FC rear suspension and starting alignment/ride height

[jdm91t]

Hello all,

I'm finally moving forward on my Crap can project FC. It's a weird one and has a vg30/33e stroker swap with baffled oil pan (done by someone else) that I had to completely rewire. It's running on a haltech sprint 500 and now a 10 circuit painless racecar wiring harness. It's pretty cool actually and was oddly fun to rewire. A few pictures below.

Anyway now that the car is running properly and fully wired I'm ready to move on to the suspension. This will be mostly a track car with street use driving to and from the local tracks (2 hours max), and the interior is stripped (came that way). A friend and I bought this thing because it was very cheap and wanted something to practice with and not be too worried if it ends up totaled. We've collected some parts for it, but looking through the rear suspension threads are kinda confusing so I wanted to see what you guys thought.

Currently I have the coilovers pictured below. From what the seller said, these are the bilstein race shocks front and rear mounted into the housings you see, with ground control spring perches and camber plates. Springs are currently 400/275 or about 7kg/5kg which I'm cool with as a starting point. Ultimately I might change them to 9kg/6kg. Currently on the stock sway bars as well. Also the car has solid DTSS bushings. I have the energy suspension bushing kit and I'm going to install the front control arm bushings from that.

So looking at the rear suspension, I think I've narrowed down what I want to start with but I still have a lot of questions. take a look at the parts list below and let me know what you think.

Powered by max FC Trailing Arm Forward Bushings, Spherical Bearing Conversion Pair. These are the ones that bolt the control arm/trailing arm to the subframe right?
Powered by max FC RX7 toe adjustable rear lateral rods
Powered by max FC Sub Frame Camber Arm
Ronin Stage 2 camber links
Powered by max FC Trailing Arm Rear Upper Bushings Pair (I was thinking about picking these up as well as I have the DTSS bushings. They are optional)

The big question comes with the differential and subframe bushings. The car is stripped and I will be driving it from and to the track, so I'm worried about solid bushings. I don't want to hate driving the car. I have an FC S4 NA clutch type diff for it that I need to install so I'll be in there. What should I do about the diff and subframe bushings?
It seems like solid bushings transmit horrible levels of noise. Is there an alternative like delrin or poly that work ok and will be manageable noise? which bushings really need to be changed out?

Finally, what kind of ride height and alignment specs should I start with? Currently the car has lowering springs and when measured from ground to the top of the wheel arch at the fender 25 1/8 inch front and 25 7/8 inch rear. It does seem like there is some rake front to rear visually. The gas tank is full.

Thanks, Ryan.

[largeorangefont]

Yep I’d buy all of that stuff. That is all you need. If your current toe links are straight and not sloppy, you could omit the adjustable toe links.

As for bushings, whatever you do for the rear diff you need to run the same on the subframe. This allows you to run a solid front diff mount if you run solid other mounts. Powered By Max makes a solid front diff mount. If you run rubber subframe and diff mounts you CANNOT run a solid front diff mount. You will need the Mazda Motorsports rubber front diff mount in that case. The stock rubber front diff mount WILL break no matter what other mounts you use. Replace it while you are in there. When I ran the NA Mazda diff, I ran a solid front diff mount as well as delrin subframe and diff mounts. Yea there was some more gear noise and NVH, it did. It bother me driving to and from the track.

I would get an RB or ST front sway bar. You might try a stiffer rear bar, but the more power you make the less rear sway bar you need.

How tall are the tires you are running? You don’t need to run front super low, you should lower the rear or raise the front slightly to even out the car.

What front control arm bushings are you running?

As far as alignment, start with over -2 degrees of front camber, you might need close to -3. Toe out of 1/16” total if you have solid front bushings, maybe 0 or 1/16” total toe in if you have rubber front arm bushings.

Rear start with 1/16” total toe in, add more if you need more rear grip. -1.3 degrees rear camber.

[jdm91t]

So the noise didn't bother you with solid front mount and delrin diff and subframe bushings?

Currently the car has 205/55/16 tires all around on crown vic wheels looks like 24.88" height.

I'm planning to use those Energy suspension poly bushings for the front control arms.

Thanks for the tips. I plan on getting the car even height front to rear. Miatas like a little rake so I wasn't sure if FC's might.

[SOB Racing]

I run poly diff bushing with 1/4" aluminum hat bolting it to frame.   Madzacomp front mount with a solid bar link to keep the pinion from rising.   The gear whine on decel really starts to wear on you.

[largeorangefont]

So the noise didn't bother you with solid front mount and delrin diff and subframe bushings?

Currently the car has 205/55/16 tires all around on crown vic wheels looks like 24.88" height.

I'm planning to use those Energy suspension poly bushings for the front control arms.

Thanks for the tips. I plan on getting the car even height front to rear. Miatas like a little rake so I wasn't sure if FC's might.

No the noise doesn’t bother me personally, but it made extra gear noise. I had interior in the car then too. Now I have no interior, and delrin bushings with an solid mounted 8.8.

Your quiet option is to do Mazdacomp bushings for the diff, subframe, and front diff mount.

My suggestion would be to do delrin for the front control arms. It does not affect the ride too much at the softer spring rates.

[jdm91t]

Awesome thank you for all the tips! It really helps out. I'll end up doing delrin diff and subframe bushings with the solid PBM front diff mount. I found delrin bushings on ebay for the diff and subframe.

I can't seem to find any front control arm kits in delrin, but I already bought and have the energy suspension kit so I'll just use those for the front LCA. Sounds like I'm all set on everything I need, thanks for the help!

[largeorangefont]

No problem! It should work out great with that setup.

[jwvand02]

Awesome thank you for all the tips! It really helps out. I'll end up doing delrin diff and subframe bushings with the solid PBM front diff mount. I found delrin bushings on ebay for the diff and subframe.

I can't seem to find any front control arm kits in delrin, but I already bought and have the energy suspension kit so I'll just use those for the front LCA. Sounds like I'm all set on everything I need, thanks for the help!

Is this the seller you found? I haven't been able to find a full set of matching diff mounts and subframe bushings other than this guy, and he's gone until end of March
https://www.ebay.com/itm/Solid-Delrin-Rear-Differential-Bushings-Fits-MAZDA-RX-7-RX7-FC-FC3S-1986-1992/114015596845?hash=item1a8bdbf12d:g:45oAAOSwYHxWONeR

Another question too (maybe a dumb one) - I'm doing the exact same thing with similar/identical parts - Do you still use the stock cam bolts with the spherical bearing conversion? Mine are trashed and it looks like the plates are no longer available anywhere but the bolts are. Also wondering if you could just replace that with a standard bolt/washer if using adjustable toe links.

I've also heard the subframe camber link can be disconnected with solid subframe mounts, anyone know if there's truth to that?

[largeorangefont]

You can weld the rear trailing arm eccentrics but you will need to get adjustable toe links to align the car. I would not remove the subframe camber link in any circumstance personally.

[Supe]

Removing the camber link sounds like a great way to snap the subframe mounting studs off.

[jwvand02]

Removing the camber link sounds like a great way to snap the subframe mounting studs off.

Turns out you can't believe everything you read on the internet!

[largeorangefont]

Removing the camber link sounds like a great way to snap the subframe mounting studs off.

Turns out you can't believe everything you read on the internet!

If it is the club or any rotary related site.. no, the info can't be fully trusted

[jwvand02]

Removing the camber link sounds like a great way to snap the subframe mounting studs off.

Turns out you can't believe everything you read on the internet!

If it is the club or any rotary related site.. no, the info can't be fully trusted

Again, don't mean to hijack the thread but it was timely. I've got clunks/pops under acceleration and can't adjust toe right now, both of which I want fixed. I think I've settled on:
AWR Spherical Bearings (Twice the cost of PSM but I feel a lot more confident in the completeness and long-term durability of the kit, as opposed to "dorifto, yo" parts. They have replacements for the eccentrics that appear to stay in one spot)
Mazdacomp Diff bushings (front and rear)
Stock Subframe bushings filled with 80 durometer urethane casting material
Custom adjustable lateral rods (1 1/4 .120 wall, weld on tube ends, heim joins)

[shainiac]

I'm running PBM rear sphericals and haven't had any issues after a few thousand street miles. Since I have adjustable toe links, I actually drilled out the control arm mounting tabs on the subframe and PMB spherical spacers to 1/2"ID and replaced the stock eccentric bolts with nice 1/2" hardware. The 1/2" washers I used just happened to end up being the exact same OD as the alignment washers. I honestly only did this because my stock eccentric bolts and washers were shot and wanted to get the car together quickly. It worked out well. I also upgraded my toe link heim joints to QA1 PTFE-lined bearings and there is basically no rear suspension noises now, even with Delrin subframe bushings. Non-lined heim joints will clatter.

[largeorangefont]

I have the MMR rear spherical trailing arm bearings in my car and still use the factory toe eccentric and factory toe links.

Everything is mounted with solid bushings - solid heim subframe link, UHMW diff and subframe bushings, Solid front diff mount, PBM camber links, DTSS eliminator and PBM solid rear upper hub bushings. Suspension is silent, and it never has any wheel hop.