Stock Miata autocross alignment specs?

Donnie Barnes · **Posted:** Thu Dec 14, 2006 3:37 pm

Oh, the bigger front bar helps with the trail braking thing, too, I think, because it slows body roll and weight transfer to the outside front which keeps the inside front from locking up as quick.

--Donnie

Eric Peterson · **Joined:** Mon Sep 01, 2003 10:24 am **Posts:** 494

What Donnie & Dick said plus this...

You can drive the car deeper and harder into the corner, once trail braking is complete then you can jump on the throttle hard and the diff will help push/throttle-on rotate you out of the corner...and the bigger bar helps you put the power down. It's very subtle and not always easy to see from outside the car, but once you've seen it done correctly a few times it's easy to understand how it works.

Yes, you can get on the gas even earlier with a smaller bar, but unless you revalve the stock Bilsteins to make them *a lot* stiffer you will be slower with the stock bar. The Wootens ran the stock bar, but did the revalve and their car was wicked fast in really tightt stuff and it was impressive how early they could get on the gas on corner exit. But, it was very loose in transition and a handful to drive according to several folks. It sounds like that may be the setup for you *if* you are willing to get the shocks revalved. But, a bar is usually cheaper and easier to install that a shock revalving. Also, you can always run the RB bar on the softer setting if you want.

The big bar makes the car very controllable and easier to recover whether in transition or in a sweeper. It is truly amazing how hard you can push (or beat) on that car and keep in under you. In fact, my biggest problem has been *not* driving it aggessive or hard enough. When I drive that car angry and hard is when I'm the fastest. When I try to get cute and overly smooth I'm off the pace. Part of that is the great shocks, but an equal chunk is the bar.

The big bar also helps the car slalom quicker...if you stay ahead and stay in the gas the car may slither a lot, but it will generally stay under you. If you plan on driving at or near the limit all the time, then the bigger bar helps keep the car under you and helps to salvage many runs.

It's taken me two years to start to figure out how to drive the silver Miata closer to its potential, but I see the beauty of the setup. Once again, there have been a variety of succssful setups in 1999 Miatas, so there is no one right answer. After watching the class for years, I do think the big bar setup is generally going to be the fastest and most consistant...but, once again we are always talking about tenths of a second. I'd be shocked if you didn't think the car was better with the RB bar after a few events.

I hope that helped muddy the waters for you :-)

Eric

Eric Peterson · **Joined:** Mon Sep 01, 2003 10:24 am **Posts:** 494

Eric Peterson wrote:

What Donnie & Dick said plus this...

You can drive the car deeper and harder into the corner, once trail braking is complete then you can jump on the throttle hard and the diff will help throttle-on rotate you out of the corner...and the bigger bar helps you put the power down. It's very subtle and not always easy to see from outside the car, but once you've seen it done correctly a few times it's easy to understand how it works. The hardest part for me was learning to brake with less pedal pressure, but elongate my braking zone so as to keep the car from pushing on entry...the lighter one brakes with this setup the faster you go.

Yes, you can get on the gas even earlier with a smaller bar, but unless you revalve the stock Bilsteins to make them *a lot* stiffer you will be slower with the stock bar. The Wootens ran the stock bar, but did the revalve and their car was wicked fast in really tightt stuff and it was impressive how early they could get on the gas on corner exit. But, it was very loose in transition and a handful to drive according to several folks. It sounds like that may be the setup for you *if* you are willing to get the shocks revalved. But, a bar is usually cheaper and easier to install that a shock revalving. Also, you can always run the RB bar on the softer setting if you want.

The big bar makes the car very controllable and easier to recover whether in transition or in a sweeper. It is truly amazing how hard you can push (or beat) on that car and keep in under you. In fact, my biggest problem has been *not* driving it aggessive or hard enough. When I drive that car angry and hard is when I'm the fastest. When I try to get cute and overly smooth I'm off the pace. Part of that is the great shocks, but an equal chunk is the bar.

The big bar also helps the car slalom quicker...if you stay ahead and stay in the gas the car may slither a lot, but it will generally stay under you. If you plan on driving at or near the limit all the time, then the bigger bar helps keep the car under you and helps to salvage many runs.

It's taken me two years to start to figure out how to drive the silver Miata closer to its potential, but I see the beauty of the setup. Once again, there have been a variety of succssful setups in 1999 Miatas, so there is no one right answer. After watching the class for years, I do think the big bar setup is generally going to be the fastest and most consistant...but, once again we are always talking about tenths of a second. I'd be shocked if you didn't think the car was better with the RB bar after a few events.

I hope that helped muddy the waters for you :-)

Eric

Donnie Barnes · **Posted:** Thu Dec 14, 2006 11:15 pm

Is there an echo in here?!?

--Donnie

Chuck Frank · **Posted:** Fri Dec 15, 2006 6:52 pm

Whatever you do, if you go for a siffer bar in the front be sure to put on a set of reinforced mounts. When we put on the 1 1/8" bar it destroyed the stock mounts in one event. Went with the ones Mazda sells for spec Miata, pricey even thru Mazdaspeed parts program, but the frame will break before they ever will. Changing the front mounts is legal for stock class on the Miata as long as they are not tied together side to side. We hardly ever ran our Miata after putting on the DAs and big bar, but after the last two events we ran with it, I wish we had. 2nd and 3rd Pax; 3, 4th raw at the Mazda school and we hadn't competed with it in > a year so were not pushing it hard and were on year old SO5s.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Chuck Frank wrote:

Whatever you do, if you go for a siffer bar in the front be sure to put on a set of reinforced mounts. When we put on the 1 1/8" bar it destroyed the stock mounts in one event. Went with the ones Mazda sells for spec Miata, pricey even thru Mazdaspeed parts program, but the frame will break before they ever will. Changing the front mounts is legal for stock class on the Miata as long as they are not tied together side to side. We hardly ever ran our Miata after putting on the DAs and big bar, but after the last two events we ran with it, I wish we had. 2nd and 3rd Pax; 3, 4th raw at the Mazda school and we hadn't competed with it in > a year so were not pushing it hard and were on year old SO5s.

Eric are you running the reinforced mounts?

Dustin Fredrickson · **Posted:** Sat Dec 16, 2006 9:06 am

MikeWhitney wrote:

Chuck Frank wrote:

Whatever you do, if you go for a siffer bar in the front be sure to put on a set of reinforced mounts. When we put on the 1 1/8" bar it destroyed the stock mounts in one event. Went with the ones Mazda sells for spec Miata, pricey even thru Mazdaspeed parts program, but the frame will break before they ever will. Changing the front mounts is legal for stock class on the Miata as long as they are not tied together side to side. We hardly ever ran our Miata after putting on the DAs and big bar, but after the last two events we ran with it, I wish we had. 2nd and 3rd Pax; 3, 4th raw at the Mazda school and we hadn't competed with it in > a year so were not pushing it hard and were on year old SO5s.

Eric are you running the reinforced mounts?

FWIW, I've run the 1" Solid bar full stiff for 2+ years, and don't think I've had mount problems. I DO get a pop on quick transitions, but I think it's a bind due to the end link angles (when run full stiff) combined with bushing compliance in the front suspension pieces.

Donnie Barnes · **Posted:** Sat Dec 16, 2006 11:16 am

Eric's car is running mounts that Telehowski had custom made back before anything else existed. That car went through a couple sets of stock mounts before he had those done. I think Dustin has been fairly lucky, but I know if you go to the bigger bar you won't be lucky for very long.

--Donnie

Eric Peterson · **Joined:** Mon Sep 01, 2003 10:24 am **Posts:** 494

We ran Tim's 10AE the whole season and never had trouble with the mounts, but we were 1) running 205 Kumhos (smaller & less grip than 225 Hoosiers), and 2) had the bar on the soft setting so there was less pressure on the mounts.

Chances are you'd go a good while before the mounts break, but they will break at some point.

Eric

Chuck Frank · **Posted:** Sat Dec 16, 2006 3:27 pm

Dustin Fredrickson wrote:

MikeWhitney wrote:

Chuck Frank wrote:

Whatever you do, if you go for a siffer bar in the front be sure to put on a set of reinforced mounts. When we put on the 1 1/8" bar it destroyed the stock mounts in one event. Went with the ones Mazda sells for spec Miata, pricey even thru Mazdaspeed parts program, but the frame will break before they ever will. Changing the front mounts is legal for stock class on the Miata as long as they are not tied together side to side. We hardly ever ran our Miata after putting on the DAs and big bar, but after the last two events we ran with it, I wish we had. 2nd and 3rd Pax; 3, 4th raw at the Mazda school and we hadn't competed with it in > a year so were not pushing it hard and were on year old SO5s.

Eric are you running the reinforced mounts?

FWIW, I've run the 1" Solid bar full stiff for 2+ years, and don't think I've had mount problems. I DO get a pop on quick transitions, but I think it's a bind due to the end link angles (when run full stiff) combined with bushing compliance in the front suspension pieces.

I too ran the 1" FM solid bar for two seasons without a stock mount failure, then I put on the 1 1/8" hollow bar on the soft setting, and both mounts broke after 1 event.

Dustin, you may want to check your mounts very carefully, I did not have popping with the 1" bar, but I did start getting it with the 1 1/8 bar almost immediately. I knew other Miatas that have popping so I attributed it to the bar itself until the mounts disintegrated. After I changed the mounts I've not had any popping.

Eric, I thought I remembered Tim having to get his mount(s) welded at a national event?

Donnie Barnes · **Posted:** Sat Dec 16, 2006 5:50 pm

IMHO, if you have popping you have metal hitting metal -or- you have binding. Both are bad. Metal hitting metal can happen if your links are too long, too short, or if your bar is shifting side to side (which can also cause the binding problem). Binding can happen if your mount bushings aren't lubed.

The RB bar has no provision to keep it from going side to side, and it's bot bends just outside the mounts, so if it goes sideways much you end up with the bent part of the bar binding in the mount and such. You can buy fancy metal collars that are two piece and can be added inside the mounts to the bar to keep it from going side to side (McMaster Carr has something perfect for this). You can go cheap and just go to an auto parts store and buy some rubber hose with an ID big enough to go around the bar. Cut a 1" or so piece of tube and then split it down one side. Slide over bar and slide to one side. Put a hose clamp on it to hold it in place. Repeat for other side. You have to do this on the inboard side and not the outboard side as there isn't room outboard before the bend.

Popping noises as a result of binding may not *feel* like a problem and *may* not be while on course, but I think it's not a good situation. Keep those mounts lubed regularly and stabilize your bar side to side and you shouldn't have any popping.

--Donnie

Dustin Fredrickson · **Posted:** Sat Dec 16, 2006 9:09 pm

Donnie Barnes wrote:

IMHO, if you have popping you have metal hitting metal -or- you have binding. Both are bad. Metal hitting metal can happen if your links are too long, too short, or if your bar is shifting side to side (which can also cause the binding problem). Binding can happen if your mount bushings aren't lubed.

The RB bar has no provision to keep it from going side to side, and it's bot bends just outside the mounts, so if it goes sideways much you end up with the bent part of the bar binding in the mount and such. You can buy fancy metal collars that are two piece and can be added inside the mounts to the bar to keep it from going side to side (McMaster Carr has something perfect for this). You can go cheap and just go to an auto parts store and buy some rubber hose with an ID big enough to go around the bar. Cut a 1" or so piece of tube and then split it down one side. Slide over bar and slide to one side. Put a hose clamp on it to hold it in place. Repeat for other side. You have to do this on the inboard side and not the outboard side as there isn't room outboard before the bend.

Popping noises as a result of binding may not *feel* like a problem and *may* not be while on course, but I think it's not a good situation. Keep those mounts lubed regularly and stabilize your bar side to side and you shouldn't have any popping.

--Donnie

Good ideas Donnie. I do have a DIY inner-stop on both sides, but a relube and inspection of the setup is in order.

Chuck, per one of our previous discussions on this subject, I have done a pretty close inspection of these mounts from all angles to see if I could find any issues. So far so good.

DickRasmussen · **Posted:** Sat Dec 16, 2006 10:42 pm

In regard to binding in a sway bar linkage:

Way back when (think late 70's) I decided to try hard rubber endlink bushings on the already proven larger than stock front sway bar on my Datsun 260Z. Took the car on a test drive with my normal autocross tires. Experienced sudden loss of front grip in numerous "on the limit" second gear corners where I had never had a problem before. Went home and changed back to the normal rubber bushings. Repeated the test drive. Problem was GONE. My assumption at the time was that the hard rubber bushings caused a BIND rather than just making the bar react sooner.

Dick

Chuck Frank · **Posted:** Sun Dec 17, 2006 1:25 pm

The miata uses a swaybar link with tie rod end type connectors that have a fair amount of range of angular motion. I don't think they can bind within the suspension travel limits. side to side sliding of the bar could possibly cause a rub, but IMHO would not cause a pop. I could not find any signs of any binding or rubbing except minor tire rub on the bar when I removed the bar to replace the mounts. I never used any centering stops on the 1" or the 1 1/8" bar and both bars were well lubed and swung freely in the bushings with the endlinks disconnected. I never had any popping with the 1" bar.

Donnie Barnes · **Posted:** Sun Dec 17, 2006 6:42 pm

Lots of people use lots of different types of endlinks, including using different lengths of links and different joints. There are a ton of different links on the market.

The side to side thing may not have happened to you, but it *does* happen. The reason it causes binding is that the bent part gets into the end of the bushing as it gets compressed and it "grabs" the bushing for a bit and then the pressure gets great enough that it "pops" to a new location. This is why if you look at the bars on a lot of cars in the nationals grid you will see "centering" collars being used.

The noise could also come from one side getting in a bind and then the wheel on the other side compresses and pushes in such a way as to push the bar back out of a bind altogether, but if it is bound up when this happens it "pops" back into place.

As for the type of endlinks, there are a lot of good reasons to switch to something with heim joints, including but not limited to the fact that with the bigger bar you may eventually rip the tabs off the lower control arm that the link attaches to. On the Miata this is an "L" bracket welded on to the control arm. On Eric's car we replaced those L's with U's that a heim joint link fits in between for added strength. Now, I'm not sure that's a concern for folks racing mostly at a local level...remember this particular car has a LOT more autocross time than most folks here will do *and* a LOT more of it was on bumpy concrete than most folks will ever do.

--Donnie

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Stock Miata autocross alignment specs?

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