Need help identifying fork springs.

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Off Road
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Joined: Thu Oct 01, 2009 1:31 am
Location: Alberta, Canada

Need help identifying fork springs.

#1 Post by Off Road » Tue Jan 13, 2015 2:15 am

I disassembled what I thought was a set of stock forks from an 83 RZ.
When I pulled the springs, they appear to be a set of progressive springs.
(The coils are tightly spaced at one end, and are widely spaced at the other end).

The springs are 506 mm long, which is the same as the spec for a stock RZ, (According to my 83 Yamaha manual (PN 33E28197-70).
The manual also only lists a single spring rate of for the front spring (3.33N/mm, 0.34 kg/mm, 19.0 lb/in)

According to Progessive's website, their RZ spring is 502 mm.
I pulled one of the Progressive springs out of my other bike, and it did measure 502 mm.

Image


Is that a stock spring for an RZ350?
Are the RZ springs progressive?
Anybody got a picture of stock springs?

hondaror
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Joined: Mon Mar 03, 2014 8:44 pm
Location: Alberta, Canada

Re: Need help identifying fork springs.

#2 Post by hondaror » Tue Jan 13, 2015 6:03 am

This isn't what you want to hear, but, I'd say they are from another bike. Some big guy stuffed them in there.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

solo 2
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Joined: Fri May 27, 2011 9:20 am
Location: Edmonton, Canada

Re: Need help identifying fork springs.

#3 Post by solo 2 » Tue Jan 13, 2015 10:26 am

They look exactly the same, measure the diameter of one of the coils and how many coils there are, this will tell you if they are different. Try a spring rate calculator, but you can only use it for coils that are the same distance apart.

http://www.thespringstore.com/spring-ca ... lator.html" onclick="window.open(this.href);return false;

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Off Road
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Re: Need help identifying fork springs.

#4 Post by Off Road » Wed Jan 21, 2015 2:54 am

Did a quick search and found the following:

"There are 3 primary variables that affect Spring Rate

1. Wire Diameter: When the diameter of the wire increases so does the Spring Rate. When the wire is thicker it becomes stronger and more difficult to deflect.

2. Spring Diameter: When the diameter of the spring increases the Spring Rate decreases.

3. The number of coils in the Spring: As the number of coils increase the spring rate decreases."


http://performancetrends.com/Definition ... g-Rate.htm" onclick="window.open(this.href);return false;


The previous owner of my supposedly stock 83 front end, kept ALL of his receipts. Hundreds of them.
Item 9, on invoice 202438, dated July 31, 1997, is for a pair of #1114 fork springs, at a cost of $87.69.

So it appears that I might have 2 sets of Progressive springs.
My 1st set. which are 502 mm long, and the 2nd set which are 507 mm long.
(I remeasured the springs today, using a more accurate tool).


The wire diameter of both sets, is the same. 4.37 mm.
Both sets of springs have 68 coils.

The 1st set of springs has an outer coil diameter of 27.05 mm.
The coil diameter of the 2nd set is slightly smaller at 26.65 mm.
This would make the 1st set of springs a bit softer than the 2nd..

I also noted that the center to center distance between the coils, is different on each set of springs.
On the tightly spaced end of the spring, the 1st set of springs has a tighter coil spacing than the 2nd set.
On the widely spaced end of the spring, the 1st set of springs has a wider coil spacing than the 2nd set.


So, my 1st set of springs (502 mm) were definitely made by Progressive Spring. It says so on the box.
The 2nd set of springs (507 mm) are also progressive, but because of their extra length,
I'm not 100% sure it they're made by Progressive, or some other manufacturer.

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