A company which reconditions these shock absorbers is;
Stevson Motors Ltd (Specialist classic car hydraulic component manufacturers and recoditioners of lever arm and telescopic shock absorbers)
Unit 1, 2a Harrow Road
Selly Oak, Birmingham B29 7DN
Tel: 0121 472 1702
Email: stevsonmotors1@aol.com
The following contact details and addresses are for companies who undertake supplying spares and who conduct strip and rebuilding of automatic gearboxes (ie Torqueflte) and Salisbury axles.
American Auto Spares Ltd. no longer conduct strip and rebuilds but can provide most engine, gearbox, starter motors, alternators, etc. which is now the focus of their business.
The others are renovation companies who have conducted strip-down and rebuilding of Bristol V8 gearboxes and axles in the past and felt confident in ensuring a good outcome.
They always prefer to have the vehicle and are quite prepared to remove the gearbox which is taken out from the inside of the car and replaced. Both stated that the final adjustment to the auto-box is best achieved by a series of road trials.
The axle can also be stripped whilst still assembled to the vehicle saving the cost of removing it and the shipment cost of transporting such a large and heavy item.
One set of data produced by Geoff Dowdle in Australia is currently being checked out in the UK for possible local supply. The 407 listing does not appear in the current Koni online catalogue, although the numbers are valid. The SPAX numbers are also being checked out.
| Model | Setting | Compression | Rebound | Possible Replacement |
| 407 Front | ——– | ——– | ——– | Koni 82.1328 OR SPAX 210-S or G712 For Armstrong see below |
| 407 Rear | ——– | ——– | ——– | Koni 82.1059 OR SPAX G211 or G713 For Armstrong see below |
Front Upper Wishbone bump stops – 4off – Jaguar Part No. C29979 (NOTE: the hole size in the wishbone has to be enlarged to 5/16ths (appox 8mm) to accommodate the stud on the bump stop fixing plate.)
Upper ball joint front suspension – Jaguar Part No. CAC9938X (NOTE: the fixing nut is larger than the original part. However, there is sufficient space to tighten up with a shallow socket, the taper identical to original but it is advisable to pull taper into its locked position on the forging with a bare nut and washer. Then once locked up, replace with the Nyloc nut provided.
Front upper wishbone bump stops (4 off) – Jaguar Part No. C29979. Source: British Parts UK Tel: 01438 – 354816 www.britishparts.co.uk. Cost (Oct 07) £2.45 each + VAT + post NB. The hole size in the wishbone has to be enlarged to 5/16th to accommodate the stud on the bump stop fixing plate. Upper Ball Joint – Jaguar Part No. CAC9938X Source: British Parts UK Tel: 01438 – 354816 www.britishparts.co.uk. Cost (Oct 07) £9.99 + VAT + post.
NB. The fixing nut is larger than the original part. However, there is still sufficient space to tighten up with a shallow socket. Taper is identical to original but it is advisable to pull the taper into its locked position on the casting with a sacrificial bare nut and washer and then remove the nut before attempting to put on the nyloc nut.
Shock absorbers don’t really absorb shock, they dampen it, hence they are often referred to as dampers. Why is this important for you to know? To improve ride quality. Basically put, a shock absorbers sole purpose is to dampen the compression and rebound of any suspension system by controlling the speed at which a suspension cycles. Without them, your car would continue to bounce up and down until the kinetic energy is finally dissipated from the suspension’s springs (e.g. leaf springs, coil springs, torsion bar, etc.) and sea sickness may follow.
Now let’s think about the law of conservation of energy. With this law in mind, shocks will perform two functions. The first function is to slow the suspension’s cycling of compressing or rebounding. Secondly, since energy can’t be destroyed, the shock transforms the kinetic energy into heat as it dampens the “bouncing” of the springs. That’s it. That’s what a shock does.
Or otherwise put – in a vehicle, it reduces the effect of travelling over rough ground, leading to improved ride quality, and increase in comfort due to substantially reduced amplitude of disturbances. Without shock absorbers, the vehicle would have a bouncing ride, as energy is stored in the spring and then released to the vehicle, possibly exceeding the allowed range of suspension movement. Control of excessive suspension movement without shock absorption requires stiffer (higher rate) springs, which would in turn give a harsh ride.
Shock absorbers allow the use of soft (lower rate) springs while controlling the rate of suspension movement in response to bumps. They also, along with “bounce” in your tyres, dampen the motion of the unsprung weight up and down on the springiness of the tyre. Since the tyre is not as soft as the springs, effective wheel bounce damping may require stiffer shocks than would be ideal for the vehicle motion alone.
Spring-based shock absorbers commonly use coil springs or leaf springs, though torsion bars can be used in torsional shocks as well. Ideal springs alone, however, are not shock absorbers as springs only store and do not dissipate or absorb energy. Vehicles typically employ both springs or torsion bars as well as hydraulic shock absorbers. In this combination, “shock absorber” is reserved specifically for the hydraulic piston that absorbs and dissipates vibration. Below are some images which illustrate these principles, and the technical features of dampers.
Investigation work is currently being carried out on shock absorbers as they relate to Bristol’s, and the confusing world of different and changing part numbers that have been used over the passing years, especially as a result of consolidation in the number of producing companies.
Paraphrased extract from the Bristol 400 Workshop Manual – Bulletin 2 August 1955
“The Newton & Bennet shock absorbers originally fitted are S.12490 and are no longer available, but reconditioned units could be fitted OR you could fit S.14490 as the new recommendation. However, they were not interchangeable and if S.14490 was being used it necessitated the replacement of the bottom lugs. It was also important that both rear shock absorbers should be renewed.”
One set of possible replacements, produced by Geoff Dowdle in Australia, is currently being checked out for possible local supply in the UK. Note that whilst the Koni numbers are valid in their type, they do not appear in the current Koni on-line catalogue. The SPAX numbers are also being checked out, and some makes possibly not relevant to the UK have been left out.
| Action | Setting | Front | Rear |
| Compression | 6.5″/Sec. 19.0″/Sec. |
5 – 25 Lbs 65 – 85 Lbs |
70 – 70 Lbs 115 – 135 Lbs |
| Rebound | 6.5″/Sec. 19.0″/Sec. |
35 – 55 Lbs 105 – 125 Lbs |
115 – 135 Lbs 190 – 215 Lbs |
| Model | Setting | Compression | Rebound | Possible Replacement |
| 400 Rear | Newton & Bennett Max 21.75″ – Min 13″ |
100 – 140 Lbs | 150 – 190 Lbs | SPAX 170/561G |
| 401 Front | N&B Setting WE4C4 Max 425mm – Min 305mm |
100 – 140 Lbs | 150 – 190 Lbs | KONI 80.1149 WYLIE 25 MR 36-2 |
| 401 Rear | N&B Setting NE7C3 Max 15.5″ – Min 11.375″ |
120 – 190 Lbs | 290 – 360 Lbs | KONI 80.1080 WYLIE GT130 |
| 403 Front | ——– | ——– | ——– | Spax 170/120G Koni 80.1149 |
| 403 Rear | Newton & Bennett | ——– | ——– | Spax G4.5SL Koni 82.1087 |
| 404 Front | See Workshop manual data below Max 430mm – Min 290mm |
——– | ——– | Spax G4.5SL Koni 82.1087 See Girling below |
| 404 Rear | See Workshop manual data below |
——– | ——– | Koni 80.1149 See Girling below |
| Arnolt Front | ——– | ——– | ——– | Girling DAS6 Armstrong AT7 1185 |
| Arnolt Rear | ——– | ——– | ——– | Girling DAS9 Armstrong AT7 1186A |
| 405 Front | See Workshop manual data below |
——– | ——– | Koni 80J.1107 See Girling below |
| 405 Rear | See Workshop manual data below |
——– | ——– | Koni 80.1215 See Girling below |
| 406 Front | ——– | ——– | ——– | SPAX SG712 |
| 406 Rear | ——– | ——– | ——– | SPAX SG713 |
The first link does not apply to the earlier 2 Litre models, but is more relevant to 405/6 onwards through Chrysler V8′s etc. This and other information has kindly been donated by Per Blomquist and comes from a Motor Trader article from May 1958. It is reproduced here so that the technically minded can get a better understanding of how things work. The second link is an article by Phillip Herbert.