Rear Camber link(s) RX7...

[mbuskuhl]

Hello to all, I've been reading this forum for a few months and am a new ITS RX7 racer in the SOWDIV. Made the mistake of building a car but it's about 85% complete (damn it's been expensive and stressful), if all goes well it'll be done at least for now by the end of February. I've ran it in 2 regionals already and did okay. Here's my first post...

I am stuck on an issue with the rear camber link(s). I am being told they are illegal (by my regions head tech), can anyone point me to where in the GCR they are allowed... either a single rear camber adjustment link or the rear individual camber link adjusters? I need to be able to adjust rear camber!

Here's my research so far...

I pulled up the 2007 GCR - IT section online and did a search in the PDF for "camber" (so I wouldn't miss it in the book). Only 3 times does the word appear...

9.1.3.d.5.d.1 - does not appear to allow usage of an adjustable link

9.1.3.d.5.d.2 - does not appear to allow usage of an adjustable link

9.1.3.d.5.d.4 - this is interesting, does not allow for link but does allow for "independent rear suspension mounting holes may be slotted and reinforced for purposes of camber and/or toe adjustment."


Perhaps 9.1.3.d.5.d.5 qualifies the single camber link, but I doubt it...

"Cars may add one (1) front stayrod located in one of the following areas: A. Between lower suspensions mounting points. B. ...., C....."

"Stayrod" defined by the GCR "A rigid reinforcement bar or rod interconnecting opposite sides of a car at structurally significant locations".

Even if this argument was attempted to be used, it says "front" and it does not say anything about being adjustable. Then again, I have an adjustable "strut bar" on the car and would someone want to trade this out for the single camber link if it qualified?

9.1.3.d.1.r - "one (1) engine stayrod may be added" - so maybe this is the "strut bar" and the one above is the link?

Right now I have offset bronze bushings being machined up to fit in the stock dog bone links. These may end up working but not the ideal solution.

Thanks to all!

[mbuskuhl]

Maybe that's too much text... here's some pics...ITS legal? Yes - No

RX7 individual rear camber adjusters...

http://www.mazdatrix.com/pictures/h-susp/2camblinks.jpg

RX7 single rear camber adjuster...

http://www.mazdatrix.com/Pictures/racing/CamberGC.jpg

[mbuskuhl]

No replies...hmmm, answers itself. Until the GCR is changed, here's my solution

Stock RX7 dog bone link -
http://www.mazdatrix.com/pictures/mvc263.jpg

Bushings are free game, adjust away....ready to be tested (that's a bronze bushing... and some paint!)
http://img184.imageshack.us/img184/3882/pict0165ig6.jpg

[bldn10]

"....ready to be tested"

Looking for guinea pigs?

[mbuskuhl]

"....ready to be tested"

Looking for guinea pigs?
[/b]

I'm the guinea pig, I got them on yesterday... so far so good. It'll be another month before I can get it on the track to see how it holds. It's got more adjustment than the individual camber adjusters.... *and legal* ...just not the simplest to adjust.

[bldn10]

Mark, did you make them/have them made or are they commercially available? If so, where?

[ddewhurst]

Mark, I been wondering why no one has goten involved with this thread. Makes me go, Hmmmm. We all know plenty of people have viewed the thread. When I first read your thread I needed to get out a book & look at the details of the 2nd gen. I race a 1st gen & the succeding is not a slam at your camber design.

After looking at your aproach & the rules I have a curious question to ANYONE with respect to dis-assemble of anything that is bonded as in rubber to steel within our cars. Some bushing assemblies are pressed in & some bushing assemblies are bonded together making the part one piece. I presume your OEM link has the tublar insert with rubber bonded to the outside diameter of the insert & the same rubber is bonded to the inside diameter of the link. Is this OEM part considered a one piece? Is it legal to dis-assemble the parts assocated with this OEM one piece assembly?

If your part is a pressed in assembly my same question will be directed towards the 1st gen upper traction bars described below.

This same legality question will go with the upper traction bars on a 1st gen RX-7. When one installs the added third upper traction bar (Tri-link) & removes the same bonded bushing material/tube from the two OEM upper traction bars & lmplements the any bushing material bushings (soft sponge) is this action legal?

9.1.3.D.5.6.

Bushing material, including that used to mount a suspension subframe to the chassis, is unrestricted. This includes the use of spherical bearings, so long as no suspension component is modified to facilitate their installation.

Are we modifying a ONE PIECE BONDED together suspension component ? The bushing material is unrestricted (use any material of choice) BUT where is the licence to cut apart a ONE PIECE BONDED together suspension component?

Have Fun ;)
David

[mbuskuhl]

Mark, did you make them/have them made or are they commercially available? If so, where?
[/b]

One of a kind, machined by a race shop. Paid $150 and I supplied the stock dog bones.




Mark, I been wondering why no one has goten involved with this thread. Makes me go, Hmmmm. We all know plenty of people have viewed the thread. [/b]

I wonder the same thing. I suppose no one wants to publicly admit what we have come to conclude on the links or ?



I presume your OEM link has the tublar insert with rubber bonded to the outside diameter of the insert & the same rubber is bonded to the inside diameter of the link. Is this OEM part considered a one piece? Is it legal to dis-assemble the parts assocated with this OEM one piece assembly? [/b]

Correct on design. Good question and points you raise. There is a "bushing" on the OEM dog bones, that being the "rubber" and "metal sleeve". According to tech in my region, the part removed was a "bushing" (and free game). Isn't the stock dog bone link very similar in design to the sway bar links? I just replaced my sway bar link bushings with some from Energy Suspension. (I know sway bar and their links are free game).

http://www.mazdatrix.com/Pictures/racing/EndLinkPolyS4.jpg

You bring up a lot of good points David. Maybe my solution which works for my regions tech could be questioned elsewhere. Maybe there is no solution to adjust rear camber on the 2nd Gen ITS without re-wording of the GCR. My solution may be light gray where as camber links appear to be black and white. I've tried to comply!

[dj10]

No replies...hmmm, answers itself. Until the GCR is changed, here's my solution

Stock RX7 dog bone link -
http://www.mazdatrix.com/pictures/mvc263.jpg

Bushings are free game, adjust away....ready to be tested (that's a bronze bushing... and some paint!)
http://img184.imageshack.us/img184/3882/pict0165ig6.jpg [/b]



I would think this is legal, UNTIL you offset the holes in the bushings. Now you have the factory intent, have you not?

[Andy Bettencourt]

I am 100% confident that your new design is legal under the reworded rule. Unrestricted is unrestricted. Not super happy the CRB wanted to go that way, but they did.

[ddewhurst]

Mark, yes I would also treat a pressed in rubber with a bonded tubular insert as fair game under the unrestricted "material rule".

My question was, is it fair game when the same parts are bonded to the inside of the dog bone link. At that point I would call the OEM part a one piece suspension component & that would require a person to modify the suspension component to install the unrestricted "bushing material". The rule does not say unrestricted manufacture techniques may be used. The rule specs that a suspension component can not be modified.

Andy has stated "I am 100% confident that your new design is legal under the reworded rule". That is the same as me stating that what Mark has completed is 100% illegal without backing up my statement with a rule. I am presenting my understanding of the rule based on the thought process that when parts are bonded together that is similar to parts that are welded together.

Andy please inform us if when the tubular insert is bonded (not pressed in) into the link is the piece then a one piece OEM part. Factual rule response please.___________________________________________ _____.

Andy if the part is in fact a one piece OEM part after the bonding which rule allows someone to modify a suspension component to install the unrestricted "bushing material"? Factual rule response please.________.

Have Fun ;)
David

[Gary L]

I am presenting my understanding of the rule based on the thought process that when parts are bonded together that is similar to parts that are welded together.[/b]

David - Not making an argument one way or another here, just pointing out something you may have missed in the GCR glossary: Welding </span></span>– The process of fusing one or more components into a single unit by means other than adhesives or fasteners (i.e. TIG, MIG, soldering, brazing, etc.).

<span style="font-family:UniversUnivers">This would appear to differentiate between welding (fusing) and using an adhesive (bonding).

[Andy Bettencourt]

David,

I guess to me just because rubber and metal are &#39;bonded&#39; in some way doesn&#39;t make them one piece (ie: welding definition). One acts as the core suppoet and one acts as the bushing. They are attached, but not considered &#39;one piece&#39; (again, specifically pointing to the definition of welding).

Now, looking at the picture of the new piece a little closer, it does look like the stock piece has been modified to include &#39;set screws&#39;. This IMHO would be not be permitted. I was fixated on the &#39;bushings&#39;.

[mbuskuhl]

How about a GCR change so we can legally adjust rear camber with the links?

On another note, good point on the set screws Andy. This may make the offset bushing design questionable...

I think the answer to rear camber adjustment on the RX7 is contained in this sentence below.... now, if someone can just come up with the design.

9.1.3.d.5.d.4 - "independent rear suspension mounting holes may be slotted and reinforced for purposes of camber and/or toe adjustment."

[Gary L]

On another note, good point on the set screws Andy. This may make the offset bushing design questionable...[/b] Not if the set screws aren&#39;t there. :D

You use the set he already has made, as adjustable templates to build a few (or several) sets of links with offset holes in various positions, for varying amounts of camber. The "real" links would have offset bushings pressed (or bonded, whatever yanks yer crank) inside OEM links. Voila! No set screws, no modification to the links.

[lateapex911]

It could be argued by a very strict view, that "bonding" the new offset units in the unmodified link would indeed be modifying it. Another method would be to heat the stock unit, and make the insert a bit large, and deep freeze it before installation. When both normalize, the unit is in place with no mod to the stock bit.

One concern would be if the corrct final position was oriented so the forces acting on it caused roation, that the insert could "walk".

Or.......

If i remember the rule as written, it allows "tack welds" to locate the bushing if needed, so the bushing could become weldable and have notched areas for tack welds.

[mbuskuhl]

9.1.3.d.5.d.6 - "Bushing material, including that used to mount a suspension subframe to the chasis, is unrestricted. This includes the use of spherical bearings, so long as no suspension component is modified to facilitate their installation. Retention of spherical bearings by use of tack welds is allowed, as long as the welds serve no other purpose".

My links are illegal. Protest away... Not only did the set screws make them illegal, but I have discovered the inside was honed out to provide for a clean straight inside edge.

I&#39;ll have to bring this up with my regions Tech, after all it was him who had the problem with the camber links eveyone uses. His shop came up with the offset bushing idea and machined these parts. I&#39;ll bring that up when I bring him his check for $150 tomorrow...

I still think the answer to the problem is below, now if only someone can come up with a design.

9.1.3.d.5.d.4 - "independent rear suspension mounting holes may be slotted and reinforced for purposes of camber and/or toe adjustment."

[seckerich]

And people wonder why they never get any response to questions on this board :bash_1_: . PS. The ones you designed will not pivot with the rear control arms and will break. The stock ones will allow for flex in both directions.

[ddewhurst]

***They are attached, but not considered &#39;one piece&#39; (again, specifically pointing to the definition of welding).***

Andy, the SCCA definition of welding somewhat off the wall because welding, brasing & soldering are three totally different process. Within their definition they are identifying fasteners & adhesives as not being welding. I do not see where their definition of welding has anything to do with what one piece is. When a steering wheel has ruber/plastic or whatever surrounding the metal hub & spokes we tend to call the steering wheel one piece. We don&#39;t order one part which is metal & one piece that is ruber/plastic & assemble the parts when we receive them.

***I guess to me just because rubber and metal are &#39;bonded&#39; in some way doesn&#39;t make them one piece (ie: welding definition).***

Andy, if we were to agree that molten rubber was poured in place to give the tubular insert position to the link end housing with no adhesive could we also agree that there is a chemical reaction that bonds the rubber/steel & we have one part. IMHJ & as far as when we order new links we would receive one OEM part which Mark included a photo of. Even if the rubber was molded around the tubular part & adhesive was used to position the two piece sub assembly to the link end housing the second we impact/modify the chemical reaction bond or the adhesive bond we have modified a suspension component. When we press something non bonded in or out or we use fasteners to to dis assemble something we do not modify that suspesion component. Yes we are allowed to tack weld a suspension component housing so that Spherical bearing will stay within a housing per the rule BUT that is a whole different ball game. At a latter date we may grind/modify suspension component housing tack weld to get the old bearing out & install a new bearing.

Mark, with your latter responses about the non legal ream & set screws your being very real & truthful. I will presume that if you looked at sloting the mounting holes where the link mounts at the upper & lower position you could do a design that falls within the rule 9.1.3.d.5.d.4 - "independent rear suspension mounting holes may be slotted and reinforced for purposes of camber and/or toe adjustment." you specified. Also is the rear shock mounted to what I&#39;ll call the bearing hub in two places. One place at the hub top & the second place at the hub bottom. If these two locations had Spherical bearings & you sloted the top of shock chassis mounting holes would that improved adjusting/holding the camber. Asking/making suggestions without seeing the car/parts.

Have Fun ;)
David

[ddewhurst]

***And people wonder why they never get any response to questions on this board***

Steve, I am here to tell you that whenever someone asks what to do with a 1st gen RX-7 I&#39;ll pass on what I know. I also like to throw things about with respect to the rules. How many of you 2nd gen RX-7 owners have finally responded to this thred that could support Mark with his rear camber situation but you all have said nothing openly within this thread. If anyone has sent a pm to Mark I&#39;ll thank you. :D

Have Fun ;)
David

[seckerich]

The piece in question is actually a spherical bearing with a rubber seal pressed into both ends. I run them stock with no problems. I got burned once too many time trying to help on this forum so a PM is the only way to go. I did not PM because someone I know and respect already has. :rolleyes: Seems a little strange that the chief of tech has all the answers for a fee. As with doctors--get a second opinion. Do your adjustment at the subframe as the rules allow.

[mbuskuhl]

And people wonder why they never get any response to questions on this board :bash_1_: . PS. The ones you designed will not pivot with the rear control arms and will break. The stock ones will allow for flex in both directions.
[/b]

Let me be clear, I did not design these. A local race shop did where the shop foreman is head of tech in my region and the owner has been racing SCCA for 30+ years. As far as them breaking, I do not have the knowledge to comment but would suspect and hope the designers knew what they were doing. That can be questioned though since we have concluded the design is not legal. I&#39;m just a rookie trying to have a good time and learning.

Anyone care to comment on what they use for rear camber adjustment on the 2nd Gen?

Stock dog bones and somehow do some type of modification at the subframe seems like a logical approach...

[seckerich]

Let me be clear, I did not design these. A local race shop did where the shop foreman is head of tech in my region and the owner has been racing SCCA for 30+ years. As far as them breaking, I do not have the knowledge to comment but would suspect and hope the designers knew what they were doing. That can be questioned though since we have concluded the design is not legal. I&#39;m just a rookie trying to have a good time and learning.

Anyone care to comment on what they use for rear camber adjustment on the 2nd Gen?

Stock dog bones and somehow do some type of modification at the subframe seems like a logical approach...
[/b]
Get in touch with mazdaspeed and register with them if you have not done so already. The link that sets the subframe angle is where you want to adjust your camber. it will do the same for both sides unless you want to stagger the left and right. Feel free to pm me and I will give you a phone number and give you all the help I can. You are new to this and don&#39;t know how "tech" discussions on this board go south fast.

[Duc]

Bring up a dead horse as I am just trying to understand what is legal. I have come across rear upper links like these:

http://www.ingallseng.com/graphics/Product_Pictures/38720.gif

So instead of using something like this we have to "slot" the mounting points? (I am having a hard time with this as the above seems safer).

Or Camber bolts:
http://www.ingallseng.com/graphics/Product_Pictures/35420.gif

What about adjustable ball joints like:

http://www.ingallseng.com/graphics/Product_Pictures/35590.gif


Or adjustable mounts:

http://www.ingallseng.com/graphics/Drawings/35710-assembly.gif

Thanks,

Derek

(Oh and if you don't want to respond, then PM me please).

[mbuskuhl]

What kind of car are you referring to? I don't see any of the posted pictures as options for a 2nd Gen RX-7 but maybe you are talking about a different car.

I have come to the conclusion and no one has proven me wrong that there is no legal way to adjust rear camber on a 2nd Gen RX-7 for IT. Do people do it anyways? A quick glance at the rear suspension would tell you. Note I run ITE where there really aren't any rules and yes I have camber links.

[Duc]

Any car, what this thread is more about adjusting camber on any multi link suspension. The examples I was pulling are cars that are running in IT looking through: Ingalls Engineering (http://www.ingallseng.com/Vehicle%20applications.htm)

If you look through you will see a lot of other examples like shims (you could change toe in as well by using combinations of shims) for the GTI. I am just wondering at this point does it make sense to have the only way to adjust be elongating and re-enforcing the mounting position, vs. opening the rule up to allow for the use of adjusters for upper links, or shims in the GTI example, but still limit the use to stock lower control arms. This way the base suspension design does not change, and we can run the correct camber to not tear up tires.

Just some thoughts.

Derek

[mbuskuhl]

There are several options that fall within the rules (below). Why adjustable links are not included is beyond me. I believe the intention of the IT rules is to allow for adjustment of camber, caster, and toe settings, however in some instances the way the rules are written this becomes very challenging as evidenced by this thread. Send in a request for adjustable links, although I would suspect the response would be "inconsistent with class philosophy" or "the rules are adequate as written".

1. Cars equipped with MacPherson strut suspension may
decamber wheels by the use of eccentric bushings at
control arm pivot points, by the use of eccentric bushings
at the strut-to-bearing-carrier joint, and/or by use
of slotted adjusting plates at the top mounting point. If
slotted plates are used, they shall be located on existing
chassis structure and may not serve as a reinforcement for
that structure. Material may be added or removed from the
top of the strut tower to facilitate installation of adjuster
plate.
2. On other forms of suspension, camber adjustment may be
achieved by the use of shims and/or eccentric bushings.
3. All forms of suspension may adjust caster by means of
shims or eccentric bushings. Additionally, MacPherson
strut-equipped cars may adjust caster at the upper strut
mounting point/plate.
4. Independent rear suspension mounting holes may be
slotted and reinforced for purposes of camber and/or toe
adjustment. Material may be removed from the top of the
strut tower to facilitate installation of adjuster plate.

[chuck baader]

Mark, I like the design, and think it could be successfully argued as legal. I would make one change, though. Start with hex stock and leave a wrench area if possible. Chuck