Rear Drum Brake Upgrade

A common upgrade to the braking system for Bugeyes is the replacement of the rear  drum brakes which use a single action 7/8″ rear cylinder with later MG Midget rear brakes using a larger 3/4″ dual action rear cylinder. We were able to acquire the later backing plates, wheel cylinders, and brake shoes with springs, and handbrake levers from Gerard Chateauvieux of Gerard’s Garage. He indicated that the donor car was in the 1968-72 time frame.

Rear Brake Components

LH Rear Brake Assembly with Shoes and Cylinder

LH Rear brake assembly

The conversion also required using new crossbars or rods for the handbrake system as the original Bugeye crossbars are not shaped properly for the later brakes. These were purchased from Mini-Mania.

Adjustable Handbrake Crossbars

We did have problems with the drums rubbing against the backplates and had to grind away some material from the hub edge to avoid the conflict. 

More information about the build-up of the rear brake conversion including an assembly video that details the problems we encountered may be found in two other posts: “Rear Drum Brake Upgrade”  https://valvechatter.com/?p=13399 and “Bugeye Rear Axle Assembly” https://valvechatter.com/?p=13569 in the restoration series. These posts and their included videos show the mounting of the rear hubs and brake assemblies to the rear axle.

Chapter 17 – Cleaning and Trial Fitting

February 13 , 2004

Rear Disc Brake Conversion 

Decided to convert to disc brakes in the rear of the car and purchased the kit from Cape International. The kit consisted of two machined caliper mounting brackets, two Jaguar calipers including handbrake calipers, linkage for the handbrake, two disc rotors, templates for modifying the axle flanges and mounting hardware. The instructions provided assume the axle is on the car, but it appeared that the kit would be easier to install if the axle was removed from the car. I hope that the assembly can be inserted into the car from the right side once complete.  

First modified the axle flanges using a dremel tool. The templates were used as a guide to mark the axle for cutting. The axle was repainted following the cutting. The caliper mounting brackets (not handed) were mounted to the axle flange using four 3/8” UNF bolts and nylock nuts.

rear caliper bracket 1

rear hub removal

rear hub spacer,washer,nut

rear hub bearings

New rear bearings, and seals were pressed into the hubs. The bearing should protrude .001 to .004 from the surface of the hub after the outside washer and “O” ring seal are installed. Care must be taken to not drive the hub onto the axle too far or the bearing will be pushed too high. The tab washer and hub nut were then installed and tightened. The tab washer will not be bent down over the nut until absolute final assembly. The paper gasket was not affixed at this time since the half shafts will need to be pulled later for the installation of the differential. The half shafts were inserted and fastened to the hubs with one flat head tapered screw with a pozidrive head.

The new disc rotors were then attached with new hub extensions for the wire wheels. Care should be taken to put the proper hub extension on each side. Ten new conical lug nuts were provided in the kit. The calipers were then slotted over the disc rotors. 

The first flaw in the Cape International kit was discovered at this point. The inside of the caliper rubbed against the rotor preventing free turning of the disc. A grinder was used to remove some material so prevent rubbing. It was then discovered that the outside of the disc also contacted the adjusting screw on handbrake caliper. The grinder was called to action again. Once these modifications were made, the caliper slotted over the caliper and mounted easily, aligning precisely over the mounting holes on the provided mounting brackets. Two 7/16”  UNF bolts were used for each caliper mounting. The bolt heads are drilled so that they may be “wired” to prevent loosening.

The calipers were painted Eastwood Silver wheel spray with a clear coat. The caliper units had a bronze anodized finish as delivered.

The second flaw in the kit was the lack of inclusion of the short brake lined used to connect the two sides of the same caliper. An email to Steve Norton resulted in the pipes being shipped right away. Once received the pipes were bent and installed without difficulty. The two brake pipes running along the axle were rebent to work with the new calipers.

rear caliper brake line

The third flaw was the discovery that the short rod provided for the link between the handbrake caliper on the right side of the car and the rotating handbrake lever did not come close to fitting. This is when I discovered quite by accident a web site created by Ed Driver in Canada. His web site contained a detailed explanation with photos of his installation of the Cape International disc conversion. He had run into the same difficulties and had fabricated a new short rod after receiving little satisfaction from Cape. He graciously sent me a photo and scale drawing of his new rod to use as a template for my application. Lifesaver!!

handbrake link rods 1

Disc Brake Custom Handbrake Connecting Rod

rear brake hub assembly

Handbrake caliper pad 4

March 24 , 2004

Return to Front Suspension Assembly

Shock Rebound – Installed the front shock rebound bushing on the shock tower.

Front Shock Rebound buffer

Caliper Brake Lines – Installed new stainless steel brake lines to the front calipers ordered from Cape International.

Stainless Brake hoses

Fresh Air Intake Clip – Installed the clip for the air hose to the front wheel arch.

Air hose wheelwell clip

Fuel Tank Straps – Installed the two fuel tanks strap brackets to the rear boot panel. Each bracket has a backing plate on the other side of the boot panel. Note that the bracket curve Is on the top of the bracket.

Fuel tank strap bracket 4

Fuel tank strap bracket 3

Fuel tank strap bracket 2

March 24 , 2004

Cooling 

Cooling Recovery Tank – Began the installation of the radiator expansion tank from Cape International. However, I decided to wait to determine the final location until after the motor is installed. I don’t want to inhibit access to distributor or oil filter.

Coolant Recovery Tank with custom Bracket

Brakes 

Brake Fluid Reservoir – Installed new brake fluid reservoir and will need to put thread sealer on fittings for final assembly.

Brake reservoir clip 2

Brake Reservoir Mounted

April 17 , 2004

Handbrake Restoration 

I decided to restore the original handbrake rather than purchasing a new one. This will require rechroming several pieces. Removed small split pin securing the rod to the lever. Then removed the small split pin and washer from the lever holding the pawl.

Handbrake Assembly 1

Handbrake Pawl split pin

Disconnected the rod from the pawl and lifted the pawl off. Removed bracket with a hole and a rectangular opening for a key by heating with a torch and knocking out the piece. (Note orientation for reassembly). Hammered ratchet plate off of the mounting shaft to handle. There is a thin shim washer on the handle post before the ratchet plate is inserted on the shaft. The handle, pawl and ratchet plate will be chromed. The bracket and two spacers were painted black.

Handbrake connecting plate

Handbrake Assembly 1 2

Handbrake Assembly 2

Rear Axle

Rear Axle

All of the MK2s are fitted with a 4.HA Salisbury axle. The rear axle assembly is a semi-floating type with shim adjustment for all bearings and meshing of the hypoid drive gear and pinion matched assembly. The axle shafts are splined at the inner ends, which engage splines in the differential side gears, while the outer ends have tapers and keys to fit the rear wheel hubs. The hubs are supported by taper roller bearings pressed on the axle shafts and located in the end of the axle tubes. A cover on the rear of the gear carrier allows inspection without dismantling the axle.

Additional information about the axle installation and its related components in the rear suspension can be found in the “Rear Suspension” post at https://valvechatter.com/?p=3826.

Refurbishment

There is a big component stored in the garage that I have had trouble ignoring, but I have been putting off cleaning and refurbishing the rear axle for sometime. Perhaps it was Thanksgiving or the approaching holiday season, I don’t know, but I got motivated to start work on the axle. The axle images are sans the rear hubs. A description of the removal of the rear hubs is available in the disassembly section of posts,  Entry 39 .

For starters, I took advantage of having the lift in the garage and used it to  make it easy to access the axle for cleaning.

Rear Axle on Lift for Cleaning

Rear Axle on Lift for Cleaning

It was really just a matter of using the putty knife, cleanser, throttle cleaner, a wire brush and rags to remove the dirt and grime. After getting things as clean as possible I then used POR 15’s painting prep product called Prep & Ready. Prep & Ready is used to neutralize any rust and etch and clean bare metal to allow better adhesion of POR-15. Directions call for soaking the metal and keeping it wet for approximately fifteen minutes and then washing it away with water and then dry.

Prep & Ready

Prep & Ready

Axle Degreased

Axle Degreased

Axle Degreased

Axle Degreased

Axle Degreased

Axle Degreased with Prep & Ready

The differential casing on my axle had very little (if any) black paint and so I wondered if it should actually be painted red. I did a little research and this is what Rob Reilly contributed on the Saloon-Lovers email list:

In the build process, after the cast iron center pumpkin was shaken out of the sand mold and shot blasted, it was dunked in Glyptol, usually orange or red though Glyptol comes in other colors. This is to seal in the microscopic sand particles remaining in the boundary layer at the surface of the cast iron. Same as XK engine blocks and Moss gearbox main housings. It was very dry in the foundry and the Glyptol stuck very well. Then it went to the machine shop, where the machining work was done on it, which takes off the boundary layer. It is not necessary to repaint it on these machined surfaces. Then the axle tubes were pressed in and welded through plug holes in the casting. Then the parts were assembled into it. At this point it was very oily all over the outside of the diff. Then the whole thing was painted black without any primer, but they did not clean it very well first, if at all.

So after a few years the black flaked off, revealing the orange or red. If you look carefully as I did on mine, you may see black on the axle tube plug welds, because the welding burned away the red/orange and the oil, so the black stuck better there. Mine had small flecks of black remaining on the outside of the diff. I also saw only black on the outside of the rear cover, and nothing at all on the inside of this cover. It is not necessary to restore the Glyptol on the outside of the diff. It is only important on the inside.

Thanks to Rob, for providing the history on why the differential casing on my car was red/orange – they all were!

Brake Caliper Adaptor Plates

I then removed the LH and RH brake caliper adaptor plates. Each was secured to the axle with four 3/8″ – 24 x hex head bolts and nylock nuts, bolt heads to the outside. Each caliper was mounted to the adaptor plate with two 7/16″ -20 x 1 1/4″ hex head drilled bolts with split washers and safety wire. Shims were found on three of the caliper mounting bolts. They were noted for reassembly.

LH Adaptor Plate

LH Adaptor Plate

LH Adaptor Plate

LH Adaptor Plate

Oil Seal Assembly

The next task was to remove the LH and RH oil seal assembly from the axle. The assembly consisted of: the oil seal on the end of the carrier tube axle shafts, the hub bearing adjusting shims, and a gasket. I was careful to record the number, location (LH or RH), and size of the shims, and I will replace the bearings and gasket later.

RH Oil Seal Assembly

RH Oil Seal Assembly

The image below shows the face of the timken bearing ( 14130-X-14276) 7HA-025).

RH Axle Shaft with Bearing & Seal

RH Axle Shaft with Bearing & Seal

After cleaning up around the removed adaptor plates, I then painted the axle tubes and casing with two brushed coats of glossy black POR-15 followed by one sprayed coat of gloss Blackcoat which is a permanent overcoating developed as a non-porous finish that as advertised will not crack or chip. Unlike the POR-15 it is not harmed by exposure to sunlight.

Rear Differential Carrier Cover

Rear Differential Carrier Cover

Rear Differential Bottom View

Rear Diff Bottom

Painted Axle

Painted Axle

Painted Axle

Painted Axle

 

Newly Painted Rear Axle

Newly Painted Rear Axle

Rear Differential Identification Tags

Two stamped tags were located on the upper and lower mounting bolts for the carrier cover. One was stamped 49/13 which is the final drive gear ratio or 3.77. This ratio was the gear set fitted for overdrive equipped cars. I am told that the other which was stamped with “BP-L” signifies that the differential is a Powr-Lok  Limited Slip.

Differential ID Tags

Differential ID Tags

Bearings and Seals

When I purchased the MK2, I drove the car for five-six miles. I did not hear anything unusual from the rear end, and the differential does not appear to be leaking from the pinion. I will replace the axle shaft/hub bearings and seals and gaskets along with new hubs, but upon the advice of others, I am going to leave everything else alone for the time being. I have taken off the carrier cover and visually inspected the crown and pinion surfaces with no apparent wear problems.

Oil Seal Assemblies and Brake Caliper Adaptors

The final components of the ale to clean and reassemble were the LH and RH oil seal assemblies and brake caliper adaptors. The LH assembly had four shims (.o1″, .01″, .03″, and .03″) while the RH had only one shim (.03″). The assemblies were bolted to the axle ends with four 3/8″ -24 x 1 1/8″ hex head bolts and 3/8″ – 24 nylock nuts. Sandwiched between the oil seal assembly and the adaptor was a paper gasket. The original oil seal was a metal encased leather seal, while the new replacements are an improved rubber seal as shown in the images below.

The brake calipers were mounted to the adaptors with two 7/16″ -20 x 1 5/16″ drilled (for safety wire) hex head bolts with split washers. The RH adaptor had two .02″ shims on each bolt, while the LH side had no shims.

Shims

Shims

Oil Seals

Oil Seals

LH and RH Oil Seal Assemblies and Adaptors Cleaned

LH and RH Oil Seal Assemblies and Adaptors Cleaned

RH Oil Seal Assembly Components and Caliper Adaptor After

RH Oil Seal Assembly Components and Caliper Adaptor After

Installing the Axle and Springs

Based on comments of others, this is my plan for reinstalling the axle and springs into the car.

  1. Loosely mount the springs to the axle,
  2. Roll the axle under the car on the wheels and tires
  3. Lower the body to loosely attach the torsion rods
  4. Swing the springs up into the front mounts
  5. Raise the axle up into place
  6. Secure with the spring mount plate

 

 

 

 

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