GM H-Body Front Suspension FAQ
(frequently asked questions)
By Bob Gumm
The H-Body cars (Chevrolet Monza Spyder/Mirage, Oldsmobile Starfire Firenza, Buick Skyhawk Roadhawk/Nighthawk, Pontiac Sunbird Formula) and Vega, as well as Pontiac Astre have a lot in common and can share a lot of the Chevy Monza parts. Since this site’s focus is mainly V8 equipped cars, I’ll cover only information pertaining to V8 front suspensions. If you’re installing a V8 and want to be sure your vehicle can handle the extra weight, have the front suspension checked before the swap to make sure it is in good shape. The weight of a V8 on non-V8 equipped vehicles can worsen any pre-existing suspension problems and can lead to suspension failure. The front suspension is not the greatest on these cars to begin with, so be warned and after the swap have it inspected periodically. Suspension failure can result in costly repair, damage to property, and serious injury and or death. If I have your attention good, nobody wants a street rocket that doesn’t handle well and takes forever to stop. If you want to convert an H-Body or Vega to 5-lug front suspension, you can use any aftermarket kit made for Vegas or any other H-Body, but they are very expensive. Most kits are advertised to fit the Chevy Vega, so look for those. Some folks have even suggested using dropped spindles made for the G-Bodied cars in conjunction with the other swaps mentioned here. As for myself and many other do-it yourselfers, I prefer to install readily available used factory parts (in good condition of course) easily obtained from salvage yards for a fraction of the cost of factory or after-market parts. It does require some modification of the factory parts and some ingenuity on your behalf.
This FAQ is a compilation of my experiences as well as other’s with the V8 Chevy Monza, Vega and other H-Bodies. There are some sections that have no information in them yet, but I’m always adding to it, so if you don’t see what you’re looking for check back regularly or e-mail me. Also, read this information the same as any information you find on the internet and make your own decisions about what you read. If you find errors, have any suggestions, personal experiences, or information you think would be useful here, please e-mail me. I make no attempts to mislead you, I only know what worked for me and I won’t be liable for any damage to equipment, injury to persons, errors in judgement, or depletion of your finances. Hey, I gotta protect myself.
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5 Lug Upgrade:
See the Step-by-Step Guide
The reason to upgrade the front suspension to 5 lug with factory made parts is to acquire better braking ability as well as have readily available parts for replacement and repairs. Also, the factory caliper mounts (pins with clips) have a nasty habit of losing the clips under extreme vibration and then the rods migrate into the wheels. This results in a situation where the wheels can actually be cut in half if they are aluminum. I should know, I’ve seen grooves (although minor) cut into steel rims when this happened to me. I have considered using bolts instead of the rods, but the appeal of bigger brakes and available parts may drive me to modify the suspension to accept Monte Carlo spindles, calipers and rotors.
5-Lug Front-End via Adapter Bushings and/or Chevy S10 Ball-Joints
If you’re using the balljoint adapters, you MUST use the larger Monza lower ball-joints.
Upgrade your front suspension by installing the spindles and rotor/caliper assemblies from 79-88 Monte Carlo/Malibu/Century/Regal/Cutlass/Grand Prix/Lemans/S10/S10 Blazer or GMC Sprint (S10 parts are preferred, see the parts list) using a balljoint adapter kit. The good thing about using the balljoint adapter kit is it’s a bolt-in application and no modification to the control arms is required. However, you must use late model (1975-80) Monza lower ball-joints in the lower control arm.
If you prefer you can install S10 upper and lower balljoints in your control arms. This is simply a matter of modifying the control arms to fit the S10 balljoints. To use the upper S10 balljoint, you must enlarge the large center hole and weld up the rivet holes and drill new ones to match those in the S10 upper balljoint. To use the S10 lower balljoint, a company called U.B. Machine makes a part called a Ball-Joint Sleeve. It’s part number 40-3301 and it can also be ordered from Lane Automotive. The difficult part when using S10 balljoints is that the lower control arm must be cut slightly and the new sleeve welded into place. Then, the ball-joint Moog part number K-1277 must also be ordered. It is a press-in ball-joint. There is a screw-in type, but for a DIY’er, the press in will be better. S10 lower ball-joints are prone to premature wear, so don’t skimp on them and buy quality MOOG parts. All parts can be ordered from Lane Automotive. I plan to try these adapters and I’ll post the results here for all to see when I do.
As for mounting the 5-Lug parts, there are two methods:
Using the Balljoint Adapter Kit:
Monza lower ball-joints are required.
Follow the instructions that come with the kit or refer to the Step-by-Step Guide available online that is updated with the latest information.
Always perform a front suspension alignment after modification.
Using Chevy S10 upper and lower ball-joints:
Modify the upper control arms: Remove the old ball-joints. Then make a template that matches the diameter and bolt pattern of the S10 upper ball-joints. Using this pattern, identify witch holes in the A-arm need to be welded closed and which ones need to be adjusted to match the template. You will also have to slightly enlarge the big hole to allow the larger Chevy S10 ball-joint to fit. Then simply bolt the Chevy S10 upper ball-joint in-place.
Next, modify the lower control arms: Remove the old ball-joints. U.B. Machine makes a part called a Ball-Joint Sleeve. It’s part number 40-3301 and available at Lane Automotive. The sleeve allows the fit of Chevy S10 lower ball-joints. The sleeves must be welded in-place of the original lower control arm ball-joint sockets (after the old sockets are cut out). Be careful not to remove too much material, just enough to fit the sleeve and then weld it in-place. You must then install Chevy S10 lower ball-joints.
Hope this helps,
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For those of you who wish to give it a go, the part is sold by two companies. You can reach them here:
Lane Automotive” in Coloma, MI
7181 Red Arrow Hwy, Watervliet, MI 49098
or call them toll-free at: 1-800-772-5266
toll free 800-430-7223