suspension – Chris Vine – Restoration of NNF 10H

A milestone is reached – back on 4 wheels … almost!!

Front Suspension Comments Off

Sep 042013

The issues getting the rear suspension fitted meant that there wasn’t time to fit the front suspension let alone the engine.

The front frames were removed to fit the tiny radiator support brackets. As the frame bolts pass through the front suspension mounts, these and the roll bar were refitted at the same time as the frames.

I must mention to Andy at Hutsons that it would be a good idea to fit the radiator brackets on S2 cars before bodyshells are returned to customers.

I started with the easier upper wishbones and found the castellation nuts need to be fully tightened to compress the rubber bushes. This pulls the front and rear fulcrum mounts together so the bolts holes line up.

The original camber shims had been re-plated and were fitted behind the front and rear mounts. I suspect the shimming will need to be changed when the geometry is finally set up because the new engine frames have been fitted.

At least it should be a good starting point. The rear mounts also have a strengthening plate fitted on the reverse side on the engine frame, under the nuts. One of these was missing so I suspect at some point the suspension had been dismantled and they’d forgotten to refit it.

The castellation nuts were then backed off as they should only be fully tightened once the full weight of the car is supported by the suspension to avoid damaging the rubber bushes. The wishbone pinch bolts were also not tightened as the fulcrum shaft will need to be rotated during the final setup to set the castor angle.

The upper wishbones were fairly easy to install as they simply bolt on

The lower wishbones were much harder as both the front and rear mounts need slotting into the engine frame

For now the aim is to get the car back on four wheels so it can be moved around more safely. The front suspension can only be completed once the engine has been installed when the torsion bars are fitted. This will require the upper ball and steering arm joints to be separated. So at this stage, only the lower ball joint was fully tightened. Without the torsion bars the car should just settle on the shock absorber bump stops.

The moment had arrived. The lowering of the car back on to its own four wheels. Something that hadn’t happened for many, many years. The trolley jack was lowered very gently …. touch down (pats on back etc) …. then lower …. and lower …. and lower …. and so it carried on. I had to close the bonnet and control the jack from underneath but I was getting worried that the bump stops wouldn’t be reached. Do they even have bump stops?!

Will the bump stops ever be reached? ..... No! The car had to be put back onto the axle trolley.

The trolley jack finally reached it’s lowest height so I had to revert to Plan B – back on to the axle trolley until the engine and torsion bars are fitted. Ho hum …. a FAIL! I really should have just measured the compressed shock absorber length when it was off the car and then done some simple Maths. Another lesson learnt!

Installing the IRS – it’s only a matter of 8 bolts …

Rear Suspension Comments Off

Aug 232013

I had been waiting on the completion of the front suspension components so that everything would be in place to transform it from a bodyshell to a rolling chassis; installing the front & rear suspension as well as the engine over a weekend. I even dared think we might be able to have a stab at starting the engine.

I had read and re-read all the available manuals a number of times to produce a detailed list of tasks that needed to be completed prior to and over the installation weekend.

Adapting the IRS trolley to fit under the IRS cage and raising the platform height The first task was to adapt the original IRS trolley I’d made; reducing its footprint to a little larger than the base plate of the IRS cage so it wouldn’t get in the way during installation, giving it sufficient ground clearance to allow the trolley jack to be inserted underneath and raising the height of the cage so the wheels could be put on while on the trolley.

I’m not sure about the need for the latter but it made sense at the time! The aim was to be able to lift the IRS and trolley to meet the chassis.

A number of other tasks before the weekend involved the IRS unit which had been sat on its trolley for over a year. Even though it was dry stored, the caliper plating had already deteriorated in this time. These were removed and painted in a tough, silver caliper paint and a remote bleed kit fitted.

The IRS cage had also picked up a variety of scuff marks when it had been delivered and moved around. It was therefore given three coats of 2 pack black paint and two clear satin coats. I didn’t have the luxury of a spray booth so boards and boxes were used in an attempt to keep bugs and leaves off while it dried.

Masking up on the smaller trolley	Attempt to keep bugs off	Re-painted – not much different!

The planning was finally over and the installation weekend had arrived. Much needed help was drafted in, John had been granted a pass for the dereliction of parental duties who then managed to persuade Martin to travel down to complete the line up. Both had ample engineering knowledge to complement my tea making skills!

Four Metalastik mounts connect the corners of the rear suspension cage to the chassis. Restricted access during the fitting the IRS unit is overcome by pre-fitting the rear mounts to the chassis and the front mounts to the IRS cage. ‘All’ that remained was to raise the IRS to the chassis and fit the remaining 8 bolts. I had foolishly assumed this would take an hour or so at most.

John and Martin assessing how to overcome the fitting problem None of the bolt holes were close to lining up. Hmmm. The IRS was removed and all the mounts then fitted to the cage in order to compare the centre to centre distances. The C2C distance between the mount holes was 6mm greater than the chassis holes.

As they are attached at an angle of 45 degrees, this would need each rubber mount to compress by √2 x 3mm to obtain hole alignment. So they became the prime suspect in the fitting problems.

A few tests of a mount in a vice suggested that it might be possible to achieve the necessary compression in the rubber section but exactly how was still to be determined. So the decision was made to continue rather than abandon the installation weekend.

The front of the chassis was raised in relation to the rear in an attempt to use the weight of the car to compress the rubber in the rear mounts. It still wasn’t sufficient – we needed more weight in the rear. A few moments later, Martin and I were standing in the boot while John assessed whether this had achieved anything other than a comical moment.

Eventually each bolt was persuaded one by one until the IRS had been fitted. A successful method was to insert a screwdriver into the second bolt hole to lever the first bolt hole into alignment and then tap the bolt home. I later found out that such fitting issues were far from uncommon.

We just needed to connect the radius arms to complete the job. Unsurprisingly they were also a country mile off fitting on to the cups on the chassis and were also twisted in relation to the cups because there was no load on the suspension. The solution was a three man job. John applied a tourniquet to draw the IRS cage forward so the radius arm and cup aligned. At the same time I rotated a G-clamp attached to the radius arm while Martin fitted the retaining bolt.

Just the radius arms to go	Applying a tourniquet to pull into alignment	G-clamp was also needed

Almost the entire day had been taken up with fitting the rear suspension but at least we had the satisfaction of finally lowering the car onto two of its new 5″ wheels. I had been wildly optimistic on what could be done in a day but nevertheless was pleased with what had been achieved.

The front suspension and engine would have to wait for another day ….

Rebuilt IRS

Rear Suspension No Responses »

Aug 212013

This is more of a retrospective post as the IRS rebuild was originally completed in line with the indicative chassis completion date of May 2011 given by Hutsons. I had stripped and painted all the components but needed a specialist to address the differential. By chance I decided to get it done by Alan Slawson from AJS Engineering.

I wasn’t aware at the time but one the two Jaguar World books that persuaded me to buy the E-Type included a section covering the IRS rebuild. Alan was the person they entrusted to do their rebuild so it seemed fitting he would also be doing mine.

When I arranged to pick up the diff I asked him if he would be prepared to do the full IRS rebuild. Although he was semi-retired he agreed, as long as I wasn’t in a rush for it. The aim was to free me up to tackle the 101 other things needed to be ready for the return of the chassis.

In the end Hutsons took much longer than hoped due to a very healthy backlog of restorations. It was shame really as I’d have preferred to rebuild it myself and would have had ample time to do so. Several months after dropping the parts off, Alan had completed the IRS and even drove over from Essex to drop it off. At his suggestion Gaz adjustable shock absorbers were fitted in preference to the Koni Classic ones I’d supplied.

Also at his recommendation was to rotate the larger radius arm bush through 90 degrees. The rubber section has two elongated holes which are normally orientated so they are front and rear. Rotating the bushes so the holes are at the sides marginally increases the fore and aft stiffness, which is in the direction of forces through the radius arm. I subsequently found out that this is common practice.

The IRS unit is quite a heavy unit so I knocked together an amply sized trolley using two sheets of 22mm chipboard. Great for moving it around but the down side of its generous proportions was that it bent significantly under the weight.

Front Suspension Ball Joints

Front Suspension, Rolling Chassis No Responses »

Jun 042013

An almost standard replacement for the front suspension lower ball joint is the later sealed for life units. Less so is fitting a modern upper ball joint as it requires the case hardened wishbone to be machined to fit. If wear occurs in the upper ball joint, it is often as a result of wear in the wishbone’s ball joint seat, which becomes more oval in shape.

After a lot of deliberation, I opted to change the upper ball joints as well, using a kit from CMC as the local machine shop agreed to do the necessary milling of the wishbones.

I was less convinced of their ability when the kit was taken round and thought it wise to seek someone else to do the work. The instructions suggest annealing by heating the wishbones to cherry red and allowing it to cool slowly. All the larger firms weren’t interested and the independent machinists were few and far between.

The components of the CMC ball joint kit, including the mystery small nylon washer In my hour of need I turned to E-Type International Rescue – McLaren’s Skunk Work team. There was some bemusement as to why the kit contained a pack of 9 shims rather than machining the wishbones correctly.

Also the brevity of the instructions had not explained the need for a small nylon washer in the setup.

After a few discussions it was decided that a grease nipple inserted into the cover plate would protrude below the plate. So the kit included a nylon spacer and a similar depth of shims to allow for the depth of the nipple below the cover plate. Ideally the plate should have been designed accordingly rather than requiring shimming and therefore additional machining.

The wishbone was media blaster before profile milling to match the shape of the nylon ball joint cup The ball joint bores were profile milled with a ball-ended tool around the circumference, progressively stepping down after each revolution until it had cut to the required parallel depth.

At which point the wishbones were machined to match the curvature of the green nylon ball joint cup by reducing the circumference with each step down.

I’m really pleased as I had precious little chance of fitting newer ball joints without their help. I now owe several loans of the car … once it’s finished!

The completed wishbone and new ball joint awaiting fitting of the circlip