DNM burner rcp-2s spring

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j bjork   100 W

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DNM burner rcp-2s spring

Post by j bjork » Jun 14 2019 2:12pm

I have one of these on my bike, with the standard 550lbs spring.
The bike is about 60kg, and I am almost 90kg.
The bike is one of those dirtbike look alikes, and i mostly drive it on forest trails.
Here is the build thread: https://endless-sphere.com/forums/viewt ... =6&t=98723

I have to set hard preload to get it in the right ridehight, and it bottoms out easy. So I want a stiffer spring.
I think I have seen those with 750lbs springs, but I have´nt found those springs now.

Does anyone here know where I can find a suitible spring?

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MadRhino   100 GW

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Re: DNM burner rcp-2s spring

Post by MadRhino » Jun 14 2019 8:32pm

There is a number punched on the spring. Ex.: .550 2.75

The first number is spring weight (lbs required to compress one inch), the second is the travel.

Once you know the spring weight and travel that you need, you can buy the spring used or new, steel or titanium. I would first check for used ones on Pinkbike, or new at Chain Reaction Cycles.
Make it fool-proof, and I will make a better fool.
Current bikes
Street: https://s20.postimg.org/ewrvugywt/Session_04_2015.jpg
Dirt: https://s20.postimg.org/lbqwr55ml/IMG_0157.jpg

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brumbrum   100 kW

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Re: DNM burner rcp-2s spring

Post by brumbrum » Jun 15 2019 2:53am

MadRhino wrote:
Jun 14 2019 8:32pm
There is a number punched on the spring. Ex.: .550 2.75

The first number is spring weight (lbs required to compress one inch), the second is the travel.

Once you know the spring weight and travel that you need, you can buy the spring used or new, steel or titanium. I would first check for used ones on Pinkbike, or new at Chain Reaction Cycles.
You may be able to find a dnm 650 or even 750lb spring if lucky, otherwise, from memory i believe the dnm spring is an unusual internal diameter compared to the leading market springs so it might be difficult getting a 3rd party replacement. Try and measure and see what you can find
My NYX and cromotor build
viewtopic.php?f=6&t=74615
My LMX 161 dirt bike build
viewtopic.php?f=6&t=94074

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Overclocker   10 kW

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Re: DNM burner rcp-2s spring

Post by Overclocker » Jun 15 2019 7:25am

was on the same boat. 550 was too soft

em3ev used to sell springs but not anymore

you could also contact DNM in taiwan to get spare springs

i ended up getting a slightly longer RCP-3 w/ 650lb spring

j bjork   100 W

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Re: DNM burner rcp-2s spring

Post by j bjork » Jun 15 2019 8:06am

Thanks guys, the spring does´nt have the travel marked on it from what I have seen.
But the travel on the shock should be 56mm or 2.2"

I did some mesurements on the spring and shock with everything still mounted on the bike.
It seems like the maximum lenght of the spring could be 135mm, but then it would probably be difficult to mount. So I think 5" or 127mm is about right. Maby slightly less.

The outer diameter is about 53mm, and the thickness of the spring is 8,5mm. So the inner diameter should be about 36mm or 1.42", I think 1.4" sounds about right.

I would like to find something in EU to avoid import charges, but it is not critical.
I have looked at some sites, and the most springs did´nt have mesurements. Only what shocks they were intended for. And they were for the most part not stiffer then what I already have.

I haven´t found much of anything on DNM:s webb page, but I haven´t wrote to them asked so far.

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brumbrum   100 kW

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Re: DNM burner rcp-2s spring

Post by brumbrum » Jun 15 2019 8:42am

Taken from Ti-Springs website "36.5mm ID Fitment - For Use With DVO Suspension, Cane Creek, BOS Suspension, Ohlins, Marzocchi, Manitou Shocks & X-Fusion Shocks" So springs made by those companies should fit

35mm and 38mm are also other standard sizes
My NYX and cromotor build
viewtopic.php?f=6&t=74615
My LMX 161 dirt bike build
viewtopic.php?f=6&t=94074

j bjork   100 W

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Joined: Aug 31 2018 3:01pm
Location: Linköping, Sweden

Re: DNM burner rcp-2s spring

Post by j bjork » Jun 16 2019 6:37am

Thanks, I took off the spring to check.
It is 130mm long, and 36mm id. The plates it stands on (I dont know the name in English) are 35mm where they fit in the sping. But i guess 36.5mm is closest, 35mm would be very tight.

Image

I also measured the stroke on the wheel and spring. Those 56mm might be possible without the rubber stopper, it is 44mm before it hits the rubber.
With a slight compression of the rubber, about 45mm stroke on the shock I get about 160mm travel on the rear wheel.

Image

This is how I mesured travel.

I tried the calculator on ti springs site, they just want travel and rider weight. Nothing about bike weight.
I figured my bike is a lot heavier then a downhill bike, and added some weight.
With 280lbs I get a spring of about 1350lbs :shock:

Already with 200lbs I get a spring of about 1000lbs, and I think that is about what I weight..

I don´t know if something is seriously wrong with my measurements, or if all bike stuff is made for 40-50kg people :?

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