how much camber?

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DavidM938
Posts: 33
Joined: Fri Jul 26, 2013 10:20 am

Re: how much camber?

Post by DavidM938 »

I have a friend and fellow miata racer who is a mechanic at the local mazda dealer. As a "plan B" in case my original shop that did the spring install can't fix this, I asked him about how they do the Mazda TSB, if only so I am not missing any instructions (along with yours) to take to my shop. He tried to look up the TSB, but not knowing what year or model car, he couldn't find it. he asked I could give him the TSB number so he can look it up. Does anyone know more details on the Mazda TSB? thanks to all! David in Nashville
DavidM938
Posts: 33
Joined: Fri Jul 26, 2013 10:20 am

Re: how much camber?

Post by DavidM938 »

Brian, I wanted to commend Ryan's help in getting me prepared for my open track day last Saturday at Nashville Superspeedway. The porterfield RA-1 pads worked great, had to get get OEM replacement rotors at the last minute, but had a great day, hitting around 110 on the high bank Nascar turn 3 and 4 and on through the tri-oval before diving off onto the road course around turn one and two and onto the back straight chicane. Had a great instructor who had his NA spec Miata there too, who showed me how to pass BMW's lol. The next day, ran autocross in Huntsville Alabama. I would think the car is now fully settled on the new Progress springs and those pesky bushings, but here are my measurements when sitting on a flat surface: 13" on ALL locations except right rear which is 13 1/2. My initial thought is that based on what I've seen on this forum, the Progress/Koni combination should have about 1/2" rake, and my problem might be that the left rear is too low? what would cause only one corner to be 1/2" off? When I had the Koni shocks installed last spring, I also installed the FCM sport bumpstops. Do I need to get the ones for lowered cars now, or trim the ones I have? Any ideas on what my next step is? the car seems to drive ok, not doing anything weird, and was really stable at speed on the track, so should I even be trying to correct this? Thanks DavidM Nashville
Brian
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Re: how much camber?

Post by Brian »

Any Miata that usually has just one person in it all the time will tend to be lowest at the corner where that person's weight is located, driver's front. Conversely, highest corner tends to be passenger side rear....opposite of that driver's front corner. Think of your weight in the car as beating down on the bushings daily, it makes that front driver's corner tend to settle faster and lower than the rest, and the back passenger corner will tend to sit higher. Thus, the only way to consistently get all four corners perfect on height is coilovers so you can change and adjust as things settle. Now the irony is that racers will use those coilovers to corner balance the car with the entire car sitting on four scales, one under each wheel, and they will intentionally jack that passenger rear corner higher than the rest to shift weight that direction (like the longer leg of a stool having that corner a bit higher will shift some load onto that corner). In other words, I would not worry about it, having that passenger rear corner slightly higher is helping your weight balance.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
DavidM938
Posts: 33
Joined: Fri Jul 26, 2013 10:20 am

Re: how much camber?

Post by DavidM938 »

brian thanks for helping with that explanation. I do wonder about the bumpstops because especially on bumpy roads the car skitters like it is indeed "on" the bumpstops. the overall ride is a lot more busy than I had expected so do you think I should go with the shorter FCM stops? Again, here is my setup: Yellow Koni shocks, progress spring, progress sway bars, full stiff front, full soft rear, GWR links,FCM 58 sport stops. street tires are Michelin Pilot super sports on the stock rims, auto cross setup is Re-71 on 8" 6ULs. I would like to get it to be a bit more compliant on the street now that the racing season is over here in Tennessee. What would you recommend? thanks for all the help DavidM Nashville
Brian
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Re: how much camber?

Post by Brian »

Yes, you are certainly riding the stops over rough roads with the KONI in there in addition to the lowering springs, and the short stops should indeed cut down on the chatter over rough road sections.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
DavidM938
Posts: 33
Joined: Fri Jul 26, 2013 10:20 am

Re: how much camber?

Post by DavidM938 »

Brian, I wanted to do a follow-up post after my most recent round of tweaks on the suspension. Installed the front FCM lowering bump stops only (did not realize the rears in that kit were the same as the ones I already had previously installed in the Sport kit). Had the car realigned, reset the Progress sway bars to middle hole in front and "soft" in the rear and was able to get 2.4 neg camber up front, 2.2 in rear with a tiny bit of toe out up front (will try that since this is rarely driven on highway except to races). Initially, the car finally sat level side to side with the front at 12 1/2 (!) and the rears 13 1/2. I was worried about that 1" difference front to rear, thought it was a bit strange, but given the issues I've had with the bushings, I thought I was just going to have to live with it. I even posted these heights on this forum to the person asking about Koni/Progress heights in late January. I have since done some spirited drives on some of Tennessee's famous winding country roads, and the car somehow finally "settled". It's now 12 1/2 front (both sides) and 12 3/4 rear both sides! Looks and drives so much better, I'm having to relearn the handling all over again. I'm delighted with the improvement in ride with the proper bump stops, but puzzled why the car seemed to fight me for so many months? March 5th is our first test n tune autocross here, so my question is how to best use a tuning session. Would sway bar adjustments be the first step? Since I'm using the same RE 71Rs and know what pressures are in the ballpark, I want to do the biggest variables first, I would think? Should I plan on going stiffer on the rear bar as my first adjustment? Thanks David Nashville
Brian
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Re: how much camber?

Post by Brian »

For first event I would leave sways alone and see if you can get the balance you want within the range of adjustment of the KONI shocks and perhaps slight variation in tire pressures. If using everything you have with the KONI and tire pressures you have terminal overteer....or understeer....then change the sway settings and start again.

Note your own idea of what is 'balanced' will likely evolve as you drive it more and get more comfortable. Most drivers go from wanting a little 'safe' understeer to wanting more and more tail out behavior as they get more and more comfortable with the car at the limit.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
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