140 replies to this topic

[Danica Davison]

3. The mold was broken when the bushings were allowed in the front. DO NOT add a camber rule...

 

You know ... Michael has a point here. If we have an open camber rule ... we can finally convert more of the people from the #cambergang street hoons to join Spec Miata!!!

[ccambern]

Is there an advantage to running -4? I strongly suspect that the answer is yes, at least on some tracks (and Jim seems to agree). Is there an advantage to -3.5 instead of -3? Absolutely. So we have two problems:

 

1. If my subframe won't let me get to -3.5, I need to start swapping parts, or I am at a disadvantage to legal cars.

 

2. If my car can get to -3.5, but the track requires -4, I am at a disadvantage to illegal cars.

 

Problem 1 can be fixed with a stack of parts and a ton of time: not a great solution for a weekend warrior. Problem 2 can be fixed if tech has a complete set of suspension jigs with published dimensions and tolerances for each part and pickup point: not gonna happen.

 

Teching for slotted control arms is easy. Teching for intentionally bent uprights is practically impossible. If -4 is faster, people will find a way to get there. We can eliminate the problem by simply allowing slotted arms. It costs nothing and only takes a few minutes. People aren't going to suddenly start running -6, or even -4.5, because it won't be faster. But people with tweaked subframes (or tubs!) will be able to get the numbers they want. And none of us will have decide if we're willing to bolt on illegal (but non-tech) parts.

 

I'm reasonably certain that some very fast cars are already running intentionally tweaked uprights. I REALLY don't want to do the same and I REALLY don't want to let those cars have an unfair advantage. This is exactly the same problem that led us to allowing offset bushings in the front. I understand the worries about rules creep, but this is honestly a no-brainer for me.

[davew]

I have jigs for all control arms and rear uprights. In fact the rear upright is the easiest to check. Not for sale, yet.

 

I have subframe measuring sticks for sale, have for years. Cheap and will save you lots of time when diagnosing why you can not get the numbers you want.

 

Do you really want to slot an arm to compensate for a damaged part. Personally, I don't want to race on a damaged part for fear it may have more damage than I thought and fail at the wrong moment.

 

Part of the reason we got the offset front bushings (I was against them) was because Mazda did not want us modifying a suspension part. Do you think they will sign off on allowing a modified arm?

 

Collectively we need to decide if ultimate speed is our primary concern? Or is it staying within the written rules? 

 

My opinion for what it is worth, is to stay withing the written rules.  Adding an allowable modification, every time somebody gets caught with their hand in the cookie jar, is not the answer. All control arms must be stock. All subframes must be unmodified. All these are easily checked for really very little money.

 

Just my opinion

Dave

[BNaumann]

I agree modifying stock pieces is a bad idea. I also agree using adjustment to compensate for damage is a bad idea (not to mention your damaged pieces are out of spec even if they are bent in a disadvantageous direction).

I am for rear bushings so we can re-center the adjustment range around numbers we actually use. And extended lower BJs in the front if those have proven durable - I still max out in front with UCA bushings.

[38bfast]

just for a note .05" (under 1/16 of a inch) deviation in anyone of the parts (subframe, A-arm upper, A-arm lower, rear upright, lower outer A-arm bolt) or a combination of them all adding up to .05 is .5 degree of camber. This is why mazda designed in the adjustable cam bolts. Since most want to work on the upper end of the scale of camber now we have cars that can give lots of rear camber and some that won't. The cam bolts our out of their nominal range of adjustment. It is simply manufacturing tolerance stack up of parts. 

 

I don't believe that a sheet metal part (subframe, a-arms) bent .05-.1 is at serious risk of failure. But thats just me. 

[Jim Drago]

I am for rear bushings so we can re-center the adjustment range around numbers we actually use. And extended lower BJs in the front if those have proven durable - I still max out in front with UCA bushings.

what? 

What camber are you running? 

[ccambern]

While I like the idea of equipping tech with jigs as Dave seems to be suggesting (sorry if I'm putting words in your mouth), I don't think it actually solves the problem. These are old cars and they see plenty of contact. If you start measuring suspension components for compliance, you need to build a certain amount of tolerance into the official measurements, or people will get tossed every time they bang wheels. As Ralph pointed out, very small changes yield big differences in camber (I've found the same). Are any of us willing to give tech an "official dimension" with less than 1/16" tolerance? And once you build in tolerance, you're right back to people tweaking parts to hit the maximum. 

 

I'm totally fine with the written rules as long as they are enforced and are genuinely the same for everyone. In this case, they are not. 

 

And for the record, my subframe checks out fine on Dave's subframe checkers

[BNaumann]

what?
What camber are you running?

On MY gauge that looks like this:

https://www.racerpar...r_Camber_Gauges

4.0~4.2. No idea if my gauge is accurate. It's repeatable though. That's why I don't like to tell people numbers. Your gauges may differ.

[Steve Scheifler]

just for a note .05" (under 1/16 of a inch) deviation in anyone of the parts (subframe, A-arm upper, A-arm lower, rear upright, lower outer A-arm bolt) or a combination of them all adding up to .05 is .5 degree of camber. This is why mazda designed in the adjustable cam bolts. Since most want to work on the upper end of the scale of camber now we have cars that can give lots of rear camber and some that won't. The cam bolts our out of their nominal range of adjustment. It is simply manufacturing tolerance stack up of parts.

I don't believe that a sheet metal part (subframe, a-arms) bent .05-.1 is at serious risk of failure. But thats just me.

Thank you, less typing on this damn phone!

But I feel the need to add emphasis, particularly with respect to running damaged parts that might fail. Seriously, that’s the best argument against? These are race cars, many wrecked while they were street cars and wrecked again on the track. We are all responsible for checking damage and integrity of the parts, I hardly think that a very small tweak in the strongest part of the structure is posing a major risk. As for Mazda approving or not, no disrespect to them but why the heck do we care??? If this were any other class it wouldn’t even be raised as an issue. Like any big corporation they are pretty much locked into NO as the only sensible CYA answer, but fortunately they don’t run the club or this class.

Dave, I bought your subframe gauges and like them, recommend them, money well spent for a quick check for large issues, emphasis on large. They are not precision instruments because the parts they measure are not. Unless you have a known good example for comparison it isn’t even clear exactly which reference points to use. I have a brand new rear subframe that is “narrower” than seversl used ones. Does it fail? Beats me, I didn’t bother to install it.

[Jim Drago]

On MY gauge that looks like this:

https://www.racerpar...r_Camber_Gauges

4.0~4.2. No idea if my gauge is accurate. It's repeatable though. That's why I don't like to tell people numbers. Your gauges may differ.

there ya go.. thats way more than you need  No need to be maxing them out there

[BNaumann]

there ya go.. thats way more than you need No need to be maxing them out there

Why not give folks the ability to adjust themselves out of contention?

[Jim Drago]

Why not give folks the ability to adjust themselves out of contention?

It seems like you are.. I am trying to help

[Jim Drago]

1) allow -4 degrees +

2) we need better hubs

3) we need subframe gussets

4) we should be allowed to suare the back up with the fronts...

5) we need new rear hub flanges

6) we need rear subframe gussets

 

then where?

[Michael Novak]

1) allow -4 degrees +

2) we need better hubs

3) we need subframe gussets

4) we should be allowed to suare the back up with the fronts...

5) we need new rear hub flanges

6) we need rear subframe gussets

 

then where?

1. yes

2. No we need hubs that are the same quality as the original hubs.--Replacements are not as good--THAT"S the problem.

3. Maybe or maybe the cars are getting old and the tires are too sticky. and you said there is no problem with the subframes??

4. Yes

5. Same as 2--or old age of the parts---being run too long.

6. Same as 3..

 

see this is easy...

[Bench Racer]

Ok, it's ^ easy.

 

When I attempt to open Runoffs results, lap chart or time cards, neither will open for me. HELP....................  My computer or otherwise?

[Steve Scheifler]

1) allow -4 degrees +
2) we need better hubs
3) we need subframe gussets
4) we should be allowed to suare the back up with the fronts...
5) we need new rear hub flanges
6) we need rear subframe gussets

then where?

Although I suspect his math was faulty, Dan’s point about the small change in lateral forces due to increased camber is close enough to illustrate that nothing being proposed will have a meaningful effect on the failure rate of hubs, subframes etc. even if it all transfers to the much higher instantaneous loads that are more likely doing the damage rather than sustainable cornering Gs. It might play well as a fear tactic but I don’t believe it is actually relevant.

[Jim Drago]

Although I suspect his math was faulty, Dan’s point about the small change in lateral forces due to increased camber is close enough to illustrate that nothing being proposed will have a meaningful effect on the failure rate of hubs, subframes etc. even if it all transfers to the much higher instantaneous loads that are more likely doing the damage rather than sustainable cornering Gs. It might play well as a fear tactic but I don’t believe it is actually relevant.

 

I agree with that.. but that doesnt mean we wont be going there

[Richard Astacio]

It seems like you are.. I am trying to help

[Richard Astacio]

As far as the front offset bushing...I have gone thru 2 sets already...For me they are not lasting more than a year...

[38bfast]

As far as the front offset bushing...I have gone thru 2 sets already...For me they are not lasting more than a year...

 

Drago forgets to put in the sleeves :0