# Changing the spring in a Fork?



## DanZo337 (Jun 4, 2012)

The bike I just got came with a set of RST GILA TnL front shocks. I was already under the impression that they wouldn't be the greatest but after going for a 2 hour ride yesterday on a somewhat bumpy trail, I noticed my forearms getting fatigued.

The preloaders seem to be gimmicky so, I was thinking perhaps I could swap the spring out for a softer one hoping to make use of the preloader for more efficient travel. Buying a new fork is out of the question at this point.

Is changing the spring really as simple as these videos make it out to be?











Other than a torque wrench, it doesn't seem all that technical to do. The spring doesn't even look like it's under that much compression in the stanchion.


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## AndrwSwitch (Nov 8, 2007)

There's a lot of variety.

A common way for a nicer fork to be set up is to have a spring in one leg and a damper in the other. Mine actually has air springs in both legs and a damper on one side, but it's older...

I took apart the RST fork that came stock on my bike and only found one spring in it. I was never able to get it working well, so I threw it out and got something on EBay. The problems you're going to run into are that you need the right size spring, and your fork has crazy amounts of stiction. Unless it's better than mine was, anyway.

Why not move your old fork onto the new bike? Unless you want to keep both of them rolling and as 'A' bikes. You could also do a rigid, for a low-cost solution.


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## Hundun (Jun 2, 2010)

Yes it's as easy as that. I swapped the spring in my Tora by watching that bottom video. The owners manual makes a big complicated deal out of it to discourage DIY. Mine was slightly different than the video but used a crescent wrench to open it up. The most time consuming part was cleaning up the grease since I was liberal in hand smearing grease on the new spring before installing it. Basically can be done in five minutes or less.


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## DanZo337 (Jun 4, 2012)

Thanks for the responses.

I just found the manual and it looks like there is a cartridge (damper?) on one side, and a spring on the other.

I guess this shock isn't a considered a common modder so I'm not coming across any springs, LBS guy looked at me like I was nuts when I said I wanted to change it.

Here's a tech working on the "cartridge."


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## pfox90 (Aug 8, 2010)

DanZo337 said:


> I guess this shock isn't a considered a common modder so I'm not coming across any springs, LBS guy looked at me like I was nuts when I said I wanted to change it.


While it isn't common to want to take apart a lower end fork for a new spring and dive into somewhat complicated DIY fork maintenance, the dude at the shop shouldn't really have that reaction and should try to help you out and get the spring you need?


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## DanZo337 (Jun 4, 2012)

That's what you would figure; odd fellow probably won't be seeing my face again.

I noticed on the RST site, you can order parts, and it would appear that they have 3 coil springs for the GILAPRO TnL, they list them as:

1-4A
M5DSPB91260-110
Coil Spring-K=1.10

1-4B
M5DSPB91260-132
Coil Spring-K=1.32

1-5C
M5DSPB91260-092
Coil Spring-K=0.92

They don't include a bodyweight for the spring though unfortunately -_-; Anybody know what these decimals might mean? Currently waiting to see what RST might say.


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## pfox90 (Aug 8, 2010)

I would assume they come with medium coils, and the ones we sell (suntour) seem pretty squishy and I'm about the same weight. So maybe they come with a heavy spring in that model?


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## DanZo337 (Jun 4, 2012)

That's what it seems like, not sure what kind of mass they were assuming would be on a 15" frame.

With the preloader all the way down, I can barely get it to fully compress... That's pounding on it, pushing with all my weight.

@AndrwSwitch: I already sold the bike.


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## dhelm72 (May 4, 2012)

before buying a new spring, you can remove the spring and cut a few coils out of the spring. Shorten the spring by an inch or so and you will dramatically decrease your preload...if that doesn't help, then buy a new spring. It doesn't hurt to try since you're already going contemplating a new spring purchase. You can trim a very small amount and try it (one coil) then trim more if you like or leave it.
I did this on my old Harley and it worked well.


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## DanZo337 (Jun 4, 2012)

I've thought about that but I'm worried about comprimising the spring.

1. It wasn't engineered to have coils cut, and usually when you cut springs, it makes it even more bouncy. Atleast on a car I've experienced that.

2. I don't want to have the bike all lopsided, I'm sure the spring has a length it needs to uphold to keep the stanchions level with one another.

Just seems like a ghetto way to get more sag IMO.


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## dhelm72 (May 4, 2012)

DanZo337 said:


> I've thought about that but I'm worried about comprimising the spring.
> 
> 1. It wasn't engineered to have coils cut, and usually when you cut springs, it makes it even more bouncy. Atleast on a car I've experienced that.
> 
> ...


Getto? maybe, maybe not. Four things affect spring rate:
The material itself (type of metal), the diameter of the wire, the diameter into which the coils are wound (diameter of the fork tube) and the number of coils in the spring. There is one thing you can change with the current spring..... the number of coils.

Since you are about to buy a new spring and get rid of this one, I didn't think it would hurt to cut a coil or two and try it first.... Cutting one coill will change your spring rate very much like getting a slightly thinner material spring with the same number of coils (or a softer spring that you are seeking). The softer spring you purchase may end up having the same material with the same thickness but a few less coils....you never know how they achieve final spring rate.


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## dhelm72 (May 4, 2012)

My brother is a mechanical engineer with a PhD. He is also an auto racing fan. He told me once that they frequently change their spring rates and handling with a "wedge" adjustment. Basically, they add or remove coil spring spacers to change the spring rate. Changing the number of active coils in the system completely changes the firmness or softness of the ride and the handling characteristics....It's not too ghetto if professional engineers do it on $500k race cars.


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## DanZo337 (Jun 4, 2012)

Common logic, less coils will naturally make the spring more "ridgid" because now there is less volume for the weight to transfer during compression.

If your logic was right, then lowering springs for vehicles would not exist because people would just be cutting stock springs. There is a reason why it's illegal to cut springs on vehicles.

Adding coils would work but that ultimately means redesigning the entire spring...

I believe the decimals in the coil specs listed above would be the gauge (diameter) of the coil, lesser gauge probably means that it's the softer spring.


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## DanZo337 (Jun 4, 2012)

Well, after much debate, I will probably be swapping the fork.

The RockShox Tora 302's are about only $200 new and seems like a well worthwhile upgrade for what I'll be doing. Having rebound control on both my rear and front shock will probably compliment eachother nicely.

Will pawn these Gila junks off I guess, keep them new for the next person. Or maybe I'll stick them on my GF's dept. store bike 

Thanks for the help everyone.


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## AndrwSwitch (Nov 8, 2007)

DanZo337 said:


> Or maybe I'll stick them on my GF's dept. store bike


Do you love her?


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## Apache249 (Jul 30, 2009)

AndrwSwitch said:


> Do you love her?


If you love her, chuck the RSTs.


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## dhelm72 (May 4, 2012)

DanZo337 said:


> Common logic, less coils will naturally make the spring more "ridgid" because now there is less volume for the weight to transfer during compression.
> 
> If your logic was right, then lowering springs for vehicles would not exist because people would just be cutting stock springs. There is a reason why it's illegal to cut springs on vehicles.
> 
> ...


Okay...I stand corrected. Don't tell my brother. At least I understand more about the "wedge" adjustment he told me about.

Yeah, probably best to get a new fork. Maybe save that fork and put it back on if you sell the bike some day. I save all my old parts if I upgrade for spares or future bike builds.


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