Anybody care to critique my propsed layout before I start welding?

[dennis68]

This is what I came up with, it was the best compromise I thought. The spring frequencies are not correct as I do not have corner weights or an accurate rear rate yet.
I should add that the front came out very nicely, it is accurate.

[Mean 69]

I didn't study the front stuff, but some of the numbers look a bit strange at first glance.

The rear stuff looks pretty good, the LCA's are parallel to the ground, slightly converging in plan view, so your roll axis is neutral/favorable. SVSA is decent, and not too bad on the anti-squat. Something was a bit confusing on the upper link numbers, probably a typo? Looks like it is offset on the differential a bit, but the offset on the front mount looks rather large offset from center (plan view angle), or I might just be looking at the numbers wrong. I like the RRCH, and the PHB is nice and long.

Looks pretty good to me overall, not regarding any of the spring rate stuff which you'll need to tune afterwards anyway (along with a rear sta-bar due to the relatively "large" rear roll moment). I would guess that there is a fair amount of compromise for packaging considerations, as there always is, in particular it looks like you left the LCA's as they came from the factory? I think you'll like this setup more than the factory setup, provided I am interpreting everything correctly (haven't looked at the Perf Trends software in a while). You may want to put some adjustment in the system to play around a bit with anti-squat. I don't know what the weight distribution is like on an El Camino, but I always thought that they were tail-light, in which case a bit more anti-squat at the expense a small amount of roll steer, for instance, may be beneficial to get the power down. Just don't go nuts with regard to short SVSA, or roll axis, especially on the race track.

Just a couple more thoughts. If you are going to weld onto the axle housing, make sure ALL of the grease and gunk is off of it. If you weld to the tubes, you will very most likely need to straighten the housing afterwards for toe and camber, it is not hard and I can offer some pointers if you need them. I had to do that on my setup a few weeks back.

Keep us posted!
Mark

[airrj1]

Dennis,

Sorry I can't offer too much input for you on your numbers. I am still a few months before you on my 3-link knowledge. :rolleyes5 I just wanted to make sure that I read your numbers correct. How does this sound...

LCA - 22.14" long
UCA - 12.21" long
PHB - 40" long
LCA Axle Mount - 8" off GND
- 21.5" from CL
LCA Frame Mount - 8" off GND
- 19" from CL
UCA Axle Mount - 20" off GND
- 4" from CL (to the right?)
UCA Frame Mount - 18" off GND
- 12" from CL (I am guessing this is the typo Mark is speaking of.)
PHB Axle Mount - 10" off GND (left side?)
- 20" from CL
PHB Frame Mount - 9" off GND
- 20" from CL
PHB distance from Axle CL ???

IC 8" from GND and 54" from Axle CL
RRC 9.5" off GND and centered
Anti-squat 88.9%
SVSA 54.2"
Roll Steer % ???

Do I have this right?

BTW I can't wait to see what you build.

[dennis68]

Yeah, those look correct. No typo, the upper link is going to be the OE mount for now. Need to get something going FAST (UCA bushings are totally wasted and this is my daily driver).

I'm going to run a bolt-on PHB mount to the axle for now.

As it sits is the best AS/SVSA compromise I could come up without totally refabbing a new mount, which I will wind up doing later. For now I'm just going to some minor relocating.

Thanks for the input, I'll post pics and ass-o-meter results ASAP.

[airrj1]

Understood. That answers a few questions that I was thinking of.

[Salt Racer]

Personally, I think 54" SVSA may be a bit too short for 116" WB, light-tail Elky. But this is just my gut feeling, and I'm pretty sure it will work just fine on street and twisty short tracks. Like Mark said, build in a lot of adjustability when you build new UCA brackets.
Roll steer is like 0.8% under, so it's good (I see why you shortened up SVSA to raise AS).

Looks like PHB is not level. Is that because you're trying to re-use some existing brackets, or is it just typo? I'd make chassis side infenitely adjustable (slot instead of holes, or use screw adjusters) so that the bar can be leveled in case you change ride height and/or tire diameter later.

Other than that, it looks good to me. Don't worry about ride/roll rate yet. Get the geometry right for now. One thing at a time.


Are you planning to do anything to the front? It could use some improvements.

[dennis68]

PM sent Katz----

[Jagarang]

DUUHHHHhhhhh..... That's all I can offer....maybe if a stronger nucleophile was used in a polar aprotic solvent with a primary substrate...ahhh I regress!

[MrQuick]

Kevin get back the books dude.... he he