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Discussion Starter · #1 ·
Hi,
Does any one know the difference for Lockheed brake rotors with part numbers 37-7175 and 37-4275? Both are 4 hole mounting. I am guessing one could be 10"dia and the other 250mm dia.
As a linked question: When the 250mm dia disc was introduced, where any changes made to fork leg, caliper or caliper mounting location? Also, do the "metric" discs have different pads?

No pressing issue, just curious!

Regards,
Andy
 

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Hi Andy,

the difference for Lockheed brake rotors with part numbers 37-7175 and 37-4275?
one could be 10"dia and the other 250mm dia.
As well as difference in finishes, could be the difference in diameters? Afaict, 37-7175 first appears in the 1980 parts book and 1980 is about when AP 'went metric'.

My 79 had a chrome front and non chrome rear.
Just as matter of interest, you ever measured the two diameters?

When the 250mm dia disc was introduced, where any changes made to fork leg, caliper or caliper mounting location?
No.

do the "metric" discs have different pads?
Yes, the edge of the braking material is 2 mm. or so further away from the locating holes in the backing.

Hth.

Regards,
 

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never measured but I think I still have the discs (off the bike) that were on it in 84

I will measure them if I can find them
 

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Discussion Starter · #5 ·
Thanks Dave and Stuart.

Does anyone know the thread size of the small pozidrive head screws that hold the chrome caliper cover on?

TIA,

Andy
 

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I will look in a minute

But I found it in the back of the parts book.

The studs that hold the cover on are tapped but the rear ones are not.
I got a mate to tap them for me so that I could fit my modified cover

Edit.

It isn't in the book but I got it maybe from the stainless bits catalogue and whatever it was, it works

6-32 X 1/4 unc

Part number 21-2196
 

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I am pretty sure that I am correct but.....

I did this 4-5 years ago and my mate was an engineer.
I would tap a hole in something spare to check that the screw fits before going for it.

I can't remember the guy telling me that my description was wrong but I can't 100% guarantee that there wasn't some "buggeration" factor.
He was in a University engineering workshop with tons of kit and drilled/tapped it in a lathe.
Like an idiot I assumed that he'd do it on a pillar drill or freehand.
 

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Discussion Starter · #10 ·
Hi,
Just to confirm that Dave and Stuart are correct. I ordered 6-32 UNC x 1/4" CSK from Spalding Fasteners. They arrived today and fit perfectly.

Regards,
Andy
 
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