Feb 262015

The brakes have been connected and plumbed in for quite a while now. The system only had to be filled with brake fluid and bled, so I had assumed the brakes were essentially complete and wouldn’t be noteworthy. I should have known by now that was almost certainly going to be wildly optimistic …

I had dithered on the type of fluid to use, glycol base or silicone, changing my mind almost on a daily basis before finally making the decision to stick with glycol based DOT4 fluid. The ‘this is absolutely my final decision’ was subsequently reversed to silicone following an interesting article on the subject sent to me by Chris Jackson, whose restoration is being covered in the E-type Magazine.
DOT5 Silicone Brake Fluid

The debate regarding DOT4 (Glycol) verses DOT5 (Silicone) seems to be quite polar in nature. A bit like Marmite – people are either for it or hate it and never the two shall meet! At the time I’d just been working through fixing leaks in the cooling system. Reports of leaks from weeping hoses and splitting repro reservoir bottles are all too common. The thought of brake fluid leaking onto the paint work and remaining undetected paid a significant part in opting for silicone.

However some have raised concerns that silicone fluid might cause rubber seals to swell. Possibly but the composition of the rubber seals has changed over time, with natural rubber no longer used. Modern rubber should now be compatible with all types of fluid.

Automec DOT5 Silicone Fluid

The manufacturer’s blurb suggests silicone fluid is a ‘fill and forget’ solution but I think this is a little wide of the mark as water will find its way into the system. As it doesn’t mix with the brake fluid, it would then pool and cause local corrosion so I’m still planning to replace the silicone fluid periodically, although less frequently than would be the case for DOT fluids.

Apart from the additional expense, the down side of silicone is that, when it is agitated, it has a tendency to absorb tiny air bubbles that are not visible to the eye. This can cause a spongy pedal as the bubbles compress under braking. The simple solution is to leave the fluid to settle overnight before bleeding the system, although that would be more problematic if it ever had to be refilled on a trip.

All the compression joints were checked and tightened. Now the front calipers were bolted to the uprights, sufficient torque could be applied to the bolts clamping the two caliper halves together. Correct torque settings are not published but a brake refurbishing company recommended to torque the 7/16″ diameter bolts to 70 lb-ft and the 3/8″ diameter bolts to 40 lb-ft. I’ll need to keep an eye out for any initial issues.

Remote rear bleed kit

Stevson & Fosseway kits

Another of Chris’ suggestions was to fit one of Fosseway Performance’s remote bleed kits. The standard bleed valves are hard to reach at the best of times, so moving them to a more accessible position on the IRS cage is quite a popular modification. In fact I’d already fitted a similar kit sourced from Stevson Motors prior to installing the IRS unit.

My kit was definitely more agricultural than engineered so I had been a little disappointed when it arrived. The mounting brackets were just pieces of brass sheet that looked as though they had been hand drilled and then bent in a vice.

Still their function is fairly basic and the aesthetics is not a great issue, being tucked up underneath the car, so I had fitted the Stevson kit. It was only later, when I was working underneath the car to re-fit the handbrake cable, did its design start to irk me. My patience was wearing thin after catching the sharp corner of the brass bracket for the umpteenth time.

The revisiting of the handbrake was because I’d routed the cable incorrectly. It should pass through an eyelet on the inside of the transmission tunnel, with a rubber grommet protecting the cable. The cable was too stiff to re-route in situ by disconnecting the cable from the handbrake mechanism. So the entire cable had to be removed.

Re-routing couldn’t be achieved by just disconnecting at compensator linkage Correct routing of cable through grommet in transmission tunnel eyelet

The final straw came when I found that the seat for one of the bleed valves had been machined too far. So the coned face at the end of the valve could never make contact with the seat, let alone form a seal. Longer valves are available … but not in the course thread used in the kit. There was no alternative – it had to be replaced.

I’m sure Stevsons would have rectified the problem but I now had the opportunity of fitting a better quality of kit. An order was placed and the Fosseway kit arrived the next day! The main difficulty was, with the IRS now in place, access was severely limited. The front pair of springs and dampers had to be removed to access the calipers.

Forward rear springs removed for access The Fosseway kit has better banjo attachments Fosseway kit uses sprung bleed valves

The Fosseway kit uses a banjo attachment at the calpiers which is a neater solution and much easier to fit, as it doesn’t require the flexible pipe to rotate when tightening it into the caliper. The other difference is the style of bleed valve used, sprung valves rather than standard solid valves. The sprung valves help with bleeding as the spring stops air entering the system between pumps of the brake pedal. In the end, replacing the remote bleed kit was easier than I had thought and only took an hour and a half.

Brake Bleeding Woes!
This was another task that proved far more troublesome than I had expected. Most methods of bleeding require the help of an assistant. The exception to this is vacuum pumps, such as the Mityvac, which can be operated single-handed. The vacuum is applied to the bleed valve to draw the fluid through the system so both the vacuum and bleed valve can be controlled from one location.

Mityvac vacuum bleeding tool

It was for this reason I purchased a Mityvac pump to replace my old Eezibleed tool. The Eezibleed pressurises the reservoir to push fluid through the system but still requires two people to operate. So doesn’t really offer anything over the traditional method of pumping the brake pedal.

The correct bleeding sequence according to the service manual is the near-side followed by the off-side, starting with the rears and finally moving to the front brakes. The reservoir bottles were filled, the RH reservoir feeding the front brakes and the LH reservoir the rears … let the bleeding begin!

After about 1/2 hour of trying with the Mityvac, absolutely nothing had come out of either of the rear valves. Time for plan B – the Eezibleed was rigged up to the reservoir. All this achieved was pressurising the bottle to what looked like bursting point and spraying fluid everywhere from around the cap. Thank goodness I’d gone for silicone fluid! Still nothing was coming out at the rear calipers.

Plan C! The traditional approach – the good old brake pedal and a patient helper! The resistance started to build after 20-30 pumps of the brake pedal. However this would dissipate after about 30 seconds. Frustratingly there was still no fluid coming from the rears. I suspect pumping the pedal was only pushing fluid into the front circuit and the resistance felt at the pedal was due to the air in the pipe being compressed. Once the pumping stopped the air pressure would force the fluid back into the reservoir.

Stumped, I decided to search the web to find out if there was a specific technique or trick that might help. At least I found out that I certainly wasn’t alone in having trouble bleeding the rear brakes, especially filling a dry system. One tip was to try bleeding the brakes with the engine running as the servo would be boosted by the vacuum. Still no joy!

Another suggestion was to first check the operation of the valve located in the output port of the servo cylinder. Once it had been confirmed fluid was coming out of the servo cylinder, simply loosen the rear bleed valves in turn, allowing the system to bleed naturally, under gravity. Note: the sprung valves need pressure to compress the spring to allow fluid out and so had to be removed for this method

The height of the reservoir above the remainder of the system provides a sufficient head of fluid to allow gravity to do the work for you. Whether the removal and inspection of the cylinder valve had fixed the restriction I’m not sure, but fluid was now coming out of both rear bleed valves.

Success was short lived …. when the brake pedal was depressed, fluid leaked out of the three way union mounted on the IRS cage. The problem was found to be the new flexible Goodridge brake pipe. Although sold as a direct replacement for the E-Type, the rear attachment was too short. It was a similar problem to the remote bleed kit – the attachment could never make contact with the seat and therefore create a seal.

Short end of Goodridge brake hose was too short! The additional mechanical brake light switch

Several days and a new hose later, the system was finally bled. At the same time the last few braking tasks were completed: the brake pedal was much higher than the accelerator pedal and the mechanical brake light switch was fitted.

The height of the pedal is set by adjusting a ‘stop’ screw in the pedal housing, which was set to remove any free travel in the brake pedal. Unfortunately the clutch pedal is too high as well but this doesn’t have any adjustability. Other owners have had the same problem, caused by the push rod being 1/2″ too long on the replacement master cylinders. Another job to the list!

Jan 202014

It was frustrating to have gone through the process of re-plating/re-chroming all the individual components and to have rebuilt the handbrake, only to find that the ratchet had been butchered to fit an incorrect cable. Rather dispirited, I decided to keep the rebuilt handbrake as is and reuse the offending cable.

I’d hoped that it would be possible to rig up an alternative method of mounting the handbrake switch. However I wasn’t able to come up with a solution that I was happy with. Plus I’d found a number of forum postings of issues setting up the handbrake mechanism even with the correct, unmolested parts.

Old & New Clevises Correct cable is shorter

The existing cable was either incorrect for the car or a poor reproduction part. Both of its clevises were far too long, resulting in an inner cable length that was over 1/2″ too long.

I’m fairly sure that a previous owner/garage had relocated the cable abutment on the ratchet about 1″ rearward as a bodge to compensate for the oversized clevis.

The knock-on effect is the distance between the outer cable abutment on the ratchet and that at the handbrake compensator mechanism on the IRS has been reduced by the same amount. Squeezing the outer cable into this shorter distance effectively reduces the overall inner cable length by 1″ – so a net shortening of approx. 1/2″.

The handbrake compensator offers some adjustment to cater for stretching of the cable over time. Even so, 1/2″ would almost certainly put it at the limit of its adjustability. I’d probably be on a losing wicket trying to get it to work correctly. It was better to bite the bullet now rather than later. So a correct cable was obtained from the Jaguar Enthusiast Club, who now offered them via their online shop.

RM & J Smith were able to supply new ratchets which came as a relief, so it wasn’t necessary to buy a complete new handbrake. The only obvious difference is the pivot bolt spacers are welded to the replacement ratchets.

The fitting of the new ratchet was a simple task but the completion of the handbrake was foiled yet again. The bore of the outer cable abutment was 1/32″ smaller than the 3/8″ cable diameter. It has a slot machined into its circumference and is designed to allow a slight expansion, so I didn’t think anything was amiss.

The bolt securing the switch bracket then clamps the abutment onto the outer cable.

The only way I could get the outer cable into the hole was by continually twisting and pushing it. It didn’t feel right the more I progressed. Considerable effort had been needed just to get the cable half way home. So I decided to remove it and have a re-think. It might be possible to re-drill the bore although I was concerned the slot might cause problems.

I needn’t have worried. As soon as the cable was twisted in the reverse direction, disaster struck …. one half of the abutment fitting snapped clean off.

Aaaaargh and much cursing of repro parts!! Another case of what I now refer to as the Restoration March …. 1 step forward, several back!!

Looking at the fracture, it appears that the whole ratchet is hardened during the manufacturing process, presumably to provide the necessary hardness in the ratchet teeth. The downside, as I found out, is it makes the part brittle and prone to stress fractures. Not ideal for clamping parts which need a degree of ductility, such as the cable abutment.

RM & J Smith have been an excellent source of difficult to find parts and, to their credit, were very good, offering to send out a replacement immediately free of charge. They had identified the problem with the size of the hole and returned the ratchets to their manufacturer to be corrected. I had received one that slipped through the net. The following day the replacement arrived and it fits perfectly.

Getting the warning light switch properly set up proved to be much trickier than I’d anticipated and quite frustrating. The switch is activated by a ‘S’ shaped spring striker. When the handbrake is fully released the protrusion at the base of the lever presses against the striker, which in turn depresses the switch.

The main problem was mounting everything far enough forward so there was sufficient pressure on the striker to operate the switch.

Both the switch and striker are mounted to the bracket by two locking half nuts. So there is very little fore and aft adjustment that can be made. Mounting the switch progressively nearer to the striker starts to pre-engage the switches’ plunger, making the switching more hairpin-like until ultimately it’s permanently on.

I finally got it set up and working on the bench although I still wasn’t 100% happy. The switch had to be angled slightly and the warning light would be on as soon as the lever was moved off the end tooth of the ratchet. The plan was to mount the pre-built handbrake and switch but much to my dismay, I’d completely missed that fact that the cable has to be fed forward into the cabin through a guide bracket in the transmission tunnel.

All the set up was then lost, as the handbrake switch needed to be removed to free the cable. In situ, it wasn’t possible to reproduce as good a set up as before because the floor pan was stopping the angling of the switch. I found the best fit to mount the ‘S’ shaped striker horizontally.

I’m tempted to add some packing washers between the striker and bracket to allow the switch to be moved forward slightly. I think I’m going to leave the fitting the central console until after its first MOT so I’ll still have access to the handbrake.

Handbrake puzzle – one step forward, two back

 Brakes  Comments Off on Handbrake puzzle – one step forward, two back
Sep 072013

The missing handbrake parts for the warning light switch were ordered from SNG Barratt – the bracket, switch and ‘S’ shaped spring. It looked fairly obvious how it should all go together but what puzzled me was the parts list indicated only two nuts are required to secure both the switch and spring to the bracket.

The switch is actuated by a finger-like protrusion at the base of the handbrake arm, which should press against the spring as the handbrake is nearing the fully released position. This causes the spring to depress the switch’s plunger, breaking the circuit and so switching the warning light off.

The handbrake warning light switch set up - something's wrong but I couldn't work it outThe only way I could get the switch’s plunger anywhere near to the ‘finger’ protrusion was to mount the switch to the bracket and then use two locking nuts to position the spring at the end of the switch – as shown in the photo.

I’ll be swapping to half nuts to secure the spring but pressing the spring just about operates the switch. However the problem is the ‘finger’ protrusion of the handbrake only just brushes the spring and doesn’t push it against the switch.

I posted the photo on the E-Type forum and within no time at all the moderator, Angus, had responded, directing me to an image of the correct set-up on a S2 car currently going through his workshop, Moss Jagaur.

I went backwards and forwards between the two set-ups but still couldn’t see how mine was so far out. After all, the geometry is fixed. Eventually I noticed the length of my cable fork was much longer and then it dawned on me what was wrong.

The correct position for the switch mounting pointMy handbrake had been hacked about at some time in the past. The bracket attachment has been cut off and welded further back.

There had been some obvious welding around the attachment point but I had assumed this was just a repair to strengthen it and, as it has come off the car, was correct. It now explains why they hadn’t refitted all the switch parts!

The annoying thing is all the parts have been re-plated and the ratchet teeth are all in good condition. I think I’m going to keep it ‘as is’ and adapt the bracket, although it’ll bug me now!

Further responses to my forum post pointed out that the handbrake cable is an incorrect reproduction item, which would explain why the clevis fork is longer but more importantly that they cables are too long to get the handbrake to work correctly.

The repro cables have been on sale for many years, and still are!, and it points to a previous owner having gone the wrong way trying to find a solution to the problem. The repro cable problem had been picked up by Jaguar Enthusiast Club, who now offer the correct cable so one is now on order.

It’s cases like this where the E-Type forum is invaluable. There are members with a wealth of knowledge of these cars who are happy to spend time offering others advice and solutions to their problems.

Handbrake rebuild

 Brakes  Comments Off on Handbrake rebuild
Sep 022013

The re-plated handbrake component ready for assemblyThe handbrake had been sent off to ACF Howells for re-chroming as a complete unit. With hindsight it would probably have been better to dismantle it myself and just send them the pieces that needed re-chroming.

I therefore had to work out how the pieces should go back together. The original fittings for the handbrake light switch were missing from the car so the replacement parts would also be added to the puzzle.

Fortunately most of it is fairly self-explanatory. The only issue was having to cut down a roll pin to replace the retaining pin for the push button which wasn’t in the parts returned after re-chroming.

The first task is to reunite the push button operating rod and the pawl of the ratchet mechanism within the handbrake arm. The operating rod is fed through the access hole at the rear of the arm and the pawl is inserted up through the base of the arm, complete with its distance tube and a spacer either side.

Orientation of the operating rod & pawl A clevis pin connects the rod & pawl

The pawl needs to be orientated with the hole for the clevis pin rearward so the hole and fork end of the rod can be manoeuvred to protrude through the access hole in the arm. The clevis pin can then be inserted and secured with the split pin.

The push button needs to be fitted before the pawl pivot bolt, otherwise there’s not enough clearence to insert the retaining pin. Without the bolt, the operating rod can be pushed down the handbrake arm until the hole for the retaining pin is clear of the handbrake arm.

At rest the pawl is held in the locking position by a spring which is inserted onto the operating rod before the push button is fitted. The order of fitting is a washer (not shown in the photo) which sits against protrusions inside the handbrake arm, the spring, a retaining washer and then the push button.

Sprung push button components Roll pin inserted to secure button
The operating rod needs to pushed so it protrudes beyond the end of the handbrake arm (further than in the photo!) so the retaining pin can be inserted Copious amounts of grease was applied before the roll pon was hammered home

A forum member had a thin rubber washer between the second washer and the button. As a rubber washer wasn’t in the returned parts, I can’t be sure if my handbrake originally had one. When the button is fitted the spring is already under compression, providing a cushioning effect and wear isn’t an issue. Therefore I didn’t feel the need to fabricate a rubber washer.

Next the ratchet gear needs to be inserted into base of the handbrake arm followed by fitting the outer cable attachment bracket. Similar to the pawl, the ratchet gear uses two spacers to fill the internal space within the handbrake arm.

The two bolts securing the outer bracket can then be fitted. One acts as the pivot point for the pawl and the other as the pivot for handbrake arm in relation to the ratchet gear.

The final piece in the puzzle was the fitting of the handbrake warning light switch. As mentioned, these parts were missing and so replacement parts were ordered from SNG Barratt.

It looked fairly obvious how things went together. A bracket mounts the switch to the base of the handbrake ratchet gear and it appears that a ‘S’ shaped spring attaches to the end of the switch.

When the handbrake is fully released, a ‘finger’ protrusion at the bottom of the outer cable attachment bracket presses against the spring, which in turn depresses the Push-to-Break switch.

The parts manual indicates two nuts are needed to secure both the spring and the switch. I’m obviously missing something as I can only see how to get it to work using three nuts – one to secure the switch to the bracket and two half nuts to lock the spring at the correct distance from the activating ‘finger’.

Handbrake caliper rebuild

 Brakes, Rolling Chassis  Comments Off on Handbrake caliper rebuild
Jul 032013

Now the handbrake calipers have had been painted, all that remained was to rebuild them …. for the second time!

The service manual suggests the two rear calipers and handbrake mechanisms should be removed as single units. However this needs the half-shaft inner joints to be broken and the front springs/shock absorbers to be removed, which seemed unnecessary.

The components for the handbrake calipers and self-adjusting mechanism ready to be re-built

I found it much simpler to detach the handbrake mechanism from the rear calipers in situ and then remove them separately. So they won’t be re-united with the rear brake calipers until the refitting of the brakes into the IRS unit.

The handbrake system is self-adjusting using ratchet mechanisms to automatically compensate for the pad wear. The distance between the pad faces is determined by how far the caliper adjusting screw has been screwed into the ratchet gear.

When the handbrake is applied, the operating arm pivots on the pin attaching it to outer caliper arm. This effectively draws the caliper adjusting screw and attached inner caliper arm towards the outer caliper arm, resulting in a clamping force.

The pivoting action also allows the ratchet gear to move relative to the sprung pawl and the extent of movement is determined by the amount of pad wear.

As the wear increases, the movement becomes sufficient such that the pawl slides along the shallow slope of the ratchet gear tooth and its spring forces it to drop onto the next tooth.

The ratchet gear moves back relative to the pawl when the handbrake is released. However the pawl now engages with the steeper slope of the tooth resulting in a turning force on the ratchet gear.

This torque rotates the ratchet gear further onto the adjuster screw and therefore reduces the distance between the two pads. The photos above attempt to show the ratcheting process, although in reality the ratchet gear will only be tightened one tooth at a time.

All the moving parts a given a generous covering of Lucas green brake grease before the cover plates were addedI’m not sure if there is a correct or recommended order for rebuilding the handbrake mechanism. I started with the internal parts of the operating arm; the pawl slots onto protrusions on the arm which guide and limit its travel. A tensioning spring attaches to the pawl and the other end to an anchor pin pushed through the operating arm.

The ratchet gear can then be installed which has a friction clip attached to its base. The clip provides sufficient resistance to stop the gear rotating when the pawl is gliding over the shallow tooth face. Once these were in place all the moving components were covered in high temperature brake grease.

The anchor pin for the return spring needs to be inserted into the outer caliper arm before the pads are fittedThe operating arm could then be attached to the outer caliper arm. I found it easier to fit the operating arm return spring first which is attached at one end to an anchor pin pushed through the caliper arm and the other to a shaft in the operating arm.

Note: the spring passes through a protective cover so this needs to be positioned before the spring is hooked over the operating arm shaft.

The pivot pin between the caliper arm and operating lever was then inserted and fixed with a split pin. A slotted screw and nut then clamp the two protective covers to the operating arm.

Finally the inner caliper arm was attached to the caliper adjuster screw with another split pin and screwed into the ratchet gear to complete the rebuild.

The caliper adjuster screw is fixed to the inner handbrake caliper with a split pin

The completed handbrake mechanisms awaiting fitting