Bristol lever type shock absorbers

[Superfine]

I have acquired a 400 with the original Bristol lever type shock absorbers/dampers front and rear. I am considering options to either keep these or go telescopic.

I would prefer to keep the original Bristol equipment to preserve the car's originality but have concerns about their maintainability, reliability and spares availability.

Any observations/advice gratefully received.
Many thanks

Superfine

[Stefan]

My 400 has a set of adjustable Koni telescopic shock absorbers but this is only possible by
1.My fitting a 406 Front axle complete with steering and disc brakes, and
2 because it had a factory modification to the rear - a hefty frame bolted across the rear chassis to allow mounting points for rear telescopics.
Handling, with a rollbar,is excellent but in today's climate you might even decrease the value of the car by this modification. The original shocks are complex and wonderfully engineered.
Look after them and they will serve you well.

[Geoff Kingston]

Checking the 401 parts book I see the change over to Telescopic's on the rear of the 401's took place before they changed over to them on the front, I am sure as Stefan has said you would have to carry out alterations to the rear of the car to make them fit, at the front you could change to the later 401 or 403 suspension units that take telescopic's but an awful lot of work for no real benefit. My 1951 401 still has the Bristol shock absorbers on the front and as Stefan said they are beautifully engineered and the only thing we had to do was to change some small paxolin discs in them to restore proper damping action, I never had any complaints when we ran that car and I certainly would not change them now even though I have a spares car to donate the later parts.
I read years ago that the main reason Bristol went over to telescopic's was the cost saved rather than any ride or handling improvements.
There are also a number of firms who repair this type of shock absorber and I have seen reference to this service on one of the club websites.

[Geoff Dowdle]

Superfine ,
The original lever arm shockers work very well when adjusted correctly and have the correct oil to the recommended level .
Problems can occur when the seals leak and the oil level drops , owners often don't take care in cleaning around the filler caps before toping up , this can allow debris to enter the shocker and work like grinding paste on the piston bores.
As mentioned by Geoff Kingston the Tufnol valve discs can split over time, which have the effect of the shocker not working in one direction.
These shockers are extremely well made and fully adjustable in both directions .
I suggest you read the 400 - 403 workshop manual before you make a decision on which way to proceed, it gives a step by step account of how to repair and adjust them correctly .
On high mileage vehicles the shock pads can wear , which gives a slight clicking sound but does not effect the functioning of the shocker .
These shock pads might not be readily available .
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If you decide not to stick with the original shockers you can fit the appropriate front shocker parts from a 401 of chassis number 1006 or later and all 403's .
These parts bolt directly to the 400 cross member without major modification .Depending on the specification / production date of you car the front inner wing ducting might need modification for clearance with the telescopic shockers.
or
As Stefan suggested, fit a complete front cross member from a 405 or 406

Brian May could have some of the parts available .

On the rear ,the later 400's (late 1950 production) were originally fitted with Telescopic shockers . There is a section in the Workshop Manual on how to convert a early 400 to telescopic shockers on the rear .
I have made kits of parts to do this conversion and Spax adjustable shockers are available for front & rear.
It is a time consuming job but usually within the capabilities of most home mechanic/restorers .

Could you please advise the chassis number of your 400 as I'm currently trying to update the 400 Register .
Have you recently bought the 400??

Regards
Geoff D