39 replies to this topic

[AW33COM]

What is the best bushing kit for my 90 Spec Miata?

I thought it's going to be simple, but then I found many different sets out there.
I'm looking for the best performing set (front and rear) that is legal in SCCA.

My assumption is every bushing in the arms can be changed and I do not need to buy new arms.
The only things that can not be changed are: tie rods, upper and lower ball joints.

[davew]

Always remember the golden rule of Spec Miata, If the rule book does not specificly say you can, then you can not. Do not assume, it will cost you in the long run

The ONLY allowable bushings are factory oem stock bushings from Mazda.

Dave

[Jim Boemler]

Also, don't go changing the bushings just "because". Most bushings survive nicely, and the old bushings may even have a (miniscule) advantage due to hardening over the years. Unless they're rotted and loose, I'd just leave them alone. Besides, it's an expensive PITA.

[dmathias]

Don't listen to those guys - in this class it's only illegal if you get caught.

[AW33COM]

Always remember the golden rule of Spec Miata, If the rule book does not specificly say you can, then you can not.

Stupid me. Dave, do you sell the kit? I will order shocks from you, so I may as well order the bushings if you have them.

Also, don't go changing the bushings just "because".

- Hm. To be honest I'm doing everything just because. That's why I missed this season and will be ready in about 3 months. I'm a perfectionist. It's hard to drive knowing my bushings are not perfect. All of them look good except lower shock bushing and ball joints.

Besides, this is the part where I do not agree with you. I do not think bushings harden over time. My street cars do not support your theory. Since I'm removing the shocks (again just because) I may as well do it all. I bought a Miata on this forum that was not really taken care off. Good engine and good cage, but the rest I replaced or will replace.

Don't listen to those guys - in this class it's only illegal if you get caught.

- nice, but knowing how slow I am so far it would really feel bad to cheat and come last.

[dstevens]

Schabi do you have a Mazdaspeed account yet? The part #s are in Dave's book or James and MSM knows which ones you will need. IIRC it's around US$160 for the set. I didn't remember correctly, the ones I needed were about $50 total and my build sheet says $309 for the set. The goal in bushings is to have them less pliable over time. In some circle track classed we use steel inserts. That's also why in many classes they allow urethane bushings. In my case the few bushings I did have to replace were more pliable new than the ones I decided to keep.

[AW33COM]

No account at Mazdaspeed, because I could not find any parts on that website and the one I found was super expensive. I use that website only to look up part numbers. If you say it's worth setting an account there I will set it up.

In my case the few bushings I did have to replace were more pliable new than the ones I decided to keep.

- maybe quality changed over the years at the factory.

[Terry Whitlock]

The Mazdaspeed membership application process is outlined on their web site. The discounts that they provide are significant and invaluable to those building/maintaining Mazda race cars. You do not have to have a completed car. If you provide them with a picture of the current car in your build stage and club association, they will give you membership which allows you access to their web site and parts listing. They have a kit that contains all of the control arm bushing (23 If I remember correctly). The savings over dealer prices is significant and this will be true for your other parts purchases.

[dstevens]

No account at Mazdaspeed, because I could not find any parts on that website and the one I found was super expensive. I use that website only to look up part numbers. If you say it's worth setting an account there I will set it up.

- maybe quality changed over the years at the factory.

That ASSuming is costing you money again. Until you sign up you can't see the racer pricing. Like Terry says, that's how you sign up, it's quick and easy and the discounts are steep on most items. There have been a few things that I could get for a bit less at NAPA but by and large everything is priced well (and always far less than dealer) and the service is top notch. Some of the best service I've had in 10 years of racing.

As for the bushing, they're rubber and it hardens over time as it starts to deteriorate. Personally I think bushing rules should be open rubber or urethane as I can get a Energy set for around $120 or so.

Back out to the shop, it's only 102* or so today so I can work for more than a half hour at a time.

[AW33COM]

I did sign up. Waiting verification. Thanks.

[Muda]

Don't listen to those guys - in this class it's only illegal if you get caught.

Shuush, it's called Tech Shed Legal.
But since all the tech sheds in these parts don't do much more than look at weight and on the rare occasion plates, anything goes.

[Jim Boemler]

If you're just starting out, Schabi, take the bushing money and spend it on track time. Trust me, it'll be a long time before you can tell the difference between old and new bushings, and even longer before they'll make a difference in your lap times. Stop worrying it to death, and go drive.

[AW33COM]

If you're just starting out, Schabi, take the bushing money and spend it on track time. Trust me, it'll be a long time before you can tell the difference between old and new bushings, and even longer before they'll make a difference in your lap times. Stop worrying it to death, and go drive.

The problem with that is I started enjoying changing parts and making the car look new as much as I enjoy racing
Btw, what kind of Engineer are you?

[Jim Boemler]

Primarily software -- sorry if it shows. BTW, I've been very much like you, keeping my car as pristine as possible. I really do get it from that standpoint.

And I still think you're wasting your time!

[wreckerboy]

The clown knows of what he speaks. Older, harder, less compliant bushings are what you want. Remember, your OE bushings are designed to locate the suspension, allow articulation, and to minimize NVH issues. NVH is no longer a concern for you (unless you'd really rather be racing Spec Lincoln), so locating the suspension and articulation become key.

For example, when I built my car many years ago I replaced all of the bushings "because" they were 12 years old or so. My car was built from a high miles (240K +) rust-free southern donor, and every bushing I took out of it was both intact and rock hard. I could have saved myself a fair amount of money and time by thinking the process through first. However, if you are determined to replace the bushings anyway, get the Harbor Freight tool which makes the job stoopid simple. I've done complete bushing sets on several cars now, and assuming no delays for bolts frozen in place, it is a quick and easy job with that tool.

[AW33COM]

First things first, I had a feeling you're a software engineer. I was a .NET developer and an architect for about 10 years. Are you at Microsoft?

Back to the topic. I'm going to assume you are correct and I will not change the bushings, even though I always thought brand new cars felt firm due to bushings. Now, I just removed everything in the rear. It turns out the shocks were missing bolts, the brake pistons had missing dust covers, sway bars missing washers and etc.

On top of that my shocks can be compressed using my hands. They feel way to soft comparing to other shocks I tested (Dodge Viper GTS). I think I will replace them as the bottom bushing there is squashed.

I do know about the Harbor Freight tool, but since you say old bushing as good I will use them. BTW, by old bushing I mean someone changed them about 5 years ago when they built their race car. Thanks for that.

[Jim Boemler]

"Old" is five years? Wow, you're in for some recalibration!

Are the shocks you're talking about the spec Bilsteins? If so they should compress by a strong arm, especially pressing down against the floor. I doubt "hand" pressure is enough. Check them against each other -- they should all feel about the same. If any have gone, they surely won't ALL have gone; if they all feel about the same, you're good. Again, it'll be a long time before you'll be able to feel any difference, and the spec shocks hold up quite well.

Sounds like your car got a lot of typical race-car maintenance. It's good you're interested in doing better, but there's still no point in just throwing money at it.

In fairness, this is said by a guy who bought all new screws for the plastic under trays.

No, not Microsoft -- I wish. I worked for IBM for 15 years, and was laid off in January 2009. Very little paid work since then, although I've been working on some automotive (OBDII and logging) projects.

[wreckerboy]

Schabi, I see that you are here in The Garbage State. Are you planning on coming to the race this weekend at NJMP? Sounds like it might be a good time for you to walk around the paddock and ask questions. There are something like 60 Miatae registered between SM, SSM, SM5, and SM2.

[Bruce Wilson]

You want squished lower shock bushings because that gives you more available camber. Test the shocks the way Jim describes or have them dynoed, but you'll probably want to keep them.

bw

[davew]

You want squished lower shock bushings because that gives you more available camber. Test the shocks the way Jim describes or have them dynoed, but you'll probably want to keep them.

bw

What do shock bushings have to do with camber????

What has been said here is correct. All rubber gets harder with age. Just think about old race tires! Since suspension bushings actually twist the rubber, when the rubber gets too hard, it cracks. When it cracks, everything can move out of place, causing some weird handling problems.

How do you know if a bushing is cracked? Take it out. If you take it out, you may as well replace it.

Many people have tested the Mazda Comp harder bushings. With no measurable difference. Except to your wallet !!!

But you decide

Dave