G80 Steering feels vague

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Posts: 4
Joined: Thu Mar 07, 2019 4:19 pm
Location: midlands

G80 Steering feels vague

Postby G80RIGID » Thu Mar 07, 2019 4:55 pm

Hello - I have a 1946 rigid/tele G80L which I absolutely love riding EXCEPT for it's 'nervous' steering. I recently removed the forks to investigate and found that it is fitted with the original 'floating' cups (radiused fit into headstock - top & bottom). The bearing tracks were a little marked, but not enough to feel. I was told that replacement cups were virtually impossible to obtain, and was advised to reassemble with new balls and fresh grease. This was done and particular attention paid to their correct adjustment (although the adjusting nut had to be tightened right up to eliminate any stem rock !!).(The handlebars move freely lock to lock) The bike still feels vague on the steering and is awful in cross-winds.
Has anyone any thoughts on this issue - my mind has been wandering off towards a taper roller conversion, but have been advised that this is not at all straightforward to achieve. I'm also loathed to carry out a complete strip to get the headstock modified !! Any thoughts greatly appreciated. Paul

Member
User avatar
Posts: 10041
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: G80 Steering feels vague

Postby Rob Harknett » Thu Mar 07, 2019 9:07 pm

Was the bike better before new balls were fitted? Were correct size and number of new balls fitted.

Member
Posts: 2088
Joined: Wed Oct 12, 2005 9:45 pm
Location: N YORKS UK

Re: G80 Steering feels vague

Postby 56G80S » Thu Mar 07, 2019 9:09 pm

IKBA but there could be various causes.

It was relatively recently I found that I had been running modern tyres under inflated by using the handbook settings which are fine for the old construction and materials but not now.

It's one easy to cure thing although there are lots of others. Leave them to other contributors

Johnny B

Member
Posts: 1008
Joined: Wed Oct 12, 2005 9:45 pm
Location: KENT UK

Re: G80 Steering feels vague

Postby alanengineer » Thu Mar 07, 2019 10:36 pm

101 different things that could be wrong. i definitely would not be looking to modify anything at this stage.I assume you have adjusted the head bearings up to where they should be. How much slack in the wheel bearings have you got, front and back for a start question. And for a second question, have you been to your local section to discuss it with them yet?

Member
Posts: 6133
Joined: Wed Sep 01, 2004 12:00 am
Location: WEST SUSSEX UK

Re: G80 Steering feels vague

Postby SPRIDDLER » Thu Mar 07, 2019 11:09 pm

Welcome Paul.
Have you got the Workshop and Owners manuals and Spares List?
If not, they can be found here (under 'Books'):

http://archives.jampot.dk/

The correct number of balls is one fewer than will fit into the races.
Not sure why you should have to tighten the adjuster nut hard down though. Presumably the balls are the correct size? They're not metric ones are they?
When correctly adjusted and with the wheel off the ground the 'bars should just fall rather slowly to left and right under their own weight.
As Alan said, the nervous steering could be due to many things but from personal experience it can be due to worn swing arm bushes.

Apologies if you already know the points mentioned but I assume we haven't had the pleasure of your company before. ;)

BTW - You have posted in the 'Buyers Guide' section where it won't get as many views/replies (as it's for potential/first time AMC owners to learn about the different bikes generally) than if you put it in the G80 technical help discussion forum here:

viewforum.php?f=18

Hope you decide to join the Club since it's members' subs that maintain the website and all club activities, thanks to the hardworking volunteer committee and many others.
I poke badgers with spoons.

Member
User avatar
Posts: 10041
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: G80 Steering feels vague

Postby Rob Harknett » Fri Mar 08, 2019 10:49 am

If the complete wheel is 100% perfect, that will not take up the steering play. Tyre pressure is last check on the list, as far as the wheels concerned. Bearings, wheel true, tyre fitted correctly. Odd things can also happen. I once trailered a bike over 300 miles. First few yards riding the bike was scary. Front tyre had moved, needed refitting.

Posts: 4
Joined: Thu Mar 07, 2019 4:19 pm
Location: midlands

Re: G80 Steering feels vague

Postby G80RIGID » Fri Mar 08, 2019 2:17 pm

Many Thanks for all your very speedy replies …. and for your kind welcome !! ( It is my first post on this Forum, but I have been a keen biker for 50 yrs and I have to say that the Matchless has been one of my real favourites !).

In response to the points raised :-

No. / ball bearing size - Yes, correct 3/16" dia balls and one fewer than would actually fit in each race. ( counted old ones out and new ones in - same ).

Wheel bearings - had both wheels completely apart, they have the original taper roller bearings fitted - happy with correct adjustment ( very slight play at wheel rim ).

Tyre pressures - front is a ribbed Avon Speedmaster Mk 2, 3.25 x 19 running at 22psi, rear is an Avon S-M Mk2 3.50 x 19 which I run at 20 psi (softish due to rigid rear end). Both tyres are concentric with the rims, and the wheel alignment is good. I haven't, as yet, experimented with changing tyre pressures.

I take the point about worn swing-arm bearings because I have experienced that for myself on other bikes - doesn't apply here of course, but I do remember once having to tighten the central bolt holding front / rear frame sections together !

When riding the bike over a cobbled surface I am aware that there is a very slight 'clunking' from the steering stem ; the bearings are correctly adjusted , but I've had a thought !! - I am wondering whether the radiused cups are, themselves, moving within the corresponding shape in the steering head ?? This 'clunking' can also be felt under heavy braking on the front. I note that the later bearing cups had flat registers - could this have been a design improvement to overcome what I'm experiencing ?

In anticipation :P

PS Excellent manual /spares list reference !

Member
Posts: 1485
Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: G80 Steering feels vague

Postby Mick D » Fri Mar 08, 2019 2:27 pm

Hi

Are you sure the clunking you hear isn't the forks topping / wear in the bushes? Have you confirmed the oil level to be correct?

There are issues with replacement bearing cups being undersized - are your cups replacements or original? (I know you say they are original but are you sure?).

What happens when you put the bike on the centre stand and heave the forks backwards and forwards?

Regards Mick

Member
Posts: 2088
Joined: Wed Oct 12, 2005 9:45 pm
Location: N YORKS UK

Re: G80 Steering feels vague

Postby 56G80S » Fri Mar 08, 2019 4:00 pm

"Tyre pressure is last check on the list, as far as the wheels concerned."

Never said there weren't other things, in fact said there were. However, if using modern tyres a very simple check / change. Paul's not using modern tyres, so pressures instantly discounted.

As others have said, all the rest is in the manuals and handbooks. Changing pressures from handbook figures in order to suit modern tyres isn't in the historic documents.

Johnny B

Member
User avatar
Posts: 1928
Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: G80 Steering feels vague

Postby dave16mct » Fri Mar 08, 2019 4:07 pm

Not modern tyres Johnny, but Speedmasters now have modern compound. I'd increase the front to say 26lbs and see if it makes a difference.
Dave.

Next

Return to G80 / Model 18

Who is online

Users browsing this forum: Google [Bot] and 13 guests