Propshaft changing

As I'm still not happy about the vibrations in my car, I had a new propshaft delivered from Dave Mac. The company where I had bought the first one from wanted another £75 to re-balance it, plus three days to do the job, whereas Dave Mac delivered a new one for £95, which meant the car would not have to be left disabled for long. Oh, it's 29" long just in case anyone is interested.

In-between working on the Lightweight Land Rover I managed to find time to do a few jobs on the GT6. First off was the propshaft, but to do that I had to remove the centre section of exhaust, not that hard to do really and it gave me a chance to have a proper look at it.
Below are the two propshafts, the newer one being at the bottom, having a smaller tube diameter and having far fewer balance weights stuck on.

In the week I also received a pair of brake drum centring rings for the CV converted cars, which are fortunately a nice and tight fit, so they should hold in place nicely with a bit of bearing lock. Part of the idea of fitting these rings is to try to reduce the problem I had with peculiar brake shoe ware, where the bottom part of one of the shoes was heavily worn. Though I am starting to wonder if that was more down the brake shoe not moving up as it should after to was tightened up on the brake adjuster.

I've still to reassemble the drum brake on one side before I can go out for a trial run, but I am hoping I have managed to do away with the vibrations I was getting at speed.

Ramblings and engine mounts

Got a couple of tyres fitted this weekend, I've been wanted to fit something half decent this time, so I went for Continental Pro Contact 3's, as I had fitted on the 2000. Was going to get them mail order, but it worked out cheaper to order them online, supplied and fitted through Kwik-Fit.

The vibrations, coming through at over 70mph, are still present. This is despite new front vertical links, trunnions and bearings, so I'm pretty sure it is not coming from the front. So what else could it be? the propshaft has only done 3.5k miles, the CV joints and driveshafts are second hand though, perhaps one of these is the root of the problem?

While the car is in the barn I've decided to reduce the camber up front by taking out one of the thin shims. It was about 2.5deg negative each side, a bit too much I thought for normal driving.

While I wait for my new propshaft I thought I'd have another crack at sorting out my engine mounts as the original type repro ones are not looking too good. The plan is to use the original GT6 block mounting point, but extend the bracket to sit on the back part of the suspension tower and use Jaguar engine mounts.

 It's only tacked in at the moment, so it'll need welding fully before cleaning up and fitting

Anti roll bar drop links

I need to go about setting up the chassis on my GT6, so I've been looking at the few remaining dodgy looking suspension parts on my car. The anti roll bar drop links from Wolfitt Racing look pretty good, but are out of stock, so I thought about sourcing the parts myself.

 I went through McGill Motorsports to order the parts, slightly more expensive per piece than eBay, but no delivery costs.

So ordered:
3/8" UNF Male-Female Studded Rose Joint Track Rod End
3/8" x 3/8" UNF Right Hand Male Economy Rose Joint
3/8" UNF Rose Joint Misalignment Spacers PACK OF 4
3/8" UNF Half Nuts Right Hand Thread

The parts were delivered from McGill Motorsports the next day (Saturday) all the way down from Fife, so I've sourced some fasteners and have welded in a spacer on top of the lower wishbone arm for the bolt to pass through. Started off with just having an extra plate on the back of the spacer to support it, but then decided to box it all the way in as it looks a bit neater.
While I was there, the brace bar on the arm was welded around to stiffen it up, which it has done a surprising amount.

Here are before and after shots:

Before

After

Not surprisingly the anti-roll bar was not flat as it should have been, so this has now been corrected for using the rod ended drop links. One thing I had forgotten about previously was that the anti-roll bar is not as free to move as it should be due to the bushes being too far along the bar and restricting it. With this in mind, I have bought some solid anti-roll bar blocks from Merlin Motorsport, unfortunately they don't sell them with 11/16" ID, so I shall have to bore them to suit.

Fuel pump mods

While doing the core plugs I also replaced the uprights, stub axles and trunnions. Having checked why I could not set the front wheel bearings properly I found that the stub axles were worn, so that was stripped down where I found the trunnions were also knackered, with pitting on the top of the threads of the uprights. So it's all new now, so it 'should' be a lot safer and better now.




The problem I was chasing next was fuel related, for some reason the Facet primer pump was running dry. It was suggested that the old CAV type fuel filter does not like having petrol forced into it, so along with a repositioned high pressure fuel pump I fitted a filter from a Volvo 240, though I needed to get some more fittings for that.
The re-positioned pump was achieved by using a Lucas fuel pump cradle, but unfortunately I soon found it was not what I needed as the pump cooling ring could not be used in conjunction with the cradle.




I set about measuring up the cradle, adding on dimensions as required to suit, which soon resulted in a template and then a sheet to bend up.




After bending to shape and a few holes cut for the pump body and fixings it was ready to be put together, it has since had a quick coat of paint to protect it.

New pipes

Following the results from the rolling road and after a brief sojourn to the secret workshop, the GT6 came back home with new under car exhaust pipes. The outlet of the 3-1 collector has been made to a larger diameter for a short length before splitting into two pipes for most of the exhaust run and then joining up again to go into the silencer.







Unfortunately I couldn't go out and test it straight away as we noticed another core plug has started leaking and I didn't have any spares to hand. I soon knocked out all four core plugs along the side of the block and as there was a bit of black residue left in the bottom of the block. I flushed the system through and once again after refitting the plugs to make sure I had water flushing through the whole system. Still not quite sure what has caused the core plugs to fail.
The plastic bags are there to try and reduce the amount of water getting poured into the starter motor and exhaust pipes as they were going to be too much of a pain to remove from the car.

Tightening-up the steering and front camber

After a week of doing not much, I set to trying to reduce the vibrations I believe are coming through the front end as the situation is improved after cleaning off the wheels, but should be better. I started off with the steering column and seeing as I have not had much luck the replacement bushes you can buy I decided to copy Dave and make up some PTFE bushes, which are almost three times longer than the originals, so much better now.




Further down the steering shaft the joint was replaced with one from Bill at Rarebits.




The only problem was that the new one was 10mm longer, not usually a problem for a standard car, but I had moved the steering rack over to the right as far as possible to give more space for the exhaust. This meant there was not enough space between the suspension tower and the upper pinch bolt of the steering joint. I tried for a time to work out how I could reduce the diameter of the joint to make it clear, but in the end I decided to weld it on to the lower steering shaft. The assembly can still be removed from the car without destroying anything.




The front end vibrations have now reduced, but I have now tracked down slackness in the steering rack, so one of the next jobs will be to try and remove some of that slack by removing a shim or two, otherwise I shall pick up another rack and re-build that in readiness to drop in the GT6.

Following Johns suggestion I bought some 1/2" aluminium bar, cut it down to length and drilled it to suit the lower wishbone arms.




It does look a lot better now as there is a greater surface area contact between the wishbone bracket and the chassis.

Wheels and shocker mounts

For a while the car had been suffering from vibrations around motorway speeds, I thought it was something up front as I could feel it through the steering wheel, but after watching the rear wheels on the rolling road it was possible to see that the wheels are nut running true. Some time this morning was spent first checking the hubs for run-out and then the wheels. Spinning the wheel over by hand you can the the wheel and tyre more in and out, at worst according to a dial gauge, 2mm.
To prove the point, the standard steel wheels were fitted, they run much more true and do not give vibrations at motorway speed. I reckon when the alloy wheels were re-furbished they did not take into account the thickness of the paint on the area where the wheel mates to the hub, so one side of the wheel is further out than the other. You can see on the inside of the wheel that it has not been contacting across the whole surface area. I removed all of that paint so it will sit flat again. They were fine before they went in, but the new paint is much thicker and having done this the car felt a lot smoother.




Following suggestions on how to make the car drive and feel better, wheel shims have been added to the rear. I started with 25mm spacers, but the studs supplied with them did not leave enough spare thread as I wanted, so the spacers were reduced down to 17mm. This means the car has a slightly wider track width than the later Spitfires with their long driveshafts, filling out the rear arches much better and noticeably improving the handling in corners.

Image on left with spacer fitted




Then a couple of weeks ago I noticed that the shock absorber top rubber was trying to escape, correctly diagnosed by charlieb as being due to the way the springs are now supported, meaning that these rubbers are now taking the weight from the spring also.




To get round this I have for now at least, fitted some re-enforced rubber washers cut using hole punches. Hopefully these should hold up better until I do something like copying Daves top mount idea incorporating rod ends.