Difference between revisions of "Brake Switch Failures"

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If your Brake Switch is beginning to require increased foot pressure to operate the Brake Lights then it is probably near to failing.
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If your Brake Switch is beginning to require increased foot pressure to operate the Brake Lights then it is probably near to failing. The Brake Light Switch on traditional Morgans seems to be a component that  'regularly' fails.  
 
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Replacements are prone to failure as well so consider the following as an alternative and hopefully enjoy a long term fix..
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Assuming you don't have mechanical brakes, and you don't have a new model with the brake light switch mounted in the footwell, on the brake pedal assembly, then you should find a five way union somewhere under the bonnet, maybe on the offside inner wing panel (on a RH drive car). The union is a meeting of brake pipes, connecting to the master cylinder, the RH and LH front, and a pipe to the rear, the fifth connection is for the brake light switch.
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There are two types of brake light switches, the differance between them is the thread, my communication with one of the manufacturers/suppliers (Intermotor) suggests the part numbers are as follows
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The Intermotor 51600 (Lucas SPB400) with 1/8" x 27 NPTF thread fits Morgan 4/4 and Plus 8 1961-74
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The Intermotor 51610 (Lucas SPB401) with 3/8" UNF thread fitting Morgan 4/4 and Plus 8 1975->
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Be a bit careful about the dates as little seems straightforward with Morgans and dates, the changeover period may not have been a clean cutoff from one type to another..
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Intermotor advise that the 51600 also fits early Minis and the 51610 fits Hillman Hunter and Hillman Imp (if you are old enough to remember these)
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Note that the NPTF thread is tapered.
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The brake switch part numbers are just quoted as examples and there are other manufacturers which may, or may not, be better than Intermotor. I believe that Bosch make a switch under a similar part number to the Lucas (e.g. RB401). Using these references should enable a cross check with other manufacturers part numbers
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Fitting the switches needs to be carried out with care. When you remove the old switch you are likely to experience brake fluid leaking out of the fitting, you will need to place some rag to protect the paintwork. It will be best to have the replacement switch to hand so it can be installed very quickly before much fluid has been lost. You are likely to have introduced some air into the system and it will be wise to bleed the brakes.

Latest revision as of 11:38, 16 March 2019

If your Brake Switch is beginning to require increased foot pressure to operate the Brake Lights then it is probably near to failing. The Brake Light Switch on traditional Morgans seems to be a component that 'regularly' fails.

Assuming you don't have mechanical brakes, and you don't have a new model with the brake light switch mounted in the footwell, on the brake pedal assembly, then you should find a five way union somewhere under the bonnet, maybe on the offside inner wing panel (on a RH drive car). The union is a meeting of brake pipes, connecting to the master cylinder, the RH and LH front, and a pipe to the rear, the fifth connection is for the brake light switch.

There are two types of brake light switches, the differance between them is the thread, my communication with one of the manufacturers/suppliers (Intermotor) suggests the part numbers are as follows

The Intermotor 51600 (Lucas SPB400) with 1/8" x 27 NPTF thread fits Morgan 4/4 and Plus 8 1961-74

The Intermotor 51610 (Lucas SPB401) with 3/8" UNF thread fitting Morgan 4/4 and Plus 8 1975->

Be a bit careful about the dates as little seems straightforward with Morgans and dates, the changeover period may not have been a clean cutoff from one type to another..

Intermotor advise that the 51600 also fits early Minis and the 51610 fits Hillman Hunter and Hillman Imp (if you are old enough to remember these)

Note that the NPTF thread is tapered.

The brake switch part numbers are just quoted as examples and there are other manufacturers which may, or may not, be better than Intermotor. I believe that Bosch make a switch under a similar part number to the Lucas (e.g. RB401). Using these references should enable a cross check with other manufacturers part numbers

Fitting the switches needs to be carried out with care. When you remove the old switch you are likely to experience brake fluid leaking out of the fitting, you will need to place some rag to protect the paintwork. It will be best to have the replacement switch to hand so it can be installed very quickly before much fluid has been lost. You are likely to have introduced some air into the system and it will be wise to bleed the brakes.