ProTech Dampers Adjustment?
Discussion
I bought a set of ProTech adjustable dampers (Series 400?) and springs from Race Tech to replace the old SPAX units on my S1. My intention was to also raise the ride height. When I opened the box I was surprised to find that they're slightly shorter than the SPAX dampers. ??? And the adjustment knob only has eight clicks rather than the thirteen everyone else seem to have. There were no instructions in the packages. I'm guessing that turning the knob clockwise increases the damping. I'm also guessing that the adjustment ring on the tube only changes the preload on the spring and does not change the ride height of the car. There is also quite a size difference in the springs on the Protechs compared with the SPAX. Photo attached. Has anyone out there got a set of these? How did you set them up? 
I've spent the last few days exchanging emails across the Atlantic with RaceTech customer service. Nice people. They've contacted ProTech who said the eight click valve adjustment is only for their racing dampers. Why they were installed on these they don't know. The dampers are short because they have the short eyes installed rather than the long eyes. Why? Unknown. Their solution is to send me the 13 click valve parts and longer eyes which I would have to install. I'm not sure I'm comfortable with this as I'd be tampering with the factory assembly, plus it's unlikely the car's ride height would be any higher which was one of my original goals in replacing the 34 year SPAX dampers. (We have the worst roads in the nation and I'm tired of occasionally grounding out with two people in the car.) There's also the fact that I'd have to experiment with the spring tension which can be time consuming and, at times, risky. So, I'm considering just shipping them back and chalking it up to yet another expensive TVR misadventure. The problem is finding a set of dampers that are compatible with the S1 and are a direct replacement without a lot of rocket science in setting them up. I found a set of GAZ, supposedly for the TVR S, on sale, but the company wouldn't ship to the US. I tried contacting Dominion Spares on this side of the pond for a set of Koni dampers but got no answers from emails or phone calls. Racing Green sells front and rear SPAX dampers and replacement springs, but, again, big money and high shipping / return costs if they're not right. So, the original SPAX unit is going back on the car to make it roadworthy, more or less, so I can shift to working out all the other problems I've discovered, or sell it and get an MG. Time will tell. Thanks for your inputs.
A positive note. Bill at Dominion Spares in Virginia has responded, confirming he did not perish from COVID-19. He has in the past fitted GAZ shocks successfully to an S1 and is searching for his notes. Which brings up the question, where can I find the numbers for spring rates, etc applicable to a 1988 TVR S1?
The answer is "yes", I turned the spring collar up about 2 inches on one of the ProTechs to make sure the rod was fully extended. Measuring bolt center to center they're about .75" short compared to the SPAX. Since it will take about three months or more to get the GAZ units made and delivered, and considering the cost of return shipping, I've decided to keep the ProTechs. RaceTech is sending the valve parts (13 clicks) and the extended eyes which should make them roughly equivalent in extended length to the SPAX units. I'm going to assume the springs are correct for the application. The old SPAX springs are almost fully compressed with two people in the car, so anything is bound to be better. This is not going to be a track car so I'll set up the corner weights accordingly using the information provided above. As for ride height, it is what it is after adjusting the springs. If it's acceptable I may cancel the GAZ order.
I am now in possession of two longer eyes for the rear shocks and four new valve adjustment knobs that will provide 13 clicks of adjustment from ProTech via RaceTech. The new knobs and eyes have, as of today, been installed on the damper units. Photo included. The dampers appear to be 400 series, single adjustment units with springs 9 inches long, 2.5 inches ID and spring rates of 300 lbs per inch ( as marked on the springs). Unfortunately I was unable to get a pre-load starting point from either RaceTech or ProTech. So, I opted to compress all four springs 0.5 inches which should give a pre-load value of 150 lbs per unit. The next move is to install them and adjust the springs if necessary. I'll let you know how that goes. 
All four ProTech dampers have been installed. Ride height is considerably higher, now about 200mm in the rear and 195mm in front (was 175mm, measured floor to outrigger corners). The passenger side is about 5mm higher. Just about what I wanted. I took the car for a test run and the ride heights remained the same. The ride is considerably improved. The bone jarring ride is gone, along with a lot of the rattles. And it never bottomed out, even on rough roads. It's almost civilized. The only problem now is that the car tends to oscillate once after hitting a bump. I think the damping valves need to be adjusted. They're set at eight clicks clockwise from zero. Which way should I go? 
Ok, I started fully clockwise on the valves then backed off slightly until I felt it click. This became the zero point. It took a couple of test drives but three additional clicks anticlockwise turned to be the golden zone. I'm leaving it there and will have the front end realigned professionally in a few days. Took it to a cars and coffee event this morning and was amazed I could actually open the bonnet all the way. My next task will be to remove the exhaust system and do some refitting. I believe the rattle and metallic buzz at around 2,000rpm is due to the exhaust system having been pushed out of position from all the bashing it takes every time the car grounded out. I hate exhaust work but it seems to be in the cards.
Thanks for all the assistance.
Thanks for all the assistance.
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