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1914
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7/25/2009
Location
Emerson, NJ
US
Edited Date/Time
2/5/2018 2:44pm
I have been looking for a 5.4 or 5.5 kg titanium shock spring for my 2012 CRF450. Besides RCS and DSP, I dont see any other vendors of titanium shock springs and DSP has little info on their site, seeming to prefer to promote their steel springs. What gives....are they becoming less popular outside of the pro ranks? I dont see anyone stocking them and my impression is that you have to call Renton and get one custom wound.
What bike did you put the spring on? Showa or Kayaba shock?
The Shop
http://www.mxsouth.com/titanium-spring-for-showa-large-body-p36036/
Pit Row
Since a lot of top pros are still using them, I would guess that the issue is quality of the spring from the vendors that sell to the general public.
I had read of people complaining that the spring rate is inconsistent and inconsistent through the stroke as you compress it with the Renton and DSP springs. I heard that Renton was revising manufacturing because of this.
I had heard that some like the feel.. that the titanium has a deader feel on compression, and more lively on rebound, and that it provides better traction in braking and acceleration bumps. I also couldnt think of an easier or cheaper way to lose 1.5-2 pounds of weight all at once.
mike
I have raced Ti shock springs for many years and wouldn't even think of running a steel spring anymore.
I guess I'm one of those racers that likes the "feel" as you pointed out in your post. To reinforce that, a while
back I ran into a situation where I was forced to switch from Ti back to steel. It didn't go well.
My normal Ti spring (RCS) was fouled by the back of the engine case on my CR500. Initially, I switched to
a steel spring because it had a smaller OD. That solved the clearance problem, but I didn't like the way the
rear suspension felt and after lots of testing, determined it was the characteristics of the steels spring causing
the problem. Now I really wanted to get a Ti spring back on the bike. I contacted RCS and they suggested
a smaller OD spring and a different perch and spring sleeve. I installed all of that, radiused the case a couple
of mm and I had my fix.
Here's a picture of the smaller OD spring on my Showa shock and the radiused case:
For comparison, here's a picture of the normal diameter Showa spring on a Showa shock. This shock is for a CR250
where the case is smaller and clearance is not an issue:
I've also noticed a lot of chatter about Ti spring rates being inconsistent. In my experience, that's more about improper
labeling than actual improper rates. Any spring rate can be calculated by knowing the modulus of elasticity of the material
(spring Titanium = 36,000 psi), coil diameter, spring length and number of coils. Any reputable spring manufacturer will be
more than happy to provide you with those numbers. Armed with that info, you can calculate (or verify), the rate and order
the correct spring for your application. Be advised, Ti springs are "livelier" than steel, so if you run a 5.4 kg/m for instance,
you'll want to specify a 5.3 kg/m Ti spring. Also, be prepared to do some testing to set your shock comp. and rebound up
for the new spring. In addition to the weight savings you already mentioned, due to fewer coils, Ti springs are less likely to
experience coil binding, and Titanium springs provide a more consistent and linear rate compared to steel - just the opposite
of what you have been reading. Another nice addition to your spring stack is a Torrington bearing mounted between the top of
the spring and the pre load retainer. When your spring compresses it actually binds a little due to rotational forces. This
bearing allows the spring to rotate and reduces friction between the spring and the retainer. These bearings are available
from Factory Connection, Pivot Works, etc.
Any time you ask for information on the internet, you're going to get a lot of "opinions". It's a good idea to research
something and get those opinions, but in the end, if you really want to try something new (within reason of course),
go for it. It's the only way to grow as a racer or a wrench.
My two cents.
dogger
I still have to wait for RCS to start manufacturing again, however.
What is that white plastic washer sitting atop your shock bumper?
mike
uses Factory Connection and his had one and he told me about it, so I decided to give it a try. It's a nice mod.
The shock on my 500 is a 2006 model and the plastic washer was used for some extra protection for the seal.
I noticed the washers disappeared after 2008, so there must have been some kind of redesign. The other shock
is a 2013 (PC made it special for me since I needed a long body for my 2009 CR250 project).
Did RCS give you a projected availability date?
dogger
Pic with steel spring:
I'll dig around a little and see if I can come up with something more definitive.
Mtek,
Take a caliper and measure the shock shaft. If the shock shaft is 16mm, then you could have anything from 2002 - 2005.
If it's 18mm (that's what it looks like), with the washer present, you could have a 2006 - 2007. The only catch is retrofitting.
As I'm sure you know, A kit parts can be rebuilt and upgraded as long as they are not worn out. For example, you could
have a 2004 shock and PC can retrofit an 18mm shock shaft and larger piston to bring that shock up to date. Normally,
when PC rebuilds a shock, they put a sticker on the back side with the date. See the numbers (just behind the PC logo),
on the picture below for what to look for:
I'm assuming you bought this used, what year did the seller tell you it was?
dogger
mike
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