This article will talk about the front brakes and suspension. Mentioned in earlier articles, I am converting from stock 11” disc brakes to the GM B-body 12” front disc brakes. Also known as the “tall” spindle conversion. They are called “tall” because the spindle is taller than the A-body spindles. Also, they inherently lower the body to the road by about an inch. B-body refers to the full-size GM vehicles such as Impala or Caprice. There is a lot of information available on this conversion, but I will describe what I did. It is slightly different then you may find elsewhere.
You can use ’78-’84 B-body as a donor or ’85-’90, whish are stronger and lighter, or ’91-’96, but just ignore the ABS stuff. I used a ’90 Caprice Police car as my donor. Be sure the rotors measure 12”. Average Caprices and Impalas came with 11” rotors, but the SS, Police cars and wagons had the 12” rotors. The 12” rotors will not fit on the spindles made for 11” rotors. You have the option to use the donors rotors, which will come with 5 on 5” lug pattern or you can get the ’88-’92 Camaro 1LE rotors, which will fit the 5 on 4-3/4” lug pattern as you had originally. I chose the larger lug pattern. I already got the rotors from the donor, it comes with ½” wheel studs, it will match my lug pattern in the rear because I have already changed that with my new axles and rear disc conversion, and I have to buy new rims anyway. From the donor I used the spindles, backing plates and rotors, turn the calipers in as cores for a new set of 1970 Chevelle calipers. The Chevelle calipers fit the spindles and give you the proper location for the brake hoses.
With the spindles sand blasted and painted, it is time to focus on the control arms. There are 2 types of factory front lower control arms; those with round rear bushings and those with oval. GM pretty much mixed and matched these at random. The round ones were the first design then the oval ones came about to give a little more shock absorption from pot holes and such. The round ones give you stiffer suspension, which is fine if you leave the round rear bushing rubber. But if you plan on driving on the street and want to use urethane bushings, I strongly recommend using the control arms with the oval bushings. The extra material in the oval bushings offset the stiffer urethane, resulting in a stiffer response suspension yet forgiving with shock from the road.
Once I selected the lower control arms I wanted, I welded in some reinforcements. These arms are known to crack and brake because of 30 years of fatigue. I have put a kit together for the mod. I plasma cut, out of 1/8” steel, the plates to be welded in. After the plates are in the 1” x 1/8” steel strips are welded. Notice the clearance hole for the sway bar mount. After the welding was finished, I had the arms galvanized and painted.
To mount the B-body spindles in the Chevelle lower control arms, the b-body ball joints must be turned down to 2.012” diameter in order to be press fit in the arms. Before the lower arms can me installed, the motor-frame mounts must be installed because the arms will block access to the brackets hardware. Next I pressed the new polygraphite bushings in. I prefer the graphite impregnated polyurethane over the straight polyurethane because it reduces the squeaking caused by no lubrication between the rubber and steel parts. Don’t forget to use the Formula 5 grease between the inner collars and the urethane bushings. After using the armor coated hardware kit I have also put together to mount the lower arms into the frame, the spindles are ready to be put on. Don’t tighten the bolts until all the vehicles weight is sitting on the suspension. The poly bushings need to rotate freely, without binding until the actual ride height is achieved before locking them down.
I have purchased new front springs with a 2-inch drop for my application. It is now time to look at the upper control arms. With the B-body spindle conversion, the spindle is taller, which changes the geometry of the upper control arms. Some people use offset shafts and lots of shims to compensate, other companies make shorter control arms specifically for this conversion. However, I found polepositionrp.com (888) 303-8555.
I ordered 9200M5 (8.25” –10”) w/metric steel cross shaft/ bolt in ball joint plate, requested: 5” & 6” sleeves w/ midsized plate and 6.5” cross shaft centers with OE pivots. These arms give all the versatility in adjustment with out requiring any shims. No shims give you the shortest distance between the arms pivot point and the ball-joint center. This equates to maximum camber roll on hard cornering, which makes the most use of the B-body spindles handling potential. The adjustable arms make doing alignments so much easier. Pole Position also offers home alignment kits. To mount the spindle to the upper arms just use the stock B-body upper ball-joint. The outmost ends of the brackets that are welded to the frame to mount the upper control arm shafts need to be bent in slightly to allow the upper arms to achieve maximum travel before hitting the frame.
This picture is to show where the brackets get bent in to clear upper control arms. The 2 places are located by the small pieces of white chalk. The area was freshly painted again because the paint chipped after hammering on it. If I’d have known, I’d have done this step prior to galvanizing and painting.
Finally, Tighten the upper control arm hardware, install springs using a spring compressor, install shocks and backing plate. Measure the material thickness of the Caprice donor rotors. Mine had “meat” left to be turned so I sandblasted, painted and turned the rotors. Install new bearings, racers and seals into the rotors, grease and install on spindles. Paint and assemble new ’70 Chevelle calipers with new hardware and Z-rated pads from Auto Zone.
The ’70 Chevelle calipers fit these spindles without any modification. You can use ’69 Camaro front disk brake hoses with the Chevelle drum brake hose frame brackets, they are a few inches longer. Be sure to use the correct “Banjo” bolt. Napa #82701 is 1.1” long. You can also use ’78 Camaro hoses but you will need to use Banjo bolt Auto Zone # 313935 which is .9” long. The ’78 Camaro hoses are cheaper and do not have to be special ordered. I found this out after already purchasing my ’69 hoses, so that’s what I used. Or you could just use the stock Chevelle frame bracket and hoses.
As shown in an earlier article, I welded 3/8” thick steel blocks with taped holes to give a much stronger front sway bar mount. I am using a 1-3/8” front sway bar and a hard corner with this heavy vehicle, there is no doubt in my mind that the mount bolts would just rip right out of the factory tapped holes in the thin frame material. I found the bar at Malibu Performance 818-222-6725. also I used polyurethane sway-bar mounts which I drilled and tapped grease fittings in.
Front Suspension Part List
Donor B-body 12”, (78-84),(85-90 stronger and lighter) or (91-96 w/ABS)
Rotors w/ 5 on 4-3/4” lug pattern (‘88-‘92 Camaro 1LE ebay $140+) I’m not using
Spindles, backing plates, rotors, ‘90 Caprice 12” - $100
Bearings, ‘90 Caprice, Timken set 6, set 3 & seals 8871 - $40
Control arms, adjustable polepossition (888) 303-8555 - $2809200M5 (8.25” –10”) w/metric steel cross shaft/ bolt in ball joint plate,Requested: 5” & 6” sleeves w/ midsized plate 6.5” cross shaft centers/OE pivots
Control arms, lower stock ’70 Chevelle w/ oval bushing, boxed & galvanized - $had
Poly-graphite bushings. (Oval), ’70 Chevelle - $100
Outer tie rod ends, Moog # ES2033RL 5/8” ‘84 Buick Regal 2 x $12= (11/16” # ES427R) - $24
Tie rod sleeves Moog # ES2032S 5/8” ‘70 Chevelle 2 x $5 = (11/16 sleeve # ES20045) - $10
Inner tie rods ’70 Chevelle 5/8” thread (’71 has 11/16 thread) - $had
Calipers, ‘70 Chevelle, 2 x $31 - $62
Pin, caliper ’70 Chevelle, Bendix H5002 (2 x $7) - $14
Bolts, banjo, ’70 Chevelle Napa 82701 (2 x $4) - $8
Pads, ’70 Chevelle, Auto zone, Performance Friction Z-rated - $40
Hardware kit, has clip that holds pads in, Bendix H5500 ’70 Chevelle - $2
Ball joint, Lower, ’90 Caprice, stock, ( I Turned down to 2.012 dia.) (2 x $13) - $26
Lug nuts, ’90 Caprice, ½” for caprice rotors only (.79 ea x 5) - $4
Hoses ‘69 Camaro, w/ Chevelle drum brake frame brackets Bendix 88520 (2 x $21) - $42
Front Suspension Torque Settings
LH/RH Lower Ball Joints Nuts - 83 lb-ft
LH/RH Upper Ball Joints Nuts - 61 lb-ft
LH/RH Front Caliber Bolts - 38 lb-ft
LH/RH Front Sway Bar Nuts - 18 lb-ft
Steering Gear Box Bolts - 64 lb-ft
LH/RH Steering Linkage Outer Tie Rod Nut - 35 lb-ft
LH/RH Steering Linkage Inner Tie Rod Nut - 35 lb-ft
Steering Linkage Relay Rod to Pitman Arm Nut - 35 lb-ft
Steering Linkage Relay Rod to Steering Linkage Idler Arm Nut - 35 lb-ft
Idler Mounting to Frame Bolts - 60 lb-ft
Pitman Arm Big Nut - 180 lb-ft
Banjo Bolt on Calipers - 22 lb-ft