Here's some advise form the B-Body web page and Scott Mueller.... See below
Installing Herb Adams Sway Bars
These sway bars will make your Impala feel much more stable and corner incredibly flat. 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 is the original designer and engineer of the '69 Pontiac Trans Am, and he also did the '73-'74 455 Super Duty Trans Ams as well. He quit Pontiac around '74 seemingly over the bean counter and government related politics that hamstrung the whole Super Duty project. You can get the Herb Adams swaybars either direct from Herb Adams VSE (their number is 408-649-8423 (or try 831-659-7660), 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.
Herb Adams' current focus is on racing cars, and most of his products are of the "some assembly required" type. Be prepared for some work, improvisation, and fabrication.
(1) Herb Adams Front Bar (with Tie Rod Ends - 33mm)
(2) Replacement Bushings
GM PN 14094388 (34mm)
GM PN 10288551 (32mm) Recommended/easier fit
(4) Replacement Bolts (non-stripped)
Totally Stainless PN 1-1273
GM M10x1.5x25mm PN 15959689
(4) Replacement 1/8" Washers
Totally Stainless PN ???
(4) Nuts (just in case you strip the frame threads)
Totally Stainless PN ???
GM PN ???
Rear Bar on a 94 Caprice Wagon w/Metco Wgn Arms
(1) Herb Adams Rear Bar
(4) Replacement Bolts (cars without newer style trailing arms)
Totally Stainless PN 2-0852
GM M10x1.5x110mm PN
(4) Replacement Bolts (cars with newer style trailing arms)
Totally Stainless PN
GM M10x1.5-120mm PN 11508196 (changed to 11504610?)
(4) Replacement 1/8" Washers
(4) Replacement Nuts (prevailing torque)
Totally Stainless PN
GM PN 10255857 (Changed to 11502812?)
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 $166.69). 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 will rapidly wear out and rattle, and they are very expensive to replace. Instead, if you purchase this bar from Herb Adams VSE directly you can get the bar modified for tie-rod end links (included). The tie-rod end links are even stronger than the heim joints, and they are greasable and do not wear out.
If you 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. Contact Herb Adams directly at 408-649-8423. The front bar with the tie-rod end links is around $320. It also needs to be mentioned that people have been unhappy with purchasing directly from VSE. Months go by without receiving their front bar. Use this information at your own risk.
Procedure (from Scott Mueller ):
You have to consider that the Herb Adams bars come with no attaching hardware, and there are really no instructions to speak of, so you are on your own. If you need instructions, use the factory service manual or the information I am giving here as a guide, since these bars install in 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 (33mm) you absolutely CANNOT re-use the stock rubber bushings. These are designed for only a 30mm bar, and simply will not fit around the 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 hole, wearing it oversize until the bar begins rattling around inside the hard urethane bushings. Hard urethane bushings also tend to squeak a lot, unless you are constantly lubricating them.
Instead 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 or 33mm High Durometer (hard rubber) bushings that have fiberglass liners. The liners prevent wear and totally eliminate noise as the bar rotates in the bushings. These are available under GM part number 14094388 (34mm) or 10288551 (32mm).
The 34mm bushings have exactly the same external dimensions as the original 30mm soft rubber bushings used in the Impala, however I have found that because of their high durometer (hard) rubber construction, they are sometimes difficult to compress in the stock Impala clamps. If you find this to be the case, then I recommend you use the smaller 32mm bushings. The smaller bushings will still fit around the bar, although a bit more tightly, and their smaller external dimensions will also fit inside the stock clamps a little easier. Either of these seem to be tailor made for installing the Herb Adams 33mm front bar in the Impala! These bushings are from the F-car parts catalog, by the way. The 34mm bushing is from an '85-'92 F-car, while the 32mm bushing is from a '93+ F-car with the special 1LE suspension (pn #10288551).
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 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 will 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. 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.
If your stock threads are not stripped, then I recommend an M10x1.5 25mm or 30mm standard (non-prevailing torque) thread bolt with a small internal hex cap head. The small cap heads 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.
The absolute best bolt for the job I have found is available 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 locktite 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.
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.
For the rear bar, the stock 7/16" by about 1-5/16" long bolts are clearly inappropriate. They 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 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 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!
Here are some installation tips for installing the Herb Adams swaybars, compiled from various sources.
Herb Adams Front Bar Installation Tips
Make sure you have the bar oriented the correct way, the tabs should be pointing UP, not down.
Get two floor jacks:
Use the one to hold the bar up firmly against the underside of the car be centering the bar on the jack and raising it until it is firm against the frame.
Use the second jack to compress the brackets onto the bushings.
The Herb Adams front bar torque specs:
Frame bushing bolts... 35 Ft/Lbs
Control arm mounting blocks... 80 ft/lbs
Stover nuts (castle nuts) that go on the tie rod ends...just put a box end wrench on them and tighten them up
Front Bolts, Bushings and Clamp preference order:
RIVNUTS(Stainless bolts), 32mm Bushing, HA Clamp
Stainless Bolts, 32mm Bushing, Stock Clamp
Stainless Bolts, HA Bushing, HA Clamp
HA front Bolts, HA Bushing, HA Clamp
As a quick work around you can try to get M10x1.5 nuts behind those holes if one of them becomes stripped. You can not reuse the stock bushings. The F-car 1LE 32mm bushings are p/n 10288551.
It is recommended to use Liquid Wrench on the bolts to the frame and control arms to help prevent them from being stripped.
Put the bushings on the bar and squeeze the clamps on with the vice, this spreads the clamp out a little at the base, which in turn widens the distance between the holes. Then squeezed the clamp on the sides to narrow that distance back to where it should be. When the bar is in place, the holes should line up perfectly, hence no striping of the threads. Using a floor jack with a block of wood, press the clamps on and install them relatively easy.
Sometimes there might still be about 1/8" space when fully tightened. Shim the gap between frame and clamp with 1/8" thick washers and Loctite Blue.
An alternative method is to take a Dremel tool with a coarse sanding drum and carve out the rubber so that the bushing will fit into the clamps. Cut a semi-circular cross section groove that goes around the bushing. It probably makes the bushings a bit stiffer, but that's rarely considered a problem.
The bushings then sit in the clamps and protruded just a bit just like stock clamps and bushings. No jacks needed, just put them in place and bolt them down.
Install steering stops p/n 10225366 RH and p/n 10225365 LH or just bend the stock steering stops to avoid the tires from hitting the bar.