Update by Tim Suddard to the
Austin-Healey Sprite project car
Feb 12, 2022
With our carrier reinstalled back in the differential housing, we could now finish up the rear brakes, install new wheel bearings, and finish the rear suspension. Our Austin-Healey Bugeye Sprite is quickly coming back together.
[How to assemble a differential | Austin-Healey Bugeye Sprite Project]
First, don’t forget that the axle threads are left and right to keep the wheels from falling off the car. On the driver’s side of the car, instead of righty-tighty, it is righty-loosey.
You can easily build a puller to remove the hub from the differential housing. Just drill a couple of holes in a piece of 1/8-inch or thicker steel and tighten the lug nuts down on this plate until the hub loosens.
We did make a few modifications, though, since we’re going to supercharge the engine. First, a later 1275 Sprite/Midget used a tougher rear axle than the earlier cars. It is marked BTA and not 2A like the earlier axles. You should mark your axles left and right, and replace them the same way for maximum durability.
We used these axles and installed new wheel bearings and larger 7/16-inch wheel studs. A Sprite came with some pretty puny 5/16-inch wheel studs.
To install bigger studs, you will have to drill your axles, hubs and brake drums. Use a centering bit to keep your holes centered. A normal bit does not necessarily stick to the center of the hole.
You will need a ½-inch hole to pick up the knurls–at least on the studs we used. You will most likely need to mill the backs of your studs down slightly at the outside edge to cover your wheel cylinders.
When installing the wheel bearing seal, the open side of the seal faces inwards. You also torque the axle nuts to 135-140 lb.-ft. Don’t forget the lock tabs on your hubs.
On the brakes, we used performance Porterfield Racing R-4S shoes. We have used these before and they are fantastic for aggressive street and autocross use.
When rebuilding your rear brakes, the emergency brake levers need to go in place before you bolt your back plates. We couldn’t see a way to snake these pieces around the backing plate once that plate is installed.
When installing bearings, remember how that bearing is created. If you hit the inside of the bearing when you are trying to sink the outside into place, you will damage that bearing.
Most parts for the rear end of a Sprite are laughably cheap. Just call Moss and replace everything.
The axles only go in one way. There is a shorter, tapered screw that holds the axle to the hub and then two slightly longer versions of these screws that you use to install the brake drums.
For best results, snug all of these–and even the wheels–to make sure your axles seals seal properly. And use differential oil-friendly Permatex or something similar to seal both sides of the paper gasket.
Don’t forget there are rubber plugs (again from Moss) to plug the back of the backing plate.
And when in doubt, use Loctite. You don’t want anything back here coming apart.
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