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2006 Thumpstar 125 rear shock upgrade

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I just picked up a 2006 Thumpstar 125 and I want to upgrade the rear shock to accomodate my weight. I'm 6'1" and just about 300lbs. My bike has the A style or triangle style swing arm. There's some decent looking 1200lb rear shocks on ebay or there's the Fast Ace 550lb rear shock on Tbolt which says is for A style swing arms. My question is, would the 1200lb rear shock be the way to go for a guy like me even on the A style setup? Also would a 280mm shock work? And does the shock have to be A style specific or not?

Edited by 06thumpstarpro

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I am no expert, but in my research I have found that the A-arm style (triangular) generally uses a shock that is considerably less "lbs" than the single swing arm (mono shock) set up.

 

For an example: (average or typical)

Single Swing Arm set up might use: 1000 lbs rear shock

A-arm (Triangular) style: Might use a 250 lbs rear shock

 

Personally, I upgraded my wife's pit bike recently.  Hers uses the single swing arm set up.  I installed a much better rear shock and it was rated at 980lbs.

It was way too soft (like for a kid weighing maybe 75-85lbs) before with no real damping. Now it's way better...More firm, with actual shock damping and resistance...It's basically perfect now, and balanced with the firmness of the front fork...It was just way too soft in the rear before.

For your situation I am thinking 1200 lb spring would be way to stiff with your style of suspension.

 

 

 

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Edited by Explorer1987Nate
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1 hour ago, Explorer1987Nate said:

I am no expert, but in my research I have found that the A-arm style (triangular) generally uses a shock that is considerably less "lbs" than the single swing arm (mono shock) set up.

 

For an example: (average or typical)

Single Swing Arm set up might use: 1000 lbs rear shock

A-arm (Triangular) style: Might use a 250 lbs rear shock

 

Personally, I upgraded my wife's pit bike recently.  Hers uses the single swing arm set up.  I installed a much better rear shock and it was rated at 980lbs.

It was way too soft (like for a kid weighing maybe 75-85lbs) before with no real damping. Now it's way better...More firm, with actual shock damping and resistance...It's basically perfect now, and balanced with the firmness of the front fork...It was just way too soft in the rear before.

For your situation I am thinking 1200 lb spring would be way to stiff with your style of suspension.

 

 

 

20180322_013519_Burst01.jpg

20180323_170845.jpg

20180323_170927.jpg

20180324_183424.jpg

Yeah I was thinking the same thing too. There's a good one on tbolt USA that is a 550lb spring that I might go for but its 130 bucks I was hoping to spend like 75 or under lol

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So, what you might do, and what I was thinking of doing, is buy the length shock you need on Amazon or whatever.   

 

Then, there is a 500lb spring and 600lb spring available (made by fast-ace) on ebay...They are like $8-14 bucks each (just the spring) plus shipping.

https://www.ebay.com/itm/600-LBS-x-3-Stroke-Fast-Ace-Rear-Shock-Spring-172mm-Length-Part-BS-58AR/111415538426?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

 

You could buy a $40 shock with a heavier spring (900-1000lbs) and then swap the springs.  I was going to do that, but ended up not needing to when I found out that a 1000lb spring is perfect (for anyone 200lbs or less - on the mono-shock single swing are type suspension).

 

 

 

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No idea if this helps  TBoltUSA

Thumpstar - Rear Shock for TSX TSB 125 2016

Vital Information

Price$125.00

Part NoTMP-10468

Location142B

Stock Level8 Left

Add to Cart

Really nice replacement shock for a Thumpstar TSB or TSX 125.
Super sturdy , High quality unit
May fit other pitbikes Like SSR and Apollo
Please check specifications.

Specifications:

Spring rate - #1000

Eye to eye spacing - 11 inches or 279mm

Bolt hole size - 10mm

 

Since 2004, every purchase from TBolt USA includes access to technical support
from our staff of experts and our online Pit Bike Technical Info Database!
We have all necessary support parts on hand.
Most orders ship same, or next business day, unless otherwise noted above.

Edited by ctfz1

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You need a much lower spring rate for the A style swingarm, a 1,000lb+ spring won’t give any suspension action at all even with a 300lb rider. I made the mistake of putting an 1,000lb shock on my bike with the stock A swingarm and it was like having a solid bar of steel instead of a shock - it wouldn’t compress no matter what.

I’d recommend the fast ace, but I think the 550lb spring would be too stiff even for a 300lb rider. I run a fast ace with a 250lb spring and it’s good for me at 160lbs, never bottoms out and rides smooth - if anything it’s on the stiff side. If I had to guess, I think you would want a 350 or 400lb spring, unless you intend to jump / race. 

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11 hours ago, OKDinosaur said:

You need a much lower spring rate for the A style swingarm, a 1,000lb+ spring won’t give any suspension action at all even with a 300lb rider. I made the mistake of putting an 1,000lb shock on my bike with the stock A swingarm and it was like having a solid bar of steel instead of a shock - it wouldn’t compress no matter what.

I’d recommend the fast ace, but I think the 550lb spring would be too stiff even for a 300lb rider. I run a fast ace with a 250lb spring and it’s good for me at 160lbs, never bottoms out and rides smooth - if anything it’s on the stiff side. If I had to guess, I think you would want a 350 or 400lb spring, unless you intend to jump / race. 

lol I bought an 800lb spring and shock on ebay but if its too stiff i'll just swap the springs we'll see how it works out. Eventually I would like to hit a few jumps on it etc.

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11 hours ago, 06thumpstarpro said:

lol I bought an 800lb spring and shock on ebay but if its too stiff i'll just swap the springs we'll see how it works out. Eventually I would like to hit a few jumps on it etc.

800lb is what most of the Chinese pit bikes with MX style swingarms come with stock.

The 800lb shocks have very different valving to control such a stiff spring, if you do throw a 400lb spring on it the damping action will be way too much and the shock will just stack up on rough surfaces and ride like garbage. 

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