RF Bottoming

[keeks]

I'm having trouble with RF bottoming. I have a 400 on there now, running an all steel motor. The last race of our season is Saturday. I have a 450 on the LF. What would happen if I just swap them?

I have a feeling that I wont get any RF bite.

[MasterSbilt_Racer]

I'm having trouble with RF bottoming. I have a 400 on there now, running an all steel motor. The last race of our season is Saturday. I have a 450 on the LF. What would happen if I just swap them?

I have a feeling that I wont get any RF bite.

Your off-gas entry will loosen quite a bit. Tighter on the throttle. This assumes you reset ride heights.

[7uptruckracer]

What kind of car and track are you on to do that. That shouldn't be an issue.....Shock settings? What Stroke Shock?

[MasterSbilt_Racer]

What kind of car and track are you on to do that. That shouldn't be an issue.....Shock settings? What Stroke Shock?

I could see it on a MasterS with a high banked track. Especially if not a one-piece lower.

[hucktyson]

Your assuming its the shock bottoming when it could be the upper ball joint smacking the shock or the frame hitting the ground. To stop it from bottoming out add a bump stop or more compression dampening . Which one of those you do depends on what the car is currently doing.

[keeks]

It's a masters, two piece lower. I'm running 3/8 highish bank. Kind of like Husets. There aren't any marks on the frame or shock that would indicate the upper is hitting. The travel indicator is right bottomed out. The RF shock is a 3-6, 7" stroke.

Car feels very good on entry and then suddenly picks up a nasty push.

What does the one piece lower add to the equation that is different from the two piece?

[hucktyson]

The 1 piece has a dropped shock mount that let's it move further before it bottoms , but then the other stuff will start to bottom. Instead of going any stiffer get a soft 2.28 tall Christmas tree style bump stop from port city And that should fix your problem

[Matt49]

You are picking up the sudden push at the moment that the shock bottoms out. This is because you are going from some predefined spring rate (in your case 400) to an infinitely stiff spring instantaneously. That shears the contact patch on the RF tire and away you go.
Just my opinion but a bump stop is only a crutch solution as you are going to hit the bump stop really hard and could still end up with a push in the middle of the corner.
I would definitely try a MasterSbilt one piece lower as this will give you more shock travel. Just be sure you are getting the correct length when you do this. If you are on the old style smack front end (not S7), I don't know for sure if you can get the one piece lower with the lowered shock mount. The old style and S7 right side control arms are different lengths.
I wouldn't swap the front springs unless you are prepared for (as mentioned earlier) your car to be much much freer on entry.
Stiffer than 400 RF is not unheard of on a higher banked track so don't be afraid to try it. Going a little stiffer on RF shock compression could help you also but that may not be a cheap option if you don't have an adjustable shock.

And before everybody bashes me, I'm not saying there isn't a time and place for a bump stop on the RF but I just don't think it will benefit the OP that much. Bump stops work best when you lay down on them nice and easy. If he is slamming down the RF hard enough to bottom out the shock as hard as described, he will hit the bump stop very hard also as it is just in the way at that point.

[7uptruckracer]

Yeah I agree and the conical style bump stops tend to be VERY progressive unless its like oh said a laid over setup which tends to not be a banked track which normally has some good transition. I don't run many banked tracks so stiffening the RF might not hurt but a lot of cars the 1 piece lower gets quite a bit more shock travel...on I work on is 2" extra he is on a 400 with moderate banking a 350 barely bottoms out in a rut or something 325 is an arm breaker! Don't be afraid to try it like he said some of the stiffer springs can shear the RF as well let us know!

[setup479point2]

Main thing I see is RF shock , not enough compression or rebound . With the banking I'd go 5 c and 10 r , slower down and hold the spring compressed longer , which stiffens spring.

[hucktyson]

Have you tested those conical bump stops in a coil load machine or are you squeezing it in your hand and guessing what happens ??? Have you bottomed
Out a shock in a coil load machine and seen what happened ??? They are not
Nearly as progressive as you think and nothing is more
Progressive than turning a shock into a solid rod
!!!

[7uptruckracer]

Yeah I have. We play with bumpstops quite a bit on asphalt. It depends which bumpstop you go with but some can be up to 600# for 1" of compression. Each company has quite a few in every style to choose from. I tend to use the Puck Style or RSW type 50 and 85 Durometers and use shims. We even have played with the nice Phantom Internal Housing Preloaded Stacks. Yes I agree nothing is more progressive then Solid Though. I try to stay off them on dirt unless the track is slick you really chase when it engages a lot

[PenskeShocks]

This is difficult to determine. If your bottoming the RF, sounds like you need more compression. If your adding more spring rate, then you also need to add more rebound. If your going to run a bump stop, and will get into it early in the corner, you need even more low speed rebound to control the force produced from the bump stop. The puck style bumps are very hard. these are used more for aero balance and asphalt style set-ups where you want a certain aero balance. On dirt, the softer bump stops will be less aggressive, and depending on how you cut them and stack them, you can really get into them quite gently and have them progress. Without data, this is something you will have to test and feel out.