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Shocks - weight of car vs spring rate


turbogrill
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Hi,

 

The shock selection to my platform is limited so I might have to pick something from a different car.

 

I have two options so far:

Bilstein B8 from VW Rabbit MK1 (1800lbs!)

Bilstein B6 from 300zx (~3200 lbs)

 

My car is about 2600 lbs.

 

The B8 for the Rabbit is a better shock but it's made for a much much lighter car. Does it matter? I would think that is only spring rate that matters.

The B8 has been used for some pretty stiff springs.

 

Thanks

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US VW mk1 golf (rabbit) weighs more than 1800 unless its gutted and doesnt have a cage.  Euro models were about 250lbs lighter and there are no us spec weights listed.  B8's with 500lbs springs are a common set-up.  You might want to look into Mk2 struts, they have a little more travel and were made for a slightly heavier car.

 

The weight of car does matter as its the weight of the car that will determine how much displacement happens when you hit a bump. you do not want to bottom out (assuming same spring rate) going to a stiffer spring reduces travel but too much spring rate can reduce the effectiveness of the strut.  

 

Shock or strut? front, rear, spring rate vs wheel rate? what car? what is your desired spring rate?  80 280z rear shocks? IMO go with vw mk2 b8,  it'll work.

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On 3/25/2017 at 1:32 PM, turbogrill said:

Hi,

 

The shock selection to my platform is limited so I might have to pick something from a different car.

 

I have two options so far:

Bilstein B8 from VW Rabbit MK1 (1800lbs!)

Bilstein B6 from 300zx (~3200 lbs)

 

My car is about 2600 lbs.

 

The B8 for the Rabbit is a better shock but it's made for a much much lighter car. Does it matter? I would think that is only spring rate that matters.

The B8 has been used for some pretty stiff springs.

 

Thanks

It will take a little research if you want to try and estimate its suitability without just trying it. If you have already done this, then ignore my dribbling...

 

Do you know the motion ratio of your shocks and the motion ratios of the ones in question? It's like the springs, rate is only 1 factor, and the motion ratio, stroke, etc all matter quite a bit. You can run a decent estimation scaling the weights you listed once you have the other info.

 

That being said, if you are talking a street version of a shock, I would go in with the assumption that the heavier car shock would be a better fit. It's not likely to overdamp the car.

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22 hours ago, JBgotM said:

 

That being said, if you are talking a street version of a shock, I would go in with the assumption that the heavier car shock would be a better fit. It's not likely to overdamp the car.

 

The heavier car insert is easier to install, so that is good :) (just need a spacer).

 

The B8 is made for lowering springs, from what I understand it has a shorter stroke than B6 but similar dampning force. 

How does that matter. What is the difference between a B6 only using 40% of it's stroke and a B8 using 90% of it's stroke?

 

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If a shock fits up correctly and has appropriate damping, I don't have an issue with a shock only using 40% of it's stroke. It won't cause an issue.  If you have confirmed that your full range of travel will not hit the end stops of the shock, then I don't have alot of of concern.

 

 

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On 3/27/2017 at 10:29 PM, turbogrill said:

 

The heavier car insert is easier to install, so that is good :) (just need a spacer).

 

The B8 is made for lowering springs, from what I understand it has a shorter stroke than B6 but similar dampning force. 

How does that matter. What is the difference between a B6 only using 40% of it's stroke and a B8 using 90% of it's stroke?

 

 

It's not that simple, here is a good link on the differences:  http://www.bilsteinus.com/news-events/news-detail/archive/2010/december/returnpage/1015/article/understanding-bilsteins-product-line/?tx_ttnews[pointer]=6&cHash=e8b993422bbc04033f85aa8f4166112a 

 

There's even a difference between B8 and B8 performance plus for some cars.

Edited by theblue
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