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Modifying for Tubular Control Arms
Posted by: mechanicalman ()
Date: December 02, 2012 01:45AM

Hey guys,

I'm thinking about rebuilding my front end with tubular control arms, mustang II spindles, and eventually mustang II disc brakes. Something similar to what Jim Acker did on his SBC Vair running a 930 transaxle.

I know he modified the spring tower by welding a plate over the stock mounting points to accommodate the wider mounting points of the control arm that he used, but can anyone post what the stock mounting point width is?

He also modified the Mustang II lower control arm with a heim joint instead of using the stock bushing, but if one wanted to use the stock bushing, would the bracket on the crossmember need to be modified, or will it work as is?

If someone has a lower control arm bushing handy, posting the dimensions would be helpful.

=================================================

'65 Black Monza Coupe w/black interior
110HP w/4-spd

Greetings from Oakland, CA!

no trim badges anywhere (and there never will be!)

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Re: Modifying for Tubular Control Arms
Posted by: Vairforce1 ()
Date: December 02, 2012 03:02AM

mechanicalman-

I've been doing some reading about how to improve 60's-era suspensions (http://books.google.com/books?id=HS4zUh_uJ_kC&printsec=frontcover&dq=inauthor:%22Mark+Savitske%22&hl=en&sa=X&ei=GSKjUOXaJIjQ2AWwnIAw&ved=0CC0Q6AEwAA#v=onepage&q&f=false) and have been researching what other sharp Vair owners have done recently. Here are some interesting projects:

Carlos' (carango) suspension
[corvaircenter.com]

Mel Francis' GT3 build:
[www.flickr.com]

Tom Z's Mustang II front suspension adaptation
[corvaircenter.com]

1bad67's modded upper control arm
[corvaircenter.com]

Jonathan Knapp's modded upper control arm and disc brakes
[corvaircenter.com]

Rick Norris' Yenko Stinger clone with modded caster adjusting rods (scroll all the way down to the section about suspension)
[corvairalley.com]

As for Mustang II spindles, I recently discovered something called a Smart Spindle, which is forged with a 2" drop that allows you to use GM midsize (G-body, I think?) rotor, calipers, bearings, and seals. If this is indeed based on G-body specs, this would allow you to mount metric D154 brake calipers. Wilwood has some attractive calipers - see [www.wilwood.com] as well as hubs and rotors (see Jonathan Knapp's link for his Wilwood brake setup).

The way I look at it, one suspension mod naturally leads to another, so pretty soon you have some serious engineering going on and a lighter pocketbook - but a Vair that is going to handle like God meant it should (again, read Jonathan Knapp's mods for correcting Ackerman and bump steer).

I'm looking forward to discussing this topic.

Dave

Dave Muhlena
Cedar Rapids, Iowa
'65 Corsa 140 project - going nowhere, fast!

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Re: Modifying for Tubular Control Arms
Posted by: mechanicalman ()
Date: December 02, 2012 08:31AM

Wow, that's some really good info.

I didn't find much just searching for "tubular control arms."

It looks like nearly everyone that installed upper control arms did it by modifying the spring tower for new mounts, but it's not totally clear to me how they did it. I would worry that simply welding another plate over the top to provide for wider mounting points would also have the effect of shimming the control arm inward.

It looks a bit like Carlos, cut fitted plates and welded them to each side of the spring tower versus welding one piece of stock to the inboard side of the tower, which is what it looks like Jim did in this picture

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Re: Modifying for Tubular Control Arms
Posted by: Tom Z ()
Date: December 02, 2012 01:33PM

..I have a pair of NOS Mustang ll lowers, a pair of new Speedway 'repros',plus the whole stock front end cut off a car..my first priority was to get better lower BJ's,but just putting them on a Corvair LCA means cutting the end and losing strength..I also wanted to use the pack/pinion BTW..the upper and lower control arm 'pivotpoints' are in different locations, and wouldn't jive with the stock Corvair steering, so it's "all or nothing"..Michael LeVeque sells modified 2" dropped (2wd s10/G-body) spindles,and runs them on his car, so unless you've got your own fabrication shop w/ a modern alignment machine to use, those would be your best bet (IMHO..)

Tom Z,,Rochester NY


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Re: Modifying for Tubular Control Arms
Posted by: carango ()
Date: December 02, 2012 02:52PM

I did not weld tabs on the sides, i cut down the back to make it flat with a sawzall, and bad one plate for the upper , kept the mounting holes in line with th old mounting holes, just wider for mustang 2 a arms, i also uswd the 5/8 narrower arms and mustang 2 2" drop spindles. you can get bearings to use GM hubs on mustang spindles., i can get you the numbers or look at speedway . i`m actually using my corvair hubs on the mustang spinles. and pro-shocks make adjustable coilovers that fit the corvair tower. they even make a shorter shock and spring

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Re: Modifying for Tubular Control Arms
Posted by: carango ()
Date: December 02, 2012 02:59PM

i forgot to mention that you can get 2 mustang2 2' drop spindles, and 2 upper control arms with ball joints on them for $237 including shipping on e-bay. i just bought another set, i have to make a new left side after a bad wreck. you can also get a threaded ball joint sleeve from speedway to make you lower arm, and use speedways late 60`s chysler threaded ball joint, thats what the uppers come with and they fit the mustang spindles.

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Re: Modifying for Tubular Control Arms
Posted by: 66cv8 ()
Date: December 02, 2012 05:09PM

No flex with my strut rod setup. 100% feedback to the steering wheel ya need to hold on with this stup. Not for the average driver.

Joe

66 500 Crown 350/4 on road
66 Corsa Convertible 140/4 rough
69 Monza Convertible 140/4 in progress (original 95/3)
Nu Joisey

" A LITTLE KNOWLEDGE IS A DANGEROUS THING"

"STUPID is the NEW SMART"

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Re: Modifying for Tubular Control Arms
Posted by: snapon13 ()
Date: December 02, 2012 06:12PM

Question for Joe, does yours have power steering?

1963 Monza, gone but still my first!
1966 Crown V8-LT1, since 1970
Ithaca NY = Long winters in the garage.
"It will have enough power when the rear wheels are still spinning
on the entry to the next corner at the end of the straight" as told by Mark Donahue.

My YouTube videos here: [www.youtube.com]
My 2010 rebuild photos here; [s683.photobucket.com]

Photobucket
------------1966 Crown V8------------2013 CORSA Convention Tweety's---"Ralph Who" can ride!!---at VIR Corvair Olympics 2013-

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Re: Modifying for Tubular Control Arms
Posted by: 66cv8 ()
Date: December 02, 2012 06:40PM

snapon13 Wrote:
-------------------------------------------------------
> Question for Joe, does yours have power steering?


Nope, power arms. 2.5 lock to lock. Would be nice though maybe power assist in the future.

Joe

66 500 Crown 350/4 on road
66 Corsa Convertible 140/4 rough
69 Monza Convertible 140/4 in progress (original 95/3)
Nu Joisey

" A LITTLE KNOWLEDGE IS A DANGEROUS THING"

"STUPID is the NEW SMART"

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Re: Modifying for Tubular Control Arms
Posted by: snapon13 ()
Date: December 02, 2012 06:57PM

I dont recall lack of power assist even being something that I thought about back-in-the-day when I had power armstrong!, but as I get older boy do I miss it at an autocross!! I may add it this winter along with power brakes. Still researching the best way to do it. The electric racks are looking good.
Dave

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Re: Modifying for Tubular Control Arms
Posted by: Jonathan Knapp ()
Date: December 02, 2012 10:51PM

Mechanicalman,

My upper control arms are custom built units (from Eric Aos in Portland, OR) that use the stock Corvair pivot shaft. They are built for Delrin bushings and for the different bolt-pattern of a late Chevelle long-stud, low-friction upper ball joint (Speedway). Modified steering arms account for the improved ackerman. Scalloped, vented, and drilled rotors (Speedway) weigh only 5.09 lbs. Wilwood Dynalite dual piston calipers have the 1.75" pistons. Caliper brackets are custom made stainless units.

Vairforce1 is right. The pocketbook does get lighter but it doesn't just start to handle like God intended, it handles like a god!

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Modifying for Tubular Control Arms
Posted by: carango ()
Date: December 02, 2012 11:15PM

mine has late 90`s mustang power steering, and it drove incredible. going to start pulling on it next week

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Re: Modifying for Tubular Control Arms
Posted by: mechanicalman ()
Date: December 03, 2012 03:20AM

So I heard a lot about options for upper control arms and it doesn't sound too difficult it you use 5/8" narrow Mustang II arms like these. But it sounds like most of the people that went with lower tubular arms had to go with custom ones or make their own like Carlos did.

Are there any good options for tubular lower control arms that don't involve a lot of fabrication? Jim Acker modified stock type Mustang II lowers with a heim joint, but he also used strut type uppers with a long-stud ball joint.

What are the issues with using Mustang II lower arms like these if I wanted to go with coil-overs? They're 13.5" from ball joint center to control arm bushing center. How does that match up with the Corvair lower control arm?

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Re: Modifying for Tubular Control Arms
Posted by: Vairforce1 ()
Date: December 03, 2012 05:28AM

One thing I've noticed with the modded upper control arms is that the horizontal positioning of the arms are angled down towards the rear of the car, just as in as in the stock orientation. Is there any benefit to altering this orientation, as in making them more level?

Another thing that could be done to improve upon camber would be to perform a version of the Guldstrand mod, whereby the upper control arm mounts are moved downward and slightly rearward. However, it looks like there is little room to allow this, so some cutting and welding of the mounting plate would be necessary, though I don't know if this would interfere with the range of motion of the arm. Using a longer upper ball joint is probably the easier way to attain improved camber.

Dave

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Re: Modifying for Tubular Control Arms
Posted by: Vairforce1 ()
Date: December 03, 2012 05:32AM

mechanicalman Wrote:
-------------------------------------------------------

> Are there any good options for tubular lower
> control arms that don't involve a lot of
> fabrication? Jim Acker modified stock type Mustang
> II lowers with a heim joint, but he also used
> strut type uppers with a long-stud ball joint.
>
> What are the issues with using Mustang II lower
> arms like these if I wanted to go with coil-overs?
> They're 13.5" from ball joint center to control
> arm bushing center. How does that match up with
> the Corvair lower control arm?

mechanicalman-

This may help: [corvaircenter.com]

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Re: Modifying for Tubular Control Arms
Posted by: Jonathan Knapp ()
Date: December 03, 2012 07:24AM

I'm not going to go so far as to say that you are wasting your time with tubular lower control arms. Jim Acker (my friend and fellow Seattle resident) has one of the most beautiful street cars I have ever seen top-side and bottom-side. The all-tubular front end has great sex appeal. However, I have not found that the Corvair LCAs are any kind of a limiting factor in the development of a truly high-performing front end.

If I remember correctly, Jim has followed my example and gone back to Corvair spindles after trying Mustang II spindles. The one-piece Mustang II spindle/steering arm has the steering arm in nowhere near the correct position for good ackerman. The Corvair spindle has bolt-on steering arms. Corvair steering arms can be cut, repositioned and rewelded according to the wheel and brake configuration you have to give much better ackerman.

The upper A-arm does not need to be changed because its cross-shaft needs wider mounting holes or because it needs to have its tilt changed or because you can't get good bushings for it. None of those things are a factor. I changed the upper A-arm for one reason: to be able to run a long-stud ball joint. That change alone completely alters the suspension geometry, giving significant negative camber gain on compression and positive camber gain on extension. The change also moves the car's front roll center up much closer to the car's center of gravity, reducing (but not eliminating) the need for roll stiffness (sway bar).

A stock Corvair front end lowered with cut springs actually has a little bit of positive camber gain on compression! While this may be good for straight line stability and good tire wear at modest speeds, this is not good for going fast around corners.

The gains in Corvair front end performance are found in: 1) moving toward optimal ackerman, 2) changing the suspension geometry to give proper negative camber gain on compression and raising the roll center. While the idea of tubular LCAs may be appealing to some people for other reasons, neither of these issues can be addressed with different lower control arms. I have addressed #1 extensively here before on CCF (ask Jim Acker why he went away from Mustang II spindle/steering arms back to Corvair spindles and steering arms). #2 was confirmed (if you don't think my results are proof enough) by Curtis Wood and Bob Coffin on a recent thread about front suspension modifications over on FastVair.

Hope that helps contribute to the understanding.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Modifying for Tubular Control Arms
Posted by: mechanicalman ()
Date: December 03, 2012 09:12AM

Man, I'm really glad I started this thread. I'm really learning a lot.

Jonathan,

What exactly did you do to correct the Ackerman geometry in your setup? Just heat and pound the steering arms? Are they modified stock or did you modify quick arms?

I also noticed in your setup that you didn't alter the strut rod or replace it with a heim joint like a lot of guys did. Any reason for that?

Finally, you don't feel there's any advantage to running a coil-over setup or you just don't feel the gains are worth the money?


\\Jim sure looks like he's running Corvair spindles in that album I linked to.

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Re: Modifying for Tubular Control Arms
Posted by: Jonathan Knapp ()
Date: December 04, 2012 06:43AM

Mechanicalman,

I started with aftermarket quick arms, cut them, then ground the two pieces down to a point where they were to connect back together. Once they were positioned correctly relative to each other so that they fit right up tight behind the brakes(built a jig) I used the MIG to weld across the joint from four angles (top, bottom, each side). Then I ground the weld down with a die grinder and blasted it to relieve stress. From there I went back with successive passes of welding, grinding and blasting until the whole arm was built back up to the approximately 1" square solid steel arm that it started out as. So in the end there is no seam that I welded across. The whole arm is one piece of metal again through and through.

I did not replace the strut rod with a Heim-joint set-up because my front spring rate is already a little weak and the stock strut rod (especially with high durometer bushings) adds to the spring rate as it deflects from its static position on compression.

It takes a lot of work to figure out the correct spring rates. I know that coil overs offer the opportunity to change springs more easily, however there is a considerable expense involved. The price of high quality coil-over shocks and springs and the cost of fabricating a modified crossmember kept me from going that route. I already had Bilstein shocks that I am very happy with and they are already paid for. Alternative springs are relatively cheap. Furthermore, proper suspension geometry is not dependent on a coil-over design. I could attain the camber gain and roll center I wanted with a custom upper A-arm that holds a long-stud upper ball joint. The cheapest solution is the best solution in my book. As for many people, money doesn't grow on trees for me.

Jonathan Knapp
Seattle, WA
'66 Corsa Autocrosser

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Re: Modifying for Tubular Control Arms
Posted by: mechanicalman ()
Date: December 11, 2012 06:07AM

Wow, thanks for all the good info. I feel like I've got a good place to start from, but I'm left wondering... what do the guys with MSII front-ends do when they want correct Ackerman geometry for a specific application if the steering arms are part of the spindle? Just cut and weld and fab like you did? Seems like someone would've figured out a bolt-in solution for that by now.

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Re: Modifying for Tubular Control Arms
Posted by: MattNall ()
Date: December 11, 2012 06:22AM

MM... placement of the Rack alters ackerman to a degree.





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