I was practicing on the above bike (which is fairly new to me) at the weekend.

When going down long hills with the clutch out and brakes on, the rear wheel 'judders' as in jumps up and down during the decent.  On closer inspection, when I compress the rear suspension and release it, there is no rebound damping.  It clonks as it hits the top stop.

This bike is in good mechanical condition with little or no free play in the swing arm or rear suspension.

I'm assuming I can adjust the rear shock to stop this.  What are the guidelines for adjusting the spring tension and dampening and rebound  settings on my bike?  I weigh 'just over' 100Kg (with my clothes on).

Any advice appreciated.

Edited October 22, 20187 yr by brucey

1 hour ago, brucey said:

I was practicing on the above bike (which is fairly new to me) at the weekend.

When going down long hills with the clutch out and brakes on, the rear wheel 'judders' as in jumps up and down during the decent.  On closer inspection, when I compress the rear suspension and release it, there is no rebound damping.  It clonks as it hits the top stop.

This bike is in good mechanical condition with little or no free play in the swing arm or rear suspension.

I'm assuming I can adjust the rear shock to stop this.  What are the guidelines for adjusting the spring tension and dampening and rebound  settings on my bike?  I weigh 'just over' 100Kg (with my clothes on).

Any advice appreciated.

Sounds like the oil has leaked out of the shock and there is zero damping effect ....even with the shock set to minimum damping you shoul have some resistance on rebound

Edited October 22, 20187 yr by oni nou

Wind in the rebound damping adjuster carefully, don’t wind it in too hard you may damage the seat. Bounce the rear and check if you still hear clonking or no rebound, if there is a rebound damping effect wind out until you just get clonkin. The previous owner might not have had any idea about set up....on the other hand they may have had a regime of backing everything off after easy trial. It’s probably as oni nou suggests that the hydraulic damping fluid has lost volume through leakage...evidenced by oil misting around the damper body. At 2014 the rear shock could probably do with either a rebuild or replacing for a newer type?

Your bike should have a SHOWA rear shock if it is standard and these are the settings

Spring length 133mm  ..........with preload 126.5mm

Nitrogen pressure 1.35 Mpa [13 kg/cm3]

Rebound adjuster  10      + or - 2 clicks from full resistance.

Thanks guys, that gives me something to work on.

3 minutes ago, brucey said:

Thanks guys, that gives me something to work on.

For your weight you should really use a heavier spring ....the standard spring is for riders that weigh approx. 80kg.

1 hour ago, oni nou said:

For your weight you should really use a heavier spring ....the standard spring is for riders that weigh approx. 80kg.

Are most trials riders 80kg?

Maybe I should bolt a sidecar to it ??

I removed the seat/mudguard last night and adjusted the knurled knob in both directions as far as it travelled.  Is made no difference to the shock 'topping out' in any position.

I then removed the shock and as Oni predicted, I found oil around the shaft and on top of the damper unit.  I have to say, I'm slightly disappointed on a quality 2014 machine, however, I don't know the history.  My Tiger Cubs are a lot easier to work on!

There are no labels or manufacturers markings on the unit so I will assume it is a SHOWA unit as suggested. 

I cleaned it and was going to remove the spring and test it but I couldn't work out how to get it off, I ran out of time and also decided there seemed little point as it probably needs replacing or rebuilding anyway.

So, can anyone recommend where I can get the unit serviced and indicate what sort of price I should expect.  Or should I buy a replacement. 

It should be noted that I am a very average (slightly over weight) 59 year old club rider and bunny hopping isn't in my repertoire.

Thanks for your help so far.

3 hours ago, brucey said:

I removed the seat/mudguard last night and adjusted the knurled knob in both directions as far as it travelled.  Is made no difference to the shock 'topping out' in any position.

I then removed the shock and as Oni predicted, I found oil around the shaft and on top of the damper unit.  I have to say, I'm slightly disappointed on a quality 2014 machine, however, I don't know the history.  My Tiger Cubs are a lot easier to work on!

There are no labels or manufacturers markings on the unit so I will assume it is a SHOWA unit as suggested. 

I cleaned it and was going to remove the spring and test it but I couldn't work out how to get it off, I ran out of time and also decided there seemed little point as it probably needs replacing or rebuilding anyway.

So, can anyone recommend where I can get the unit serviced and indicate what sort of price I should expect.  Or should I buy a replacement. 

It should be noted that I am a very average (slightly over weight) 59 year old club rider and bunny hopping isn't in my repertoire.

Thanks for your help so far.

I think SHOWA rear shock is difficult to get repaired in your country........www.splatshop.co.uk sell OHLINS replacement shocks just under £500  bolt straight on and www.roadandtrials sell a Jitsie TRP new rear shock for your bike at £425.00  or www.jbanyeres.com in Spain will repair it for approx. 325.00 euros + carriage there and back of course [not that cheap] ST Blazeys MX in Cornwall sell 4rts they may be able to point you in  right direction for a repair or buying a SHOWA shock.

Thanks again Oni ??

I pretty much came to the same conclusion after a web search. 

Tempted by the Jitsi unit but I contacted Splatshop and they will service my existing Showa unit for £120 as long as nothing too seriously wrong with it. This will be fine for my ability. 

I have also made enquiries about a stronger spring. 

4 hours ago, brucey said:

Thanks again Oni ??

I pretty much came to the same conclusion after a web search. 

Tempted by the Jitsi unit but I contacted Splatshop and they will service my existing Showa unit for £120 as long as nothing too seriously wrong with it. This will be fine for my ability. 

I have also made enquiries about a stronger spring. 

Happy days then ....good luck with the rebuild. The SHOWA unit is supposed to be the best shock of all available for the 4RT anyway

Edited October 23, 20187 yr by oni nou

23 hours ago, oni nou said:

I think SHOWA rear shock is difficult to get repaired in your country........

LAST TIME I LOOKED KENT WAS IN THE UK?

1 hour ago, nigel dabster said:

LAST TIME I LOOKED KENT WAS IN THE UK?

LAST TIME I LOOKED NOT EVERY PERSON WAS BRITISH ........not everyone on this forum is British. when a British Citizen visits the Trial-club.com site do they become French Citizens WTF.

That should help your investigation inspector Clouseau.

Edited October 24, 20187 yr by oni nou

18 hours ago, oni nou said:

LAST TIME I LOOKED NOT EVERY PERSON WAS BRITISH ........not everyone on this forum is British. when a British Citizen visits the Trial-club.com site do they become French Citizens WTF.

That should help your investigation inspector Clouseau.

the area the person is located in is on the lhs under their name?

Oh i forgot you are talking to the world. Again.

Someone asks for advice and you go off on wtf France?

Help the bloke or shut up?

Edited October 25, 20187 yr by nigel dabster

4 hours ago, nigel dabster said:

the area the person is located in is on the lhs under their name?

Oh i forgot you are talking to the world. Again.

Someone asks for advice and you go off on wtf France?

Help the bloke or shut up?

Guys,

I really do appreciate all your help and advice. 

Judging by the number of posts you have both made you share a passion for trials and you both take the time to help other people out with your valued opinions and advice.

For the sake of this brilliant website, please maintain the dignity it deserves.

 

Bruce.