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.

GT6 update, rolling road.

Hmm, news on the GT6 is getting a bit out of date, having got the PI system working as it should on the GT6, I wanted to go and do a rolling road run to help further tune the megajolt ignition map, see what sort of power/torque it is producing and get an idea of what further improvements could be made. So we went over to Maynard Ltd in Stroud to have a run up, the results of which are below

Power





Torque




The red run is with the complete exhaust system (GT supplied 6-3-1 onto standard centre pipe and back box), grey is with the rear silencer removed and black is with the middle pipe (from 3-1 collector back) removed. All figures are corrected back to the flywheel.

It seems to suggest at the moment that the back box has minimal effect, but the relatively small 48mm ID middle pipe is holding it back. So one of the next jobs is to get the constricted (48mm) output from the 3-1 collector opened out to 52mm ID

It was a good afternoon out and was interesting to record what the engine is pumping out on what is basically a standard MkII GT6 engine, but with Lucas injection and a proper exhaust manifold. I'm not that bothered about the absolute power figures (though they are a good improvement on the factory figures), more interesting to me is the shape of the torque curve, which is relatively flat compared to other GT6 engines I have seen, with bags of torque from lower engine revs. I'm pleased with the results and that's what matters to me ;)

Tractor time

There has not been much time spent on my cars recently due to work on the Lightweight (more on which another time) and work on my tractor. I've owned this for the past five years or so and has come in really handy when moving engines around or fetching wood for the farm, but the hydraulics, which provide power to lift the front loader or rear implement, have over the years grown weak.
A gear driven pump provides the hydraulic power, but this is hidden away in the back of the tractor behind the gearbox and below the axle. The combined gearbox and rear axle oil was drained and while this was happening, I set about removing any parts which would get in the way.





With all the parts out of the way the rear case came off without any problems, using the two jack-off bolts to separate it and the Massey 35 to hold the weight.






It doesn't look too bad in the rear housing, though there is a bit of silt in the bottom of the case, not too surprising to me for a farm tractor of this age. I shall clean all this out as best I can, then put new oil back in, all 12 gallons of it.

I moved the rear case, with the hydraulic pump, into the workshop to make it easier to work on. Unfortunately there are no obvious signs of failure yet, so I guess a hydraulic pump rebuild could be on the cards.