brake lines thread size

[buzzer]

I have to replace my brake light switch and struggling to find what the thread size is to make sure I get the right replacement. It connects to a union block near the engine. Any idea what the thread  is.

Dave

[4129R]

It connects to a standard 3 way brass brake pipe union, so it is the same thread as the brake pipe male union.

I think that is 5/16" UNF.

[buzzer]

Yes its the same thread on that union and thanks.

Dave

[dakazman]

  Here is a list of other s2 fittings
http://www.lotus-europa.com/manuals/misc/brakes/S2_Order2.html

Dakazman

[jbcollier]

The thread is 3/8NF.

[dakazman]

The thread is 3/8NF.

   
   JB,
Are the S1 and TC’s the same thread size? I know there are differences in the system layout.

   Dakazman

[4129R]

I have just tested the 3 way brass union off a TCS and it is definitely 3/8" UNF, the same as all the brake pipe unions on a TCS.

[jbcollier]

Sorry D-man, can’t answer that question definitely.  The most common brake fittings are 3/8NF until the switch to metric.

[BDA]

I would be surprised if the S1 and TC brake fittings have different threads. Metric stuff didn’t creep into Brit cars till much later.

[jbcollier]

Never expect the expected when dealing with a Lotus!

;-)

[BDA]

 

[4129R]

I would be surprised if the S1 and TC brake fittings have different threads. Metric stuff didn’t creep into Brit cars till much later.

Except for the Renault gearbox.

My latest car is 4688R and that does not differ in bolt types.

[dakazman]

  That sums that up🥱😂
Dakazman

[buzzer]

Ik so 3/8 unf.  cheers guys

[buzzer]

Found the original part number lucas 34619B. also used on Norton Motorbikes. so managed to pick one up on Ebay