Road legal again …. finally!

 Alternator, On the road  4 Responses »
Jul 152016
 

I’d been lucky to have an opportunity to drive an unmolested E-Type while on my recent travels (Sydney in an E-Type) and wanted to return the favour when the Christopher was next back in the UK. Not least because he would be able to give valuable feedback, good or bad, on how the two cars compare.

Crossing the Sydney bridge in an E Christopher’s original S2 FHC

I had experienced slight gear selection issues with mine when changing from 2nd to 3rd and from 3rd back down to 2nd – something I might cover in a future post. Although these were more due to being used to modern gearboxes and resolved by adopting a more sympathetic technique changing gears.

I had decided to keep reasonably close to the original spec. The most noticeable differences are the EDIS electronic ignition system and the Mangoletsi cable throttle linkage. The EDIS system hasn’t been properly mapped yet so the only real difference between our cars was the throttle linkage.

Christopher’s visit coincided with the car’s trip up to the trimmers to fit the hood. It had been up with Suffolk & Turley for a lot longer than expected and so the only opportunity for a drive was on the day he was returning to Australia.

This would have been fine had the MOT not expired while it was up at the trimmers. It had been there so long I hadn’t had an opportunity to organise a test since getting it back and now the speedo had seized. It might be possible to get away with a broken speedo on a modern car as the MOT tests are all static and the brakes tested on rollers.

However due to the limited slip differential, the E-Type had to be tested out on the road whilst travelling at 20mph. Braking efficiency is measured using a calibrated decelerometer. Therefore it would be glaringly obvious that the speedo wasn’t working. So it was a race against time to get the car road legal before he left. No pressure then!

To make matter worse, I’d noticed the ignition warning light wasn’t going out indicating the battery wasn’t charging. I had a matter of days to resolve both issues and get the car through the MOT. Things weren’t looking too promising, especially when I contacted Speedograph Richfield as the speedo hadn’t turned up as expected. I had specifically asked for a 24 hour delivery but they had forgotten, sending it out 2nd class and without the ability to track it. Aaaaaah …. and relax!

I was more concerned about the charging system since I had modified my alternator to a more modern design. This eliminates the 3AW and 6RA relays so the only two things that could be wrong were the 4TR voltage regulator or the alternator itself.

Modified alternator doesn’t need 3AW
and 6RA relays … less to go wrong!		 Three additional diodes (trio) have been
added to self-energise the field coil

A failed 4TR regulator is fairly easy to diagnose. The unit is simply removed and a jumper lead used to link its connector’s F and – terminals together. Essentially this just puts the full battery voltage across the field winding and removes the feedback loop.


Alternator components

As the alternator starts spinning it’s output voltage increases. Without the feedback, the increased output increases the current in the field coil which, in turn, increases the alternator output voltage.

It would quickly reach a run away situation and burn out the alternator coil. Therefore, as soon as you’ve registered that the output voltage is increasing, you need to immediately switch off the engine.

I had pre-ordered another 4TR unit as a precaution but it wasn’t found to be faulty. It was the alternator. The modifications I’d made to the internal electrics and external wiring give it a ‘soft start’. The voltage across the field winding starts at approx. 1.5v rather than the full 12v battery voltage.

This is because the battery voltage is applied across the ignition warning light bulb (approx. 300 ohms) in series with the field winding (approx. 4 ohms). Hence the lions share of the voltage drop is across the bulb rather than the field winding.

The measured voltage without the engine running was 2.74v which seemed a little high. I incorrectly deduced this would result in an increased current flowing in the field coil, which wouldn’t be a bad thing. Once the engine was started, this voltage only rose to 6.36v rather than the expected 14.4v.

The rotor field coil voltage was
higher than the expected 1.5v		 With engine running, the field coil
voltage should rise to 14.4v

A reduced output typically points to failed diodes in the rectifying bridge. This became my main focus. The bridge needs to be removed from the 3-star stator windings in order to test the diodes. So the alternator had to be taken apart and it revealed some interesting problems.

The AL post’s insulating piece had disintegrated. I wasn’t able to source a new one and had to rebuild it as best I could, with araldite making up for the missing bits! Not ideal but it should do for now.

Pulling the pulley wheel AL post insulator had disintegrated Temporary fix – rebuilt with araldite

The original slip rings piece was found to be cracked so I had replaced it when the alternator was rebuilt. The replacement has raised sections between the rings but, as the brushes sit either side of them, I thought nothing of it.

These raised sections had been in contact with the brush holder and had worn a groove in the nylon housing. The slip rings looked clean enough but I gave them quick polish with wire wool.

Difference between slip rings Signs of rubbing on raised sections Groove worn in brush housing

My multimeter has a diode checking function so it was easy to check the diodes once the bridge had been removed. My suspicions were that one or more of the additional three diodes I’d added for the alternator modification had failed. They hadn’t and all the diodes were fine.

Removing the rectifying bridge Diodes can now be tested

The other standard checks were made; the resistances of the rotor field and stator windings and the insulation between the rotor coil & rotor and the stator winding and stator laminations. All were fine … and I was stumped.

The alternator was rebuilt and put back on the car to test but there was no change. The ignition warning light stubbornly refusing to go out. I was getting fairly despondent. It was lunchtime, the alternator was in pieces on the bench yet again, there was no sign of the speedo, the car had no MOT and Christopher was due to turn up first thing the following morning!

For some reason I decided to measure the combined resistance of the rotor field winding and brushes. The rotor winding should be around 4 ohms. With the brushes included, I would have expected something in the order of 5 to 10 ohms (max). It varied between 30-40 ohms depending on the rotational positon of the rotor. This was way too high and would result in a significant reduction in the current in the rotor winding and therefore the output of the alternator.

Slip rings required light sanding Checking coil to rotor insulation

As a last resort and even though the slip rings had initially been cleaned with wire wool, their surfaces were sanded down with a fine wet and dry sandpaper. The combined resistance dropped to only 7 ohms. The alternator was quickly rebuilt and tested. Eureka – it was working!

I’m fairly sure the cause was due to the slip rings impacting the nylon brush housing. The resulting friction had melted the nylon to form the groove and some of the molten nylon had formed a glaze on the slip rings. The sharp points of the multimeter’s leads would penetrate the glaze to give a false impression of the resistance seen by the brushes.

I was expecting an initial voltage across the field winding of 1.5v rather than the measured at 2.74v. The higher voltage was due to a high combined resistance of the field coil and brushes compared with the 300 ohm bulb.


Refitting the alternator
… for the 4th time!

In total I had removed the alternator, taken it apart, tested each component, rebuilt it and retested it four times to get it working!

It was such a relief to get to the bottom of the problem and things started to look up when the postman arrived clutching the speedo. The garage kindly rescheduled things and its second MOT was passed late in the afternoon.

The following morning Christopher and I headed off for a drive and dropped in on his parents. His father had also had an E-Type years ago so it seemed fitting to vacate my seat so he could also go for a spin.

The feedback on how the two cars compared was positive too. The driving experience was very similar which was pleasing as there’s always a fear a restoration could change things for the worse.


Chris takes his father for a spin

One item that got the thumbs up was the PD Gough exhaust which has a lovely throaty roar from 2,500 rpm.

Something I can thank the administrator of the E-Type forum for as his advice was to stick to the standard cast manifolds, avoid the big bore systems and fit 1.75″ tubes with straight through silencers and straight through resonators.

MOT Hokey Cokey!

 Fuel Line, MOT  2 Responses »
Jun 172015
 

I was keen to get the car roadworthy as soon as possible in order to drive it up to Nuneaton to have the hood put on. The difficulty at the moment is booking it in for work as it needs to coincide with dry weather!

Fortunately the day of the MOT was a fine sunny day enabling it to be dropped off as soon as the garage opened. It had been booked into a local Jaguar specialist the following day to have the suspension geometry set up. There was a chance, with a following wind, that it might be road legal by the weekend!

After a few anxious phone calls during the day, it became clear that they wouldn’t have time to complete the MOT. They hadn’t even had time to get to the bottom of the front carb running far too lean. The car was returned to base and a second MOT appointment made for the weekend.


Back for MOT attempt 2

I decided not to cancel the wheel alignment the following day, planning a quiet route for the 2 mile journey that was not frequented by the Rozzers. Alas the car only made it about ¼ mile before conking out. After all the years of effort, it was a particularly low moment. I was certain it was due to fuel starvation and that wretched air lock.

Luckily it was possible to get the car back in 100 yard stints, by waiting a few minutes between each spluttering halt. The second MOT was essentially a repeat of the first with no progress made and the car returned yet again, without any work done either on the tuning or MOT.

I took the opportunity to take the front carb off to look into why it was causing the front two cylinders to run too lean. The jet was properly centred but the float lever arm was found to be 3/16” off resting on the specified standard, a 7/16” rod.

More dismantling to investigate the front carb The float lever should rest against a 7/16″ rod

A few days later it was back for the third attempt. The revised plan was to leave the carb tuning as historic vehicles aren’t subject to MOT emissions testing and just do the MOT checks. As they say, third time lucky …. this time it proved to be just that! It had passed the MOT and was ‘road legal’ … the first time in over 20 years!


A hurrah moment!
Passing the MOT

Although it had taken three trips to achieve, I’m considering it as passing first time! However there were obviously issues to address before it could be considered truly roadworthy. In fact, the MOT brake test has to be done out on the road due to the limited slip diff. They only just managed to perform the test and get it back to the garage before the fuel starvation ground them to a halt!

It was time to get some advice from my fellow trusted petrolists who had put in the IRS and come up with a plan. My worry was that it was the pipe running under that car that was a fault. Renewing it would require the IRS to be dropped and all that entailed – something I really wanted to avoid!

Their suggestion was to replicate the pipe run off the car using some flexible hose of the same bore. This would provide a more accurate flow rate that one could expect to achieve. If it is significantly different from the output of the under floor pipe, then it would point to this section being the root cause.

There were no kinks or collapsed bends in the pipe. The only other explanation was a blockage of some sort, but it’s a single length of (brand new) pipe which is open at one end and terminated at the other with a soldered connector that just mates with the bulkhead union. Hmmmmm …. could the soldered joint be causing a restriction and hence the reduced flow? It should be possible to poke a rod from the boot space through the union and into the pipe to get a feel to whether there was a restriction.

Rather embarrassingly, all my woes were of my own making. It wasn’t an air-lock, just my dreadful soldering! I’d almost completely blocked off the pipe by applying copious amounts of solder which had flowed into the bore. Worst still, I had compounded the error by not checking my handiwork before fitting the pipe.

My shocking soldering skills! Fabricated drill bush worked fabulously!!

Further advice was sought on how best to removal it. Within no time at all, John had kindly arranged for a 3/8” BSP bolt to be machined/adapted to act as a drill bush to screw into the rear union. This would ensure the drill bit was perfectly aligned with the centre of the pipe and I would not be making matters worse by damaging the pipe itself!

The flexible hosing that had been used find out the expected flow rate was rigged up to pass fuel back up the wrong way to blow out any swarf. The same flow rate test was repeated with the re-bored pipe.


Testing the expected flow rate

A flow rate of 1.5 litres was achieved with the flexible pipe and surprisingly an even higher rate of 1.75 litres per minute is now flowing in the pipe. Compare that to the 250ml before the re-bore! I’m just so happy and relieved we got to the bottom of the problem and resolved it!

Not surprisingly this has cured the fuel starvation problems and the engine is running much more smoothly. Although it still needs a good tune.

A couple of items were corrected as part of the MOT – even though I’d checked every suspension nut and bolt, I had still missed putting on the lock wire on the radius arm bolts. I’d also left off the jockey wheel for the water pump tensioner and the alternator fan was slightly loose. So these were corrected.

Other recommendations were to ditch the original nylon style fuel pipe in the engine bay in preference for some flexible rubber hose and always carry a fire extinguisher!! The nylon pipes are very hard and I had noticed occasional leaks if they were knocked out of position. I’d rather have a traditionalist tut-tut than run the risk of a fire!

Even though the suspension geometry still needs to be set up, I couldn’t resist taking it out on the road for its first real spin. It was actually the first time I’d driven an E-Type and I wasn’t disappointed!

The first drive in the E-Type

Finishing engine bay & pre-MOT tasks

 Air Filter, Alternator, Exterior Trim, Front Suspension, Fuel Line, MOT, Trim & Body Fittings  2 Responses »
Jun 162015
 

It feels as though the list of outstanding tasks is getting longer rather than shorter. So they have been prioritised into those required for the MOT and those that can wait. Due to the age of the car the MOT is essentially limited to checking the suspension, fuel/brake lines and lights. However, knowing the person doing the MOT, I’d asked them if they would cast a more critical eye over the whole car.

I’d been having trouble balancing the carbs and, although it’s not part of the MOT, I thought it best to have a second pair of eyes look over them. The front two cylinders are running too lean, even though all three carbs have been set to the standard reference point for tuning. So it will be tuned and the headlights aligned beforehand.

I also have concerns about the fuel flow. Last year the petrol tank had be put in-situ to just to start the engine for the first time. The tank was then removed to be painted and since then I noticed that the fuel flow seems to be rather low. Although I suspect I just hadn’t noticed the problem before.

Testing fuel flow from pump Comparing the fuel flows per minute:
250ml at front bulkhead in bottle,
2litres at rear bulkhead in jug

The measurements of the amount of fuel pumped in one minute was taken at the rear bulkhead union and then at the other end of the pipe at the union on the front bulkhead. Although it’s not really a valid test, as there wouldn’t be any back pressure at the rear union, it did provide a feel for the drop off in flow – 2 litres per minute measured at the rear bulkhead union and only 250ml per minute at the front bulkhead union.

Suspicion is that it may be due to an air-lock created in the pipes. However advice from the forum suggested that a pump in good working order would have more than enough ummph to purge any air locks. Some further checks will be done to get to the bottom of the problem.


Longacre Camber/Castor Tool

The intention was to set up the suspension geometry myself and so I’d purchased a Longacre electronic camber/castor tool and a Trackace tool for the wheel alignment. The camber/castor tool has three legs which rest against the wheel rim with an accurate inclinometer attached in the centre. However I wasn’t thinking things through and had completely overlooked needing clearance for the central spinners.

The prongs on the legs don’t have the reach so I’ll have to have some made up. Unfortunately the MOT centre no longer has accurate electronic measuring tools for suspension set up. This will have to wait until after the MOT.

For some reason one of the dash indicator tell-tale lights had stopped working and the fault traced to the switches in the indicator stalk. It was easier to take the whole steering column off and investigate further on the bench. A loose back-plate on the switch mechanism had allowed the indicator contact to move about and be bent out of shape. So it was easily rectified.

The clamping bolts on the upper and lower steering column’s UJs had been taken off to aid the removal of the upper column. However, I’d become side-tracked and had not refitted them before attempting to tick off another pre-MOT task … making sure the speedo drive was working.

Needless to say, as I was turning round, after completing a successful straight 40 yard speedo run up the drive, the lower column dropped out of its splines. All steering was lost, blocking a now busy communal drive!
Apart from being stupid, it was a rather timely reminder! The complete suspension parts list was used as a check sheet to ensure every suspension nut and bolt was revisited to make sure everything was correctly torqued.

Mudguards, shields and undertrays
The various mudguards, shields and undertrays aren’t strictly necessary for the MOT. However they were fitted, as the horn relay needs to be mounted on the LH mudguard. John Farrell had produced a good guide to the locations and orientations of the five different types of brackets:

Front frame bracket locations Five different bracket sizes

The first to be installed was the air in-take shield which is attached to bracket A at the top and B at the bottom. The leading face is also bolted directly to the frame. It’s worth noting that bracket E for the floor undertray needs to be put in place around the frame before the shield is attached. In fact it’s worth putting all the brackets in place before attaching any of the mudguards, shields and undertrays.

A & B brackets for air intake shield Bracket E for undertray is fitted
before in-take shield!

The bracket attachments to the frames are identical on both sides of the car, with the obvious exception of the air in-take shield. The torsion bar shields are attached by three brackets – the rear two have the tab with the bolt holes pointing upwards while the front one points downward. Note: the middle bracket on the LH frame is also used to secure the bottom of the exhaust heat shield.

Alternate rear torsion bar shield
& undertray brackets		 Shield bracket also attaches bottom
edge of exhaust heat shield		 Front torsion bar bracket (L)
and mudguard bracket (R)

The two floor undertrays are simply bolted in place. Although the right hand undertray has a cut out with a separate cover to provide access to the oil filter.

Left hand undertray Right hand undertray,
without oil filter access panel

There wasn’t any point in completing the fitting the mudguards because they will have to be removed to provide access to set the camber and castor. So at this stage they were only bolted to the sill end panel and attached at the front to a side frame bracket. At least this allowed the horn relay to secured for the MOT. Normally the alternator and aircon (when fitted) relays would also be attached to the LH mudguard, but by modifying the alternator it no longer requires a relay.

LH mudguard temporarily in place just for the MOT Location of horn relay. Alternator relay isn’t needed

Air Filter
I was regretting not trial fitting the air filter earlier. The new fuel pipe I’d made protruded too far from the face of the toe box, hitting the air filter. Fortunately it was possible to remove a short length from the filter end which resolved the fitting problem but re-introduced all the air bubbles causing the air locks.

It took a while to work out the best method of fitting the air filter element, canister lid and air plenum. Once the canister lid and rubber grommet are in place, there wasn’t sufficient access to pull the grommet up around the lip of the plenum chamber. Eventually I found the best solution was to connect these components off the car and then fit and remove as a single unit.

Filter canister was hitting the fuel pipe Adjusted fuel pipe now narrowly misses it Fitting canister lid first didn’t work

Alternator testing
Another task was to ensure the alternator was charging properly when the engine was running at higher revs. The outcome wasn’t as I’d hoped – it wasn’t charging at all, measuring only 12.5 volts! The converted alternator is now self-energising – the AL terminal, normally used for monitoring the alternator output via the ignition warning light, now provides a DC supply to power the field coil. Finding earth via the field coil through the 4TR voltage regulator.


Testing the alternator

The AL terminal was reading zero voltages at idle rather than the expected 14.3 volts! The voltage regulator controls the alternators output to avoid ‘run-away’ where its output would continue increasing until it burnt out the various internal components and/or windings. Increasing the voltage across the field coil increases the alternator output voltage, which in turn increases the field coil voltage.

The 4TR regulator acts as a fast-acting on/off switch. When the output of the alternator increases above a determined voltage (around 14.6v), the regulator switches off the current flowing in the field coil and therefore the alternator voltage drops. Once it has dropped sufficiently, it switches the current in the field coil back on and the alternator output starts to increase, until the cycle repeats.


A passing peacock offered
no helpful advice!!

Suspicion fell naturally on my modifications to the alternator and also the 4TR regulator, which are known to be fragile. A faulty voltage regulator can easily be identified by removing it and using a jumper lead to connect the F and ‘-‘ leads in its connector.

If it is faulty, starting the engine will cause it to start charging (indicated by the alternator output voltage or the battery gauge rising above the battery’s normal 12.3-4 volts) If so, the engine should be switched off immediately and the 4TR unit replaced. It was a great relief to find it was the 4TR unit that was at fault and not my handiwork! A replacement was ordered which confirmed the diagnosis and it is now working as expected.

Crossing fingers
I didn’t want to drill holes in the bodywork for side mirrors and so some clamp on mirrors have been attached to the window frames. That just about completed all the pre-MOT jobs.

Clamp on side mirrors fitted After all this time, it’s finally ready for the MOT!!

For the first time in several decades, 1R1421 hit the road …… on it’s way to the MOT centre! …. fingers firmly crossed!!