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    *Technical Service Bulletin* Suspension Upgrade

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    Sweet Seventy9
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    *Technical Service Bulletin* Suspension Upgrade

    Post  Sweet Seventy9 on Fri Jan 24, 2014 11:17 am

    This will work on all 77-90 B-bodies.


    Suspension Upgrade
    By Scott Mueller
    I have found a suspension upgrade that everybody SHOULD be interested in. I know that it will be considered expensive by some, but after you read this I'm sure you will agree it is important.

    I found out that GM made a significant upgrade to the front lower (load bearing) ball joint in the 9C1 Caprice for late '95 and '96 ONLY. This upgrade was ONLY installed in late '95 and '96, and ONLY in 9C1 (Police) and 9C6 (Taxi) cars as well as 1A2 (Special Service) wagons. All other B-cars INCLUDING the Impala were NOT upgraded in a
    similar manner, although IMHO they should have been.

    Note that although the Impala was largely derived from the 9C1 (police) package, the 9C1 cars are actually better in many ways compared to the Impala. This ball joint change is a perfect example. 9C1 cars use an SEO (Special Equipment Option) 7B3 suspension, which in many ways is better than the FE4 (Special Handling) suspension used on the Impala. Only Caprices with SEO 7B3 get the big joints, and only in late '95 and '96.

    What I found out is that the Caprice and Impala use a standard 9/16" front lower ball joint. This is the joint that carries the bulk of the front end load, and is highly stressed in cornering and braking as well. Starting in late '95, the 9C1 and 9C6 cars used an upgraded 5/8" ball joint, which was taken from the D-car (Fleetwood) Limo
    package. This ball joint is SIGNIFICANTLY stronger and more durable.

    I spoke with a friend who has worked as a mechanic in a local municipal shop for many years and he says they have been breaking 9C1 ball joints like crazy. I asked him what happens when they break? He said "the wheel folds up into the fender, and the car comes in on a wrecker!" Needless to say you don't want this happening while you are cornering at high speed. In fact two of their cars crashed when the joints broke, fortunately there were no injuries. They have experienced 4-5 broken joints per year out of the 10 to 15 '94-'95 cars they have now. This is not a new problem as the same 9/16" joint has been in use since the current B-car chassis debuted in '77. A lot
    of the recent rash of problems was caused by the joints being improperly torqued from the factory (there is a TSB on that), but even after they were re-torqued after delivery many still have had problems.

    After the ball joints break, they have to replace the control arm (including the joint) and the knuckle as well. They found that if they don't replace the knuckle, the new joint will quickly fail again. This is because if the tapered sleeve on the knuckle is damaged, the new joint will not be retained properly.The lower ball joint has a tapered stud which fits into a tapered hole in the steering knuckle. When overloaded, the stud separatesfrom the knuckle and begins to wear both the stud and knuckle surfaces. Instead of a tight fit, they become loose, and even re-torqueing does not help. This can manifest itself in front end clunking, which many have experienced in the Impala. If allowed to wear in this manner, the joint can eventually fail, resulting in potentially serious consequences.

    IMHO this is especially important for Impala owners, since the greater G-forces generated by the large wheels and tires on the Impala, not to mention the high performance FE4 (special handling) Impala suspension are very capable of overloading the smaller joint.

    They first discovered the change in the 9C1 cars when they got some new '96 cars last year and noticed that none of them had the same ball joint problems, in fact not one '96 they have has broken a joint or had any problems at with them. That was when he discovered that the '96 9C1 cars changed to a different lower control arm and
    steering knuckle which takes the larger (and significantly stronger) 5/8" ball joint instead of the smaller 9/16" joint previously used. The only changes to accommodate the larger joint are the different lower control arm (which comes with the larger joint and nut included) and the steering knuckle (which is modified to accommodate
    the larger 5/8" stud). As such it is possible to upgrade a car originally equipped with the small joint by simply replacing these components.

    I have ordered the new '96 9C1 lower control arms (which also include stiffer bushings than what come on the Impala PLUS the monster 5/8" Limo ball joint) and the upgraded knuckles as well. They cost about $500 total for both sides, which some may consider steep, but for me the peace of mind, absence of clunking, not to mention better handling- I feel it is well worth it. These are the parts you will need to perform the upgrade:
    Part no. Description Net List
    12529790 Lower Ctrl Arm, LH, incl. 5/8" ball joint 100 $150
    12529791 Lower Ctrl Arm, RH, incl. 5/8" ball joint 97 150
    18021377 Knuckle, LH, 2nd des. for 5/8" stud 145 218
    18021378 Knuckle, RH, 2nd des. for 5/8" stud 145 218
    The net prices are discounted prices, about what you should pay at your dealer, note that list prices are higher. If your dealer won't give you a price this good, contact Dal Slabaugh mailto:lockitup@bright.net at Lambert Buick. The total is close to $500, well worth it for the peace of mind, plus the reduction in rattles and clunking from the smaller joints which wear much more rapidly.

    A fringe benefit is that the 9C1 control arms actually have a higher durometer (stiffer) rear bushing than what comes on the Impala control arms, which will allow less deflection and improve handling the same way stiffer rear control arm bushings do. Out of the two front bushings, the rear one takes most of the load, hence that is
    why the factory only makes that one stiffer on the 9C1 cars. Impalas unfortunately have the same wimpy bushing there as a base FE1 (Soft Ride) Caprice!

    Changing the control arm and knuckle are fairly easy. If you follow the Factory Service Manual (FSM) procedure, they call for a Kent-Moore J-23742 Ball Joint Separator to remove the existing ball joints (both upper and lower), without damage. You can get all Kent-Moore GM special service tools (the ones listed in the Factory Service Manual) from Kent-Moore directly (800-345-2233 or 810-574-2332). If you call, be sure to ask for their latest catalog, which lists over 2,500 tools by application.

    Note that oftentimes a hammer can work just as well for removing balljoints, as long as you use the proper technique. I recommend backing off the nut on the joint stud so that it is even with the end of the joint, then when you hit the end with a hammer it will spread the load over the nut as well and prevent tuliping the end of the
    stud on the joint. This is most important for the upper joint which you will be re-using.

    Note also the front springs have to be removed as well. In this case I don't recommend the FSM procedure since it requires that you remove both front shocks as well as the steering linkage tierod ends. This is a LOT more work than the technique I will mention here, not to mention it will require tools that the average person doesn't have.

    Interestingly enough, the much easier technique for front spring removal and replacement I discovered is the one that is shown in my '78 B-car service manual, while the '88 and newer books show the much more difficult (and tool intensive) technique. Using the older method, no special tools are required at all, while the newer method
    they show requires a ball joint separator tool to separate the steering linkage (tie rod) and the lower ball joint, as well as a spring compressor to remove and install the spring.

    The simple technique is as follows: Place the car on jackstands; Disconnect the swaybar end links (the bar does not have to be removed); Disconnect the lower shock bolts, you do not have to remove the shocks; Place a jack on the bottom of the control arm; Remove the two bolts that attach the arm to the front crossmember; Then simply lower the jack to release the control arm and subsequently the spring. The spring will literally fall out! To reinstall the springs, just do the opposite, no compressor or other special tools are needed. In fact you can do this job with nothing more than a ratchet and a jack. I changed both my front springs in about 2 hours with no
    assistance using this technique.
    Return to Technical Forum


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    Re: *Technical Service Bulletin* Suspension Upgrade

    Post  GM B-Body Forum on Fri Jan 24, 2014 1:24 pm

    thanks for the bulletin, i actually have heard about this, but i know most others have not. I think ill move this to "upgrades"


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    Sweet Seventy9
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    Re: *Technical Service Bulletin* Suspension Upgrade

    Post  Sweet Seventy9 on Fri Jan 24, 2014 3:49 pm

    OK, cool. Thx.

    Yeah, most people don't know about the ball joints.


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    78i6belair
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    Re: *Technical Service Bulletin* Suspension Upgrade

    Post  78i6belair on Sun Nov 16, 2014 7:18 am

    Thanks for this info!
    So your still able to get those front end parts from a GM dealer then?
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    Sweet Seventy9
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    Re: *Technical Service Bulletin* Suspension Upgrade

    Post  Sweet Seventy9 on Sun Nov 16, 2014 12:02 pm

    78i6belair wrote:Thanks for this info!
    So your still able to get those front end parts from a GM dealer then?

    All those PNs are now disco'd but you might be able to find some NOS pieces.

    Astro Van parts are interchangeable though. Someplace here on the forum I posted about them, along with the current PNs.

    You can always get used parts and re-do them too.

    To be completely honest though, you don't need them. It was proven that all the broken BJs were caused by a disgruntled GM worker that was deliberately torquing them at the wrong specs.

    I've had a whole bunch of these cars and some of them I've really beat the crap out of. I'm talking backyard dirt tracks with jumps. I've never broke a BJ, ever. Personally, and this is just mho, I feel the money can be put to better use somewhere else.


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    Re: *Technical Service Bulletin* Suspension Upgrade

    Post  78i6belair on Mon Nov 17, 2014 6:29 pm

    I always had a gut feeling that the last GM vehicles to use or share B body chassis parts are the 2005 and down Chev Astro/GMC safari RWD vans. Do they use the same upper and lower control arms, knuckles, ball joints and steering gear?

    Well thanks for being honest and I would love to spend money on better updated front end parts but my factory original components are tight and not sloppy. Only the centre link has been replaced and one adjustment to the steering box worm nut.
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    Re: *Technical Service Bulletin* Suspension Upgrade

    Post  Sweet Seventy9 on Mon Nov 17, 2014 7:24 pm

    78i6belair wrote:I always had a gut feeling that the last GM vehicles to use or share B body chassis parts are the 2005 and down Chev Astro/GMC safari RWD vans. Do they use the same upper and lower control arms, knuckles, ball joints and steering gear?

    Well thanks for being honest and I would love to spend money on better updated front end parts but my factory original components are tight and not sloppy. Only the centre link has been replaced and one adjustment to the steering box worm nut.

    Hmm, I don't remember for sure. I'm pretty sure all that info is in the post I mentioned though.


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    1977 Caprice Coupe x3, Sedan x3
    1978 Impala Landau x1, Sedan x2, Station Wagon x1
    1978 Caprice Landau x1, Caprice Coupe x2
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    1979 Caprice Coupe x7, Landau x4, Estate Wagon x1
    1981 Impala Coupe x1
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    1984 Caprice Landau x1, Sedan x1
    1985 Caprice Coupe x1, Landau x3, Sedan x4
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    1987 Caprice Landau x1, Sedan x4
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