Be curious to see how the mild steel or stainless works out. I went with 4340 much stronger and easier to machine than stainless came with a turned and cold finished surface like a hydraulic ram shaft. it was about $80 taxed and shipped for a 4' stick of 3/4" and a 10-12" random cut of 7/8" from Online metals. It's 4 hours or more worth of machinist time for a 1-off set is where the big cost is.

My lathe guy can only drill in 1/2" increments so I had to buy my stock as 4130 DOM tube with the ID as close to optimal as possible. I found hardened round shim steel on mcmaster to use for the camber bolt washers.

It's been a few months since I did the research on bronze, but I just finished building and installing a machine that uses a bunch of graphite-impregnated bronze slide plates against hardened steel wear surfaces. Based on what I learned on that job, I think the biggest (and almost only) thing we need to be worried about for the shaft material is surface hardness. The base material needs to be strong enough to handle the compression force from torquing the bolt, but I think that's pretty much it. And it needs to have decent corrosion resistance. Pretty much any case-hardened mild steel should be strong enough for the job but stainless might be worth the effort for corrosion reasons.

I was actually digging for hardness numbers earlier because I noticed that mcmaster sells precision 3/4" anodized 6061 aluminum shafts with a rockwell C70 surface hardness. I want to talk to some guys at work tomorrow, but I think it might work and would be super easy to machine. My only concern is that the C70 anodizing is only .002" thick compared to a .060" deep C60 case on the hardened steel shafts.

Also, I think you guys might be getting too precise with the lathe work. I'm thinking I can knock these out in an hour or so with mild steel or aluminum. If you're careful with drill bit selection you should be able to just drill the hole within 0.1-0.2mm, which is plenty good for this. And a decently set up bandsaw can easily do +/-1mm and then you can trim the ends down on a belt sander if it's on the long side. Obviously bad practices for a production part that you're going to sell, but we're talking about a cheap way to make a cheap set of poly bushings work better. The energy suspension parts that I still have on the shelf look to have something like a -0.1/+0.5mm inside diameter tolerance.

Yeah most of my IDs are just going to be the as drawn surface. The tolerance for sticking a bolt through a hole on the tube is fine. Its the outer surface that takes time, to get the bearing fit and surface finish just so. I plan on greasing mine just for the water rejection and corrosion protection.

Shit, I misread your post. I see what you meant now. And yeah, I'm just using mild steel if I decide against the aluminum shaft. My car sees so little rain that antiseize on the inside and grease on the outside will be more than enough protection.

I did the math on the resulting clamp load from the torque I was using on the camber bolts to keep them from slipping and looked at the contact area that load had to go through with the slotted holes in the chassis and got scared away from mild steel. My previous ones were slightly mushroomed out on the ends already and I was going smaller diameter. yield strength and hardness is low with mild steel. same problem with aluminum.

the 4340 bar stock I got had like a precision ground surface finish that looked like polished rod and it had a very tight OD tolerance like it was made to have bushings or seals contacting the surface. Its just a shitload of boring holes and parting stuff off its a lot of bushings.

Same as Codrus... Even at 4'' pinch welds on XIDA, no contact anywhere with 15X9 and 225 Nitto NT-01 + 5mm spacer (TSE BBK) maybe at full lock but I don't remember trying it. Was running 275 Hoho when turboed with JIC magic coilovers (the same 15X9 no spacer) and they rubbed the swaybar and polished the towers.

Props for those infos !:makeout:

Do you have an NB as well or is this NA?

on my 90 NA, with 15x9 dial ins and 205/50 rivals, 4.5" pinch height, 3 degrees camber, no spacers: i have a small gap between the FM vmaxxes and the tire. upper offset bushings would make this uncomfortably small with 205s, and would rub with 225s. i would have to go to smaller diameter springs.

I've had ISC bushings in Rover for about two years now. I run a 5mm spacer to keep the tire off the shock tower. To be honest, they aren't necessary unless you are looking for a huge amount of camber - I was running ~3.8* degrees or so to compensate for the crappy NA front subframe/suspension.

I just looked at the numbers and you're right. Any of these steels are right on the edge once you factor in the reduced 3/4" diameter, the slotted hole, and overtorquing the alignment bolts. The mild steels I was looking at are actually higher yield strength than 4340 though. 4340 is 68,500 psi, 1045 is 77,000 psi, and 1566 is 75,000 psi. I'm not going to mess with stainless or aluminum. I think I'm going to buy the 1566 shaft, mcmaster 6061K84. The 1566 has the added benefit of the .060" thick case with a 250,000 psi yield. That .060" case covers around half of the surface area that's getting clamped on.

Also, since I'll be greasing them, I think I'm going to use the non-PTFE 863 bronze bearings (2868T171) instead. I know "contains more iron" sounds bad at first, but iron is actually a really good bearing material at low shaft speed.

I also chose 863, I wanted the higher safety factor on the P term.

Cool. I really need to sit down and read through the spherical thread. I have a feeling I'll find that you guys already figured out and posted this stuff months ago. Lol

um 4340 has 186,000 psi tensile strength and 125,000 psi yeald. and a B100 hardness. Its a long way from mild steel.

https://www.onlinemetals.com/product...steelguide.cfm

I also made 4mm thick 7/8 od washers out of it to butt up against the slotted holes on the ends for the camber bolt locations.

Washers are an effort to keep the slotted holes on the chassis from looking like this after it slips cause its not tight enough, you over tighten it to yield material, or you readjust it a bunch of times and eventually squash things so bad it dosnt work quite right.


https://www.miataturbo.net/attachmen...ine=1425073818

I was just going by the numbers on mcmaster. Looks like the mcmaster stuff is annealed and what you bought is normalized.

MatWeb - The Online Materials Information Resource

MatWeb - The Online Materials Information Resource

So what you bought looks pretty good. I might go that route instead.

Also, I loled at this on the onlinemetals site:

At OnlineMetals, we all failed shop class. Multiple times. As a matter of fact, our employment applications specifically ask to see people's grades for their high school shop classes. If they're too high, they go into the rejected pile. We're also not engineers, and cannot make any specific recommendations about the suitability of a given alloy, temper, or shape for your project or application.

All technical data is for comparison purposes only and is NOT FOR DESIGN. It has been compiled from sources we believe to be accurate but cannot guarantee. This ends the part of the website that our pointy-headed lawyers made us put in.

They do offer Certification with their materials though.

Yes on a nb1 with up to 4* of camber and 5-6* of caster.

I still have some regular poly bushings from the whole kit in case sitting on a shelf.