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Larger, full fendered rods over 3000 pounds should consider vented disc rather than solid disc. Vented rotors provide about 25% increase in area for heat rejection by air flow as compared to a solid disc. Vented rotors also run cooler than solid disc and add to lining life.

Herbert and Meek did a disc conversion using vented GM rotors on '37-48 Ford spindles. This requires machining the early Ford hub to accept the GM rotor. This machine setup and rotor mounting is similar to the procedure found in the Bell Auto Airheart brake in this story. Sometimes a spacer/adapter is required for clearance between the Ford hub and rotor. There are no kits currently manufactured so you'll have to engineer your own brackets.

There are manufactured kits to adapt the Corvette disc to '49-54 Chevy spindles. Custom tube axles can be ordered from assorted manufacturers for the Chevy spindle. You can also adapt your own GM spindle as outlined in the GM shoe brake conversion in this story.

One of these conversions requires two '49-54 Chevy spindles with hubs, a pair of '66 or later Corvette disc brakes and calipers, brake hoses and fittings. S & J Chassis offers an adapter kit that consists of two caliper brackets and ten wheel lug bolts.

This is how it works. Drive or press the lug bolts out of the drum so you can get to the rivet heads and grind those off. Remove hub from drum and rivets from hub. The new lug bolts in the S & S Chassis kit have a serrated shoulder on them that lock in place when pressed in the hub. These lugs are available at any wheel and brake house but we don't know how long they are. The lug shoulder protrudes through the hub about the thickness of the rotor hub to locate the rotor. Use a 9/16-inch bit to drill the rotor lug holes to fit the new lug shoulders. It can be done using a hand drill but do yourself a favor, use a drill press.

A sure-fire way to get the studs in is done without a press. Acquire a hand full (8 or 10) of 9/16 or 5/8-inch flatwashers. Then place the lug in the hole and place the 30 wt. oiled washers over the threads. Leave enough to get a full set of threads in the nut. Grab your Mexican adjustable speed wrench and give 'er about four or five good turns. The oil keeps the washers from galling. Remove the nut and put some more washers on according to how far you went. Replace the nut and do it again. Keep stacking washers and turning the nut till the lug bottoms. Then give it about 40 ft. lbs. of torque to be sure. This procedure can be used on any lug bolt replacement and it works.

With the rotor/hub unit installed, a caliper bracket can be measured and made. Choosing a piece of hot rolled steel about 3/8-inch thick, use the upper and lower backing plate holes that face the front to anchor the bracket. The bracket bolts to the axle side. Set the caliper on the rotor to measure with. Be sure the caliper is high enough to clear the rotor as it turns, and making full lining contact on the disc. Drill your holes as you see fit. Cut the plate to make it look like a bracket but do it so it just clears the axle and the caliper. Don't clearance too far or you will loose your bracket strength.

The caliper must be spaced away from the bracket. Measure the distance between the caliper mounting surface and the bracket. Make the spacers as outlined in the pre-OS Mustang disc conversion on stock early Ford spindles in this story. When you buckle this operation together use grade 8 fasteners, whether socketheads (allen) or bolts with six lines radiating from the center on the head. If the caliper doesn't align dead-on with the rotor, back to the drawing board; it has to be right, If it fits but the caliper sets too far one way or the other, either make new longer spacers or trim the ones you have, depending on which way you need to go. The J & J Chassis bracket bolts on in less time than it takes to read this.

If your bracket works, cinch it down with lockwashers or self-locking nuts. Because this system was designed to be used with rear drum brakes, no pressure booster is required.

Herbert and Meek at one time offered adapter kits for '64 and later Corvette disc to '49-59 Chevy truck spindles and 'Vette disc to '49-54 Chevy passenger spindles. Due to minor engineering problems the home brake swappers didn't see or understand, difficulties arose. Herbert and Meek no longer supply these kits on the market but they are most definitely available for installation at their shop.

The '49-54 Chevy passenger spindle kit is very similar to the J & J Chassis kit. A phone call to Andy Herbert cleared the air on one of his older disc conversions. This conversion uses the rotor from the intermediate size GM car. It is smaller in both diameter and surface width than the 'Vette. The caliper used on the small rotor is a floating single piston type. Andy said the braking was about as good as the 'Vette but lining life was not as long. These floaters can be adapted, but not as easily as the four-piston 'Vette caliper which will work on the smaller disc. He recommends the 'Vette rotor because of the simple procedure of placing the hub inside the rotor. The smaller disc must have the hub placed outside on the rotor because it will not fit inside. Andy recommended trueing the hub-to-rotor surfaces on both the hub and rotor. He said the metal around the lug shoulders will raise a little sometimes I and the rotor will not fit flat on the hub and viceversa. This is one of the engineering problems brake swappers skipped over, which led to brake problems.

To true the hub flange use a three-jaw lathe. Chuck up a three-inch diameter bar with~ about 1-1/2-inch protruding from the jaws. Set the compound to 600. To be sure about which 600 you want, take the ball bearing dead center and set it parallel to the ways next to the compound. The nose angle of the dead center should be parallel to the compound side looking down from the top. If they are not parallel move the compound to the 3Q0 mark. Some lathe compounds are degreed with the 00 reference point being parallel to the ways (running lengthwise). Other lathes have the 00 point being perpendicular to the chuck turning center (running crosswise). Some lathes have both reference points on the compounds. These lathes will show a 300 at one reference mark and 60~ at the other reference mark which is 9Q0 around the compound base. If it seems confusing, just put the deadcenter up to the compound side and make sure the degree numbers 30 or 60. You are going to cut the three-inch roundstock to the same taper as the dead center, got it? After you have secured the compound base, the compound will move in toward the chuck from the left of the carriage.

If it doesn't move in that direction, move your compound degree. If it doesn't look right that way it is because you will run the spindle in reverse and cut the taper on the opposite side from you. Some lathes don't have a spindle reverse. It takes a little bit of rigging but you can get the taper cut on the side closest you, it's just a hard way to go.

Cut the taper with the compound, but only cut enough to give a true surface for the inner hub race to seat against. Now place the hub inner bearing on the new center and slide the tailstock ball bearing center into outer bearing race. Secure the tail-stock and crank the center into the hub to hold it between the centers. Yes, that is "turning between centers." Standard procedure is to use a lathe dog to secure the position of the workpiece in relation to the chuck (so it won't slip). We have nothing to secure the lathe dog to, and we are only taking off a few thousandths anyway. All you want to do is face the hub, so cut a few thousandths at a time and feed the tool across the face slowly. Too fast, too deep, or both can stop the hub from turning and put a groove in the chuck center.

If you have a solid dead center (no ball bearings) or a ball bearing center too small for the outer race you can chuck the little beggar up in a four-jaw. The whole set-up procedure is outlined in the Bell Auto-Airheart part of this story.

The outside of the rotor surface can be done in several ways. First, turn the disc face for a true surface. The rotor hub face can be trued in a three-jaw lathe by gripping the inside of the rotor. Dial indicate the disc face to true in chuck. Use a soft hammer or mallet to move rotor in chuck. When the indicator reads 0 all the way around the disc face, face the rotor hub with a tool bit. Only take off enough metal to clean the surface of high and low spots. You can also true the surface in a horizontal mill, vertical end mill, or surface grinder. Just clamp the disc to the table on the mill and make a clean-up pass. It would take a rather large surface grinder to handle the rotor but it is the easiest if it has a magnetic chuck.

To true the inside of the rotor hub, place the rotor in a three-jaw and dial indicate the disc face in. You will need a boring bar that is designed or set up for bottoming and facing, and long enough to go to the inner rotor hub face. Once again, just cut enough metal, a few thousandths at a time, to true the surface. Trueing the faces of the rotor hub and spindle hub are as important as surface grinding the brackets.

Herbert & Meeks '64 and later 'Vette disc to '49-59 Chevy pickup require two '53-54 Chevy drums. They have larger bearings and fit the pickup spindle. The difference between the '49-'54 passenger and '49-54 pickup spindle that concerns the adapter is the steering arm arrangement. The passenger steering arm bolts between the spindle and backing plate. The pickup steering arm bolts on the outside and spacers are used between the spindle and backing plate. These steering arms are not interchangeable from one to the other. Because of the difference in spindle flange spacing, Herbert & Meeks came up with a three-piece caliper bracket for the pickup.

The first piece is cut from 1/2-inch hot rolled steel. Measure and drill the four backing plate holes 7/16-inch on the top and 1/2-inch on the bottom. Torch or mill the center out so the spindle bolt can pass through and seat against the backing plate flange. The caliper will bolt on the back in a vertical position, so leave some metal to drill into.

Set the Chevy hub into the rotor as outlined in the I & J Chassis 'Vette disc to '49-54 Chevy spindle in this story. Assemble rotor unit on spindle to measure how far away the caliper will fit from the spindle. Make another bracket from 1/2-inch hot rolled plate that bolts to the caliper. With the caliper at its correct height and position, a portion of the caliper bracket overlaps the extra portion on the spindle bracket. There should be enough room to drill three equally spaced 1/2-inch holes into both brackets to locate the caliper in the correct position from the spindle bolt. To get the correct centering of the caliper over the rotor, a 3/16-inch spacer between the two brackets, the length of the brackets, with the three holes to match is needed. If the caliper does not sit over the rotor with full lining contact, back to the machine shop. It's gotta be right,

When it is right, surface grind or Blanchard grind the brackets, easy on the 3/16-inch spacer. Use socket head or grade 8 bolts to bolt the conversion together. The pickup front end must use 15-inch wheels to clear the caliper, mount and the tie rod end.

Our records show that the 10.7 inches tall Volvo rotor from the 142, 144, 145 and 185 coupe, station wagon, and four-door coupe from '67 to '70 can be adapted to the '49-54 Chevy spindle. Check with your Volvo dealer as to how far beyond '70 these brakes are made. For information refer to Volvo disc to early Ford spindle.

First, drive or press (we prefer press), the lug nuts out of the drum so you can get at the rivets to grind the heads off, Remove hub from drum and rivets from hub with a drift punch. Set up the hub in a four-jaw lathe chuck with enough of the flange circumference past the jaws for a dial indicator to rest on. Dial indicate the circumference and drum face of the flange to 0. Support the small bearing end with a ball bearing center and turn the diameter of the hub until it is true from the tip of the hub to the flange face. Also true the flange face. Leave a small radius at the flange/hub point intersect because a square shoulder is a weaker point and will fracture quicker than a round or concave shoulder. The hub can also be turned between centers as outlined in the Herbert. & Meek '49-54 Chevy spindle to 'Vette disc brake story in this article, Just use light cuts with this setup as there is no way to anchor the hub to the chuck.

So the rotor will slide easily on the hub flange, machine the hub diameter .010 from the tip toward the flange, leaving a shoulder for the Volvo rotor to locate on. Measure the larger diameter and machine the rotor hub locating hole out to .0005-inch over or slip fit. The set-up procedure to machine the rotor and hub is outlined in the '49-54 Chevy spindle to 'Vette disc changeover by Herbert & Meeks. Be sure to give the inside rotor locating hole a radius to match the hub.

When assembling the rotor to the hub use the same method as in the J & J Chassis 'Vette disc to '49-54 spindles. Place the assembled unit on the spindle and set the caliper on the rotor to measure for a caliper bracket that will hold the caliper in a vertical position at the front of the disc. Make a bracket as outlined in the J & J Chassis 'Vette disc to '49-54 Chevy spindle in this story. Spacers may be needed between the bracket and caliper, which is also outlined in the J & J Chassis conversion.

Assemble the unit with grade 8 or better bolts and lockwashers or lock-nuts after all the clearances have been double-checked for spacing and concentricity.

Hamilton Automotive Industries offers a kit for the large Volvo disc that includes the bracket, Volvo hubs, rotors, bearings and fasteners to '49-'54 Chevy spindles, Kit also contains a combination grease seal and spacer so all Volvo parts can be used. The Chevy spindle needs machine work on the inner bearing diameter, Hamilton will machine your Chevy spindles, or use his spindle exchange program, or buy the Chevy spindles outright in the kit. The lower steering arms have to be milled for clearance. Steering arms are available at extra cost. He can also supply dropped Chevy passenger lower steering arms. All he does it use the passenger upper half of the arm and the lower half of the pickup steering arm and weld them together.