Another year of NA ownership beckons. How to make an old vinyl roof supple again?

I was anxious about the MoT on my NA this year despite having had very little use since the last one.

Sure enough, it failed on inner sill corrosion too close for comfort to the seat belt mounting. I had some MoT welding done on it 5 years ago, so I was thinking it might be curtains this time. The MoT place don’t do welding and thought my usual old school body basher had stopped doing it. Luckily, as a regular customer ( they service my1996 Toyota Granvia 3/0TD 4WD), they were willing to have a look. Sorted for a couple of hundred quid plus a bit more for ‘descaling’ and treating some underpinnings and suspension arms with poor man’s waxoyl.

I was so relieved, I treated it to an oil and filter change despite having done < 1000 miles since the last one. So little used, that I had to have the offside front caliper freed up (plus new pads) in the spring.

126000 on the clock now. My DIY cambelt change has been tested well on the odd outing though.

Too many motorcycles. The fleet has been joined by a 1937 Sunbeam 250 Sports. It replaced the 1994 Gilera GFR125 that was getting just impossible for me to ride (race replica). Enormous fun bimbling along at 40 mph on a rigid rear end and girder forks. Long stroke engine that idles at 390 rpm and maxes out at 5500 (if you have no mechanical sympathy) :wink:

I must use the MX5 more. The vinyl hood that I had fitted is ageing and though I have cleaned and ‘proofed’ it with Renovo, it has lost its suppleness so that I am reluctant to fold it down for fear of not getting it up again. Living outside in the sun/wind I suppose. I’ve seen mention of a mixture of mineral oil and ??? as a cure.

What is the preferred treatment?

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Once a Vinyl hood starts to crack there is no solution other than to replace. If it’s still OK then a vinyl dye in the appropriate colour may give you another couple of years. The normal life of PVC exposed to the elements is 8 to 10 years so yours is doing well. The other alternative is to replace and there are plentyof people who will do this. If youcan find a used fabric hood in good condition this may provide a cheaper option. Whatever you do don’t try to stretch the vinyl to lock it in place when cold, this will inevitably crack it. Make sure it’s warm and at least a bit supple before trying to secure it.

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The roof isn’t actually leaking yet.
It was fitted about 10 years ago. I’m not sure the life expectancy of the car now warrants another. Then, just when I think its end has come, it gets a reprieve.

Avoid lowering the roof when its cold, always unzip the rear window.

The vinyl shrink, pulling it away from the sides, and causing splits in the binding over the windows. Often just cosmetic, but shrinkage can result in leaks to the footwells.

I would avoid “treatments”; some of these can affect and weaken the vinyl, causing splits, particularly around the “grab handle” and in the quarters. This happened to me after I used a Meguiars branded hood cleaner. What came off with the cleaning cloth was really sticky, and first I thought this was evidence the cleaner was clearly doing its stuff, and pulling out tree sap etc. But then the hood started disintegrating, Some areas became really stretchy, and eventually, feeble. I patched it from the inside, but eventualy hood number 3 had to be replaced with a 4th hood (25 year old car, original hood was in shocking state after 9 years, replaced with a ex-VR hood that had been stored since 2000 in a loft, that lasted 4 years before the splits appeared. A BAS hood lasted from 2009-2018, before self-destructing. I picked up a good used hood on a frame, its not OE, got some splits, but the car isn’t used that much anymore).

Keep an eye out for a car being broken, Mk1 or 2. It might have a hood better than the one you have right now. A used hood on a frame should be about £100-150.

The patch I applied and ‘reproof’ seem to have helped with the elements but I haven’t dared put the roof down recently.

No chance of replacing the NA now, so long as it can be coaxed through an MoT. Just ‘invested’ in a replacement for my Toyota Granvia campervan. A Fiat Ducato based panel van motorhome conversion with heating and a wet room. A whole new can of (possibly rust) worms, though as a 2017 a lot of underpinnings are galvanised. . At least the cambelt has just been done.