Boxed Rear Control Arms
J._. - What are the benefits of boxing rear control arms? I have seen a lot of people talk about doing that,but nobody says what is to be gained.
J.D. - Jeff, Boxing rear lower control arms does 2 things. Both having to do with strength. 1: Rear sway bars attach to the lower arms & boxing them makes a stronger mount & also keeps them from distorting from the twisting action of the bar. 2: If you put serious torque to the rear end a boxed arm is less likely to become a pretzel. Also, I've heard boxed arms with urethane bushings cut down on Chevelles evil problem of wheel hop.
Hope this answers your question well enough, JeffB.T. - Boxing the control arms helps stop wheel hop when the rear tires spin, urethane bushings also help so if you are going to do one do both.
C.M. - Jeff, My 66 had wicked wheel hop before boxing. After boxing the lower & upper control arms, adding a sway bar and polygraphite bushings, The car had NO wheel hop - NONE. The ride also improved significantly. - Chris
S.B. - Does anyone know where I can purchase the kit for boxing rear control arms on a '71 Chevelle?
B.D. - Someone on this site had recommended a kit by Dick Brandt at True Connections (909)688-6040. They said the kit cost less than $50. I don't know who put out this info, because I just printed the message contents. Hope this helps!
DavidB.T. - Any place that has sheet metal. A rectangular piece of 10 gauge is all that's necessary and a few pipe fittings around the sway bar mounting holes.
M.S. - I bought mine from OPGI [gag] But I must say they were good quality. I just welded them on and they look and function fine. They wont be show quality but work great.
B.D. - Do 71 rear lower boxed arms fit on 70? Are the rear uppers boxed also?
M.D. - The 71 lower boxed arms will fit on your 70, I don't think the factory ever boxed the upper arms but it could be easily done.
M._. - No need to box the upper arms, would not have any benefit. Reason for boxing of the lower arms is to support the sway bar. Without boxed arms the strain would distort the control arms.
J.T. - I want to improve the handling on my 71 Malibu and am considering installing a rear anti-roll bar in addition to some other improvements. I had assumed I would need original style boxed control arms to mount it on, but I read in a recent publication that the original, non-boxed arms would work by simply drilling mounting holes into them. Does anyone have any experience on this, or advice. Is their a downside to using the originals over boxed arms? Thanks.
J.E. - You're original non-boxed control arms will collapse if you install a sway bar. If you are going to use those, they will need to be modified so they won't. I've never boxed them before, but it should be simple.
N._. - I have seen it done with non-boxed arms before; what they did was cut some pieces of pipe just long enough that they fit on the inside of the control arm where the holes are. These chunks of pipe are needed to support the control arm, otherwise when you tighten down on the bolts that hold the sway bar on it will collapse the control arm. I believe that there are smaller pre-drilled holes on the arms where you need to drill the bigger ones, just drill them out larger.
Having said this, however, let me say that I would not recommend going this route. The boxing of the control arms increases their strength considerably, and with the sway bar acting on them the stresses are higher than it was before. You could make your own boxed arms by welding plates across the bottom of the arms after tack welding the chunks of pipe in place. I believe that I have heard of plates pre-made for converting these arms; how about it guys, does anyone know where to get these?
F.L. - OPG (1-800-243-8355) lists a Boxed Lower Rear Control Arm Conversion Kit (p/n RCAI001 - $39.95/pr) that consists of the metal reinforcement plates that can be welded to your standard arms. Ausley (1-800-228-7539) has the sway bar (cheaper than OPG -p/n SB4002 - $65). All you would need then would be shims (Year One - 1-800-950-9503 - $9/set) and the best grade bolts, washers, and nuts you can find (like Grade 8). I'd recommend installing polygraphite bushings while you're at it, too (order them at www.p-s-t.com - $100 or shop around).
F.L. - Here's a P.S. I forgot the Year One p/n for the shims - try TD4SET.
B.A. - Here's a plug for Malibu Performance's 1 3/8" Front and rear sway bars....they're expensive, but the biggest available and the work great.
(Mal. Perf. 818 222 6725)N._. - Buy the conversion kit or by arms that have already been converted. I just bought a pair af boxed arms from True Connections in Riverside 909-688-6040. His prices are a few $ less than most other places and the best thing is his customer service. The rear sway bar is by far the best improvement you can do for your Chevelle, what an unbelievable difference. Do it but do it right, it is worth every penny and then some.
M.S. - If you want the original sway bar try your GM dealer. It's still avalibile. Most of the vendors sell this same bar. If you can get your dealer to give you a repair shop discount It's usually cheaper than any vender. Don't forget when you buy mail order they tack on a pretty good shipping and handeling charge,so shop around.
B.D. - Will rear boxed lower control arms and sway bar from a 72 Monte fit on a 70 chevelle.
H50 - They will fit. The G-car used A-car chassis components, and 1973-77 lower arms will bolt in, along with the OEM sway bar or the 1977-96 GM B-car 1" sway bar.
M.H. - I have read most of the articles about boxing the control arms. My question is: Did any of the Chevelle's come stock with boxed arms from the factory? Were they options, or never available. Confused.....
B.D. - From my studies, I know 70 chevelles came with the rear boxed lower control arms with an SS package. The suspension package was F41; heavy duty springs, shocks, 1.25 inch front sway bar, 7/8 inch rear sway bar. hope this is accurate, if not someone will correct me....
D.C. - In 69 they did not come as standard equipment with the F41 suspension but in 70-72 they did.
M._. - 65 Z16 THINK, 66 SS, AND 67..... The boxed area is not a solid strap welded down. Normally with BB SS cars with posi, along with extra supports running from the upper arms forward to the forward of the lowers...
M.R. - 1964 thru 1972 Chevelle's the boxed lower control arms were used on cars equipped with factory rear sway bars, aka HD suspension! This was not just a SS only item but could be ordered on just about any car. If you are using a rear sway bar you must have the boxed arms for the bar to function as it was designed. Stock arms are just a 3 sided box but when a sway bar is installed the bottom of the arm has a steel plate welded on to support the sway bar. If you use non-boxed arms with a sway bar they will collapse and distort under the pressure. Both sides use the same arm. Year 1 has these.
M.S. - Chevelles didnt have rear sway bars until 67, possibley late 66's.. but never seen them on a 66 that someone didn't add them self....
M.S. - update:: 65-z16 had sway bar
B._. - I just picked up a brand new pair of boxed lower control arms complete with polyurethane bushing for $78. These arms are considered "blems" because they drilled the sway bar mounting holes .75" to far in. The dealer is called Performance Suspension, 1-800-572-3768. I'm not one to pump a vendor, but this deal is to good to pass up.
B.D. - With the holes .75" off, can you reuse any of the pre-drilled holes and does it cause a problem with drilling new holes. Would the new holes show or be covered? Sounds like a good deal.
I found a place in Winston-Salem that has the inserts for boxing in standard control arms, but you would still need the bushings.
Classic Muscle from Modern Chevrolet part # RCLAIF41 @$54.95/pr
H50 - Non-boxed arms can be boxed, in which pipe inserts, which measure 3/4" x 1", are used around the OEM sway bar mounting holes. A MIG welder is used to install the pipe inserts, and scraps of steel pipe will work.
A steel plate is the final link in which the arms are boxed, and a 3/16" piece is tacked on the lower side.
I have seen a mid 70s El Camino with a 1" sway bar from a 1977-96 Caprice 9C1 cop car, and the OEM hardware can be found in wrecking yards. This makes a low-dollar alternative to boxing in the lower arms, in which the OEM brackets (from a 1977-96 GM full size car) for sway bar mounting are inserted in the arms.
B.D. - On my 70, the rear lower control arms are not boxed. I can buy the parts from GM to box them or purchase new boxed arms. I'm interested in installing a rear sway bar. Thanks. Brad
B.T. - Do It! I did not know that you could still buy the inserts to box the control arms, this is not very difficult if you have access to a welder.
B.D. - do you need to mount the sway bar before boxing the control arms?
B.T. - No the sway bar can be installed later the boxed control arms have spaces bent in to access the entire bolts.
M._. - The bolts go through the entire control arm, not just one side!
F.L. - Be sure to let the car completely settle on the suspension before mounting the sway bar, to avoid locking in a pre load to the control arm bushings.
B.D. - I've gotten a bunch of inquiries regarding the arms inserts. I have a local GM shop that specializes in 64-77 Chevelles. I have not called or stopped in yet, but it's listed in their catalog. Classic Muscle from Modern Chevrolet. Winston-Salem, NC 1-800-722-4828. Ask for Rick or Lee. The part # is listed as RLCAIF41, Inserts Only (for boxing in standard arms) @$54.95 pr. Hope this helps everyone. Let them know Brad Duffner sent you. I live in Advance and purchased my 70SS conv from a mechanic in that shop two years ago. Good Luck guys.....
A.L. - I just picked up a set at a swap meet for 30 bucks, so keep your eyes open.....
R.G. - If you guys are not worried about keeping the car stock, try a set of Hotchkis rear control arms. There a little pricey, about $500.00 for all four control arms. But there worth it they eliminate wheel- hop, give car better launch and they look great.
R.A. - I JUST BOUGHT NEW GM BOXED ARMS WITH OEM RUBBER BUSHINGS INSTALLED, 225.00 A SET FROM GROUND UP RESTORATIONS IN NEW HYDE PARK NEW YORK,11040 THE PHONE NUMBER IS (516) 248-4567 ask for ken.
B.D. - I keep seeing ref to a "spacer" on the rear control arms for rear sway bars. Just a few questions:
1. What should this 'spacer' be made of (size, thickness, etc...)?
2. Where exactly should it be placed on the arm?
3. Is there some documentation (book, mag, whatever) where I can learn about this? (I have read the tech article in Chevelle Tech).
4. Should I purchase an after market rear sway bar, should I pull one from the salvage yard (my dad's friend owns a yard: cheap parts!)? What years/models would be best to use?
I am working on a '70 Chevelle on a tight budget and have a father who owns a welding/Mfg shop (cheap labor!). Sorry if these are dumb questions - but I just don't know.
Anyway, thanks for your assistance (not only on this problem, but your many responses on Tech that has help me this far!).
T.B. - David, spacer(s) goe between the control arm and the sway bar. they are only about a tenth of an inch thick. I believe that correct installation should include installing a max of five shims. Year one sells a complete sway bar kit (including nuts, bolts and spacers for about $100 - $200. You can also order a kit to box your lower control arms (a must if using the factory rear sway bar) for about $35.
D.C. - David, If you were to install a bolt through the control arm (which is how the sway bar bolts on)and tighten it, it would colapse or squeeze the sides of the control arm together. There is a short piece of tube that goes inside the control arm for each bolt, it's length is the same as the inside width of the control arm. The sway bar mounting bolts goes through these "spacers" inside the control arm to prevent this from happening. I think 1/4" pipe has about the proper inside dia. for the job.
W.V. - David; Here is what I learned when I "boxed" the arms on my 64 wagon;
As stated in the prior posting, the "spacers" are to prevent collapsing the arms when you tighten down the bolts for a sway bar.
You could go to a steel supply shop and just get the thickest wall tubing that they have, that still has the correct inside diameter. There are two spacers required per arm (yes, I know that it seems dumb to say, but I thought I'd just say it).
When I purchased my rear bar from OPG (an ADDCO unit), it came with the spacers.
I located the holes by holding the bar in place and marking the arms with a felt marker.
Pull out the arms, drill the holes, install the spacers, put in the bolts, tighten the bolts, THEN have the spacers tack welded in place.
You can then weld on the "boxing" plate.
I just got some 1/8" by 2" flat plate from Home Depot and used it. The plate is about 24" long.
The "shims" that are refered to go between the sway bar and the control arms. The reason for this is that the sway bar is a certain width (bolted section to bolted section). The control arms are at a certain width (distance apart) based upon the frame and rear end. The shims are added to prevent the sway bar from pulling the arms together (towards the center of the car) and as a result, side loading the bushings. You could use fender shims if you wanted. My bar didn't require any shims.
Wes.
C.M. - David, I believe any sway bar from a 64-72 A body will interchange. They should all be 7/8 inch diameter. As long as it's not bent or damaged it should be just fine. If you want super stiffness, call Malibu Performance @ 818-222-6725. I think they offer one in 1 3/8 inch.
Chris MartinArchivist: Tom Wilson
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