Well Vince, looks like somebody beat us to press on the "A" body 3-link

[sinned]

Ryan over at TC just finished his 3-link, pretty basic design. He kept the 3rd link very short, I would imagine to keep construction simple and prevent having to build a new crossmember. He did get 'er done though so thumbs up to Ryan.
link to Ryans post at TC (http://www.chevelles.com/forums/showthread.php?t=110734)

[MrQuick]

thats great lets see how he does with it. BTW im not out to compete with others, thats why I never keep things secret. If you ever see or hear anything im doing just ask and i will usually share info. Are you ready for your set up? We need to pull your bed. I'd like to run a 18-21" link.

[sinned]

Yeah, 18" sounds about right. I think I need to figure out what axle I am going to run first, looks like a full floater 9".

I know there wasn't a race but we have talking about it sooo long I figured we'd be first.

[MrQuick]

mine will bolt up to a GM housing no 9 needed.

[sinned]

Yeah but a GM housing....yuck. That means either running c-clip eliminators (big yuck) or paying to have Ford ends welded on and still having to deal with the hassle of gear set-up in the car (with no hoist anymore). The full floater appeals more and more every time I think about it (That and the fact that I can pick one up all day for under 800 complete less 3rd member). Plus I can order it bare with no brackets, Hate having unused bracketry on the axle, it's just plain ugly. No offense at all to Ryan, his set-up is simple and probably works but looks so; well I'll just leave it that.

[Elusive R]

Thanks for the props, Dennis. It's ok, you can say it - it looks cheap. Well, it is. Definitely on a budget. I will post here and on TC with the numbers once I get them finalized. I'll also comment on how it drives, etc, etc. Dennis, you're right about the link being short to simplify the brackets. I was encouraged by the new *cough* Mustang having a short link as well.

I couldn't have done it without the resources like this site and probably never would have even considered it had you guys not been talking about it. I also hope I didn't step on anyone's toes, but I'm not going to be selling anything so I figured I'd be ok.

Ryan

[gchandler]

Take a look at this el camino. I shot these pics at Tony's book signing.

http://www.hotrodhomepage.com/gallerys/sire_performance/

notice the rear suspension. he runs it at willow and i guess it goes pretty good.

[derekf]

Does it make a difference/create any unusual effects with the way the upper link connects to the rear axle behind the axle, or is that a non-issue?

[sinned]

Derek, it looks to be equal to the axle centerline so it shouldn't be a problem, anything behind the axle centerline could create an issue.


NICE Geoff, that looks to be about an 18" link, pretty close to how I wanted to run.

[Travis B]

Looks good......I plan on doing a 3 link in my chevelle but have not gotten too far on it yet

Dennis for the 18in upper are you going to run stocklength lowers?? I am actually planning on running a split lower seat cushion so I would have plenty of room for a long upper link I was actually thinking 20-22 would be no problem in my car but like I said I have not gotten there yet!

[Norm Peterson]

Does it make a difference/create any unusual effects with the way the upper link connects to the rear axle behind the axle, or is that a non-issue?Other than complicating the installation of a PHB and/or its brace, Watts link bracketry, or other lateral location device, I don't see why it should. The 3rd link has no effect on rollsteer (maybe there is a little if it's offset laterally), and you can always set the pivot points to arrive at the same SVIC.

But for a few inches of lateral eccentricity, this same rearward location of the axle side 3rd link pickup is the solution employed in the Factory Five spec race cars.

Norm

[JMarsa]

Yeah but a GM housing....yuck. That means either running c-clip eliminators (big yuck) or paying to have Ford ends welded on and still having to deal with the hassle of gear set-up in the car (with no hoist anymore). The full floater appeals more and more every time I think about it (That and the fact that I can pick one up all day for under 800 complete less 3rd member). Plus I can order it bare with no brackets, Hate having unused bracketry on the axle, it's just plain ugly. No offense at all to Ryan, his set-up is simple and probably works but looks so; well I'll just leave it that.

Correct me if I'm wrong, but if you have disk brakes on the rear it eliminates the need for c-clip eliminators. The caliper and it's mounting bracket would hold the axle in place if it broke. A 4th Gen Camaro rear brake conversion is a low buck upgrade IMO.

--JMarsa

[sinned]

Correct me if I'm wrong, but if you have disk brakes on the rear it eliminates the need for c-clip eliminators. The caliper and it's mounting bracket would hold the axle in place if it broke. A 4th Gen Camaro rear brake conversion is a low buck upgrade IMO.

--JMarsa
I'll correct you, having a caliper is not the same as having an actual retainer when an axle decides to break near the wheel at 100mph+ in a corner; although the bracket on a C5 or 4th gen “F” body would do better that is not its intended application. I didn't even mention all the other advantages of running a full floater...like for example, the floater.



Travis, yeah, I am keeping the lowers at their current 22" length.

[protour_chevelle]

Well isn't this interesting.... Removing my rear seat all of a sudden doesn't seem like a big deal anymore to me.

Denny, I like your idea on the 9 inch floater.... I have a 10 bolt, and a 12 bolt. Maybe I'll look around for a 9 inch. Damn innovation.

-Matt

[sinned]

Check this out Matt- Randys full floater (http://www.randys-racemart.com/9infoflas.html) kit. All you need to add is a 3rd member and some mounts (also available with mounts for an extra fee).

[Mean 69]

Just keep a couple things in mind with a floater rear setup, not so obvious until you do one.

One, the hubs are wide, meaning that the brake setup will be pushed inboard quite a ways. Make sure you clock your calipers accordingly to minimize clearance issues with the inner fenderwells (been there).

Two, the register on the hub/drive plate will likely be bigger than the register on the ID of your wheels, meaning you'll have to lathe down this feature, if possible (been there too).

Three, the stock car stuff comes with 5/8" axle studs, but typical street wheels use 1/2" stuff. This is more of a PITA than you will think about, until you have to deal with it (been there, three).

Four, make sure the rotor adapters that are provided adapt to the typical rotors available, or you might be "forced" to use the thin-ish .810" thick units that are often used by circle track folks/be prisoner to their bolt patterns (been there, four).

Five, make sure you buy extra axle seals, to keep as spares, so that if you are in the middle of b-f-nowhere (otherwise known as Buttonwillow) and you cut one, well, you won't waste a whole weekend and track dues due to a leaky seal. Yes, been there too.

Other than that, knock yourselves out.
M

[gchandler]

I will second that 5/8 studs issue. it is much more difficult to find wheels that fit the 5/8 setup then you think.

I eventually went with stock car wheels after a couple of, "yes they will fit" -> buy -> don't fit -> return to sender, situations with wheel suppliers.

[sinned]

Just keep a couple things in mind with a floater rear setup, not so obvious until you do one.



One, the hubs are wide, meaning that the brake setup will be pushed inboard quite a ways. Make sure you clock your calipers accordingly to minimize clearance issues with the inner fenderwells (been there). No problem, I think the Elky has plenty of wheelwell room




Two, the register on the hub/drive plate will likely be bigger than the register on the ID of your wheels, meaning you'll have to lathe down this feature, if possible (been there too). Lathe down the hubs…no problem




Three, the stock car stuff comes with 5/8" axle studs, but typical street wheels use 1/2" stuff. This is more of a PITA than you will think about, until you have to deal with it (been there, three). PITA, I agree. Anybody looked into wheel studs in a ½” thread with a spline big enough to bite the hubs? I can always have our weld shop seal them up and re-drill the correct pattern with the appropriate sized hole.




Four, make sure the rotor adapters that are provided adapt to the typical rotors available, or you might be "forced" to use the thin-ish .810" thick units that are often used by circle track folks/be prisoner to their bolt patterns (been there, four). I think the Winters stuff I was looking at use the standard 7” 8 bolt pattern




Five, make sure you buy extra axle seals, to keep as spares, so that if you are in the middle of b-f-nowhere (otherwise known as Buttonwillow) and you cut one, well, you won't waste a whole weekend and track dues due to a leaky seal. Yes, been there too.



Other than that, knock yourselves out.

MYes, I remember, extra seals would be good.





I just realized I have completely hi-jacked my own post. What a dumbass

[protour_chevelle]

Check this out Matt- Randys full floater (http://www.randys-racemart.com/9infoflas.html) kit. All you need to add is a 3rd member and some mounts (also available with mounts for an extra fee).

Thanks Dennis. My post made me come off as I could do anything(which I sure as hell can't). I'm up for a challenge and theres tons of resources on here to allow me to complete a given task :firefire:

I'll have to get my car on the road before I buy a full floater but thats alright. My dads buddy will be paying me very well(under the table work) so I should be able to get some fundage in to do the suspension. I think I might run the car a couple times in stock trim in Solo II just to set a baseline.

I've already had to get hubs lathed down to clear my current wheels. But like Denny said. Worse comes to worse... Plug the wholes up and will a new bolt pattern. :)

On another note... To get the upper link to 18-20 inches long... a seperate crossmember will need to be fabricated correct? I havn't looked under my car in a while. Too damn cold out.

Take care,

-Matt

[sinned]

Oh yeah, the factory cross-member is about 9-10" from the top of the center section so it will either need to be cut out or you will need to go over it (read: major sheet metal surgery). That factory cross-member is pretty weak anyways; it was barely intended to support the loads through the upper links, never to serve as an actual triangulation of the frame. Adding a proper cross-member and tying into the frame rails appropriately will not only serve as a great upper link mount but will also do tons towards stiffening the chassis flex through resisting frame rail twist.

[protour_chevelle]

Oh yeah, the factory cross-member is about 9-10" from the top of the center section so it will either need to be cut out or you will need to go over it (read: major sheet metal surgery). That factory cross-member is pretty weak anyways; it was barely intended to support the loads through the upper links, never to serve as an actual triangulation of the frame. Adding a proper cross-member and tying into the frame rails appropriately will not only serve as a great upper link mount but will also do tons towards stiffening the chassis flex through resisting frame rail twist.

When I was under the car last(looking at the tranny), it got me thinking about a bolt in style crossmember(which could eventually be weld in style) But essentially making a 2nd tranny crossmember with the proper mounting height for the upper link, then have braces coming back that would share the mounting points of the tranny crossmember(so it would triangulate things)

Hopefully you understand, I'll have to draw a pic of to explain myself better.

-Matt

[93Polo]

When I was under the car last(looking at the tranny), it got me thinking about a bolt in style crossmember(which could eventually be weld in style) But essentially making a 2nd tranny crossmember with the proper mounting height for the upper link, then have braces coming back that would share the mounting points of the tranny crossmember(so it would triangulate things)

Hopefully you understand, I'll have to draw a pic of to explain myself better.

-Matt
I had thought about something along those lines. If you swap to a 9" get the bracket the 3rd and 4th Gen F-body guys use to mount their tq arm to the chunk and make an addition crossmember to mount the front link to the tq arm. I wander how much the drive shaft tunnel would need to be widened to fit the tq arm and how the geometry would work out.

[Elusive R]

So here are some numbers for the wolves:

Roll center height: ~14 inches, down from 20.5
SVSA: ~64 inches, up from 57
Anti-squat: ~78%, down from 84%

The upper link is 10.5 center to center, the panhard is 31.5 center to center. Roll oversteer comes up at ~20%, but that seems misleading to me and it definitely doesn't want to swap ends. I may be miscalculating this as well - I'll look into it.

Overall, I'm still very, very pleased with the setup. I got my ignition issues fixed, so it's getting all the torque a ZZ4 with TPI injection can give it and all I can say is that I have all kinds of traction. Don't know about a hard drag launch, but I'm only on 225-70/15's, I'm sure tire spin will be an issue at the strip.

I've tried to push as much as I can on city streets without getting arrested, and it's very stable and neutral. The predictability is fantastic. I now know I can make a corner instead of just hope.

Ryan

[Norm Peterson]

20% vehicle roll oversteer with a 14" RCH would put the vertical coordinate of the LCA virtual intersection somewhere in the vicinity of ~27" if this virtual intersection is also 64" ahead of the axle.

With LCAs that are level and ~9" above the ground, you'd have something much more like 7% vehicle roll understeer. If the lowers are slightly uphill toward the chassis, probably less than 7% U/S.

Edited

Norm

[Elusive R]

Thanks, Norm. I found that I was referencing the wrong box in my spreadsheet, so I now get ~9% roll oversteer because the roll axis slope runs up towards the front of the car. Isn't the 27" point you mention for the lateral restraint point of the lower control arms? If so, I get 26" on mine as my lowers do run up towards the chassis. For the stock configuration, I came up with about 4% roll oversteer. I'm looking at RCVD right now, so I think I've got it right, but please correct me if I'm totally screwing this up.

Thanks again,
Ryan

[Norm Peterson]

Isn't the 27" point you mention for the lateral restraint point of the lower control arms?OOPS. That would be correct, for a virtual lateral intersection that happened to coincide with the SVIC. If you have the XYZ coordinates of all of the various pivot locations (plus CG and wheelbase information), I can toss them into one of my spreadsheets and see what antisquat and rollsteer comes out. With plots showing the variability against ride height.

Maybe just my opinion, but 4% roll oversteer doesn't sound like anything the OE's would let loose for sale.

Will edit earlier post.

Norm

[Elusive R]

Thanks again, Norm. I think you're right on the OE, also, but I don't think I'm at a stock ride height, either. If lowered the rear end just an inch, the original roll steer number would go to understeer, but the new one would still stay at a slight oversteer.

Ok, new question: does the roll axis go through the rear roll center and the IC? I am under the impression that it goes through the rear roll center and the intersection of the lower control arms in plan view, but that occurs at 126" from the rear axle at 26" from the ground. If I used the IC instead, I would for sure have roll understeer.

Ryan

[Norm Peterson]

The rear axle's kinematic roll axis is defined by two points of lateral restraint. Usually these are the virtual intersections of lowers and uppers, intersection of lowers and a PHB, intersection of lowers and a Watts link, etc. In the specific case of lowers that are parallel in plan view this 'intersection' is taken to be at infinity.

Where this axis crosses the rear axle line is defined as the roll center for that end of the vehicle. IOW, the RC is defined by the roll axis rather than it being the other way around. As the suspension moves into bump or rebound, the RCH for most arrangements also moves vertically, so you can't normally use the RC as a fixed reference point.

Note that with a sloping axle roll axis, the RC will be at a different elevation than either point of lateral restraint (usually being closer to the elevation of the intersection of the uppers or the elevation of a PHB or Watts link).

Norm

[Elusive R]

Thanks once more, Norm. I think I'm calculating everything correctly, but I don't have a way to check, so I may take you up on your offer. If I have some time this weekend, I'll get you my XYZ coordinates in some kind of organized fashion. Then I'll know how far off I am with my own spreadsheet - hopefully not much.

Ryan