"Top Lock" nuts

XK-Engine
1

I was planning on buying nyloc nuts for my MK 1’s engine stabiliser and top lock was suggested as an alternative to nyloc. Has anyone used a “top lock” nut when a self locking nut is called for in the parts book? Did nyloc nuts exist in the 1950’s?

From the Web:

“These all metal locknuts withstand higher temperatures than nylon insert locknuts. Top thread section is deformed to create two or three locking zones; they start easily by hand, then must be wrenched into final position. Grade C equivalent to Grade 8”

“Toplock nuts are also similar to elliptical offset nuts, except that the
whole thread on one end is not distorted. Instead only three small
sections of the thread are deformed on one end.”

2

NYLOC is of course a trade-name, for a generic Nylon-Insert self-locking nut.

I am not sure about what trade-name/brand was used, but in these earliest years most probably NYLOC, but first use of these was in about 1955 on XK140 in a couple applications only, with other forms of all-metal lock nuts used elsewhere.

The part number tells you whether a Nylon-Insert self-locking nut, or whether one of the other three versions of all-metal self locking nut.

If C.8150/x series it’s an UNF threaded Nylon-Insert self-locking nut.

If C.3320/x series it’s an UNF threaded Phildas all-metal self-locking-nut.

If C.3968/x series it’s an UNF threaded Split-Beam all-metal self-locking-nut, often referred to as Aerotight, albeit this is the brand name as I believe was used by Jaguar, as was Nyloc a brand name.

If C.2593/x series it’s a BSF threaded Pinnacle Nut.

IN all cases the /x denotes a /1, /2, /3 etc suffix representing the increasing size thread diameter.

There are a few other period variations, but above covers 99%.

And indeed these days, there are all sorts of other ideas/designs/concepts of self-locking nuts, as it would seem is your ‘top-lock’ nut.

Just be a bit careful – some can be reused, others can’t, some damage the male-thread that the nut is locked onto, others don’t, and they have different purposes, thus Jaguar using four different types during the 1950s.

I would stay with a Nyloc nut if that was the original decision by Jaguars engineers.

Roger

3

Thanks Roger

Do you know what these lock nut part numbers indicate?

C.8667/x
C.8737/x

4

How hot does the engine stabilizer get? Nylocs are rated to something like 280F or more

https://www.afsrsimmonds.net/pdf/M3k6913_Flier_Nylstop_TypeT.pdfe

5

G’day Bruce,

Sorry, nothing definitive, although in my references although C.8667/x (and specifically C.8667/2 – 8667/7, /10, /17 and /20) is definitely listed as a LOCK NUT, the C.8737/x (/1 to /9) is only listed as a NUT, and not as a Lock-Nut.

With these C prefix numbers you need to see/confirm actual original examples, as the C.xxxx number allocated is purely sequential and gives no clues, whereas the standard fasteners use a decipherable coding system.

Where have you actually seen any C.8667/x or C.8737/x mentioned, as that may give a clue.

Note the previous C.xxxx Lock Nut numbers I listed are all thread specific, so C.8667 may simply be one of those types of Lock Nut, with simply a different thread – BSF, BSW, UNC or metric, albeit a 1950s part number would not be metric.

Roger

6

Roger,

I found these lock nut part numbers C.8667/3 and C.8737/4 in the Two-Point-Four Litre Spare Parts Catalogue, page 6, for use in assembling the stabilizer. They are described as “nut, self-locking.”

They are also listed in the Jaguar Fastener Guide under Self-Locking Nuts. On page 3 of the 7 page document, 8667 is defined as a tall skirt self-locking nut and 8737 as a short skirt self-locking nut.

8667/3 is visible at the top of the stabilizer, I might have to look at photos of unrestored cars to learn more about this self-locking nut.

7

i would use a nyloc, as they do the job fine, are easy to use, and thats the spec

metal-loc items are an absolute mongrel to remove, and may possibly corrode or damage thread.

I would only use one if specified