Pegasus parts news

COMMERCIAL NEWS

One of our members refurbishing his brakes on his 403 enquired whether Pegasus knows of a supplier of the banjo bolts that fit into the wheel cylinders and copper sealing washers to fit these bolts.

I gave him the following company:-

Stevson Motors
Unit 1, 2A Harrow Road
Selly Oak
Birmingham
B29 7DN

Contact: Derek

Tel: – 0121 472 1702

http://www.stevsonmotors.co.uk

They can supply refurbished, lever arm shock absorbers, stainless braided flexible hoses of all kinds, brake fittings and thick wall rubber tubing as used on our 2 litre vacuum wiper systems.

Derek could not help with the banjo bolts but he recommended another company. They were able to supply them and he stated they stocked other Bristol bits.

John Lawley
Spares & Technical Support Officer

V8 shock absorbers and suspension

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.

 407 shock absorbers

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

Armstrong Shock Absorbers

chrysler-armstrong-shocks

408 Suspension

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.

General V8 suspension

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.

411-belt-heading

How shock absorbers work

(Extracted by K. Lutz)

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.

2 Litre shock absorbers

 Shock Absorbers

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.

 The Bristol Workshop manual states “there are three types of Newton & Bennett shock absorbers fitted to Bristol Cars and they are not interchangeable with each other. One type was fitted to 400 cars; all 401 cars up to chassis 1155 have a second type and from chassis 1156 onwards a larger type is fitted”. Sadly they do not quote the three numbers, but see Bulletin 2 quoted below.

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

404-405 shock absorbers

Original data from the workshop manual

 

Salisbury Rear Axle

Click here to download (TYPE, 1.31MB)

Click here to download (TYPE, 22.93MB)

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.