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This will be my first time doing an alignment with the ELBJs. I read all the posts I could find about the ELBJs affect on caster. Should I just start out with the rear alignment bolts pointing outward and go from there? I haven't messed with caster in a long time. It's always been fine from where it was the first time I actually set it. I don't even remember what it was.
I'm shooting for -3.2 degrees camber at 4.5" pinch weld height up front with a properly depowered rack. She maxxed out at -2.7 with standard ball joints, which was fine when I was driving her to events. Now that I'm trailering her, I wanted to try some more camber.
I’ve found, like others, with a depowered rack the car is a bit easier to drive at low speed with less caster. Reasonably at that camber you’ll have a pretty limited range of caster available without giving up a lot of camber, so I’d aim for your camber targets and then just even up caster left to right while maintaining your camber angles
For what it's worth, I'm running 4.7* of caster with ELBJs, a proper rack depower, 4" front pinch weld height and a 330mm steering wheel. That's the lowest amount of caster I can get out of my car with 3.5* of camber up front.
I honestly can't tell a substantial difference in steering effort at 4.7* vs. the 4* of caster I was able to achieve with the same setup before I installed poly suspension bushings on my car. Obviously lower caster is better up to a point with the depowered rack, but for me and my not-so-strong arms, 4.7* still works fine.
For what it's worth, I'm running 4.7* of caster with ELBJs, a proper rack depower, 4" front pinch weld height and a 330mm steering wheel. That's the lowest amount of caster I can get out of my car with 3.5* of camber up front.
Can you do me a favor and tell me what clock positions your rear (for the FLCA) alignment bolts are at. All I want to know is if I adjust for my desired camber and set the rear bolts for minimum caster and I get some large caster number, that's it. There's no fighting the system.
I am a contractor supporting the DoD. As such, sometimes I have a lot of free time on my hands. I spent yesterday searching for the end of the internet, and learning how to measure caster on a Miata.
Here are the instructions from my SmartCamber Gauge.
This is quoted from a thread in MazdaRacers."Turn wheel 1/2 turn in one direction, measure camber. Turn wheel opposite direction 1 turn (1/2 turn the other way). Measure camber and record difference. Wether you turn out, then in or vice versa only tells you if you have positive or negative caster. Since no new car has been built with negative caster since the early 1970's (bias ply tires) our number is always positive."
I saw a lot of other "formulas", most of which didn't make sense. The two above seem to agree. So, correct me if I'm wrong, the reason turning the wheel half a turn each way works is because it turns the wheel more than 20 degrees, enough to make the multiplier (See the box in the instructions above) close to "1", so there's no multiplication involved. Is that correct?
I've still got a rough alignment in place, but I wanted to check the caster since I've been reading how the ELBJs affect it. The rear alignment bolts are set at the minimum caster position. Here are my numbers.
Camber LF -3.0. RF -2.7. 4.5" pinch weld height.
LF Camber wheel 1/2 turn to the left -1.7. 1/2 turn to the right -3.9. Difference equals the caster, which is 1.2 degrees.
RF Camber wheel 1/2 turn to the left -3.7. 1/2 turn to the right -1.5. Caster is 1.2 degrees.
Is my math correct? Research had me believing I would see some huge number for caster, but I don't. The front tires are sitting on a couple of cellophane WalMart bags each, and turning the wheel on my depowered rack was not difficult, which agrees with the numbers. I did it standing outside the car with one hand.
Just curious, is that with your rear FLCAs set to minimum caster similar to mine in the photos? That caster number seems super low given all the other inputs but there may be factors at play that I'm not considering.
That's a super cool way to measure caster if it works. I'd personally be lost without the use of alignment rack haha.
Just curious, is that with your rear FLCAs set to minimum caster similar to mine in the photos?
Yes.
That's a super cool way to measure caster if it works. I'd personally be lost without the use of alignment rack haha.
I saw a better way. A company made an attachment that screws onto the remaining threads of the upper control arm ball joint. It takes a small digital level. You align it parallel to the frame and read it. Voila.
I'm a retired B-52 Navigator. 1/2 turn of the steering wheel did not look like more than 20 degrees at the tire, so I got out my combat proven protractor. It's just 13 degrees. I laid out a line at 15 degrees and remeasured and recalculated. I'm at about 4.5 degrees of caster, using the instructions in the box above.
I'm an engineer, and I grew tired of reading 6 different ways to measure caster, none of which were in agreement. So when I found a found a formula that seemed to be actually mathematically derived, I decided that was better than whatever approximation people use that involves math a 5th grader could do in their head.
It's pretty simple to use. Set the turn angle you're going to use, then turn one way and measure camber. Turn the other direction, measure camber, put it all in this sheet, and it should spit out your caster value.
At the end of the day though, I'm taking measurements to only 1/10th of a degree and this formula is way overkill for that low level of precision. If you're experimenting with your own alignment, all that really matters is you use a consistent measurement and calculation, that the caster measurement is consistent from side to side, and your own driver feedback.
Have you considered taking it to a shop that does alignments, so you’re not guessing?
If everyone took the easy way out, this site would be called corvette.net. Seems like a discussion worth having based on the number of methods to measure caster that don't agree with each other.
Motorsports alignments aren't cheap. Regular corner tire store alignments aren't that cheap either. It's a lot easier to justify experimenting with my suspension setup when it doesn't involve immediately spending hundreds of dollars every time I want to change something.
It's not that I wasn't sure--I know the instructions provided by SmartCamber work. I was looking for a shortcut, a Miata shortcut. I've reverted back to the written instructions and it's all good.
Going to an alignment shop doesn't just cost money, it costs time. My time is valuable to me.
New question.
After some adjustments, I magically have the front camber at -3.3 on both sides. I calculate 5.6 degrees caster on the left, and 5.4 on the right. I can't get any less on the left.
When I add student ballast in the right seat, will that caster number increase on the right? I don't see how it should for any appreciable amount, but I wanted to ask.
I stated above I was looking for a Miata shortcut for measuring caster. I found that with my NB1 (de) power steering rack (I honestly don't know if the NB2s had a different rack) a 3/4 turn of the steering wheel was spot on at 20 degrees at the tire.
I just drove it for the first time since rebuilding after the crash. Steering is definitely heavier than it was before, but not annoyingly so, and I never got above about 35 mph in my little town. However, there is almost zero self-centering of the steering now. I measured -3.2* camber on both sides, and my calculations gave me 5.4* of caster on both sides. Both of the caster alignment bolts are at the minimum adjustment.
I just drove it for the first time since rebuilding after the crash. Steering is definitely heavier than it was before, but not annoyingly so, and I never got above about 35 mph in my little town. However, there is almost zero self-centering of the steering now. I measured -3.2* camber on both sides, and my calculations gave me 5.4* of caster on both sides. Both of the caster alignment bolts are at the minimum adjustment.
Any words of wit would be greatly appreciated.
You may need to actually measure the caster. I run 2.7 camber up front with ELBJ and 4.5 caster and there is definitely self centering.
01-17-2023, 05:59 AM
First time aligning with ELBJs
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