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 Post subject: Rear axle location
PostPosted: Thu Nov 21, 2019 12:25 pm 
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Joined: Sun Oct 08, 2017 2:58 pm
Posts: 37
Location: Dousman, WI
All right; I'm in the process of gathering parts and firming up ideas for an EP 1st gen RX-7. And yes, of course I'm trying to engineer a slightly better mousetrap, I'd stick with a spec car otherwise. And I just had the urge to throw this out here instead of writing a letter because it'll probably get a faster response. :lol:

I'm looking at 9.1.5.E.5.b.3 which is what has traditionally allowed the 3-link setups and panhard bars and the like. What exactly is the last sentence (Rear axle traction bar(s) used to control axle housing rotation must be solid bar or tube) trying to guard against? It looks like weldments have been used a lot for 3-links (I'm looking at the ones KC Raceware advertise for example) which is made of bar and tube... is the "solid" the key part to outlaw stuff like decoupled 3 links with sliders and stuff?


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 Post subject: Re: Rear axle location
PostPosted: Thu Nov 21, 2019 12:36 pm 
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Joined: Fri Dec 23, 2011 6:59 am
Posts: 1325
Location: Spring Hill, FL.
My guess is to not allow soft bars. Like dirt uppers with rubber snubbers and or plastic leaf trailing arms for more bite.

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 Post subject: Re: Rear axle location
PostPosted: Thu Nov 21, 2019 2:08 pm 
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Joined: Thu Oct 03, 2002 10:34 am
Posts: 2932
Location: Wauwatosa, WI
Dan DeRosia wrote:
All right; I'm in the process of gathering parts and firming up ideas for an EP 1st gen RX-7. And yes, of course I'm trying to engineer a slightly better mousetrap, I'd stick with a spec car otherwise. And I just had the urge to throw this out here instead of writing a letter because it'll probably get a faster response. :lol:

I'm looking at 9.1.5.E.5.b.3 which is what has traditionally allowed the 3-link setups and panhard bars and the like. What exactly is the last sentence (Rear axle traction bar(s) used to control axle housing rotation must be solid bar or tube) trying to guard against? It looks like weldments have been used a lot for 3-links (I'm looking at the ones KC Raceware advertise for example) which is made of bar and tube... is the "solid" the key part to outlaw stuff like decoupled 3 links with sliders and stuff?


These solid bar or tube (with spherical ends attached to aluminum tubes) would replace the original lower Trailing Arms and likewise with your 3rd link. On my ITA RX7 I used G-force third link. Bought the new lower aluminum trailing arms and for whatever reason left the upper trailing arms in place with soft foam bushings to make the upper trailing arms useless, they had mounting bolts and flopped around like fools. Fabed my own PanHard bar and support tube structure. When installing the 3rd link front mounting stuff, you need to pay close attention to your driveshaft angle from transmission to the differential.

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David Dewhurst
CenDiv Milwaukee Region
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 Post subject: Re: Rear axle location
PostPosted: Thu Nov 21, 2019 2:18 pm 
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Joined: Sun Oct 08, 2017 2:58 pm
Posts: 37
Location: Dousman, WI
I have a car with the G-Force 3rd link... I'm trying to puzzle out the specifics of what the rule means to figure out something that might be better. I can make it as a machined bar, but it would be nicer to do things as a weldment, and by the wording I'm really not sure what they have in mind to outlaw.


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 Post subject: Re: Rear axle location
PostPosted: Thu Nov 21, 2019 4:51 pm 
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Joined: Thu Oct 03, 2002 10:34 am
Posts: 2932
Location: Wauwatosa, WI
Dan, why would anyone redesign the wheel. I know Charlie well from KC Raceware, why would ANYONE weld up a piece like he has. Check out this G-force Tri Link scroll down to post #3 and look through the pictures. Straight 3rd link of the KISS philosophy. Maybe KC had a different mounting type which demanded the oddball welded piece. Straight tube with a spherical rod end is a KISS philosophy for me.

https://www.rx7club.com/1st-generation- ... nk-628899/

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David Dewhurst
CenDiv Milwaukee Region
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 Post subject: Re: Rear axle location
PostPosted: Thu Nov 21, 2019 5:21 pm 
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Joined: Tue Dec 31, 2013 10:40 am
Posts: 412
Location: Huntsville, AL
http://kcraceware.com/suspension.htm

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 Post subject: Re: Rear axle location
PostPosted: Fri Nov 22, 2019 12:45 am 
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Joined: Thu Oct 03, 2002 10:34 am
Posts: 2932
Location: Wauwatosa, WI
Exactly Brett, when looking at the RX7 part, why weld several parts up which will increase the stress points for breakage.

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David Dewhurst
CenDiv Milwaukee Region
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 Post subject: Re: Rear axle location
PostPosted: Fri Nov 22, 2019 4:16 am 
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Joined: Sun Oct 08, 2017 2:58 pm
Posts: 37
Location: Dousman, WI
David, I have a G-Force tri-link and have had for 15 years, a long with a bunch of Susko's other stuff including the book. For that matter I have a bunch of Simaris's old stuff when he changed cars, even if most of it went to the Barrington Hillbillies. I'm not trying to copy Charlie Clark's welded 3-link, I'm looking at it and going "OK, if that was legal I have some options in how to build what I want to try", which is a new idea that may or may not work.


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 Post subject: Re: Rear axle location
PostPosted: Fri Nov 22, 2019 5:02 am 
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Joined: Thu Oct 03, 2002 10:34 am
Posts: 2932
Location: Wauwatosa, WI
I get it Dan, a better mousetrap. You have the last white Simaris brothers RX7 :think: and Hillbillies :roll: , you must be local, WI IL.

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David Dewhurst
CenDiv Milwaukee Region
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 Post subject: Re: Rear axle location
PostPosted: Fri Nov 22, 2019 5:31 am 
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Joined: Sun Oct 08, 2017 2:58 pm
Posts: 37
Location: Dousman, WI
David Dewhurst wrote:
I get it Dan, a better mousetrap. You have the last white Simaris brothers RX7 :think: and Hillbillies :roll: , you must be local, WI IL.


Oh, I forgot to set location didn't I - I'm in Dousman WI, South of Oconomowoc. I'm doing a new build; Rich Olson has the last car but I'm planning on borrowing the molds because I like how they turned out. I do have about 3 engines worth of irons and housings though from Jim and Jay plus a bunch of miscellaneous smaller stuff. Dad ran in Council until taking a step back to a T4 spec MX-5 to actually learn to drive, I'm going the other way of learning to drive in the MX-5 before trying to tune the RX-7.

So I'm fine if it takes a few years before it gets on track. ;)


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