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Herd WebMaster
Forum Admin
USA
165 Posts |
 Posted - 04/13/2007 : 2:47:44 PM
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Swaybars Setup
By Scott Mueller.
One of the best mods anybody can make to their '94-'96 Impala SS (or for that matter any '77 or up GM B-car) would be the installation of the Herb Adams/Matt Adams VSE (Very Special Equipment) stabilizer (anti-sway) bars. These monster bars will make your Impala feel much more stable and corner incredibly flat, you might actually think you are driving a Z28! The Impala will feel like it lost 1,000 lbs. with these bars installed, and the cornering limits will be beyond what you ever could expect for a vehicle this large.
Herb Adams was one of the designers and engineers of the original '69 Pontiac Trans Am, and I believe he also worked on the '73-'74 455 Super Duty Trans Ams as well. He quit Pontiac in the early '70s seemingly over the bean counter and government related politics that hamstrung any performance car projects at the time. His focus since then has been racing applications, and he has always specialized in suspensions, especially stabilizer bars (anti-sway bars). Recently his son Matt Adams has taken over the VSE business. Their philosophy for maximum handling performance is to recommend softer rate (stock type) springs to allow the wheels to travel, and then add cornering control through the use of very high rate stabilizer bars.
You can get the Herb Adams swaybars either direct from Herb Adams VSE (their number is 408-649-8423, tell them I sent you!) or from Summit racing, however a better version of the front bar is only available from Herb Adams VSE directly.
You can get the rear bar from Summit racing (216-630-0200) under the Herb Adams/Moroso name, part number MOR-86516 ('77-up B-car, cost $119). They also carry the front bar under part number MOR-86015, however they only carry the bar with heim joint end links. These end links are very strong, but they are designed for racing and will rapidly wear out and rattle on the street in my experience, plus they are expensive to replace. Instead, if you purchase the bars from Herb Adams VSE directly you can get the front bar modified to use tie-rod end links (included). The tie-rod end links are even stronger than the heim joints, plus they greasable and have sealed bearing joints that do not wear out on the street.
I would definitely NOT order the front bar through Summit as you will only get the version with heim joint end links that wear out rapidly and once they wear, they start to rattle. Replacing them is almost as expensive as purchasing the whole bar. Instead you should get the front bar direct from VSE modified for tierod end links, and it is only sold that way through VSE directly. The bar has to have different ends welded on to accept the vastly superior (greasable) tierod links.
Because most of their products are intended for racing, they are often of the "some assembly required" type. That is the reason for the additional instructions and hardware recommendations I have written.
As far as installation goes, you have to consider that the Herb Adams bars come with no attaching hardware, and there are only minimal instructions to speak of. You can order an optional installation kit for the front bar, which consists of clamps and bushings, but I would recommend instead re-using the stock clamps, and new bushings and bolts that I will specify. If you need more detailed installation instructions, use the factory service manual or the information I am giving here as a guide, since these bars install in exactly the same manner as the factory bars. The big difference is that you CANNOT re-use the stock mounting hardware, or at least you SHOULD not.
Here is what I recommend:
To install the Herb Adams front bar (1-5/16" or just over 33mm) you absolutely CANNOT re-use the stock rubber center bracket bushings. The brackets are fine, but the bushings are designed for only a 30mm bar, and simply will not fit around the larger 33mm bar. I don't recommend using polyurethane aftermarket bushings either (such as supplied by Herb Adams in their optional installation kit), as in my experiences the bar will abrade the inner bushing hole, wearing it oversize until the bar begins rattling around inside the hard urethane bushings. Hard urethane bushings also tend to squeak, unless you are constantly lubricating them. Energy Suspension (714-361-3935) makes a new design urethane bushing and bracket which feature internal passages and grooves to hold grease. The brackets feature a grease fitting to make re-lubing easy. These will probably work well, but I have an even better recommendation.
Instead of urethane center bracket bushings I would recommend a factory replacement bushing from another GM application. The stock bushings feature a 30mm hole, are made of soft rubber, and have no fiberglass liner where the bar runs through them. I recommend you replace these with factory 32mm high durometer (hard rubber) bushings that have fiberglass liners. The liners prevent wear and friction, and totally eliminate noise as the bar rotates in the bushings. These are available under GM part number 10288551 (32mm). These bushings are from the F-car parts catalog, by the way. The 32mm bushing is from a '93+ F-car with the special 1LE suspension.
Now, on to the brackets and bolts. The bushings I just listed have the same basic form factor of the stock bushings (except the larger hole for the larger bar), so the stock brackets (clamps) can be used. The bolts, however should be changed. The original bolts are a metric M10x1.5 30mm prevailing torque bolt. I do not like these bolts at all and absolutely recommend you DO NOT re-use them. The problem is the prevailing torque feature means they have distorted threads that will strip the threads in the frame if installed more than once, as well as making it very difficult to "feel" how tight they are when you are installing them, causing you to easily strip the threads.
If you look at these bolts, you will see that the threads are distorted into a triangular shape, which makes them difficult to insert and remove, and virtually guarantees that you will strip the threads on re-installation. If you strip the threads, you will then be required to install either a 10x1.5mm rivnut or a 3/8" nutsert, which are devices that place a captive nut behind the frame. This is actually much stronger than the stock setup, which has the bolts simply threaded directly into the frame itself with no nut behind! When you see how thin the threaded area is you will be surprised.
If you want to avoid stripping the stock 10x1.5mm thread holes, then I recommend replacing the stock bolts with non-prevailing torque bolts of the same size. These will tighten much more easily, and you will know when they are getting too tight. One problem is that the stock bolts are metric and have a very small 10mm hex head to allow for wrench or socket clearance for installation and removal.
If your stock threads in the frame are not stripped, then there are several ways to go for a replacement non-prevailing torque bolt. The factory offers a perfect replacement bolt in a non-prevailing torque version which is even stronger than the original bolts. Part number 15959689 is an M10x1.5-25mm bolt that fits perfectly in place of the stock bolts (4 are required). This is a virtual duplicate of the original bolt, except it is much stronger (metric 10.9 grade), and has a slightly larger flange. The extra strength is really not necessary, as these bolts thread directly into the soft frame metal, but it can't hurt. The head is exactly the same small 10mm hex head as the stock bolts, and it already has blue loctite applied to the threads!
If you are in a bind, you can probably get M10x1.5 25mm or 30mm standard (non-prevailing torque) thread bolt with a small internal hex cap head from the hardware store. Socket head bolts have small cap heads that will easily clear the bracket, and you can use a large (8mm) allen key or allen hex tool to tighten them. Conventional hex head bolts do not leave enough room against the bracket to work properly, and you cannot get a wrench or even a thin wall socket on them easily.
If you want a "show quality" bolt, then you might want to try some hardware from a company called Totally Stainless (800-767-4781). Their motto is "In Stainless we Trust, In Chrome we RUST!" They specialize in nothing but stainless steel fasteners, and have an excellent catalog that every car crafter should have. They have high strength M10x1.5 25mm bolts with hex socket cap heads in pure stainless steel which will never rust or corrode, and which do not feature the distorted threads of the stock bolts. They are available under part number 1-1273 (4 are required). Use loctite 242 (blue) to prevent them from loosening, and to act as a lubricant when they are being installed. These are what I recommend if you have not stripped your stock threads. Tell Totally Stainless I sent you!
If you strip the threads in the frame, you will have to either get an M10x1.5 nut (also available from Totally Stainless) on the inside of the frame rail (which is very easy to do on the RH side, but difficult on the LH side), or install a "nutsert" type fastener. Nutserts are special nuts that are installed through the frame holes, and then a special tool (included when you buy them) is used to crush them against the inside of the frame rail, where they will stay. Then you can use a conventional bolt to tighten the bracket. In most cases, installing the nutsert will require that you drill the frame holes out to a larger dimension, but in the end you have a much stronger set of threads than the stock setup. Nutserts are available in english sizes only, so you will need to get new bolts to go with the nutserts.
If you are using the nutsert approach, then I recommend a hex cap head bolt in whatever size is required by the nutsert threads. A 3/8 version would be the closest to the factory metric size and would fit the best. The bolt should be a 3/8" diameter by about 1-1/4" long, and should feature the small internal hex cap head. I recommend Totally Stainless as a source for these, as they have them in special high strength versions with small hex heads just like the stock bolts.
For the rear bar, the mounting system may vary. '94-'95 and early '96 Impalas used the same rear bar mounting system used on all B-car since '77! In mid-'96 the factory changed the rear bar mounting hardware for even greater durability.
The standard mounting system uses english 7/16" by about 1-5/16" long bolts are clearly inappropriate. Yes it is true that the factory front bar is mounted with metric hardware while the rear bar is mounted with english hardware! The factory rear bolts feature only 1-1/4" of thread length after the 1/8" thick washer is installed, and the Herb Adams rear bar is 1" thick at the attachment points. This leaves only about 1/4" of thread to engage the nut in the control arm bracket (absolutely not enough!). Instead I recommend you use a longer bolt with the same 7/16" diameter as the stock one.
Absolutely the BEST bolt for the rear bars using the older mounting system are the ARP Grade 8 stainless steel bolts. These are available in a 7/16" diameter by 2-3/16" long version, that leaves over 2" of thread after the 1/8" thick stock washers are installed. These are also available from Totally Stainless as part number 2-0852 (4 are required). These bolts are absolutely a work of art, in fact they are aerospace quality and just beautiful to look at. I have extra ones in stock just so I can occasionally pick them up and admire them, but then I am not normal!
If you have the mid-'96 or newer mounting system, then you have very long metric bolts (M10x1.5-110mm) that run all the way through the lower control arm. You will also need longer bolts, I recommend the factory M10x1.5-120mm bolts which are part number 11508196, and are the same metric 10.9 grade as the shorter originals. Except for the finish and length, they are the same as the original bolts. With these I recommend a special high strength flanged prevailing torque nut part number 10255857. You will need 4 bolts and 4 nuts to complete the installation.
If you have the new style mounting system, then you could use stainless fasteners, but you would have to switch to english as nobody makes metric ones that long in a high strength version. Totally Stainless does have ARP high strength (stronger than grade 8) long 7/16 bolts you can use, but you would have to slightly enlarge the hole in the control arm and the small metal lower bracket to use them, plus you'll need to find a high strength nut as well.
In summary, you will need 4 bolts to install the front bar, and 4 bolts for the rear, plus 4 nuts if you have the new design rear lower control arms on your car. These bolts can be ordered from your dealer, or in some cases optionally from Totally Stainless.
For the HA front swaybar I recommend the following bolts from GM:
Qty p/n Description
---------------------------------------------------------------
4 15959689 M10x1.5-25mm Grade 10.9 small hex bolt w/flange
Optionally you can substitute the following bolts from Totally Stainless:
Qty p/n Description
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4 1-1273 M10x1.5-25mm Stainless socket cap head bolts
To install the rear HA swaybar on cars with the 1st design ('94-early '96)
rear lower control arms I recommend the following bolts from Totally
Stainless:
Qty p/n Description
---------------------------------------------------------------
4 2-0852 7/16"x16 2-3/16" ARP Grade 8 Stainless bolts
To install the rear HA swaybar on cars with the 2nd design (mid-'96) rear
lower control arms which uses longer bolts and nuts that go completely
through the arm from the top, I recommend the following hardware from GM:
Qty p/n Description
---------------------------------------------------------------
4 11508196 M10x1.5-120mm Grade 10.9 hex flange bolts
4 10255857 M10x1.5 flanged prevailing torque nut
Hopefully the information I have provided here will help those of you who are considering the Herb Adams bars as until you have driven a car with them, you don't know what you are missing! |
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Swaybars Setup
