Bolt on camber/caster adjustment

[RebekahsZ]

Overview of my experiences with adjustable bolt-on front suspension. I did a coilover conversion 10 years ago, but never worked on camber/caster. I had fixed top-hats that were in the stock location for mounting the upper spring perch. Finally got tired of understeer. Installed EMI camber plates last year and love them. As part of my Ls2 swap, I thought I would try to get increased caster. On JohnC's recommendation, installed zccjdm.com RACE-spec TC rods and Techno Toys' adjustable LCAs in order to have spherical-type LCA bearing to avoid bushing bind. Installed RACE-spec TC rods adjusted as short as possible and wheel was in total contact with front fender and airdam. Unstated in John's recommended alignment specs is the understanding that the front fender and airdam will have to be cut (clearanced). Well, I didn't want to do any cutting-so I decided to compromise and just GET AS MUCH CAMBER AND CASTER AS POSSIBLE WITHOUT CUTTING. So, I got zccjdm.com to sell me just the STREET-spec TC rods. They are 2-inches shorter than the RACE-spec rods. Mocked it all up, and put front tires on ramps. Set ride heigth with coilovers, then started pushing front wheels forward until they were as close as I thought reasonable. Turned steering wheel and found angle of tires where clearance was minimal, then readjusted to ensure clearance. Bounced up and down on fender to ensure clearance, then moved jacks to each corner to ensure clearance throughout range of suspension travel. Set second TC rod to same specs. I have street, drag, autox and drift wheel/tire combos - used widest/largest diameter tires when mocking up to avoid having to go thru this again after a tire change. Rotated EMI camber plate bolt holes to trade a little camber in favor of caster (I had 3.5 degrees of camber)-see white lines on photos to judge effect. I think I'm done with front end until I take it to the alignment shop.

 

Photo key: 1-zccjdm.com adjustable TC rods, 2-fender gap w/ stock TC rods, 3-gap w/ RACE TC rods, 4-gap w/ STREET TC rods after adjustment, 5-comparison of STREET and RACE TC rod length, 6-change in camber w/ EMI camber plate with front bolt in max camber hole and back bolt one hole less, 7-change in caster adjustment at camber plate by rotating camber plate, 8-suspension completed and on the ground.

Edited October 31, 2011 by RebekahsZ

[BrandenZ]

Thanks for taking the time to document and post all of this! This is exactly the issue that I'm struggling with currently, wondering how much caster I can get out of the car without cutting up the fenders. I'll be very interested to see how much of a change you were able to get from stock with the combination of the street-spec T/C rods and the EMI camber plates (rotated). Please update this thread in the future once you get your official alignment specs in!

 

Can you describe in a bit more detail the change you made to the camber plate in favor of caster adjustment? Given that I see a swaybar, I assume this is the driver's side of the car. It looks to me like in picture #6 you could actually adjust for more caster (at the T/C rod) than in picture #7. When you say #7 gave you more caster, is that because you ran out of adjustment, and rotating it put you slightly further forward? Again, it seems like if there were adjustment threads left on the T/C rod, that #6 would've allowed you more room to push the wheel out, but perhaps I'm looking at things in the wrong way.

 

Also, when you say you lost camber my rotating the plates a bit, can't you just easily get back to 3.5 degrees by adjusting the LCAs? Or is your goal to keep the LCAs at stock length and ONLY dial in camber at the towers instead?

[JMortensen]

Also, when you say you lost camber my rotating the plates a bit, can't you just easily get back to 3.5 degrees by adjusting the LCAs? Or is your goal to keep the LCAs at stock length and ONLY dial in camber at the towers instead?

You have to be careful when adding length to the control arm because the tie rods aren't that long. Not saying that this would prevent the OP from fixing his problem in this way, just pointing out that there is a pretty limited amount of adjustment before you need to start thinking about longer tie rods.

[BrandenZ]

Interesting. In my particular case I had the opposite problem. I've got a set of Mikelly's adjustable LCAs and T/C rods, and the alignment guy stopped adjusting the LCAs out for camber at near -2 degrees, stating that he was close enough to running out of threads to be uncomfortable going much further, while the adjustment on the T/C rods had to stop because the wheel was pushed into the fender when turned a bit on the passenger side.

 

If it's best to dial in all the camber with the plates, why even bother with adjustable LCAs on the front, then? Is it strictly to prevent binding by going with rodends instead of bushings?

[RebekahsZ]

Yes, that's right. I only went with adjustable LCAs for the spherical bearing. I plan to keep them stock length. The camber shots were taken on opposite sides of the car, so that may be confusing. If you look at the white scribed lines, you will see that I lost about a 1/4" of "push in" at the camber plate in order to gain 1/4" of "push back". The EMI and DP plates have bolt holes pre-drilled in them. If you push them in straight you get just camber adjustment, but if you rotate them, allowing one bolt to be in hole number 4 and one to the be bolt hole #3, it rotates the upper mount back a bit. Really, I don't know if 1/4" is even significant. Drive over from Atlanta some weekend and have a look. I'd put you up and feed you.

[BrandenZ]

Ha. I may take you up on that some time, but I'll admit that I'm way more interested in seeing the LS2 swap bits than the 1/4" of extra caster! Let me know if you get to a point where an extra set of hands would be useful.

 

BTW -- Is there a similar bind issue in the rear? Is it better to use plates for camber adjustment there as well?

[RebekahsZ]

No binding in rear, since you can't adjust caster and don't need to, the rear wheels don't steer. You can adjust camber with aluminum offset bushings, but they transfer a lot of rattling noise into the cabin area-I thought my car was falling apart! I had some and removed them and gave them away. It is funny, as you lower the z, the front loses negative camber and the rear gains some. You get some rear increased neg camber just by lowering. You can use camber plates if you need more than that gained by lowering. I recommend getting your front end sorted out then go race. If you find that you are spinning the car out all the time, then work or rear. The most benefit is gained from fixing up the front end. It might be worthwhile to do something to be able to adjust toe-in in the rear, but it looks like a lot of work. I'm constantly dropping my rear suspension for this or that-I'm chosing to blow off any worry about toe adjustment back there. Last year, the front camber plates made such an improvement, the rear felt twitchy and I had to baby it a lot coming out of turns, but overall the car was much faster and more competitive.

[RebekahsZ]

See bjhines recent build in fabrication thread. He has EMI camber plates and has trimmed his front airdam and has flared fenders. The photos are excellent. From the quality of his build, I would do well to copy anything bjhines does.

Edited November 4, 2011 by RebekahsZ