Author Topic: Testing rear suspension units  (Read 521 times)

Offline rowan.bradley

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Testing rear suspension units
« on: 20.11. 2017 11:18 »
My A10 swinging arm Super Rocket is not roadworthy at present (engine in the middle of a rebuild). What is the best way of testing the rear suspension units to see if they are good enough to retain, or whether they need repair (are they repairable?) or replacement, before stripping them from the frame for a frame repaint? What tends to go wrong with these? Presumably the springs can break, the shock absorbers can leak oil, or can be worn to the point that they do not do their job properly. So if I just visually inspect them, and bounce up and down on the bike, is that good enough? Once I've finished the bike needs to pass its MoT test, so I don't want to rebuild it and then have it fail the MoT and have to yet more work on it.

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Online ellis

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Re: Testing rear suspension units
« Reply #1 on: 20.11. 2017 11:35 »
Hi   
rowan.bradley. Take the springs off your dampers and see if there is any resistance when you pull the piston up. You wont feel any resistance when you close the damper as they are only a rebound damper. If no resistance is felt then they need to go in your recycling bin   *wink2*

ELLIS



 

Offline A10 JWO

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Re: Testing rear suspension units
« Reply #2 on: 20.11. 2017 17:46 »
You won't need an MOT after May 18th 2018.

Offline rowan.bradley

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Re: Testing rear suspension units
« Reply #3 on: 20.11. 2017 18:10 »
You won't need an MOT after May 18th 2018.
Thanks for pointing this out. I was not aware of this change. The chances of me having the bike back on the road by May 2018 are small, so it looks like no MoT is necessary. However, I still have to meet road-worthiness requirements, so I still need to make sure the rear suspension is working as it should.

Take the springs off your dampers and see if there is any resistance when you pull the piston up. You wont feel any resistance when you close the damper as they are only a rebound damper.

I was also not aware that this damper is only meant to work in one direction. I will test it as you suggest.

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Offline JulianS

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Re: Testing rear suspension units
« Reply #4 on: 20.11. 2017 18:49 »
You need to check the rubber bushes and the spring lengths.  Expect that the inner seals to be worn or age damaged.

Worth getting new units for safety of all road users.

Online BSA_54A10

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Re: Testing rear suspension units
« Reply #5 on: 21.11. 2017 08:58 »
And if you actually ride the bike get a set of modern 2 way dampers.
Much much easier on the rear end, the one that gets off the bike & walks inside after a ride.
Bike Beesa
Trevor

Offline rowan.bradley

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Re: Testing rear suspension units
« Reply #6 on: 21.11. 2017 10:55 »
So do people think that the old one-way rebound-only damper was a bad idea, and that a two-way damper is much better?

Any particular make/model of dampers that you would recommend?

Do I need to change the springs too?

What should the length of the springs be? there's no point in measuring them unless I know what they ought to measure...

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Offline JulianS

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Re: Testing rear suspension units
« Reply #7 on: 21.11. 2017 11:22 »
I use and would recommend Hagon units, more expensive than the far east made, but top quality. Complete with springs and shrouds.

Below from Girling catalogue from years ago give spring dimensions.

Offline jachenbach

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Re: Testing rear suspension units
« Reply #8 on: 21.11. 2017 14:12 »
IMO nothing will transform (improve) a ride, whether on 2 wheels or 4, more than a new set of shocks. Well, maybe replacing 20 year old tires......

Offline rowan.bradley

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Re: Testing rear suspension units
« Reply #9 on: 21.11. 2017 15:50 »
It seems that I can buy a pair of brand new "Girling" shock absorber units for about £50, whereas I have to pay £178 for Hagon units. Why would it be worth paying over three times as much for the Hagons?

Thanks - Rowan


Current bike: 1958 A10 Super Rocket (in bits), purchased in 1967.
Previous bikes: M21

Offline chaterlea25

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Re: Testing rear suspension units
« Reply #10 on: 21.11. 2017 23:52 »
Hi  Rowan,
If you are referring to something like this
https://www.ebay.co.uk/itm/TEC-Classic-Girling-12-9-inch-Rear-Shocks-BSA-A10-A7-A50-A65-RGS-Rocket-14aal/282261526137?hash=item41b8191679:g:PA4AAOSwZVlXm00j

Reading the smaller print it says "Girling style"   *eek*

All that glitters is usually made in the far east  *????* *????* *????*

There used to be a place that re oiled / gassed Girling Dampers advertised in Old Bike mart ??
I have not heard of it being done in recent times

Hagons are ok value although I have had to renew a few sets of them as they lost damping
Hagon supplied new damper nits so I could use my existing springs and shrouds

John
1961 Super Rocket
1963 RGS (ongoing)

Online mikeb

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Re: Testing rear suspension units
« Reply #11 on: 22.11. 2017 00:48 »
Quote
I use and would recommend Hagon units
+1 to that.  i got the Hagon 33007SS - '330' prefix means 330 mm between centres, and exposed springs as i think that matches the SR. they tamed the back end of my super rocket, tho did hold it lower to the ground than the worn out previous shocks hence more scrapes on corners.

they definitely cost more than cheapies, coz you get more. amazing how expensive old bikes can become
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online BSA_54A10

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Re: Testing rear suspension units
« Reply #12 on: 22.11. 2017 03:18 »
It seems that I can buy a pair of brand new "Girling" shock absorber units for about £50, whereas I have to pay £178 for Hagon units. Why would it be worth paying over three times as much for the Hagons?

Thanks - Rowan

If you have to ask that question, you obviously never ride your bike.
£ 178 / 60 years = £ 2.97 per year, about the price of a coffee once a year or about 1/2 a beer.

FWIW  the last onse I bought were Koni's ( Ikons to be precise ) and they were $ 260 around 15 years ago and worth every cent.
Now if you only ride on dead smooth motorways, never ride over any sort of bump then fir the cheap Chinese look alikes.
Some clever Dick took a set of 40 year old Girlings to a factory and said "You make me 1000 just like this" and that is exactly what they got.
Shocks that look identical to 40 year old Girlings and work exactly the same as worn out 40 year old Girlings.
Bike Beesa
Trevor

Online mikeb

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Re: Testing rear suspension units
« Reply #13 on: 22.11. 2017 04:57 »
is that a bit harsh Trevor? I think Rowan's newly restoring it so not yet riding it. probably just watching the $$ leaving his wallet with understandable disbelief. all questions are valid
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

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Re: Testing rear suspension units
« Reply #14 on: 22.11. 2017 05:41 »
is that a bit harsh Trevor? I think Rowan's newly restoring it so not yet riding it. probably just watching the $$ leaving his wallet with understandable disbelief. all questions are valid

A bit blunt perhaps but the math still remains the same .
The cost per year of service is what is important unless you are trying to do the impossible, refurbish & sell old bikes at a profit.
Shocks, tyres, chains, sprockets, spark plugs , oil all service items that need replacing periodically.
And penny pinching on them is the sort of thing that is likely to get you seriously injured.
I sent out a mandate to all our machine examiners that a crack in a sidewall deep enough to see the chords is an instant fail.
And you should have heard all the screaming.
If a side wall has cracked that deep then you are not riding enough and the tyre will be too hard to ride on safely.
Shocks that are worn allow the swing arm to twist and again make the bike unpredictable at best and downright dangerous at worst.

This applies 3 fold if you are doing up an old bike.
Why jepordise the $ 1000 tank job or $ 600 wheel job let alone yourself for the sake of £ 80 extra on the shocks.
On top of that , none of us are getting any younger so we also risk spine damage, bowel damage from one way damping.

Been a long while since I owned a new bike but the car makers still recommend new shocks with every 2nd set of tyres and if bike riders changed them when they started to go bad as distinct from waiting for them to fail completely then the new Hagons would only be £ 100 and probably real Girlings would still be manufactured.
From memory ( always dangeruos ) I used to change shocks when I did sprockets which was on the 3rd chain because I ran 3 chains concurrently ( 5 on the SR but that was a work bike ) .
OTOH have been riding rigids for quite some time now so shocks are somewhat of a moot point.
Bike Beesa
Trevor