Ride height discussion
Registered User
Joined: Mar 2011
Posts: 354
Likes: 0
Just a guess here but I think a stock length rear damper assembly running at 13.25" height with 800lb springs with a 30mm stop is probably over the edge depending on grip level. Anything less than this and it'll be really bad, I swapped over to 20mm stops and 700lb springs and this is where my dilemma really started.
Bottoming out isn't all that big of a deal if the bump stop is matched up to the ride height, spring rate, roll rate/grip level.
Anywhere around 12 3/8 with 650lb springs, 20mm bump stop, Eibach rear bar, 3000lb chassis and driver and RS3's is enough. Anything less or more and you'll need to adjust spring rate or roll rate or both.
Hope this info is clear and makes sense
Bottoming out isn't all that big of a deal if the bump stop is matched up to the ride height, spring rate, roll rate/grip level.
Anywhere around 12 3/8 with 650lb springs, 20mm bump stop, Eibach rear bar, 3000lb chassis and driver and RS3's is enough. Anything less or more and you'll need to adjust spring rate or roll rate or both.
Hope this info is clear and makes sense
Koni 8242/TC Kline, stock length or 12", 900f/800r, Gendron 1.25 hollow bar on 6/6 front, MX5 bar rear (around ~130lbs), and GC extended top mounts in rear that should add 1/2" of bump travel. They can also add 1", but not sure if that will clear the rear rebound adjuster to the fuel piece enough to be able to adjust it, or will loose too much droop travel?
Would like to run 12.25"f/12.50"r with this setup, do you think it's doable? I have 54mm GC "soft shock" MCU bumpstops. I have heard people say they have soft smooth engagement, and are meant to be left as is, but would they be too long that way? What heights do you think I could safely run, and what bump stop size would you recommend to cut them to?
Registered User
Joined: Sep 2008
Posts: 2,380
Likes: 0
From: Arizona
1.) Calculate how your block height on your springs
2.) Measure how much compression stroke your shock will have until it hits something. Completed by testing travel without springs or swaybars attached
3.) compare the two
if your springs turn to blocks before your shocks bottom out, you don't need a bump stop unless you want to cushion the blow on the last 1/4" of spring travel. If there is significant room before they bottom out, get longer springs for more travel so you operate within 80% of the total travel of the spring. I highly doubt you will full compress your 900 or 800s. I haven't on my Hyperco 5.5" 650s. I'm moving to 6" 700s rear I think and getting 7" 750s front.
IMO, I think 12.25" front is too low. Your tire will be into the bottom of your fender on bad bumps or durring high G cornering. Just not worth the risk for a 1/4" lower ride height.
2.) Measure how much compression stroke your shock will have until it hits something. Completed by testing travel without springs or swaybars attached
3.) compare the two
if your springs turn to blocks before your shocks bottom out, you don't need a bump stop unless you want to cushion the blow on the last 1/4" of spring travel. If there is significant room before they bottom out, get longer springs for more travel so you operate within 80% of the total travel of the spring. I highly doubt you will full compress your 900 or 800s. I haven't on my Hyperco 5.5" 650s. I'm moving to 6" 700s rear I think and getting 7" 750s front.
IMO, I think 12.25" front is too low. Your tire will be into the bottom of your fender on bad bumps or durring high G cornering. Just not worth the risk for a 1/4" lower ride height.
Former Moderator
Joined: May 2006
Posts: 14,847
Likes: 10
From: Emmett
I can give you a guess from what I've learned but it'll be just that. I need more info though.
Do you have a pic of the top hat assembled on the damper by chance?
There's two different models and I haven't seen either in person but it looks like the distance away from the chassis to bump engagement is like a 1/2 - 3/4" right?
Do you have the rate of the front bar on 6/6?
Do you have a pic of the top hat assembled on the damper by chance?
There's two different models and I haven't seen either in person but it looks like the distance away from the chassis to bump engagement is like a 1/2 - 3/4" right?
Do you have the rate of the front bar on 6/6?
Former Moderator
Joined: May 2006
Posts: 14,847
Likes: 10
From: Emmett
I highly doubt you will full compress your 900 or 800s. I haven't on my Hyperco 5.5" 650s. I'm moving to 6" 700s rear I think and getting 7" 750s front.
IMO, I think 12.25" front is too low. Your tire will be into the bottom of your fender on bad bumps or durring high G cornering. Just not worth the risk for a 1/4" lower ride height.
IMO, I think 12.25" front is too low. Your tire will be into the bottom of your fender on bad bumps or durring high G cornering. Just not worth the risk for a 1/4" lower ride height.
He might be right about the last part but your concern is the rear which has plenty of wheel/tire clearance.
Registered User
Joined: Mar 2011
Posts: 354
Likes: 0
Even a guess from someone with experience would be great, as I am totally new to this and appreciate all the help!
Can't seem to find how to calculate the block height, any idea? They are 8"x2.5" springs, 900/800.
Since they're stock length shocks, does that mean the compression stroke should be similar to stock, minus ride height change and extended top mount chance? Not sure what that is, but I keep reading it's not a lot, rear is very travel limited at low heights, etc.
I could run 12.5"f/12.75"r to be safer, but would prefer the lower ride height if its achievable.
Rate on front bar at 6/6 is, 1016/904/1238, in 'Puhn'/rate at link/rate after motion ratio, per the STR sway bar thread.
They're not installed, I'm not sure how to measure the chassis to bump engagement.
They are the Honda race mount version, spherical bearing. Here are some pics:
https://plus.google.com/u/0/photos/1...CPqS5M3WrJbaeQ
The bump stops sit on top of the adapter for the bearing, which doesn't fit inside the bump stops. Not sure if they are all assembled correctly here. I think I need the dust boot, factory sleeve, metal washers, from the stock parts. Not sure if I need an upper spring perch and spring isolator as well for between the top of the spring and the top mount, and also the silver ring between the the bottom of the threaded sleeve and the cir-clip on the shock perch, in the close up shock pic.
Can't seem to find how to calculate the block height, any idea? They are 8"x2.5" springs, 900/800.
Since they're stock length shocks, does that mean the compression stroke should be similar to stock, minus ride height change and extended top mount chance? Not sure what that is, but I keep reading it's not a lot, rear is very travel limited at low heights, etc.
I could run 12.5"f/12.75"r to be safer, but would prefer the lower ride height if its achievable.
Rate on front bar at 6/6 is, 1016/904/1238, in 'Puhn'/rate at link/rate after motion ratio, per the STR sway bar thread.
They're not installed, I'm not sure how to measure the chassis to bump engagement.
They are the Honda race mount version, spherical bearing. Here are some pics:
https://plus.google.com/u/0/photos/1...CPqS5M3WrJbaeQ
The bump stops sit on top of the adapter for the bearing, which doesn't fit inside the bump stops. Not sure if they are all assembled correctly here. I think I need the dust boot, factory sleeve, metal washers, from the stock parts. Not sure if I need an upper spring perch and spring isolator as well for between the top of the spring and the top mount, and also the silver ring between the the bottom of the threaded sleeve and the cir-clip on the shock perch, in the close up shock pic.
Registered User
Joined: Sep 2008
Posts: 2,380
Likes: 0
From: Arizona
Even a guess from someone with experience would be great, as I am totally new to this and appreciate all the help!
Can't seem to find how to calculate the block height, any idea? They are 8"x2.5" springs, 900/800.
Since they're stock length shocks, does that mean the compression stroke should be similar to stock, minus ride height change and extended top mount chance? Not sure what that is, but I keep reading it's not a lot, rear is very travel limited at low heights, etc.
I could run 12.5"f/12.75"r to be safer, but would prefer the lower ride height if its achievable.
Rate on front bar at 6/6 is, 1016/904/1238, in 'Puhn'/rate at link/rate after motion ratio, per the STR sway bar thread.
They're not installed, I'm not sure how to measure the chassis to bump engagement.
Can't seem to find how to calculate the block height, any idea? They are 8"x2.5" springs, 900/800.
Since they're stock length shocks, does that mean the compression stroke should be similar to stock, minus ride height change and extended top mount chance? Not sure what that is, but I keep reading it's not a lot, rear is very travel limited at low heights, etc.
I could run 12.5"f/12.75"r to be safer, but would prefer the lower ride height if its achievable.
Rate on front bar at 6/6 is, 1016/904/1238, in 'Puhn'/rate at link/rate after motion ratio, per the STR sway bar thread.
They're not installed, I'm not sure how to measure the chassis to bump engagement.
not sure what brand you have but this will give you a good idea
http://performance-suspension.eibach...16_catalog.pdf
There's a calculation you can do though which is a little too taboo for me so I just use Eibach's chart which will get you most of the way there for Hyperco. Other Generic springs probably have less total travel available at the same OA length. Swift probably have 5% more travel than Eibach's.
Registered User
Joined: Mar 2011
Posts: 354
Likes: 0
I have Eibach ERS, thanks for the link, per the chart it says the block height is 2.71". So that means the springs would compress 5.3" before block height? At 12.5" ride height, I'd guess my bump travel is much shorter than that right? I believe I have seen people posting bump travel of 1-2", so I would still be bump travel limited in the rear first?