Knurled headset

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fausto99
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Joined: 19 Sep 2011, 10:06am

Knurled headset

Postby fausto99 » 12 Jun 2018, 9:43am

Anyone got any tips for dealing with a knurled headset race?

Image

I'm struggling with slip pliers, bits of old inner tube and an adjustable C spanner that is too thick. There are three threaded parts; which (2?) bits do I tighten against each other as locknuts? Should the topmost nut be just finger tight?

Also, the lower race in the top part (not visible) is floating inside the cup that fits in the headtube. What's the reasoning behind that?

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Knurled headset

Postby Brucey » 12 Jun 2018, 2:51pm

you can tighten this sort of headset with two tools

1) a C spanner for the middle nut and
2) a spanner to fit the top nut.

Tighten the knurled race by hand and then back it off ~1/4 turn. Snug the middle nut onto the lower race. Ideally there should be a tiny bit of free play; if not, adjust until there is.

Final tightening is to hold the middle nut with the C spanner and then to tighten the top nut down on it. Because the middle nut was snugged against the adjusting race and the threads have a little clearance in them, the load from the top nut passes through the middle nut and clamps the adjusting race correctly. Usually a tiny bit of free play disappears when you tighten the top nut fully.

The curved drop-in races were an idea that was commonplace in the 1930s (the races usually dropped into the frame itself) and persisted into the 1950s in some headset designs. The idea is (I think) that if the alignment is not perfect and/or the steerer flexes, it allows lower forces to be generated in the headset bearings. The angled seats of modern a-head headsets are a similar idea.

BTW apologies if this is B-obvious but it is a very bad idea to fully tighten a 1" threaded headset without a quill stem up the middle of the steerer; the threaded part of the steerer can deform.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

alexnharvey
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Joined: 10 Jan 2014, 8:39am

Re: Knurled headset

Postby alexnharvey » 12 Jun 2018, 4:00pm

I have used adjustable pliers and a spanner to do mine. Dribbling some oil into the joints and leaving overnight helped. Not sure about your lower race. I'd expect just to hold the knurled bit and tighten the top against it.

rjb
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Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Knurled headset

Postby rjb » 12 Jun 2018, 7:56pm

My Dawes Kingpin folding shoppers have those drop in races. Dated 1976. The races drop into the curved cups in the frame, both top and bottom. :wink:
At the last count:- Focus Variado, Peugeot 531 pro, Dawes Discovery Tandem, 2 Dawes Kingpins, Falcon K2 MTB dropped bar tourer, On One Pompino, Longstaff trike conversion on a Falcon corsa. :D

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fausto99
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Joined: 19 Sep 2011, 10:06am

Re: Knurled headset

Postby fausto99 » 12 Jun 2018, 10:25pm

Brucey wrote:you can tighten this sort of headset with two tools

1) a C spanner for the middle nut and
2) a spanner to fit the top nut.
Tighten the knurled race by hand and then back it off ~1/4 turn. Snug the middle nut onto the lower race. Ideally there should be a tiny bit of free play; if not, adjust until there is.


I''d better get a C spanner that fits the middle properly then. :oops:

Brucey wrote:Final tightening is to hold the middle nut with the C spanner and then to tighten the top nut down on it. Because the middle nut was snugged against the adjusting race and the threads have a little clearance in them, the load from the top nut passes through the middle nut and clamps the adjusting race correctly. Usually a tiny bit of free play disappears when you tighten the top nut fully.

Sounds like a bit of a learning process - like getting the feel of a wheel bearing.
Brucey wrote:The curved drop-in races were an idea that was commonplace in the 1930s (the races usually dropped into the frame itself) and persisted into the 1950s in some headset designs. The idea is (I think) that if the alignment is not perfect and/or the steerer flexes, it allows lower forces to be generated in the headset bearings. The angled seats of modern a-head headsets are a similar idea.

Persisted into the 60s too as this is a 65 Moulton Deluxe frame
Brucey wrote:BTW apologies if this is B-obvious but it is a very bad idea to fully tighten a 1" threaded headset without a quill stem up the middle of the steerer; the threaded part of the steerer can deform.

No apology necessary. I'd never heard that before. I've clearly been lucky as when I get a frame back from the painter. I always fit and adjust the BB and headset first (without stem) and had not had any problems to date. Sounds like the headset should be fitted but not adjusted 'til the stem is in.

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fausto99
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Re: Knurled headset

Postby fausto99 » 14 Jun 2018, 9:43pm

Brucey wrote:Tighten the knurled race by hand and then back it off ~1/4 turn. Snug the middle nut onto the lower race. Ideally there should be a tiny bit of free play; if not, adjust until there is.
Final tightening is to hold the middle nut with the C spanner and then to tighten the top nut down on it.


I think I have sourced a suitable C spanner. Should be here in few days. Meanwhile I have tried my best bodging without, but I can't get rid of the play without the steering binding. I assume that all bearing action should be via the balls and so I have not put any grease between the race and the cup. Is this correct? Is the race supposed to find its own optimum resting place? If so, how do I encourage it?
Also, does it matter where the non-threaded ring goes? Between the knurled nut and slotted nut or between the slotted nut and top nut?

Brucey
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Re: Knurled headset

Postby Brucey » 14 Jun 2018, 10:08pm

a smear of grease under the race inserts doesn't hurt. The parts may be worn hence the binding.

Not sure if it matters where the spacer goes except re getting the spanner on.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

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fausto99
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Re: Knurled headset

Postby fausto99 » 15 Jun 2018, 11:47am

Thanks for that. Will have another go when the spanner gets here.

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fausto99
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Re: Knurled headset

Postby fausto99 » 22 Jun 2018, 8:47am

Brucey wrote:a smear of grease under the race inserts doesn't hurt. The parts may be worn hence the binding

A smidgen of grease between the fixed cup and floating race helped a lot. Much smoother to adjust.

The 30-32mm C spanner arrived yesterday so I did the final adjustment. It was obviously much easier to make fine adjustments and I almost eliminated all play. If I went any further, it would start to bind, but I guess for a 50+ year old bike, it's pretty good. I'm always amazed at how well it rides. Much better than the later spaceframe models.Shame the rear end is so heavy.