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cornishflyer

Sherpa fork springs

11 posts in this topic

Hi all,

I have purchased some new fork springs for my #158 Sherpa T 250 which are just over 500mm long and are so stiff when I install them that I can hardly compress the front end.

My bike only came with one spring so I can't compare compression but the one old spring I have is about 450mm (50mm shorter) and comes up to the top of the tube when I remove the top cap. These new ones stick right out and it's a real struggle to the get the top caps on. The reseller tells me these springs are correct for this bike and something else must be wrong with the fork.

So, I took the fork apart and it all look ok, perhaps I have incorrect length damper rods. The top tubes are 550mm and the damping rod assembly is 100mm

My old Sherpa had very plush forks, and I tried another over the weekend that was also plush. This thing is rock hard with these springs in. 

Any help appreciated, especially the length of the springs I need.

 

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Thanks

Edited by cornishflyer

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The M158, 182, 190  250's have shorter sets of forks than other sherpas and I would assume they need different shorter springs. I am not sure of the actual measurement but your supplier should have known that. My guess would be the springs protrude about 20-25mm out of the top triple clamp before assembly, which is a lot less then yours. Inmotion list Sherpa forks at 500mm so I reckon you have springs for the standard forks and the 450mm one in the bike was the correct length original.

Cheers Greg

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I think the 158 182 190 tubes are only about 10mm shorter but the rods are also 10mm shorter as well so they use the same length springs as the 350’s of that era or maybe even all Sherpas 

Id probably just cut those 500+ Pursang  springs down to a suitable length 

All the sherpa springs I’ve measured are between 450 to 475mm long

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It makes sense that they would do that                                                                                                                                 

  I had a quick look in my shed and found two leftover springs

one is 475mm long  59 coils and 3.9mm dia steel

the second is 463mm long 50 coils and 3.4 dia     -so a fair bit softer 

I can remember trying some Alpina springs back in the day so the longer one could be Alpina but I am not sure

Edited by sherpa325
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I always used Persang springs in my Sherpas with no problems. However they were all later i.e. 198 and onwards models. 

Then again i'm 17.5 stone and one thing you havent mentioned, well i dont think you have, is your weight ?

 

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I'm 82kg, what's that? Around 12 stone? The engine is out but I've factored that in (I reckon that's another 25kg tops) still it's WAY too stiff. I can barely compress it by jumping all my weight on the bars.

I think I'll just shorten the springs to around 475 and adjust from there, like the idea of the grinder, I hadn't thought of that.

The seller has assured me he's sold thousands of 500mm springs with no issues so I don't know what the difference is in my bike. Perhaps Aussie bikes where shorter, less gravity down here, I dunno.

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Oh and the selling that was in the bike was 150mm long, 59 coils, 3.7mm wire thickness. Different again. 🤨

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Not trying to teach my grandmother to suck eggs but have you tried compressing the legs out of the yokes and with the mudguard and wheel removed ? Just in case something is binding.

 

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Hi OTF,

yes I have, they run lovely and smooth with just the old spring in there, no binding at all. I've got some video I'll try to post so you can see what I mean.

No probs about the eggs by the way, I'm all about the most obvious that I've probably missed.

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We don't know why your bike only had one spring, but what you need is another 450mm spring to make a matched pair.   Show your supplier the original spring, and ask him for another identical one, in exchange for the wrong one he gave you.

.

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5 hours ago, scifi said:

We don't know why your bike only had one spring, but what you need is another 450mm spring to make a matched pair.   Show your supplier the original spring, and ask him for another identical one, in exchange for the wrong one he gave you.

.

Yeah I tried that but he insists that 500mm springs are what I need in this bike, even though it was solid as a rock :(

All good now though, I shortened the new springs to 475mm and it feels a lot better. I will wait till I get the engine in and then set the sag properly, possibly by taking a little more off.

Thanks everyone for your help.

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