useful pics that I could have gotten (right behind pics of someone having done exactly what I'm thinking of). Thanks!
I think I'll have all the parts I need by this weekend, I'll be able to make what I need within the limitations of the info I have on a similar timeline if I try to, but I talked to my friend that works at a dealership and I can't get access to a lift for probably 2.5 or more weeks (I'm busy this weekend, then he's going on vacation, we've decided that a Sunday would be the best day...). The car is technically driveable in the meantime but it's surprising how badly one blown strut makes it bounce/wallow and the brakes are pulling hard to one side because the hydraulic fluid oiled down the passenger side brake.
If I tear it apart in the driveway and take a gamble with the weather and the county (I've been ticketed 3x this spring/summer at $60-150 all for things that have never been a problem before, I don't think I'll be doing anything breaking their rules but I will be attracting attention with a disassembled car in the driveway), but then I can make the spring pockets to exactly what I find when I test fit things and unless something goes horribly wrong I should have it done well before I would if I wait.
Oh, and look what I found in my parts pile, a set of camber bolts that will fit our struts:
I've always wondered if these could be used to improve steering geometry some. My thought was that if you can increase strut inclination angle (essentially add positive camber) and then get the camber back negative using the strut tower that you can improve scrub radius. Thoughts? Crazy? Will I run out of adjustment at the camber/caster plate? Anyone try this?
Oh, and look what I found in my parts pile, a set of camber bolts that will fit our struts:
I've always wondered if these could be used to improve steering geometry some. My thought was that if you can increase strut inclination angle (essentially add positive camber) and then get the camber back negative using the strut tower that you can improve scrub radius. Thoughts? Crazy? Will I run out of adjustment at the camber/caster plate? Anyone try this?
Yup, they work as described. I haven't used them. DSE uses different slugs in their JRi shocks to accomplish the same thing, but they're made of unobtainium ($$).
Dean had mentioned an idea of his to create an aluminum block (spindle to strut) that would benefit even more. I hope he or someone else does that.
Dean, are you out there?
Alan, this pic from one of your build threads makes it look like at least with some droop the angle of the stock UMI spring cup goes counter to where you want it to go (it makes it look like the spring is bowing outward rather that straight):
i swapped camaros on my lift to try and get some pics to better illustrate... here are a couple pics of the passenger and driver side on a fully assembled camaro sitting fully loaded on the tires. as you can see the spring pockets in the a arm are outward of where the top spring cup is and the umi piece angled outward helps smoothly arc the spring from top to bottom cup
this camaro has just full springs (eibach), no weight jack
Oh, and look what I found in my parts pile, a set of camber bolts that will fit our struts:
I've always wondered if these could be used to improve steering geometry some. My thought was that if you can increase strut inclination angle (essentially add positive camber) and then get the camber back negative using the strut tower that you can improve scrub radius. Thoughts? Crazy? Will I run out of adjustment at the camber/caster plate? Anyone try this?
Older thread I know, but it's relevant to where I'm at on my project
Did you do this with the camber bolts, any issues with gaining the neg camber back?
07-31-2018 | 07:33 PM
