D612 PNT One of these days...

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Re: D612 PNT One of these days...

Postby Geoff Butcher » Sun Jul 31, 2016 8:58 pm

Mine was never brazed and still went rusty! I've got a brand new one ready to go on just as soon as I remember how I did it last time... :?
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Re: D612 PNT One of these days...

Postby Jin » Sun Jul 31, 2016 10:46 pm

wow, a really great write up there, its always nice to read other peoples stories and anecdotes as an insight as to how others tackle the jobs.
good work mate and I remember the car from Stoneleigh and the open day, fantastic looking piece of kit - great :)
https://easywider.co.uk/ universal flexible wheel arch extensions
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Re: D612 PNT One of these days...

Postby ACourtney » Wed Mar 22, 2017 9:45 pm

I was reminded by Johno's post today that I hadn't finished this write up. In fact its around 8 months since I last posted on here and most of the work was done in 2015.
Johno's post was about tyre sizes and that relates to the next part. When Chris got the wheels back from Washford Finishers we had to choose some new tyres. The old tyres were 165/60 Goodyear NCTs and thanks to careful storage they were not cracked,or distorted. But 18 years of storage still takes its toll on the tyres and the tread was as hard as slate.
After bleeding the brakes, I had taken the car out around the estate and even a gentle application of the brakes would lock the front wheels and cause the tyres to skid. So, if they couldn't grip on tarmac, what chance would they have on the steel rollers of an MOT bay.

After looking at the different options we settled on some Toyo Proxes CF1s -175/60-13s, which Mytyres were selling at just under £50 at that time.
The original 165/60 -13s have a theoretical OD of 528mm. I use the term theoretical as that is the sum of 13" (330mm) and the tyre profiles 2 x 165mm x 0.6. In practice there is quite a considerable variation in OD to be found between different brands, so the theoretical figure is only a rough guide.
The commonly used options are:
165/55-13 Theoretical OD 512mm. Available in a limited choice of Pirelli, Nankang and a couple of unknown cheap brands
165/65-13 Theoretical OD 545mm. Available from a large range of brands, but I have seen fouling issues on a couple of Gold convertibles with this tyre size.
175/50-13 Theoretical OD 505mm. Available in a limited range from Yokohama and Nankang.
175/60-13 Theoretical OD 540mm. Available from a large range of brands.
185/55-13 Theoretical OD 533mm. (Metro GTi size) Supply is now as limited as the original 165/60s. A batch seems to come in from Toyo once a year and sells out within a couple of months!

After discussing the options with Chris we settled on the 175/60-13 Toyo Proxes as they seemed to be the best tyre at the keenest price and, having driven the car, they didn't disappoint us. However, thatis short cutting the story. Once we had had the tyres fitted I found that on full lock they were touching the front inner wheel arch front lip on both sides and the rear of the front arch on the near side. I thought it strange and a measurement revealed that the wheelbase was 4 or 5mm shorter on the near side than on the off side. Further checks showed that this was in the mounting of the front subframe. Fortunately, I found a 3mm thick stainless M16 washer that I was able to use as a shim between the mounting bush and the subframe and that brought the wheelbase back as near as dammit even on both sides.
That still left me to sort out the clearance at the front, but the beauty of GRP is that it is easy to cut and rejoin to be as strong as before. So after working out how much clearance I needed, i simply cut a section out of the lower lip and moved it forward. Then I carefully bonded it back in - after first cleaning back the surfaces to be bonded - with several layers of CSM and then finished it off with some black gel coat to cover the cut lines.
ImageDSC_0117 by Alistair Courtney, on Flickr Can You See the Joins?

I thought that the car was ready for its MOT, but I was wrong and it failed on several points, a couple of which were to prove to be my fault for driving the car around to help re-bed the slightly rusty brake discs.
So yes, the brakes failed the MOT for despite locking and skidding with the old tyres, they didn't provide enough retardation with the grippy new tyres.
It also failed because the rear dampers had started to leak oil - something they hadn't done before I drove it around the estate.
Also, by the time I had done the driving around, both front tyres were starting to touch on the back arches again - probably due to the old suspension bushes settling back after all my braking.
Finally, the car failed on emissions as it decided to start producing white smoke, which hadn't done previously and also proved to be in part due to having my warmed the car up.

I will try to get back and post again soon to explain the mystery of the smoke and how I addressed the tyre clearance issues.
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Re: D612 PNT One of these days...

Postby ACourtney » Tue Mar 28, 2017 8:59 pm

As I said at the beginning of the first post, recommissioning this car was like waking a grumpy teenager. I had already done a lot of work on it and everything appeared to be okay before the MOT, but after running it around the estate for ten minutes to warm everything up it was no longer looking so good: The exhaust was issuing white smoke as soon as you put your foot on the accelerator, the brakes were not biting firmly, the rear dampers were now leaking oil past their seals and the tyres were touching the backs of the arches again.

The dampers were the easiest fix. The car originally had Spax dampers that are not rebuildable, so a phone call was made to Dave at Dampertech - http://www.dampertech.co.uk/ and a new pair of GAZ dampers were duly ordered. A closer inspection of the front discs showed that, while they did not look rusty, their surfaces were very pitted. I suspect that the rust had all transferred to the pads, which tends to reduce their bite. Given the age of the car there was a high risk that the pads contained asbestos, so getting the discs skimmed and pads linished would not have been a sensible option. A new set of Mintex pads and disks were also ordered.

Both were pretty straightforward to fit. There has been some comment on this forum and on Facebook about the thread on the top of the Gaz dampers being too short. I did need to lower the car onto its wheels to compress the springs a little, but the top nuts both went on without any issues. The only problem that I have seen with Gaz dampers is that the zinc plating is rather minimal and, if left unprotected, rust spots will soon appear. This has also been mentioned before on this forum and I have discussed it with both Dave Ainsworth and the Gaz factory. The problem is that they cannot apply a thicker coating to the threaded body otherwise the threads will seize up and the platforms would no longer be adjustable. My solution is to spray the body with a couple of coats of anti-corrosion wax:

ImageDSC_0027 by Alistair Courtney, on Flickr

As you can see from the photo, I spray the wax on after adjusting the platforms. I used to use Waxoyl, but I have found that the spray cans of Protection Wax sold at Toolstation work better. It seems to dry firmer and the second coat does not make the first coat run.

At the front, the new discs and pads also went on without a hitch. I still had another trick up my sleeve that would move the wheels forward and improve the tyre clearance at the back: Spacing the anti-roll bar mounts.
The Metro was originally designed as a shopping car and was given a very small amount of castor in standard form. Castor is the angle formed by the kingpin, or in the case of the Metro the line formed between the centre-points of the balljoints on the front uprights as castor makes the steering heavier. A low castor angle, makes the steering lighter, but the car less stable at speed. So when they devised the MG Metro, they decided it would be wise to add a bit more castor - better stability at speed at the expense of a slightly heavier steering.
On the Metro suspension the position of the top balljoint is defined by the top arm and the bottom balljoint by the lower arm, which in turn is defined by the anti-roll bar. Anyone who has fiddled with the MG Metro anti-roll bar will know that it is mounted in nylon bushes that sit with a spacer between the bush and the front of the subframe. On base model cars this spacer was around 8mm. The MG Metro was given a 10mm spacer, and that also seems to have been fitted to all the later 1300 models. I have also come across a 1/2" spacer on a Metro turbo subframe. I don't know if that was an original fitment, but I do know that the Metro racers also varied the anti-roll bar packers to increase castor and often went further than 13mm.
Anyway, Chris's car had the standard MG Metro 10mm packer, but I knew that it would be safe to pack them out to 13mm. So I cut a couple of short lengths of 25mm x 3mm steel strap and drilled a hole in each one to create additional packers, and with them fitted I could just about slide a thick piece of card between the back of the tyre and the rear of the wheel arch.

That just left the white smoke, which was to prove to be a real puzzler.
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Re: D612 PNT One of these days...

Postby ACourtney » Fri Mar 31, 2017 8:04 pm

I finished my last posting by saying how the white smoke was a real puzzler and it has been suggested to me that, rather than explaining the cause outright, I should set it as a puzzle to see if the forum members can work out what the cause was. As an incentive I'm going to offer up a couple of Midas mugs to whoever gets it right first, or comes nearest. The prize can be collected at Stoneleigh so that sets a time limit too.

All good competitions have terms and conditions and obviously I'm going to have to exclude entries from those who already know the story. That list includes Chris Nicholls and Mike Brown, who were present when I found the cause, John Roe who visited my workshop whilst I was puzzling over the problem and made some comments that were extremely pertinent and also regular visitors to my workshop such as Tony Moss and Kelvin Kinkaid. There are also a few other people that I might have mentioned the "smoke problem" to, so I would ask you guys not to post the answer. And no it wasn't the pitted needle problem, that came later.

So this was the problem: The engine ticked over cleanly, albeit around 1100-1200 rpm (a symptom of the engine itself and not connected to the smoke) and the exhaust was clear with the CO reading in the right range. However, as soon as you opened the throttle, great clouds of white smoke came out of the exhaust. The smoke was clearly white smoke and not oily blue. If you put your hand in the smoke it felt wet.

And this is what it looked like:

ImageSmokin by Alistair Courtney, on Flickr

I tried removing the vacuum pipes to the servo and the sump, etc, but none of that made any difference. I even disconnected the water pipes to the inlet manifold in case that had gone porous, but that made no difference either. Whilst we were puzzling over the smoke issue, Chris decided that he wanted to get the head modified for unleaded fuel. I was going to have to change the head gasket anyway as oil had been seeping out of the rear N/S corner of the engine. So we decided we would go ahead and have the valve seats done and get the head checked for leaks at the same time - I'll cover this in my next posting. The head proved to be leak free, but when it was all back together again the white smoke was still there. :?:

So the extra fluid wasn't getting in from any of the obvious causes. I'll leave it at that and see if anybody out there can work it out quicker than I did.
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Re: D612 PNT One of these days...

Postby Geoff Butcher » Fri Mar 31, 2017 8:19 pm

Has it got one of those oil/water heat exchangers?
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Re: D612 PNT One of these days...

Postby Stuart » Fri Mar 31, 2017 8:32 pm

From the water pipe on the inlet manifold?
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Re: D612 PNT One of these days...

Postby ACourtney » Fri Mar 31, 2017 9:53 pm

Geoff Butcher wrote:Has it got one of those oil/water heat exchangers?


No,it had a conventional oil cooler, but that wasn't relevant.

Stuart wrote:From the water pipe on the inlet manifold?


No, I mentioned that I'd disconnected the water to the inlet manifold. I even dried the pipe with compressed air to make sure there wasn't water still inside.
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Re: D612 PNT One of these days...

Postby Stuart » Sat Apr 01, 2017 9:30 am

ACourtney wrote:
Stuart wrote:From the water pipe on the inlet manifold?


No, I mentioned that I'd disconnected the water to the inlet manifold. I even dried the pipe with compressed air to make sure there wasn't water still inside.


Oh yes so you did. Would water in the silencer vaporise like that I wonder?
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Re: D612 PNT One of these days...

Postby DavidL » Sat Apr 01, 2017 10:17 am

Something to do with water in the SU's dashpot perhaps?
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