Oct 162015
 

Default 4.2 ignition mapping

The EDIS Megajolt electronic ignition kit for the 4.2 engine was supplied with an ignition mapping that closely replicated the advance curves of the original Lucas 22D6 distributor.

The aim is to produce a mapping tailored to my actual engine by taking it to a professional outfit with a rolling road. Although I’ve been told it’s not for the faint-hearted. The engine is taken through its paces with sustained running all the way up to the red line!!

For now, I’ve followed a suggestion from the E-Type forum to load different mappings into the Megajolt controller to compare. A number of owners have produced maps for their engines and uploaded them to the forum for others to try. As the controller can store two different maps at any time, a discreet switch has been mounted in the glovebox to enable switching between two maps.


Checked into the Jaguar specialist
for further investigation

Although the final tuning and mapping is some way off as neither the garage that did the MOT nor Powerbell, a local independent Jaguar specialist, had been able to tune the carburettors to get the engine running smoothly. The latter suspected there might be either sticking valves or valve clearance issues which would require further investigation.

The engine had sat without being run for quite a long time since being reconditioned by VSE, which is far from ideal. The plan was to run the car for a while to see if the layup had resulted in a slightly sticking valve which might clear with use …. ever the optimist! Alas it didn’t! So the car was returned to Powerbell to get to the bottom of the rough running.

The first task was to perform a compression test and measure the valve clearances. The manual indicates that the expected compression pressures are 150psi for 8 to 1 compression ratio and 180psi for 9 to 1. The test showed mine were way off and in some cases almost non-existent:

Cylinder: 1 2 3 4 5 6
Pressure: 125 130 125 120 65! 10!!

The thicknesses of the valve adjusting pads under the tappets were miles out so everything was far too tight. The guys at Powerbell were shocked that they could be so far out in a newly reconditioned engine. Had I not decided to get it resolved now, they said the likelihood would have been burnt valves and a much bigger problem to resolve.

The compression test revealed very
low pressure in cylinders 5 & 6
Calculating the correct thickness
for the valve adjusting pads

I was relieved but at the same time not impressed with VSE who had rebuilt it. Unfortunately it’s way past the standard one year warranty they offer but I’ll not be using them again. It really shouldn’t be necessary to correct a simple measuring job that could have had expensive repercussions.

Removal of the camshafts to correct the valve clearances … on a newly reconditioned engine!

It was with some anticipation that I headed off to pick up the car when the call came to say it was ready. I really didn’t know what to expect but it had been transformed! It was now able to idle at the intended 700rpm, the rockiness had gone and it was running so smoothly.

They did recommend putting on another 1000-1500 miles on the clock, so the engine is properly run in, before mapping the ignition on rolling road.

 Posted by at 8:45 pm
Sep 292015
 

Progress has been slow of late and the finishing line still feels some way off. I’m still waiting for the trimmers to have a slot to fit the hood and some of the outstanding internal trim. At least the enforced delay would allow some teething problems to be addressed. The most pressing being issues with clearance of the gear lever and gear selection.


Removing gear lever gaiter
revealed lack of clearance
with the gearbox cover

Something was seriously amiss with the positioning of the gear lever in relation to the central console. The lever was too far back making it difficult selecting either 2nd or 4th. Even once selected, the convoluted rubber gaiter was being compressed against the console, resulting in a tendency to pop out of gear into neutral.

The console couldn’t be moved rearward as it was already in contact with the rear bulkhead. Likewise there’s no adjustment in the positioning of the lever so it couldn’t be moved forward. The only option would be to undo the engine mounts and stabiliser to prise the whole transmission forward, but this would only gain a millimetre or two at best.

I’d been forced to remove the centre console in order to drive the car, which allowed me to swap over the rubber gaiter to one used on the later v12 models. The bulbous, convoluted design had been changed to be more slim-line. Several members of the E-Type forum had suggested using the later design to alleviate minor clearance issues with the centre console. Although I wouldn’t consider the lever impacting the metal gearbox cover as minor!

Convoluted S2 gaiter versus
slim-line V12 gaiter
The gaiter is secured to the
gearbox cover by a clamping ring
V12 gaiter is more suited
to the shape of the console

At this point I just happened to notice the mounting of the gear lever mechanism differed from the diagram in the parts catalogue. The company chosen to recondition the gearbox had missed out some fibrous Tufnol washers and mounted the main spring washer on the wrong side of the gearbox lid!

Repositioning the spring washer to its intended location gained around 8mm of clearance and, with the addition of the Tufnol washers, removed all the free play in the gear lever action. Much better! It should be sufficient to stop popping out of 2nd & 4th once the central console is refitted.

Parts manual shows correct
location of spring washer
Incorrect location
between jaw and lid
Lever mechanism components
(now including missing washers!)

Although the clearance problem was just masking a potentially more serious issue. More often than not, changing down into 2nd gear would result in awful graunching. It was fine double de-clutching so I suspected there might be an issue with the synchromesh. I was trying to kid myself that the reconditioned gearbox just need ‘bedding in’ simply because I just couldn’t contemplate having to fix an internal gearbox issue!


Synchromesh relies on friction
between the two cone surfaces

However, from my limited knowledge of gearboxes, it uses standard interference fit synchromeshes which helps engagement by matching the speed of the chosen gear to that of the output shaft.

Therefore a gearbox with a new synchromesh would have ample friction. Graunching would point to a lack of friction and the need to replace the synchromeshes.

It was time for a second opinion so again I turned to John and Martin who’d installed the IRS many moons ago. Their advice was to perform some investigative tests; first to rule out the clutch disengagement, which might result in similar symptoms, and the second to check the action of each synchromesh to confirm which, if any, were the route of the problem.

I hadn’t considered the clutch but if it wasn’t disengaging properly, the layshaft and gears would still be driven by the engine and the synchro would be acting as the clutch. Therefore likely to produce graunching, although I guess in all gears.

The suggested test to rule out a disengagement issue was to depress the clutch, with the hand and foot brakes off. Wait for around 10 seconds to allow the layshaft and gears to stop spinning and then select a gear. If the clutch wasn’t fully disengaging, the gears would still be spinning and the car would show signs of wanting to pull away.

On the positive side, the outcome was that the clutch was operating correctly. Although it was therefore pointing more to a dreaded synchromesh problem. Their next tests were of a similar nature, depressing the clutch from neutral. However rather than waiting to allow the gears to stop spinning, the gear lever was pushed immediately and firmly into the chosen gear without any wait. This would be done for each gear, selecting with both a fast and delayed lever push.

The theory being that a worn synchro would not develop sufficient friction with the selected gear to enable their speeds to be matched before their dog teeth engaged. The faster the action the less time there would be to synchronise the speeds.

The test should be repeated several times for each gear, doing a full ‘re-set’ each time (from neutral and clutch up), to see if a pattern emerged. If the synchros were working correctly there wouldn’t graunching on either the fast or delayed action. A suspect synchro, in my case 2nd, would graunch in the ‘no-delay’ fast instances and possibly on the delayed selection.


A run in the car without the cover
revealed the cause of the problem
(note – relocated spring washer)

I was very relieved that no graunching was evident in any gear, for either action. Perhaps it wasn’t an internal gearbox problem after all, which would require an engine out fix. I took the opportunity to take the car for a spin, while the gearbox cover was off, so I could see the selection mechanism at work in more realistic road conditions.

What I observed surprised me and explained the graunching that I’d been misdiagnosing as a synchromesh problem. The corrections in the lever mechanism had made subtle changes to the geometry by moving the lever directly over the quite narrow 1st/2nd selection rod. Previously it had been at a slight angle so the lever could also catch the reverse selection rod at the same time.

More importantly the reason for the graunching was actually caused by selecting reverse gear instead of 2nd!! A sprung plunger is used to avoid accidentally selecting reverse while using the forward gears. However the resistance it offered was so weak it was quite easy to go beyond 2nd all the way into reverse without realising.

Gearbox lid removed to check
selector rod operation
Selector arrangement and
reverse plunger & adjustment

A sprung ball bearing presses into a groove in the plunger to create the resistance and can be adjusted via a setscrew. Even so, for a given setting, there was a noticeable difference in the effort required to depress the plunger depending on whether the lever was starting in the 1st/2nd or 3rd/4rd planes in the gate. This was simply due to momentum, with less effort required from the 3rd/4th side of the gate.

I opted to set the desired resistance from this position which should minimise the frequency of accidentally selecting reverse while changing down from 3rd to 2nd. The compromise is that it needs a good shove to select reverse when the lever is in the 1st/2nd plane, but this would typically be while stationary.

It was a great relief to get to the bottom of the gearbox problems although the only slight niggle is occasionally not being able to engage 3rd from 2nd. The 1st/2nd selection rod doesn’t always quite reach its neutral position but allows the lever to cross the gate for 3rd. As it hasn’t reached neutral, the interlock is doing its job and prevents another gear being engaged, in this case 3rd.

If baulking occurs going from 2nd to 3rd, the lever must be returned to the 1st/2nd plane to ensure its knocked into neutral before going for 3rd again. I took the top of the gearbox off to see if the ‘O’ rings were causing too much resistance in the movement of the 1st/2nd selection rod for the detent to pull/hold it in neutral. But all seemed in order.

It appears that this is not uncommon and can be avoided by a more sympathetic gear changing technique using light finger pressure and ‘palming’ the lever to guide it. I had been changing from 2nd to 3rd by applying a constant forward and sideways force rather than three distinct movements.

The double de-clutching I had used to overcome the graunching, adding weight to my synchromesh diagnosis, had worked simply because it changed my technique of changing gears. Therefore avoiding accidentally selecting reverse.

Fingers crossed this will be the end of the gearbox issues!!

Prop Shaft Refurb

 Transmission  Comments Off on Prop Shaft Refurb
Aug 122013
 

As the prop shaft’s spline joint is sealed for life, the refurbishment of the prop shaft is limited to replacing the UJs and tarting it up with a lick of paint. A member of the forum has suggested Epoxy Mastic 121 for a tough rust-resistant paint that is applied to bare metal and as an alternative to POR15. So I purchased both black for the various brackets etc and aluminium for the backs of the bumpers.

The prop shaft and yokes were then wire brushed back to bare metal and then given several coats of black Epoxy Mastic. It’s a lot easier to work with that POR15 although the finish isn’t as smooth, having a noticeable orange peel effect. Oddly the aluminium paint did provide a smooth finish.

Everything was going smoothly until the final UJ when I allowed one of the roller bearings to fall into its cup. Fortunately it was fairly easy to press out and start again. To seat the new UJs the prop shaft was mounted onto the rear axle and the prop shaft given a sturdy tap with a wooden mallet in each of the four directions of the UJ. The aim was to push the UJ cups hard against the retaining circlips and loosen the stiffness in the joints.

 Posted by at 6:41 am

Reuniting the engine and gearbox

 Rolling Chassis, Transmission  Comments Off on Reuniting the engine and gearbox
Jul 082013
 

My aim is to spend a long weekend in August (with the wishful thinking that it’ll be sunny!) to transform it from a bodyshell into a rolling chassis; installing the fuel system, rear suspension, engine/gearbox & ancillaries, front suspension and steering all in one hit. So I’ve got my work cut out to get everything ready in time.

The bonnet and front sub-frame need to be removed in order to fit the tiny radiator support brackets so I’m also going to remove the picture frame at the same time. It should then be possible to roll the engine and gearbox unit into place through the gap and avoid the hassles of installing the engine either from above or below.

The gap between the lobes at the lower front edge of the engine frames is only 22cm. However, if the water pump is removed, the engine is slightly narrower than this just below the height of the inlet manifold. The engine has been rebuilt by VSE with a new clutch fitted so I just had to attach the gearbox and bellhousing. However the reuniting of the transmission unit would feel like a major milestone had been reached!

The bellhousing had already been ultrasonically cleaned and just needed the rear oil seal inserted before being bolted to the gearbox. Three lock tabs are used to prevent six of the bolts from working loose. The remaining two bolts, next to the clutch fork, use safety wire instead.

I’d never needed to use locking wire on previous vehicles so needed to purchase a pair of safety wire pliers. Eventually I managed to obtain an old pair on eBay and some 0.81mm stainless wire.

The pliers were definitely a good investment, less so was the wire that I purchased. It snapped as soon as a few twists were applied. I hadn’t purchased annealed wire – dooh! After purchasing the correct type, it was a lot more successful! The main point is to make sure the wire passing round the outside of the bolt head puts tension on the bolt in a clockwise direction.

The fitting of the clutch release bearing and operating fork is all very straight forward. The fork can be inserted with the bearing attached which makes fitting the securing spring clips much easier. The clips are held in place by the curved end sitting in a slight dimple in the fork arm.

The push-fit spring clips secure the clutch release bearing to the operating fork. The curved spring end sits in a dimple in the fork

The pivot pin was lightly greased and aligned with the grub screw hole in the fork before inserting

A little Loctite was used on the grub screw which locks the pivot pin in position. A lock nut is then fitted on the grub screw.

The engine was already sitting on the DIY trolley which will be used to roll it into position once the front frames are removed. Hoisting the gearbox to the same level meant it was simply a matter of rotating it to align the drive splines. Once the splines were engaged the gearbox could be rotated back again to align the bolt holes.

Supporting the gearbox with the engine hoist made the job much easier

It was also very helpful to have the engine mobile to align the two units

The weight of the gearbox was used to help push the gearbox onto the clutch splines

The two bellhousing support brackets needed to be installed before the full weight of the gearbox could be released. Finally the flywheel cover plate was bolted on to finish the job.

I did make the mistake of fitting the clutch slave cylinder when fitting the bellhousing to the gearbox but had to remove it to fit the lower bolt for the support bracket. I’ll make the final adjustments of the clutch just before the engine is installed.

One thing I’m not sure about at this stage is the orientation of the four vertical bolts for the support brackets. One of the bolts is longer than the others and so I guess must be used to secure a bracket of some description. Another question for the E-type forum ….

Fitment of the bellhousing support bracket is needed before it can take the full weight of the gearbox

A major milestone reached - a completed transmission unit ready to fit. I hope it starts!!

The rear of the gearbox has a sprung fitting to absorb vertical movement

The gearbox is supported at the rear by a large spring between a mounting bracket and the gearbox. The spring damps the movement of the gearbox but allows for a degree of vertical travel. The spring ends sit in rubber mouldings. The mounting bracket also contains a rubber bump stop to limit the gearbox travel.