You have to measure the stud diameter where the taper ends/transitions to the full round/non-taper part ( the big end). I was pretty sure the bushing length was the same, but the diameters were different. Someone confirmed that in the DSP thread. It sounds to me like the stud is not fully inserting into the bushing, which is what I reported because of the diameter/taper difference. When you look in from the threaded end side is there a gap between that end of the stud and the bushing?

They weren’t the same on my S1 and it wasn’t the original arm. I swapped it out around 2009/2010 with another new S1 arm from Mazda. Which even Motorsports acknowledges the difference since they’re getting ready to release an S1 specific bushing.

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I'll be throwing these in my car Thursday so I can try some higher camber settings at Crow's this weekend.

https://cimg0.ibsrv.net/gimg/www.rx8...92d05e33fd.png

Aligned car the other day
 

After coilover installation and these ride heights here are the alignment specs that I was able to get out of the car.

Front L R
13 1/8" 13 3/8"
Rear L R
13 3/8" 13 7/8"

https://cimg1.ibsrv.net/gimg/www.rx8...a8d3492eb.jpeg


Front left wheel was at the maximum negative camber setting for the camber adjustment bolt, there was more camber on the table for the right front but I wanted to make everything equal.

OK, so yeah.

s2 (2009) knuckle bushing is 24.51mm tall and the taper hole is 16.52mm at the narrow end. 19.86mm at the wide end. 29.98mm outer diameter.
s1 (2004) knuckle bushing is the same, with a 26.93mm outer diameter.

Mazda mx5 offset bushing is 24.33 tall and the taper hole is 15.86 at the narrow end. 19.86 at the wide end. 30.00mm outer diameter.

So basically, the outer diameter of the mx5 bushing matches the s2 (2009) knuckle, but the taper hole is smaller at the narrow end, meaning the LCA ball joint taper will only make contact at the narrow part and not insert all the way.

I also have some LCAs off what I am told is a 2010 RX-8, and the taper on those is the same as the ones on my 2004 as far as I can tell. 17.12mm at the narrow end, 20.10mm at the wide end. Those measurements are approx 19.0mm apart. (I measured these as low down as I could get without removing the rubber boot).

It doesn’t really matter any more since they just recently released the S1 version, but thanks for following up.

OK, now for the crazy part. The taper on the mazda offset bushings seems to match the taper on my lower control arm studs much more closely than the taper on the bushings in the knuckles. The LCA studs come out to a taper of around 1.9in/ft. The offset bushings 1.98in/ft and the factory bushings around 1.64in/ft.

Using a different calculator and multiple measurements of the studs, I get 9.4 degrees for the offset busing, 7.8 degrees for the factory bushing, and a range of 8.91 to 9.85 for the stud (although seems closer to 9.85).

The stud also inserts to the same depth in both bushings. 18.6mm of thread protrudes out the other side.

So, either I'm going crazy or the oem size is different to the studs? Or the original s1 had a different taper (I replaced mine as the ball joint came apart).

now I am confused, so mx5 offset bushing is not going to fit S2?

Deleted an overly complex and rambling post of confusion. See my next post for some clarity :-)

It will. I just spoke to Mazda Motorsports and confirmed this. 0000-04-5407-NC is a direct fit for the s2.
To fit it to the s1, you need to machine down the outside diameter, or get some s2 knuckles and upper control arms to match those (or otherwise fix the upper control arm bushing taper)
The taper on both s1 and s2 LCAs is the same.

There was actually an issue with the earlier run of bushings that was the source of the confusion (those were cut with a 7-8 degree taper). TeamRX8 reamed his out to fix this, but the new ones I have (0000-04-5407-NC) are already cut to the correct 10 degree taper.

EDIT: Just to add, Mazda Motorsports are awesome. I should have called them earlier!

For anyone who wants the offset bushings now:

https://www.mazdamotorsports.com/201...fset-bushings/

Part No.: 0000-04-5407-NC – 2006-2015 MX-5 & 2009-2011 RX-8
Part No.: 0000-04-5407-R1 – 2004-2008 RX-8
Prices: $75.00

I was told that the set for the series 1 may be on backorder as they only did a small production run not knowing how much demand there would be. But anyone wanting a set should put an order in and they can have more made within a couple weeks (I would still suggest calling if you have a deadline for these).

Trust me, I called everyone possible back in 2017; lol, but I’m glad somebody finally straightened it out

It's possible this was not known at the time. I think they re-measured the stud to create the spec for the more recent revision.

Also, thank you for all the info posted in this thread. Before calling I went back to one of your earlier posts with the ball joint stud measurements and that helped a lot.

It seems like they’re being made by a different supplier now. A rep for the supplier then claimed they just duplicated the MX5 Cup car part, but otherwise didn’t seem aware of any problem. Like I stated before, imo people were likely just installing the part and bolting it up without any consideration on whether there was a fitment issue or not. I’m guilty of the same sometimes, like recently finding out that the RX8P engine mounts result in lowering the engine approx. 1/4” despite the website claiming they maintain the OE engine position. Which could cost someone a championship for certain racing classes. You need to double-check everything to your own satisfaction rather than blindly trust anyone else. That’s a lesson for RaceCar101.

I ordered a set of S1 and S2 bushings just to put on the shelf. At some point these could disappear just like most of the prior SpeedSource parts.

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Ordered 06/15, credit card just charged today, 06/30. Guess they are in and Mazdacomp works on Sundays? :dunno:

No, they would rather eat glass than be there one second more than actual business hours, lol. I’m still waiting on mine to ship that were ordered two weeks ahead of yours.

haven't seen you on the track this year at all, what have you been up to?

They still seem to be on backorder.

Hi to all again,
I finally got time to change my uca bushings with polyurethane offset ones. Before I continue, I must say the OEM bushing are very good quality. Although rubber the metal outer flanges give it that extra stiffness when needed. Felt kinda bad replacing them.
So my problem... Pressed in the polyurethane bushings, then the inner sleeve. Probably do to compressing the bushing it expanded, length wise. So now each bushing is about 2mm longer then the sleeve. The control arm wont even fit in the subframe bracket.
Im considering trimming off some polyurethane?
Is this a common practice?

I think most people just cram them in, but personally I shave down the "ears" of poly bushings until they move with little stiction when fully torqued down. To shave them I used a hand sander.

RE Vision, thats what I did. Shaved like 2mm so bracket contacts the sleeve first. Although when torqued to spec there still is some poly bushing rubbing the bracket. Dont think that will affect control arm movement.

Still awaiting a call-back from a MM rep I talked to yesterday. He was awaiting a call back from the supplier... I've been given two separate "2 weeks out", :/ It's close to 3 weeks from the last "2 weeks out".

MM has gotten a physical notation in their system now, where any service member can see an expectation of this month for fulfillment. He's still going to see if his manager can get any firmer detail. It's not exactly a promise, but getting these in for the Peru Tour does not look like an option.

Ha. Glad I'm not the only one. I was told "2 weeks out" over a month ago, and again told "2 weeks out" last week.

[sarcasm]Probably because they’re made in the USA and there’s likely some conservative western white heterosexual christian male privilege conspiracy issue going on ...[/sarcasm]

:rolleyes:
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Careful. There are plenty of people who would actually believe that, and it would make them happily outrageously outraged.