Rear Hub – Handbrake shoes

After test fitting the rear hub and prop shafts it is time again to place another order with SNG Barratt. This ordered includes the following

• 1x Pair of rear discs (part number JLM1249)*
• 1 x Pair of rear brake pads (part number JM1282)*
• 1x Pair of handbrake shoes (part number JLM2209)
• 4x Grub screws for discs (part number SF605047J)
• 2 x Prop shaft nuts (part number JZN100035)
• 14 x Shims (part number C16621)
• 2 x rear brake caliper seals (part number JLM2200), as I ordered the wrong parts last time!

*update: the rear brake pads and discs are the wrong part number for a late XJ40 like mine, a problem I noticed later and have since resolved, but that is a cockup for a future post. 

Parts ordered from SNG Barratt. 

Let the Assembly Begin

With the new parts from SNG, the topic of this post if the final stage in rebuilding the rear hubs with their handbrake shoes. The new parts from SNG are only half of the parts I required for this stage, but after a quick rummage through my box of donor parts I found the remaining items; 

• 2x painted splashed shields
• 2x partially rebuilt hub carriers (with bearings and races)
• 8x no. 8 Allen headed bolts and washers
• 4x locking pins and corresponding springs
• 4x hand brake retaining springs 
• All components for 2 handbrake shoe adjusters 
• 2x handbrake cables supplied by AK

Having found all the parts, I began as always with laying them out on the floor. 

Required components to rebuild rear handbrake.

I started with the two biggest items, the hub and the splash shield. The AK manual states that if the splash shield is damaged you can cut it down prior to fitting to the hub. You still require the inner circular section, as this holds the handbrake shoes to the hub, but the outer annulus is intended only to keep dirt and grit from the brake disc and so is not essential (especially for a relatively low mileage/good weather only kit car). Since  both of mine were in a decent condition I chose to leave them as a complete unit, as they will offer some protection. The one modification I did want to consider was a way of reducing the chance of corrosion between the shield and hub (a serious problem I found whilst cleaning these donor parts). To avoid water ingress into this area I decided to put a bead of RTV around the edge where the shield mounts to the hub carrier. The downside to this approach is that it will make it harder to remove the shield later if needed, and could also trap and keep water in this gap, if it gets in, which would make any corrosion worse. However, I decided to chance my arm that water would not get trapped in this gap and prevention was a better approach. 

RTV on hub carrier and the splash shield installed.

With a quick bead of RTV the splash shield was lowered over the hub and secured to the hub carrier by 4 no. 8 Allen headed bolts and washers (from the donor car). There was a considerable buildup of paint in these threads and so I had to run the bolts in, in stages which regular removal and cleaning of the threads. Finally, to ensure these bolt will not vibrate loose, I gave each of them a drop of locktight. 

The next step is to assemble the handbrake shoe adjuster. The cleaned adjuster (I know it doesn’t look it) is assembled from three components as shown below. Each mating surface is given a liberal coating of copper grease and rotated several times to ensure an even coating on all surface. The adjuster thread is then screwed fully into the cogged central piece before the cap placed over the top. This makes the assembling of the shoes and springer easier (or at least possible). 

Assembled adjuster.

Using the rebuilt adjuster and the pair of the springs I test assembled these with the new shoes. I did this away from the hub to make my first attempt as easy as possible as the springs are very strong and I didn’t want to scratch the fresh paint on the shield. 

As throughout this build, all metal-metal contact faces get a liberal coat of copper grease. This starts with the recesses in the shoe formers, where the adjuster and hand brake mechanisms slot into. However, the important thing to remember is that the copper grease should never touch any of the braking material and so careful application of the grease with just enough being applied is key. I know its common sense not to put grease on brake pad/shoes… but thought worth stating. 

Handbrake shoe with springs and adjuster. 

Having built up the first brake shoe the next step is to consider the handbrake mechanism. I was pleased to see that I still had the all-important small stud, which is used to secure the handbrake cable to this assembly. I was fearful of losing this and then struggling to find a new one. Before fitting this item, I ensured that all the metal to metal contact surfaces had a good coat of copper grease. This was certainly a messy job and the part required a good wipe down afterward. Despite this, the internal pieces certainly moved a lot smoother. I did leave some excess copper grease on the inside surfaces casing to avoid future ware. 

Handbrake mechanism with a light coat of copper, grease were required.

The last part of this assembly which needs to be trial fitted is the mounting of the hand brake cable. The recessed section on the rear of the hub was slightly too small for the mating surface on the handbrake cable. The solution was a small amount of filling on the handbrake cable matting surface to achieve the desired fit. 

Slightly filled down recessed lip on handbrake cable.

With this part prepared there is nothing left for it and its time to install the shoes onto the hub. The XJ40 build manual suggests applying small amounts of copper grease into the six contact points on the shield. My concern is not to apply to much grease and run the risk of this contaminating to the shoes. 

Brake shield with copper grease applied to high spots. 

With the shoes and springs assembled these are then placed over the central hub section and onto the splash shield. The next step is to fit the main handbrake mechanism. This starts by passing the handbrake cable up through the back of the hub carrier and through the tube in the splash shield. On the original donor car, there was a plastic retaining clip which I had kept, that sat between the shield and the hub carrier to keep this cable in place. However, this does not seem to fit onto the AK cable, and so can be discarded (Wish I hadn't spent 30 mins cleaning these two clips now). 

Handbrake cable being passed through hub and brake shield.

With the cable passed through the hub, the end of the cable can then be secured to the handbrake mechanism bypassing the small cylindrical stud through one arm of the mechanism and the end of the handbrake cable. This stud is retained in place solely by the overhang of the mechanisms outer casing, and so only work secured when in its 'normal' position. 

Partly assembled handbrake shoes

Each recessed end of the mechanism then gets a coating of copper grease, before slotting each end in turn into the corresponding cut out on the brake shoe. This is made a little easier by the fact the shoes can still lift up and rotate slightly, but is still a pig of a job to do thanks to the tension from the springs. 

With the handbrake cable and mechanism attached the final step is to add the hold-down pins to keep the pads on the splash shield. This is a simple job of placing each pin through a corresponding spring, then a hole in the shoes and finally the shield. These are then secured in place by pressing them down on the pin with a no. 5 Allen key and twisting to lock. Then the tension provided by the spring keeps the pin in place.

Assembled rear hub with handbrake shoes.

As someone who always wants to understand how and why things work, I must confess it took me a while to fully comprehend how the handbrake mechanism functions. So what I understand happens is when the cable is pulled, it pulls the inner section of the mechanism inboard towards the shield. Due to the arrangement of the pivot and the cable mounting location, as the cable is pulled, it has the effect of increasing the length of the mechanism, which in turn pushes the shoes out towards the drum. It also applies an outboard force (away from the shield) onto the shoes, which I guess is another reason for the pins/springs fitted in the last step. 

With the rear handbrake shoes fully assembled onto the hub, the last step is to pull the handbrake cable and check it all works. For that and a time-lapse look at the above build process, I have added the following video.... yeah video time!!!.

The process is then repeated to assemble the other hub. I must confess that despite the challenges of the springs, this is a rewarding job. I say this because afterward, you have two sub-assemblies which you can actually make do something! With these built the next step is to return to the chassis and continue with the rear suspension build. 

Rear Corner Build – Part 1

Having rebuilt the prop shafts and installed new races and bearings into the hub carries, it is now time for an initial fitment of the rear end. The plan here is firstly to check that all the parts go together, but also to get an idea of how many spacers/shims are required to achieve the desired chamber angle.

Installing the Re-built Hub

I chose to start by installing the rear hub carrier onto the swing arm using the donor lower fulcrum shaft. As is suggested in the manual, it is certainly worth trial fitting the fulcrum shaft through the swing arm by itself, to ensure it fits and there isn’t a significant buildup of powder coat. For these swing arms, it’s true to say the shafts are a tight fit but there is no real excess of paint. With a thin coat of copper grease on the shaft to ease the installation and later removal, the hub carrier was then installed to the swing arm. This job is a little cumbersome as you have to hold the hub at the correct position whilst sliding the shaft through. Gentle taps with a rubber mallet and the job is soon complete. 

Installation of rear partly rebuilt hub onto the swing arm.

Installing the prop shaft

Next, the prop shaft is installed onto the differential. AK suggests that you begin by placing the donor prop shaft spacers between the prop shaft and differential. I can’t help but think this is a strange thing to assume as both the prop shaft and swing arm are new from AK, and so not sure how they can be sure these will be correct(ish). Since my original spacers were different sizes (6.4mm and 6.55mm thickness) I was extra careful to put them back on the correct side. These spacers slide over the bolts on the output of the diff. 

Donor spacers placed back on differential output flange.

The next step is to slide the prop shaft on and secure it in place with the 4 original 7/16" Unf Nyloc nuts. I decided here to add a washer between the nut and the prop shaft flange. The original nuts are used only during the trial fitting stage and will be replaced with new 7/16" Unf Nyloc nuts later when in final assembly. Whilst these nuts could be replaced with the somewhat more interesting Philidas nuts (part number NV607041#, which lead to an interesting morning read about these nuts), AK suggests the Nyloc nuts, so I’m sticking with their recommendation. 

Fitted prop shaft.

Fastening the nuts onto the prop shaft is a tricky process, as there is precious room between the opposing universal joint surfaces and unless you restrain the prop shaft, it will rotate as you tighten the nuts. After much trial and error, I found the easiest way to fastening each nut was it to rotate the prop shaft such that the 'target' nut was just off top center with the spline end of shaft resting on the floor. In this position, I could then use a 7/16’’ socket on a 100 mm extension to fasten the nuts. As you have to repeat this process for four bolts per side, this is certainly the least fun part of this job. 

Bring it all together

Now the splined end of the prop shaft can be passed through the respective rebuilt hub. To aid this, I slowly raised the hub/swing arm on the trolley jack whilst rotating and sliding in the splined end of the prop shaft. The tricky parts of this process are to protect the freshly painted hub carrier and getting the splined surfaces to line up. This is defiantly a cumbersome job where an extra hand would have been useful, but not essential. Once the prop shaft is slide into the hub, it is secured in place with a cone washer (smaller radius inboard) and a ‘special’ 1/16’’ nut (I found out why it is listed a 'special' in SNG manual later, no spoilers yet). Both these parts are taken from my donor car. The special nut is single use only, and so whilst I will use it for setting up the camber angle it will be replaced in final assembly. 

Prop shaft nut with cone spacer/washer.

With the hub installed onto the chassis for the first time, it is time to step back and admire the progress. If only I knew at that point that this would come apart so many more times. 

Hub fastened to prop shaft and swing arm. Resting on a trolley jack.

During my first attempt to fasten the special nut onto the chassis, I must have over tightened it (a good sign for later), as when I finally removed it, I noticed that inside the nut there is an inner coil/spring,  which is now unwinding itself from the nut. This must be another type of locking nut, and I guess what makes it ‘special’ and why it is single use…. 

Prop shaft nuts – over tightened.

Adjustment, Adjustments, Adjustments

With the rear corner assembled, the camber angle of the hub needs to be checked and altered. To do this, the top surface of the hub has to be 150 mm from the top of the chassis rail. This means careful raising of the hub on the trolley jack. I found the best way to measure the required distance was to use my father’s old set square, which luckily had a tongue length very close to 150 mm. I, therefore, placed the main surface on the chassis and raised the hub until it touched the set square. 

Set square used for checking the height. 

With the hub at the correct height, the aim is to ensure the (camber) angle hub is between 0 and 0.5 degrees (top of the slightly inboard) from the vertical. This angle of the hub is altered by changing the shims between the differential and the prop shaft. The concept being the thicker the shims, the more it pushes out the top of the hub. As with the front corner, I used an app on my phone to check the angle. For completeness, I used my spirit level, as, after all, I was going for near (or just off) vertical. 

On the off side, I found that with the original shim in place, the top of the hub was several degrees out beyond vertical. To resolve this, I took the entire assembly apart and reconstructed without the donor shim in place. This seemed to create almost the desired angle of 0.4deg.

The gap between the prop shaft and output flange

To verify the thickness of the desired spacer, again dismantled the corner and begun to fill it with 1 mm thick washers. The washers fitted nicely between the recessed region of the mounting plate and the bolts. I found these were a nice tool for experimenting with different shim thickness. Whilst I was not able to obtain the final shim thickness required, I was able to get a range of thickness in which I would find the desired angle. This should help determine how many shims I need to order from SNG. 

Differential output flange with washers to approximate the required shims.

Repeating the re-assembly process multiple times, with each time carefully checking the height of the hub, you can eventually get close to the correct angle.

Double checking the camber angle with a spirit level on the off side.

Final outcome

Having repeated this long process on both the off and near side, I ended up with an idea of what size shims I needed to purchase. 

• offside required no additional shims for spacing
• near side required between 5 mm and 6 mm of washers

Whilst I do not need any shims to get the correct camber angle, speaking with AK, they suggested filling the gap between the differential output plate and the prop shift with shims. I guess this is to spread the load onto the prop shaft, rather than relying on solely the pins. 

To achieve the required thickness on the near side, I might be able to get away with using the original donor shim. Whilst this might make things easy, I may consider buying some shims for this side so I have some flexibility when it comes to final fitment.

Now that I have an idea of what size shims I require there are several options to consider. 

• Speed sensor rotor (CAC8713) which has a 1 mm thickness for £13.99. The actual speed sensor part is not required for the AK build.
• A range of thicker spacers who’s part numbers are CBC4806xx, where the last two 'xx' are the thickness in mm, for example, the 5.5 mm spacer is part CBC480655. These parts varying costs but between £30 and £55, which are eye wateringly expensive for what they are.
• Rear Camber Shim 0.020’’ (or approx. 0.5mm in useful units)  is part number C16621# and are 50p each.

Based on the prices and a recommendation from AK, I decided to go for the rear camber shims. So I added an order for 16 to my growing SNG basket. This order will also include the rear hand brake shoes, which will allow me to finish the assemble to the rear hubs prior to the final rebuild of the rear.