Can't bottom out blue/gray rocket ?

[RacerX10]

got the shock up here on my desk, did some measuring

it's 20.250" C-C full extended, and has 7" of stroke available

rocket says 17.750" C-C @ ride height. that means we're using up 2.500" of our 7" to get down to ride height

7" stroke shock - 2.500" to get to ride height leaves 4.500" of stroke available for travel

4.500" of stroke available - 2.500" tall bump spring leaves you 2" of travel before you start getting in to the bump spring

looking at Rocket's 3" and 4" numbers, it absolutely *has to* get into the bump to get the figures they're saying I'm looking for

so I'm starting to think some significant portion of my problem is that #250 spring I put on there instead of the #200 they told me to, and the remainder is my targeting the ride height load instead of the 3" / 4" loads

[billetbirdcage]

got the shock up here on my desk, did some measuring

it's 20.250" C-C full extended, and has 7" of stroke available

rocket says 17.750" C-C @ ride height. that means we're using up 2.500" of our 7" to get down to ride height

7" stroke shock - 2.500" to get to ride height leaves 4.500" of stroke available for travel

4.500" of stroke available - 2.500" tall bump spring leaves you 2" of travel before you start getting in to the bump spring

looking at Rocket's 3" and 4" numbers, it absolutely *has to* get into the bump to get the figures they're saying I'm looking for

so I'm starting to think some significant portion of my problem is that #250 spring I put on there instead of the #200 they told me to, and the remainder is my targeting the ride height load instead of the 3" / 4" loads

BUMP SPRING
Free Length = 2.25"
ID = 1.34" / 34mm
Rate = 550 lbs/in
Travel = 1.19" <===== 2" to bump spring + 1.19 travel of bump = 3.19" total travel of RF and it's solid <--- That's my point

[billetbirdcage]

Put it in the smasher and run it down to about 14.75" and slowly run smasher down like .050 at a time until you see the poundage go up at an extreme rate. Because that's when its solid around 14.56"

Think your gonna find you around 1900# at 14.75" and once you coil bind it's gonna sky rocket and can't travel any more then around 3.25" to 14.5 centers. Changing to the 200 spring will just make the 14.75 @ 1750 but still gonna coil bind at 14.50ish

[TheJet-09]

Looking at your first pic, I'd get rid of the rubber travel indicator (it serves no purpose with that set-up and will probably "remove itself" once under race conditions). It's probably only 1/8" but it sounds like you need all the space you can get right now. And once again, I've never used a bump spring, but does it need the spacer on top like that? Is there anything underneath as well, between the bump spring and the cup? Just wondering if you can't get a little more travel out of what you have.

[RacerX10]

so all of that was premised on beginning at ride height and I think I've read in rocket's notes that they're not that concerned with ride height over there so picking it up to wherever it needs to be to hit the 3 in number might be what needs to happen?

when ppl are smashing springs for the RF are they targeting the ride height number or the 3 in number?

[RacerX10]

Looking at your first pic, I'd get rid of the rubber travel indicator (it serves no purpose with that set-up and will probably "remove itself" once under race conditions). It's probably only 1/8" but it sounds like you need all the space you can get right now. And once again, I've never used a bump spring, but does it need the spacer on top like that? Is there anything underneath as well, between the bump spring and the cup? Just wondering if you can't get a little more travel out of what you have.

top and bottom cap on the bump spring need to be there, that's what locates it. yeah I guess I probably should go ahead and pull the travel indicator off there.

[TheJet-09]

You could raise the RF to gain more travel, but the travel gained would just be used up getting to the same C-C in engaging the bump spring (if that makes sense). Just thinking out loud/throwing ideas out there...I now see how the spring "cups" for the bump are machined to the ID of the spring to locate it, so I agree you need one on the top, but what if you removed the one on the bottom and let it sit on the coilover cup? I mean, where's it gonna go? That'd gain you a little more room. Lastly, how does the shock mount to the lower control arm? I assume a shock mount welded to the top of the arm? What if you could modify it to mount "through" the control arm (like on a Gen-X)?

Hopefully you don't have to redesign the car to get where you want to be. I'm sure someone with Rocket experience would have better ideas, or at least know what can and can't be done.

[RacerX10]

yeah this is just kind of strange, it's not like I'm in some fringe set up here I can't be the first person to run into this.

[Punisher88]

I had the same sort of issue in my car. I called my manufacturer and ordered a new upper shock mount with a raised pin location for the shock to bolt. Cut the old one off and welded the new one on. Problem solved. My center to center at ride height went from around 18 to 19

[MasterSbilt_Racer]

so all of that was premised on beginning at ride height and I think I've read in rocket's notes that they're not that concerned with ride height over there so picking it up to wherever it needs to be to hit the 3 in number might be what needs to happen?

when ppl are smashing springs for the RF are they targeting the ride height number or the 3 in number?

In your case, 14.75" and 13.75" loads are the most critical. That is the range you want to race in. Those need to be correct for the info you were given. Load at 17.75 can be changed to make various springs work correctly at 14.75 and 13.75.

You need 600# at ride
850# @ 16.75
1100# @ 15.75
1350# @ 14.75(bump barely touching/ not touching shock)
2100# @ 13.75

A buddy confirmed you should be able to travel 4" with drop spindles setup.

You need to change chassis upper mount, get a shorter shock body, or ditch the bump spring for a shorter, more progressive device like a bump stop.

Or lastly, just run a spring, no bump, and get the correct spring rubbers to ramp the loads at the appropriate travels.

[RacerX10]

thanks masters .. that's exactly the kind of info I needed. I have a bump stop, will try that with the 200# spring and see if I can hit the 3/4" numbers with that. will also check in to changing upper shock mount.

[7uptruckracer]

If you run a bump spring or almost any kind of bump that is a wheel loading setup not a travel limiting setup you are going to have to run the 6” body with the 7” shaft that’s just what rocket does. You can get a different mount but they purpose of the updated mount if two fold it’s for clearance and preload changes for the to fool deck height etc. call a local shock builder you can change over just the body, as long as you have room without knocking shock internals out and it’s not pricey at all.

thanks masters .. that's exactly the kind of info I needed. I have a bump stop, will try that with the 200# spring and see if I can hit the 3/4" numbers with that. will also check in to changing upper shock mount.

[MasterSbilt_Racer]

That 17.75 is just a bad oversight from years ago. The blue gray is a Rayburn front end. Rayburn used 6" front shocks. My chassis builder can't get a car around the track, but at least they got the pin to pin right.

[RacerX10]

That 17.75 is just a bad oversight from years ago. The blue gray is a Rayburn front end. Rayburn used 6" front shocks. My chassis builder can't get a car around the track, but at least they got the pin to pin right.

6" shock only has an 18.250 full extended pin to pin, maybe that's not enough shaft extension off ride height ?

[MasterSbilt_Racer]

6" shock only has an 18.250 full extended pin to pin, maybe that's not enough shaft extension off ride height ?

You will never really be above ride height with the chassis posture and rebound used these days. Not even if you leave the ground.