Looking to refresh my suspension bushings, but apparently using urethane bushings on the lower rear control arm bushings is a bad idea, as it can lead to binding.

Also, the prices of Mazdaspeed bushings I see online seem rather absurd. Like, $1200 just for the upper rear wishbones? How much are the OEM bushings by comparison?

Do the competition bushings even make that much of a difference? Do the urethane ones?

Could I maybe get away with just changing the lowers and any loose pillowballs?

I imagine the uppers don't make that much of a difference.

Of course, this will only happen if I can actually get my lower control arms off... Damn things won't budge even with an impact wrench. They're not reverse threaded, right? Hahah..

Should also mention this is for a track car.

 

Just curious where you are seeing the $1200 price for the Mazdaspeed upper rear control arm bushings? I did a quick look on Mazda Motorsports and the price of a single F128-28-8C0 part is only about $100, so a full set should run you around $400 max. You can order these directly from Mazda Motorsports, since they are a competition part number, unless Mazda Motorsports is unavailable in your location.

I believe the competition bushings are advertised as 40% stiffer rubber than stock bushings. I don't know if the actual durometer has ever been published for stock bushings to make a direct comparison to polyurethane bushings that have an advertised number.

On my car, I have swapped the rear lower control arm, lower trailing arm, and rear toe link bushings with Mazdaspeed or OEM bushings, since the original were pretty sloppy. I have noticed that the rear end feeling has tightened up noticeably compared to shot bushings, but I don't have any experience with good condition OEM bushings vs new Mazdaspeed bushings.

How much time do you have on track? In my limited experience on track, if the current bushings are in good condition, gains can be made a lot more from grippier tires, dialing in spring rate and damper settings on coilovers and finding ideal sway bar settings, if you have adjustable sway bars and end links, and of course seat time. Swapping out stock bushings for stiffer bushings could help you dial in that last 5-10% if everything else has been maxed out. Maybe someone with more experience can give some more insight on that or has a different opinion.

 

the durometer is published for the competition bushings, so it makes it pretty simple to do the math's.

 

Do you know what they are? I've not been able to find the durometers online or in some of the catalogs I've looked at before, or I just missed them.

 

The prices I found were 25,000 yen per bushing. Which seems crazy high. Maybe they’re cheaper in the US?

I mostly want to do the bushings as maintenance, since they probably haven’t been changed since 1996.. OTOH, I have pillowball toe rods and pillowball front lower arm bushings, so maybe the previous owner actually changed them.

 

Here are the mazda competition bushings for sale on atkins. Also following as I will be doing this job after my clutch job. I'm not sure of the total number of bushings needed but it seems like they they have most of the rear bushings.
Rear toe link inner: https://www.atkinsrotary.com/Race-Pa...28-28-42Y.html
Rear lower control inner: https://www.atkinsrotary.com/Race-Pa...28-28-460.html
Rear trailing link: https://www.atkinsrotary.com/Race-Pa...28-28-52Y.html
Rear upper inner: https://www.atkinsrotary.com/Race-Pa...28-28-8C0.html

 

Also here is what I can find from the mazda motorsports store:

 

I don't know which is which. Are some of these the pillowballs?... I know they're about $80-90 a piece.
Also, the prices I can see in Japan for MC bushings are 3-4 times higher. Weird.

F128-28-460 is about the same price in the US as in Japan. I don't get why MC is so much cheaper.

You can find the durometers of the bushings here: https://www.hirano-tire.co.jp/mazda-s/mazda-12.htm (use Google Translate)

 

Bushes will probably be ok on a car that's been intermittent track use - unless next to an ozone generator. I'd disassemble well before splashing out. The toe control link and those pillow ***** are the usual points of play..

 

It was a street/track car before spending a few years partially disassembled prior to me buying it.

But my money would probably be better spent elsewhere… I know that new pillowballs are actually quite stiff (stiction) and old ones will articulate easily with finger pressure. I’m not sure what the difference between used and bad is though.

I replaced the ones that were obviously bad years ago. The others only have minuscule amounts of free play, if any. It’s kind of like ball joints… borderline cases are hard to diagnose.

I replaced the heim joints on my toe rods years ago and they seem fine still.

I have pillowball front lower bushings, but I don’t really have any issues with the front suspension.

 

Here are my overview when buying them from Atkins two years ago (note: trailing arm is only available in comp)



Here is one of the sheets that contain the most parts numbers both comp and regular, but with pre-corona prices:

 

Mazda Motorsports sells OEM parts at a steep discount to Mazda racers in the US. These prices are not available to the general public / retail. I don't think the program is active in JP so you might be looking at the retail price where you are looking.

 

it depends on the part, but often full retail in Japan is cheaper than Mazda Comp
in 2023 you really need to check both, and add the shipping in, cause that costs a lot a lot

 

I know, but it’s not usually a 70-80% discount.

They're also not quite as strict about race results as they used to. For years, they sent me reminders to submit race results even though I hadn't been in the country...
I can buy from them, but I have to factor in shipping to Japan, which is not cheap, but won't be too bad for someone as expensive and small as bushings.

I think the best option for a track car is SuperPro offset bushings for everything but the rear lower arm and toe links. It also ends up being slightly less money?
Really, labor is the big expense here... maybe I should buy a press. Haha.