Tuesday, 10 September 2013

Cleaning up the mess...

I had time on my hands last week while I was waiting for the parts I need to repair the Spitfire's front suspension to arrive so I decided to spruce up the bits that are going back on.

I thought it would be a good opportunity to try out two anti-rust paint treatments that I bought a while ago (primarily to use on the Saloon) but haven't had a chance to use in anger yet - Bilt Hamber's Hydrate 80 and POR-15. It'll be interesting to see how well they do in what isn't a particularly benign environment.

The shock absorbers and spring caps were looking like this when I took them off the car:

I degreased the shock absorbers and used a wire brush in an angle grinder to remove the rust. After further cleaning with Eastwood Paint Prep I treated the areas that I'd removed the rust from with two coats of Hydrate 80.

Finally, the shocks got two coats of smooth red Hammerite that I had lying around on the garage shelves.

The spring caps were derusted with a wire brush in an angle grinder and then some 40 and 80 grit wet and dry in the areas I couldn't get to with the angle grinder. They were then given the full POR-15 treatment - Marine Clean, Metal Prep and Ready, Two Coats of POR-15 and then a single coat of POR-15 Chassis Coat Black.

I'm not claiming they're concours (that's not my thing anyway) - but they are looking much better now.

The anti-roll bar was degreased, derusted with a wire brush in an angle grinder, cleaned with Eastwood Paint Prep then given two coats of Hydrate 80. You can see the second coat of Hydrate 80 drying the following picture.

The anti-roll bar was then finished with a single coat of POR-15 Chassis Coat Black.

Almost all the bits I need to rebuild the front suspension have arrived - superb service as ever from Canley Classics (lower wishbones and mounting bracket); Chic Doig (miscellaneous bits and pieces); Chris Witor and the TSSC Shop (Superflex bushes); Jon Wolfe (wishbone bolts and solid anti-roll bar drop links) and Moss (spring spacers). I would have all the bits to hand by now if I hadn't misread Moss's web site and ordered what I thought were a pair of spring spacers only to find that in fact I had ordered only one. Doh!!

The 330lb front springs that were on the car were too soft for my liking and I'm replacing them with a pair of progressive springs that I've had sitting around for nearly two years now - the last of a small batch for GT6 that Gareth Thomas had manufactured a few years ago.

A bit of thought had to go into working out what spacers I think I need to get the front ride height right.

The combined fitted length of the old 330lb springs plus the spring spacer was exactly 7.5". This is more or less perfect for the way I like the ride height set up (if anything I'd like it a fraction higher but not by much). Subtracting the height of the spring spacer used with the old springs (0.375") gives the fitted length of the old 330lb springs as 7.125".

The free length of the old 330lb springs is 10". That means they were being compressed by a force of (10-7.125) x 330 = 948.75lbs.

The free length of the new springs is 8.5 inches. The primary rate is 380lb therefore they will compress by 948.75/380 = 2.5" when fitted, giving a fitted length of 6".

Looking at what's available I've decided to fit the 1.25" below spring spacers from Moss in combination with the 0.375" above spring spacers I was using with the old springs. That should result in a total fitted length of 7.625" which I reckon might just be perfect!

It's going to be really interesting to see if this works out the way I planned. Hopefully, I will not end up looking like a complete arse...

One very odd thing I found when checking the damping adjustment of the Konis was that they were both set to minimum. I could swear that I'd set them mid-way when I built the chassis - but it looks like I boobed. Anyway, they're set to 3/4 now which I reckon should be appropriate for the new springs. It'll be interesting to see what the rear Konis are set to when I strip the rear suspension down later in the year. Conventional wisdom has it that that the rears should be set soft and maybe at least I got that right!

I've also decided not to fit new standard anti-roll bar drop links and have instead decided to fit the solid drop links sold by Jon Wolfe (Wolfitt Racing). They are lovely bits of kit.

I've almost finished rebuilding the N/S and I reckon that with a fair wind and fair weather I'll have it all back together again for the weekend and I'm really looking forward to seeing how goes with the new springs and anti-roll bar setup.

No comments:

Post a Comment