405 disc brakes

[dangerous rob]

Hi all just purchased a 1957 405. It has disc brakes on the front but I cannot find anything in the manuals about them. I have full service history and they are not fitted after purchase can anyone help? Cheers Rob

[peterg]

As the first prototype 406 chassis were produced in 1956 it is quite possible that your 1957 car was fitted with the same Dunlop disc brakes as the 406 during construction. Being low volume cars it was quite normal for Bristol's to include modifications requested by the purchaser.

My 403 was retrofitted with disc brakes by Bristol.

They were also fitted to Jaguars, so parts are not difficult to come by. I had my discs rebuilt rather than replaced by modern four pot Coopercraft units. They are well up to the braking efficiency of my tyres!

[Geoff Dowdle]

Dangerous Rob ,

I have records of 89 ,of the approx. 265 Type 405s produced, being retro fitted with Dunlop disc brakes to the front axle between Feb 1958 and April 1961 .

Most 405 were supplied between late1954 and Dec 1957 (except one car in Feb 1958). I have never seen a BCL document that any 405 or 405 Drophead were fitted with Dunlop Disc brakes when new. There is no mention of it in the Parts Book , Workshop Manual or Sales Brochures.

The 406 with disc brakes front and rear would have been developed in 1957 or possibly earlier. The first (the Prototype ) was completed by March 1958 and production cars were being delivered by mid 1958.

The conversion from front Drum brakes to Dunlop Disc brakes required new hubs , discs, calipers , caliper carrier , servo , vacuum tank , 7/8 inch rear wheel cylinder (to stop brake lockup) and most likely a shorter sway/roll bar with offset vertical links (this gives clearance between the caliper and vertical link on full lock ). So not just a simple remove and refit.

Please advise the chassis number of your 405 and I will see if it is in my records.

Geoff

[Stefan]

Yes, discs were fitted to some later 403 models and later ones, with a vacuum tank and brake booster inside the wing space.
There is a supplement to the Workshop manual about them.
And it’s simple to fit new pads.

[Geoff Dowdle]

Stefan,
The records I have show BCL fitted front disc (in the period 1958 - 1961) to

401 10 cars
403 21 cars
404 10 cars
405 89 cars
405 DH 12 cars
(no 400 or 402 recorded)

There could have been others that were not recorded.

Geoff

[mikebro]

Originally Posted by Stefan

Yes, discs were fitted to some later 403 models and later ones, with a vacuum tank and brake booster inside the wing space.
There is a supplement to the Workshop manual about them.
And it’s simple to fit new pads.

Stefan - I have a 1953 403 which was converted by BCL in 1958 with Dunlop disc brakes. I would be extremely interested in getting sight of the supplement you mention.

Thanks in anticipation.

Mike
403 1402