Yes, as 00SPEC said.

 

Regarding the binding of relatively rigid plastic bushings when replacing rubber bushings, I understand where Blue TII, an autocrosser, is coming from as I will be making suspensions modifications for SCCA Street Prepared class where spherical metal bushings can not be substituted for the OEM bushing. My main area of concern is, as pointed out by Blue TII, the connection to the chassis of the rear trailing arm. The end of that rear trailing arm that is connected to the lower lateral link moves in two arcs. The one that swings that end on a radius about the inner end of the lateral link is likely the culprit for slight binding at the chassis end of that trailing arm if the bushing there is not able to deform.
Autocrossers strive to remove all stiction and bind in their suspensions as any discontinuity(binding) in the rapid articulation of the suspension that happens in autocross shocks the tires while at their limit more than binding may affect the more gradual loading of a suspension that happens when cornering on the street or even the track.

After having recognized the above, I have also noted the experience one of our own: https://www.rx7club.com/3rd-generati...-cheap-937852/

So, has anybody when working on the rear suspension, with the shock and spring removed, tried cycling the suspension through its limits with a plastic bushing installed to gauge the amount of stiction as compared to a rubber or spherical bushing? While concerned about the binding, I would really like to eliminate the compliance of the rubber at that connection as I suspect it contributes to wheel hop when launching on R compound tires.

Cheers, Philip

 

What you really need to do is take apart the stock "bushings" and you will see what you need to do.

You share the common misconception that the FD "bushings" use soft rubber for multi axis compliance. They instead use steel spherical bearings for multi axis compliance with a little rubber around them to dampen NVH.

Real race car suspension with a hint of civility.

The exception I found among "bushings" requiring multi axis movement was the front of the rear trailing arm, which is a traditional bushing that uses a metal sleeve in rubber, but the rubber is shaped in such a way to be compliant in the multi axis direction and non complaint in the loaded (longitudinal) direction.

For the SCCA Street Prepared classes you are not allowed to change multi axis movement by changing the "bushing" design (ie replacing compliant material with sperical bearing OR vice versa).

For the FD this is a boon compared to other cars because once you have taken apart the stock "bushings" and determined their type you can now take your preferred high density non metal material and stick it around a spherical bearing.

In actual use, most ASP SCCA FDs could be protested as illegal as they have changed stock spherical bearings for compliant material in several areas of the rear.

 

Blue TII, thanks for your experience and insight. Don't think I have any misconceptions as I have studied the various type of bushings referenced in the Workshop Manual and the detailed cross sections shown in Yamaguchi's book which show the spherical bearings encased in rubber that you refer to.

The nuance of the SCCA SP rules you highlight with your "OR vice versa" comment is one that never occurred to me so I will be as you suggest disassembling the OEM bushings, if it can be done without destroying them, to see if the rubber can be replaced yet retain the original configuration. I am not aware of that being done, however I would really like to avoid any SCCA protest craziness. My main interest was to gain more negative camber in the front through an offset bushing in the top A-arm pivot points and reduce wheel tramp in the rear. Any loss in NVH is not an issue as this will be for a dedicated autocross car. Most of the bushings appear to have very little rubber in them to deflect, (Yamaguchi calls them "Sliding Rubber Bushing" and "Rubber Seated Ball-Joint Bushings"), except the front lower A-arm rear "Fluid-Filled Bushing" and the rear trailing arm front "Rubber Bushing". My car is not available to me at the moment, so my comments are just arm-chair engineering for now.

I really hope that a plastic bushing would be considered a "close enough" configuration to the "Sliding Rubber Bushing" to satisfy the SCCA rule. You really have to look hard in the Workshop manual to note the difference. Until I disassemble one, that is just speculation on my part.

I just reread your comment "...take your preferred high density non metal material and stick it around a spherical bearing." and the SCCA SP rule "Suspension bushings may be replaced with bushings of any material (except metal)..." and " In a replacement bushing the amount of metal relative to the amount of non-metallic material may not be increased." Are you suggesting an aftermarket spherical bushing could be legally used enclosed in plastic as opposed to needing to continue to use the OEM spherical bushing enclosed by plastic? I might be able to parse that wording to get that interpretation, but I fear that was not the intent.

Cheers, Philip

 

Are you suggesting an aftermarket spherical bushing could be legally used enclosed in plastic

*1) Yes, relevant section 15.8 C. If you take apart the stock spherical bearings I believe the bearing seats are Teflon, so be aware of this as far as adding to the total of non-metal material in the "bushing". There must be a clarification in a Fast Track as to how the amount of metal vs non-metal material in busing is measured (weight? Volume?).

I really hope that a plastic bushing would be considered a "close enough" configuration to the "Sliding Rubber Bushing" to satisfy the SCCA rule.

*2) Yes, again. As long as you use the standard procedure of having a metal sleeve that slides into the two bushing halves you have a sliding bushing. When (if) the outer flanges of the bushing material deflect from force the suspension arm will slide along the metal shaft and change toe like stock. It will take much more force with the new bushing and realistically not happen, but it meets both the intent and letter of the rule.

The nuance of the SCCA SP rules you highlight with your "OR vice versa" comment is one that never occurred to me

*2) Again no change in type of busing allowed. I don't know if anyone has ever addressed a downgrade in bushing type as is sometimes done on the FD, but technically it could be protested.

except the front lower A-arm rear "Fluid-Filled Bushing" and the rear trailing arm front "Rubber Bushing".

*3) Fluid-filled bushings are an interesting case there must be a clarification on in Fast Track as well, but I would assume they would qualify as "cylindrical bushing". The fluid is simply low density non-metallic material to dampen NVH and not serve a function in busing articulation.

Again, I doubt anyone would protest bushings in Street Prepared unless you went to full metallic spherical bearings, but it is good to know at least what you are supposed to be doing.

Section 15.8 C
"Suspension bushings may be replaced with bushings of any materials (except metal) as long as they fit in the original location. Offset busings may be used. *1) In a replacement bushing the amount of metal relative to the amount of non-metallic material may not be increased. *2) This does not authorise a change in type of bushing *3) (for example ball and socket replacing a cylindrical bushing) or use of a bushing with an angled hole whose direction differs from that of the original bushing. If the standard bushing accommodated multi-axis motion via compliance of the component material(s), the replacement bushing may not be changed to accommodate such motion via a change in bushing type, for example to a spherical bearing or similar component involving internal moving parts. Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose than that of retaining the bushing in the desired position. Differential mount bushings are not considered to be suspension bushings and are not covered by this allowance."

 

Hmm, Teflon lined, that does add another twist to working within the SCCA SP rules.

Thanks for quoting all of that part of the rules, gives the other guys a picture of what we have to deal with in Street Prepared. I think the rules were developed in another time and galaxy, even older than our cars. For example, after much discussion with Doug Gill, I put in a proposal to the SEB to allow water/methanol mix in the allowed "water injection" instead of the water only that the rules permit. They let E85 slipped in the back door of being legal by SP rules as it became a recognized pump fuel, thus SP class legal, but not water/ methanol for water injection, even washer fluid! A rotary engine expert advised me to not run the FD engine on E85 as the alcohol has access to the rubber O-rings, unless its a race engine that gets torn down frequently. Should hear on the proposal soon. Apparently it had been rejected in the past according to Doug, but with the advent of E85 and new board members it might have a chance. Hopefully, if anybody on the SEB is running E85 in SP, the personal agendas that SCCA is often accused of won't be a factor in shooting it down.

Cheers, Philip

 

I've go some Super Pros on my rear toe arms and whenever I go over a speed bump they make some pretty good squeaking

 

Since were on the subject of zerk fittings and poly bushings.......

question: is there a specific brand of zerk fitting I should be looking for? I see large qty variety packs for sale for 30-50$. Then I found the website for the company that actually invented the zerk fitting and theyre prices per fitting are considerably higher. It makes me worry that those variety packs are of a lower quality and I shouldn't bother.

I just wanted an opinion from someone else. I dont know if a zerk fitting is a zerk fitting and if something like this should even be considered.

 

I work for a company who manufactures pneumatic tools and we use flush type zerk fittings in our product. We've used a few different suppliers for the fitting and have never had an issue. My experience is they're all the same

 

Excellent, thank you. Is there a specific metal i should look for these in or does that not matter either?

 

While I don't have experience in using zerk fittings in suspension bushings, I haven't noticed much difference in material in my line of work. We use this type FLUSH TYPE GREASE FITTINGS, FLUSH ZERK FITTINGS, NAS516-1A, NAS516-M1

 

Just FYI update--


Total for the SuperPro Poly bushings : 369.something from Autohausaz.com
entire front set
differential
rear Upper A arm and shock mount



Total for the remainder Mazdaspeed bushings from Mazdatrix: 688.52

--trailing links (85.68 ea)
--Rear lower control arm inner (97 ea)
--inner toe link(121.04 ea)


still need (OEM only):
outer toe link
RLCA outer bushing (???? i think i need this? or is the RLCA bushing an entire set)


moral of the story: do some track time and get a mazdacomp membership!
getting my oil pan resealed with a banzai brace this weekend---askign the shop to inspect my bushings as well and I will go from there

 

I just did mine last week and I did install zerk fittings as well, can find the pics in the build thread
I bought the full super pro kit from J auto.net for $513 also got the six OEM Pillow ***** from them for $425. I ended up getting the lower rear control arm outer bushings from Malloy, can't recall the price. You will want to get it. Just call Ray Crowe on that one. They weren't that expensive.

I actually did not use the bushings for the diff mount or the rear toe links. I will sell mine to you for $100 shipped if you want them.

 

pm'd ya!

 

Understand the squeaky thing, but are there any disadvantages to lubing the bushings? Especailly for a mainly tracked car?

 

The disadvantage would be if they weren't lubed and started binding and adding resistance to your suspension movement.



I noticed that PowerFlex now makes a bushing for the rear lower control arm whereas nobody made one in the past. Anyone see any reason to not run poly there?

 

I think people were suggesting not to because it might cause binding? I bought it anyways because the factory bushings were 80 bucks each side and I don't have access to Mazdacomp, so I went with the logical thing to do and paid 55 bucks for both bushings.

 

I don't necessarily see why the rear lower control arm would need axial movement. There is a thrust ange adjustment in the rear using that arm, but it's supposed to be zero anyway. I just wasn't sure if anyone had run the poly there yet and had some real world experience.

 

The rear lower arm needs multi axis movement as it is composed of a longitudinal link toward the front of the car as well as the lateral lower arm.

Therefore, in its motion it describes arcs along both the longitudinal and lateral planes - forcing the bushings to move not only along their rotational axis, but out of the plane parallel to the respective arms.

Real world analysis. Poly bushings will work. So does a twist beam rear axle or a leaf spring rear axle or a forklift with no suspension.

Just be aware that poly in these areas will be a downgrade not an upgrade to the stock suspension.