5 degrees of caster on a depowered rack
 

I had my car aligned with the new NB sub-frame last week. I went over all the alignment specs with the shop (TFB Awesome!). We forgot to talk about caster so he set it at 5 degrees. By conventional miataturbo wisdom it should be set at 3.5 degrees. I was surprised to find steering was great and effort was reasonable at 5 degrees. It maybe because I gutted the rack or because the steering wheel is closer to my body than a street car.

Just wanted to share the results. The extra caster helps with camber gain and has great feedback on the track.

5 degrees is the way.

5 works, but the steering has noticeably less effort at 3.5 and is generally less tiring to drive.

No doubt that 3.5 is easier than 5 but I was surprised that I never once thought this is tough on track. I assume the additional leverage from the steering wheel being closer and the properly de-powered rack played a role. From all of the bitching I have read about 5 degrees I was expecting a handful.

You rack that without blowing your bung out again?

THIS


I used about 5* when I had PS. With the "R", and thus a manual box, I started off at 4.5*. A bit stiff to be honest, but not bad. After replacing all the alignment bolts (that's another story) I decided to try out 3.5*. Overall, steering effort is much lower, and low-speed parking can be more easily done with one hand (with the other hand holding open the drivers door, head leaning out the side, lambo-style).


The car feels just as precise as before, just more delicate. YMMV.

Any doesn't downside handling wise to run less than max caster?

Let's talk about the upside of running higher caster numbers. The inverse applies to going the otherway.

Requires less static camber due to better camber gain. Less static camber helps with braking. Returns to on center easier. Jacking effect transfers weight better.

On a "race prepped" track only car you should run as much caster as you can tollerate. I tried 5 degrees by sheer dumb luck. I was expecting the worst. I found it easy to drive. Without a properly depowered rack and good steering wheel position (closer to your body) 5 degrees is likely to much.

I got an alignment today to prepare for TWS in a few weeks and I told the guy to give me as much front camber as possible, and then as much caster without affecting camber. It ended up with -1 degree camber and 6 degrees caster. This is a stock suspension 2001. Is this ok or should I go with something different?

Let's see: you're driving it from New Mexico to College Station, TX, and you're going to participate in NASA HPDE 1. Yeah, -1 camber is fine.

Later, when you're driving faster (on the track), you'll want more than -2 to get full use of the tread during hard cornering.
:2cents:

I have had my car set up at 4.5 degrees almost since I got it. Steering is effortless and the feel is great! I love it and would reccomend it!

BTW my car is a manual steering one. Not sure if anything would change in comparison to a de-powered rack. Does it?

I run 5.5* on a depowered rack. If you run longer stints or do lapping days it may get tiring, but I honestly don't notice it. even we I drove to the track and back.

Shit I just aligned my car after installing NB front subframe and V8R arms. Can't get less than about 6 degrees of caster. I wanted less. I have good upper body strength but dam I Can't see what is off so far.

I just realigned my car last week, 3 times actually. I went from 4* caster on both sides, to 5* on both sides.

After I got the new wheels/tires installed and lowered the car a 1/2in f&r, I found the car overly twitchy on the freeway. Bumping the caster up to 5* completely fixed that and I really don't notice that much extra effort required to steer it.

I ended up with -1.4* camber/+5* caster on both fronts with very slight toe out. Rear was -1.7* camber with factory toe settings.

I'm very happy with the way it handles now. Feels so planted in corners, especially with those new rivals. :party:

I’m considering shimming the upper arm big bolt to adjust some caster. With Delrin or urethane bushings and the right sizes and combination of washers ¼” shift will get almost 2 degrees of caster adjustment. I bet you could fiddle with the caster settings that way without having to re set all the other settings too.

Interesting that the NB subfram increases caster by 1 degree over the NA to stock setting of 5.48 degrees. It does this by shifting the tube the for the upper arm big bolt back further before welding it to the subframe.

I thought 5-5.5* was normal? I've had mine aligned that way for years, though if Sav says 3.5 is better on track, I'd probably take his word for it. Driving to work and lapping are different things.

I run 5.5 on a depowered rack, smaller wheel, etc. It's definitely not difficult on the street. If anything, it'll help to pump up all of you pathetic girly men.

https://encrypted-tbn2.gstatic.com/i...oZ9mUNQs-H6Dlw

double post because my computer is shitty like that.

When the shop aligned it did they zero out the V8R camber adjustment? I know caster/camber affect each other on the stock ecentrics so depending on where the camber bolt is set (stock one) it will affect caster range. In your situation I would use stock adjusters to get ideal caster (5 IMHO) and use the V8R outer camber bolt to obtain ideal camber.

My car is in the weeds with a NB front sub frame and 5 degrees caster is achievable.

Stock lower aft camber bolt is all the way inbord and the forward ones are most of the way outboard. It is pretty much adjusted as little caster is it will get.

FWIW my last setup with the NA-front subframe and stock arms I just told the aignment guy to set all 4 of the front lower adjustments full out and see what it is. the result was 3 degrees of camber and 5.1 caster and that was where I left it.

Bob