HomeDesignControlAutomationGluedotVehicle levelingContactLocationPorsche
MaintenanceflexplateX PipesTrackdayRacing
Copyright reserved 2009
Ritech Systems Limited

Telephone (0044)1380 818094

Best viewed at 1024 x 768
In the process of developing the racecar we looked at the suspension available and decided that no current offerings were suitable. Either the units were not adjustable enough or they were diabolically expensive. So we have been working with Protech to develop our own suspension units for the 928 which would suit either road, track or racing applications.

With a range of spring sizes to suit anything from road to racing the units are double adjustable for both bump and rebound.

The suspension is compact and manufactured in aluminium for lightness, anodised for protection. The bodies are fully threaded to allow all ranges and lengths of spring.


The prices are very competetive - please see below:
Total Set of 4 including springs £960 + VAT = £1152 + £18 Shipping Total £1170
OEM spring specs 300lb Front 200lb rear
Street+ 400lb 250lb
Street/Sport 500lb 350lb
Sport/Race 600lb 400lb
Race Mod* 850lb 450lb
Race Pro* 1000lb 500lb
The first production set was installed in Miles Davis's 928 S4 roadcar. He wanted a setup for fast road use which could be adjusted for trackdays.

Below is a testimonial from him:

Dear All,

I am indeed lucky enough to be the first customer of the new Armstrong suspension kit! I had meant to send out a write up on it and this thread is a very good cue…
Like Rich I had been looking to tidy up the handling of my ’88 S4 auto, and was considering the limited set of options; kits from the states or Leada’s. Richard had circulated a tantalizing picture of his new race set up very early this year, and drawn by the separate bump/rebound adjustment I pestered Richard to let me be a beta customer. Castle Coombe was the first outing for my new set and I am very pleased with the results.

The suspension kit

The kit is based on Pro-tech dampers, bump and rebound adjustable, which have beautifully engineered rose-jointed bottom ends, and conventional top mounting. The entire shocks body is threaded to provide a large range of height adjustment for the 2.25” spring platforms, and hard anodized in a gold finish. The damping adjustment is via two knurled knobs (one for bump and one for rebound) on the lower end of the shock tube. The kit takes standard 2.25” coil springs so a whole range of cheap springing options are available. Looking to stiffen things up for the track and still retain my teeth on the road went for 400lbs (12”) rear and 600lbs (9”) front – roughly doubling the standard set up.


Both the front and rear fit into the standard top mount, and the bottom end rose joints are secured into the standard mounting positions using cylindrical bushes. Because the new springs are of a much smaller diameter they easily clear the upper front wishbones for fast fitting and removal – swapping spring for different rates is now for me about a 25min per corner job. The spring platforms retain their normal on-car adjustability. Happily the bump and rebound adjustment can be easily reached and adjusted with all 4 wheels on the ground, and without getting burnt by the hot car!
(I was replacing a new set of standard Boge dampers and road spring so I did not have to do any real fighting with seized fittings.)

On the road

Naturally I didn’t finish putting my car back together until the night before, but a few quick runs up and down a local (bumpy stretch of road) had me with some well behaved road settings, which I then planned to tweek on the track at Coombe. I was really pleased with the ride, which despite doubling the spring rates was supple and comfy on the motorway. Not the most scientific comparison, but last month I test drove (several) BMW 335i’s with the sport suspension pack. From the seat of my pants the motorway ride was about the same.. On the b-roads the grin factor was huge, however top gear superlatives are not going to be nearly as telling hear as the behaviour on track…

On the track

Bearing in mind by base line is a new set of Boge dampers and standard springs…
I went up a few clicks all round on the dampers before hitting the tack at coombe. I had planned to tip-toe round very carefully to begin with until I had a good set-up figured out. Within 2 laps that plan had more or less gone out of the window - the car was great. I came back in and turned the dampers up another click all the way round and this is what I found in 112 miles (and a whole tank of super) of running at a fairly sunny Coombe;
I was a gear up on the entry apex of all the power on corners (Paddock, Tower, Camp, Folly) just because the car was so much more under control.

The Folly – Avon rise – Quarry complex was fantastic, the road car nervousness was completely gone and I was able to run the car flat in 3rd all the way from camp until the first braking zone for quarry. (The speedo was clipping about 125 indicated for me there.) The stability of the car meant I could attack the quarry braking zone with real confidence, and in fact to start with I was having to get back on the throttle for the short run toward the traffic lights. Once settled the car was tucking neatly into line for quarry.

Through the Esses the car could be chucked in with abandon (something that would have meant a lawn mowing trip on the previous set up). Further the car was really easy to get back across to the left for attacking Camp, hence 3rd gear before the apex, and the car could be held flat in 3rd all the way through Hammerdown, where hard breaking for tower did not disturb. Early throttle through tower meant the car had run out of revs in 2nd for Bobbies, and due to the sluggish change of the Auto I had to concentrate on early exit under power. All of which left me arriving very much earlier on the power at Westway.

Finally I could get the power on early on the exit from camp leaving me in 3rd before hitting the straight! Bloomin’ marvelous.
Bottom line the car was more stable, composed, and less nervous everywhere, it could be thrown around harder, and it still retained that lovely 928 neutral demeanor. The car got neither tail happy, or understeery, and inspired more confidence across the whole range of conditions on the Coombe circuit. I can’t wait to get it out onto a faster wider track like Goodwood and see how it runs there.

On the way home

Turned the dampers back down a few clicks loaded the car up and drove off down the motorway in comfort as if nothing had happened! Nice.
Hope this is of interest to the listers – I can say I am very pleased with the results.
Best Regards,

Miles, Red ’88 S4 Auto.