G80 Steering feels vague

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Re: G80 Steering feels vague

Postby Rob Harknett » Fri Mar 08, 2019 4:45 pm

Indeed new tyres of the same names as the old are not the same as the old. 22 psi will look soft and feel soft I use about 25/28 as the tyres vary, They also tend to be smaller than old so often use 3.50 instead of 3.35 IN p[articular the rear.
Sorry if there was a misunderstanding about things to check ,if afore mentioned, read as if was confirming / agreeing.

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Re: G80 Steering feels vague

Postby ajscomboman » Fri Mar 08, 2019 5:51 pm

I hate to keep repeating myself guys but as I've mentioned before, the Avon's may appear to be the same as those from years gone by but the make up is dramatically different. The recommended PSI is now 28 front and back with up to 30-32 at the rear with a load on. The need for the higher pressures is the side walls and rubber compound is much softer and grippier than those from the Golden Age.

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Re: G80 Steering feels vague

Postby SPRIDDLER » Fri Mar 08, 2019 5:58 pm

G80RIGID wrote: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 !

Ah yes, it's a rigid :oops:
Best way to check if the headstock bearings are loose/worn is to have the front wheel off the ground and put your finger at the point where the lower yoke meets the bottom of the headstock. Any play or bearing looseness will be easily felt as you (or a helper) push/pull back and forth on the fork legs.
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Re: G80 Steering feels vague

Postby Rob Harknett » Fri Mar 08, 2019 8:02 pm

ajscomboman wrote:I hate to keep repeating myself guys but as I've mentioned before, the Avon's may appear to be the same as those from years gone by but the make up is dramatically different. The recommended PSI is now 28 front and back with up to 30-32 at the rear with a load on. The need for the higher pressures is the side walls and rubber compound is much softer and grippier than those from the Golden Age.

I'd better up what I use then Rob as I am usually always two up on my bikes. I don't usually go above 30 PSI but some tyres have pretty thin walls. Tyres do seem to vary a lot now. So the guide line can vary by a few pounds of what will suit the bike and its use.

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Re: G80 Steering feels vague

Postby Rob Harknett » Fri Mar 08, 2019 8:09 pm

If you start with bearings a bit loose, you will actually see movement at the head. Feel movement rocking forks or wheel. Tighten right up. If you fell movement then, its the forks or wheel. That way you can discover better what movement is head bearings.

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Re: G80 Steering feels vague

Postby Group Leader » Fri Mar 08, 2019 8:47 pm

ajscomboman wrote:I hate to keep repeating myself guys but as I've mentioned before, the Avon's may appear to be the same as those from years gone by but the make up is dramatically different. The recommended PSI is now 28 front and back with up to 30-32 at the rear with a load on. The need for the higher pressures is the side walls and rubber compound is much softer and grippier than those from the Golden Age.

Excellent advice, they are the sort of pressures I run on my 16 with Avons. The first time the pressure in the front tyre dropped to 20 ish (and I hadn't checked it :oops: ) the bike was extremely nervous. So much so, after 3/4 mile I turned around and went home because it was too scary and to try and find out what the heck was going on. Turned out the fix was easy and a very valuable lesson (re-)learnt! :oops: :oops:

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Last edited by Group Leader on Sat Mar 09, 2019 3:49 pm, edited 1 time in total.
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Re: G80 Steering feels vague

Postby clive » Fri Mar 08, 2019 9:59 pm

I would also run the rear tyre at a higher pressure than the front one. 26 with a rigid may be too high. I would try 24 front 26 rear and see if the handling improves. If it does then drop the pressure a lb at a time to improve the ride. Easy thing to try. However if there is clunking from the forks are you undoing the two clamping nuts for the stanchions in the lower yolk when doing the adjustment?
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Re: G80 Steering feels vague

Postby Pharisee » Fri Mar 08, 2019 10:48 pm

I run a modern Avon Speedmaster on the front at 28p.s.i and a modern Avon SM on the rear at 32p.s.i.
The bike is a swinging arm G3 dating from 1953. I can tell when its lost a few pounds as it starts squirming around when pushed into fast (a relative term) corners. At the pressures the OP says he's using it would be downright scary!!

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Re: G80 Steering feels vague

Postby 56G80S » Sat Mar 09, 2019 10:10 am

Rob H, like me you are a relative lightweight. There are many variables.

Group Leader, yes, I've made the mistake of not checking pressures after a little while of not riding and had the same experience. I Had a pump with me fortunately; always have a gauge.

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Re: G80 Steering feels vague

Postby ajscomboman » Sat Mar 09, 2019 4:24 pm

56G80S wrote:Rob H, like me you are a relative lightweight. There are many variables.

Group Leader, yes, I've made the mistake of not checking pressures after a little while of not riding and had the same experience. I Had a pump with me fortunately; always have a gauge.

Johnny B


Not that many variables otherwise the manufacturers would have to account for them. They state 28 front and back is normal pressure and for loaded add 2-4lbs at the rear. That's regardless of rider weight, but we won't get into that one, I'm well aware which end of the scale I fall into!! :rofl: :rofl:

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