Fitting the Hood - Part 2

The next step was to trim the GRP Mouldings down to match the edge of the door opening:

I may yet still need to trim the vertical flange back - depends on how the sidescreen closes. The folding hood frames have a pivot and the bottom which is supposed to be bolted to the GRP Moulding:

The fixing is a single M5 countersunk bolt. I didn't think this would be strong enough to stand up to a few years of abuse so I decided to modify things slightly. I found that the pivot would fit snugly inside a wardrobe rail support bracket:

This was positioned on the GRP moulding and two countersunk holes drilled:This puts the pivot about 4-5mm further back than the position recommended by GD because I allowed a bit of edge distance to the outside hole:The final fitting will have shorter stainless bolts finished off with a dome nut. I will also "butter" the underside of the bracket with sikaflex to help take up any slight surface variations. I think I'll also drill the socket and fit a self tapper just to hold the pivot in place (or possibly araldite it into place as there is no need to remove the pivot form the Moulding) although I doubt it will go anywhere due to the tension in the hood. Now it was time to re-fit the mouldings and fit the hood frames:

As you can see they fold up quite neatly. The reason behind fitting the folding hood is the intention to go touring. This way you can carry the hood folded down on the car giving some precious extra boot space. Plus if it looks like rain you can fit the hood before leaving and it will only take a very short time to fit should it start to rain.

Temptation got the better of me so I draped the hood over the frames and screen to see what it would like:

I think it makes the car look more "vintage".

Hmmmmmm........cosy.

The last job for today was to file and sand the mouldings to get rid of any sharp edges and then prime them ready for painting on the inside. I did think of trimming them but decided it was going to be too awkward.

Fitting the Hood - Part 1

Went down to GD to pick up my hood bit and pieces on Saturday Morning. But as I had to work Saturday Night / Sunday Morning I never got a chance to start!

The first task is to take the GRP moulding and file the moulding pips down on the bottom - these mark the fixing hole centres. Mark the centres - check for symmetry then drill 6mm holes for the M5 bolts - (leaves a little tolerance). Stick some masking tape to the underside of the moulding (to prevent marking the body) and offer up to body lining it up with the doors and taping into position:

You can then drill through into the body with the 6mm drill. Remove the moulding and open the holes up in the body with a 8mm drill for the fixing inserts. You then end up with 8 nice holes in body!

Put the stainless inserts in (after a bit of a polish) and tighten up. The inserts are a top hat m8 bolt with an m5 tapping down the middle. They are fixed in place with a plain nut, spring washer and body washer:

I'm going to get some acorn nuts to finish them off underneath to prevent any water getting into the boot when the hood is not on.

The next job is to cut the GRP moulding in half and then trim 25mm of each end (same as 50mm out of the middle) with the ends cut back at 45 degrees. This is to allow the hood to fold up for storage.

I then bolted the two mouldings into place temporarily with some M5 bolts (I have ordered some M5 thumbscrews for a proper job) stood back and admired my handiwork.

Next step will be the folding hood hoops tomorrow hopefully.

Uh.Oh...... Another Distraction!

Well... my mate Dave has gone and bought hinslef a ski boat - a 1992 Mastercraft. It has an Indmar Ford V8 - looks like it's based on a 351 Cleveland. It needs a bit of TLC but has the potential to be a very nice boat indeed. Engine needs a little work mainly the ancillaries, hoses and wiring plus the exhaust / muffler is shot and needs repiars - but it shouldn't take much to get it in the water and running. Then we can see what else needs doing.

Watch this space................

Nearly didn't Make it Back from the Alps......

...... now that's what you call "whiteout".

Normal service will be resumed shortly.

Cleaning the Wheels

It is -2 degrees today and I've just spent the morning outside cleaning the wheels and polishing the rims and spinners - what a ball-ache it was with all the nooks and crannies on the Halibrands. Still it was much easier to do with the wheels off the car.

I went for the clear anodised finish on the rims and whilst it may not give the shiniest of shiny finishes it does seem to have protected them and made them easier to clean. The rims were finished off with the polish supplied by image with the wheels - which interestingly looks like, smells like, applies like and buffs off like Auto Glym Super Resin Polish!

I've put the back wheels back on(after making sure I had not forgotten to grease anything) but left the fronts off as I still need to check the front wheel bearings and callipers.


I'm too cold to be bothered to do anything else today!

Sat Nav...... In a Cobra????

Over the last few years I have become accustomed to using Sat Nav. And with the desire to travel abroad in the Cob - combined with my Wife's poor navigational skills I had been thinking about how to mount my Sat Nav in the Cobra. I had managed to conclude that the normal windscreen mounting brackets were not going to work and also that the unit needed to mounted low down to cut down on glare with having no roof. I hadn't really come up with a solution until I found a strip of spring steel in my oddments box.

And after a couple of hours here's the end result:

Very neat and discrete and when not in use the arm folds away under the dashboard:

There is a piece of chassis foam stuck to the underside of the arm to prevent the mount securing nut marking the the tunnel leather when it swings back under the dash.

The arm is fixed to the under-dash panel using a nylon washer to create a friction pivot:

The under dash 12v socket is conveniently located for powering the Sat Nav. You can also see a small aluminium bracket that the arm locates into when in the "deployed" position - here's another view:The bracket is just a cut down bit of aluminium box section bolted to the under dash panel. There is also a piece of chassis foam stuck to the top of the arm to space the arm off the bottom of the dash - just gives things a little more stability.

I got a spare powered mount off E-bay and this was simply bolted to a hole drilled in the end of the arm:Job Done.

The wires you keep seeing in the background are the leads from the battery conditioner you'll remember that I included a fly-lead under the dash to make connecting up easier.

More Winter Jobs

Tme to crack on with my list of things to do. Worked over and under the entire car checking nuts and other fasteners and lubricating / greasing every thing that needed it. All fluids were present and correct:

Whilst I was under the car I noticed some drips of oil underneath the accusump - not enough to drip onto the floor (which is why I had not noticed before) but enough to need attention:

Bit puzzling as the valve was screwd up F.T. when it was all assembled? - managed to nip it up another quarter turn so that should fettle things. Got a few more odds and sods to do but the main outstanding essential job is to fit the Hood and Sidescreens. These should be ready to collect in a couple of weeks - which will clash with going on holiday.

Adjusting the Rev-Limiter

Following discussions with Jez my engine builder, he had informed me that it was OK to turn the Rev-Limiter up to 6000 rpm ( from the 5250 it is set at now). I was a bit worried that this would turn out to be a bit of a pain as I had hidden Mallory Hy-Fire unit away behind the dashboard - admittedly to put it out of the way of engine bay heat and water.

I needn't have worried - took out the three fixing bolts and it drops down as expected:

It was then a simple matter of unplugging the three harnesses and removing the heater vent pipe and Bob's your Uncle!Took the access panel off - twiddled the dial - and put it all back together - the under-dash panel went back as easily as it had come out.

Job Done.

Adjusting Wheel Cambers

First things first, a trip to Machine Mart kitted me out with a set of "wobble bars" - socket extensions that will accommodate a +/- 10 degree deviation in line:As you can see below - the 500mm bar is just the job:With the four brake disc retaining nuts removed, 5 minutes of rotating the drive shaft and tapping with a rubber mallet saw the shaft come free allowing the shim pack to be adjusted:With the correct shims fitted new disc retaining nuts were fitted (important not to use the old ones) and tightened to the correct torque. Conveniently you can use the handbrake to prevent the shaft rotating. This becomes a bit of pain when working on the nearside as you keep having to walk round the car to operate the handbrake.

The cambers were measured before and after (at full droop) and the removal of four 20' shims on the offside saw a negative change in camber by 1.05 degrees and the removal of two 20' shims and the addition of a 10' shim on the nearside saw a negative change in camber of 0.35 degrees. This should give me near or damn it -0.5 camber at ride height on both rear wheels.

All in all quite an easy task and nothing to feel daunted by. Next up was adjusting the camber on the front offside wheel. I had calculated that I needed to remove 3/16 of shim - however this was based on the original jag set up. The upper wishbone pick up points are orientated differently on the GD so a little trial and error was required. The original 1/4" shims were removed one at a time by loosening the fixing bolt:The end result was found to be two stainless steel 7/16 washers giving a negative change in camber of 0.8 degree - which give or take 0.05 of a degree should be the same camber as the nearside wheel:

The original 1/4" shim - 250' was replaced with two 7/16" stainless washers at 45' each - so the total reduction in shim was 160' a tad over 4mm and 30' less than the calculated 190'.Quite a productive morning - although I won't be able to check the final settings until the car is back on the ground.... but the indications look good.

If there is a moral to this story then it is not to worry about cambers too much during the build as they are very easily adjusted once the car has been "shaken down" on the road.

Jaguar Suspension Development

Before I get round to adjusting the wheel cambers on the car, it is time for a history lesson with some of the background behnd the Jaguar's development of its suspension systems:

From the early 1960s to the present day virtually all serious racing cars have used the classic double wishbone suspension arrangement, or a close variation on the theme. There are many alternatives that have seen widespread use: beam axle, de Dion, swinging arm, trailing arm (even semi-trailing arm), sliding pillar (Morgan, unbelievably in this day and age), McPherson strut (front) and Chapman strut (same thing at rear), but for precise control of wheel movement and low unsprung weight, double wishbones remain the favourite. The beauty of the arrangement is that by careful design of the pivot points and arm lengths the camber of the wheel can be maintained close to the optimum even while the body rolls during cornering. Not only that but the roll centre - a term for the abstract point around which the car rolls when cornering - can be held consistent thereby helping to confer the vehicle with stable handling characteristics. Then there are ways of further refining the handling characteristics by angling the axes of the wishbones in various ways. For instance wheel toe-in and castor angle can be made to vary with body roll to enhance steering feel, or upward suspension deflection can be made to act against the forward weight transfer under braking to oppose front end dip. This is known as anti-dive and a similar arrangement in reverse, known as anti-squat, can be applied at the rear.

Jaguar's legendary Technical Director, William Heynes, knew that independent front suspension was essential for any car that claimed to be advanced and refined, so had adopted double wishbones at the front on the Mk V saloon just after WW2. However the case for independent rear suspension was not so clear cut and even the outstanding D Type had a live axle at the rear, which helps to explain why its greatest successes were nearly always at race tracks with the smoothest surfaces. Obviously this handicap would only become worse so Bob Knight and his team, with one eye on production applications, devised an independent rear suspension for an experimental successor to the D Type known as E2A. Within a year the E Type was launched (1961) with a productionised version of this same independent rear end, incorporating the now familiar rubber mountings as a vibration barrier and trailing arms to provide fore and aft control. It continued with only minor alterations until the last XJ-S left Browns Lane in 1996.

A notable but less well-known member of Bob Knight's team was Derrick White, highly regarded in club racing circles for creating his effective Impala racing car, later moving from Jaguar to be Chief Designer for the Cooper F1 team and then being credited for the Honda/Lola that enabled John Surtees to snatch a lucky win at the 1967 Italian GP. Talent was not a rare commodity at Jaguar in those days. The point of all this, of course, is to show that Jaguar were near the forefront of vehicle design with suspension systems technically superior to those of most other manufacturers of the time. It may not be obvious but Jaguar's well-known independent rear suspension assembly is geometrically very similar to the double wishbone system preferred by race car designers, in the way wheel camber is controlled. This becomes clearer when the pivot points are highlighted as in the accompanying diagram. Particularly notable is that the driveshaft doubles as the top link so that the under-floor space requirement is kept to the minimum.

Preparing to Change the Rear Camber

Double checked all yesterdays measurements - OK. Up on axles stands and wheels off. The whole chassis was then levelled by jacking up and inserting thin washers between the chassis and the axle stands and checking with my fancy new digital level.

Next step is to remove the drive shaft nuts in order to change the shims between the drive shafts and the brake discs:

That's the little beggars in the distance! Hmmmm..... I feel a trip to Machine Mart coming to get a long enough socket extension! Should be strightforward after that.

I also need to get some replacement nuts. They are steel locking nuts and as such cannot be re-used. I'll get some ordered tomorrow.

Obessive Compulsive Disorders - 1. Suspension

It's been a while but the snow eventually melted, then I was ill for a couple of weeks - so now its time to get back into the garage to start on some of those winter jobs.

First on the list - suspension settings. After Andy test drove the car after the fitting of the anti-roll bar down at GD, he recommended that I tweak the camber settings a little. The first step is to establish the starting point?

Now Santa had very kindly brought me one of these:

Very handy - loads of features and accurate to 0.05 degrees (3 minutes). The next step was to cut to length a piece of steel angle (magnetic base on the level) to fit on the wheel rims: Note the electrical tape on the ends to avoid scratching the rims. It then becomes quite a simple task to measure wheel cambers (after removing the spinners) :Before actually measuring the wheel cambers I checked all the ride heights. The car had not been jacked up since it was last driven into the garage, but still I rolled and "bounced" it back and forth a couple of times to ensure the suspension was settled. I then check the ride heights side to side at the front and rear. These checked out to be only 1mm different at the front and 2mm different at the rear - good enough.

In reality you should carry out suspension angular measurements on a level surface - my garage floor isn't level - but is pretty smooth and flat as evidenced by the uniform ride heights. The alternative is to measure the angle of the floor and adjust the measure angles accordingly. I did this my measuring the angle of a couple of the horizontal chassis rails.

I found that the car sloped down to the offside by 0.25 degrees - probably good enough for the builder of my garage floor! After measuring the wheel cambers I subtracted the floor slope to get the following results:

Hmmm...... 2 Wheels camber the right way at least!.... one doesn't camber at all and the remaining one cambers the wrong way! To be honest these aren't massive deviations. For the Jag Chassis with 18" wheels GD recommend 0.5 degrees negative camber on the rears and 0.75 degrees negative camber on the fronts.

I've got a couple of print-outs from having the tracking adjusted on the four wheel laser aligner down my local tyre place - the problem was that I didn't know which was the last one as they had no dates on - with these measurements I now know which the latest one is as the measurements are pretty close - all within 0.2 of a degree.

Now a lot more thought has gone into the design of the Jaguar Suspension than you may think. A quick look in any XJ6 service manual will reveal the following:

One 20 thou rear camber shim adjusts the camber by 1/4 of a degree.

One 1/16" front camber shim adjusts the front camber by 1/4 of a degree.

Simples!

So this would indicate that I need to do the following:

Front near-side: Measured -0.8 deg, Target -0.75 deg: Leave as is.

Front off-side: Measured 0 deg, Target - 0.75deg: remove 3/16 of shim.

Rear near-side: Measured -0.1 deg, Target -0.5 deg: remove 2x20 thou' add 1x10 thou' shims.

Rear off-side: Measured +0.55 deg, Target -0.5 deg: remove 4 x 20 thou' shims.

Before embarking on this I'll just double check my measurements.

Obviously things have changed since the build?????

• Initially the cambers were set at an estimated ride height - the actual ride height has changed a few times since the car has been on the road and with the unequal length wishbones there will be a noticeable camber change with a change in ride height.
• The front suspension was set up before the engine and the chassis brace were fitted - I had to jack one engine mount up to get the chassis brace in - and this would have had an effect on the position of the top wishbone pivot.
• The original camber gauge I used was a graduated bubble affair - nowhere near as accurate as the one I have now.
• The front camber were a little uneven at build and as I only had 1/4" camber spaces I just fitted them and forgot to remember to check it later..... until now.
• There is a limit to the accuracy that can be obtained by "reading a bubble" so even when setting the chassis level with a conventional level errors may well have crept in.

So to some extent during the build you are guessing a bit. Only when you have your chosen wheels and tyres and settled on a ride height will you be able to set things exactly.

My only worry now is that in those locations where I need to remove shim I hope there is actually enough shim in there to remove!

Watch this space........

**** STOP PRESS ****

Handy things these blogs..... just looked back through the suspension build up sections - I used 1/4" camber spacers on the front - so the offside just need to be replace with a 1/16" shim (3/16" removed) - I also used 4 x 20 thou' camber shims on the rear so I can remove them all.

Weather!!

It has now snowed virtually every day for three weeks and rarley been above freezing - if at all. Yesterday it was -13.

The End of the Driving Season?

Today was supposed to be the next Area Group Meet:

Even if I felt like driving in the ice/slush/salt I probably wouldn't get the car out of the garage:

So with the imminent arrival of Christmas it looks like the cob's going to stay wrapped up for a while: