Clamped vs. spring behind?

[kingmod5]

I am a new comer to modifieds so I am trying to learn about the difference between a clamped car and a spring behind car. Any info. would be appreciated.

[washeduptoo]

Usually clamped up refers to a 4 bar car with a seperate clamp bracket on lr with the spring mounted on that clamp bracket in front and with the shock mounted on the rear of that bracket which lets the b/c move freely. As the rear end rotates, it rotates into the spring.
Spring behind lr usually has the spring mounted on the rear of b/c and shock on front of the b/c. As rear end rotates it unloads the spring usually. Other factors come into play, such as spring preload, etc. Hope this helps some.

[dirtrace09]

Which do people prefer? Is there a situation that you prefer one over the other? I have been seeing quite a few spring behind cars with the spring on the shock behind also.

[HEAVY DUTY]

Which do people prefer? Is there a situation that you prefer one over the other? I have been seeing quite a few spring behind cars with the spring on the shock behind also.

Depends on the driver and track shape and conditions. Spring behind is better on momentum rough racetracks. Clamped in my opinion is better on stop and go type tracks, and for drivers who arent good trail brakers.Everybody will jump on here and say that spring behind is the only way to go, but 2 of the biggest car count UMP races at the end of the year were won by a clamped up car. The answer is, the one you UNDERSTAND how to adjust and which one suits your driver the best.

[johnny v]

Depends on the driver and track shape and conditions. Spring behind is better on momentum rough racetracks. Clamped in my opinion is better on stop and go type tracks, and for drivers who arent good trail brakers.Everybody will jump on here and say that spring behind is the only way to go, but 2 of the biggest car count UMP races at the end of the year were won by a clamped up car. The answer is, the one you UNDERSTAND how to adjust and which one suits your driver the best.

HD, when you say "drivers that aren't good trail brakers"... is that the same as new to 4 links or just came from a 3 link car? I was wondering what would be the best setup for novice 4 link mod drivers... (when talking about clamped up and such) ...

[HEAVY DUTY]

HD, when you say "drivers that aren't good trail brakers"... is that the same as new to 4 links or just came from a 3 link car? I was wondering what would be the best setup for novice 4 link mod drivers... (when talking about clamped up and such) ...

A spring behind car is dependent on the attitude of the car.If the LR drops too far you dont have enough bar angle to make traaction. If it too high (topped out), it doesnt develop any upward thrust to make traction.You have to hold it up by trail braking or using a brake floater ( which makes trail braking more important) or by using a stiff LR shock. The better the driver trail brakes, the less compression or gas is needed to hold the LR up. Too stiff of a LR shock and the car is too rigid to go through any roughness and it will skate across the corner.A clamped spring car isnt as dependent on the attitude of the car, because the pinion rotates into the spring and gets the movement and traction started if the driver doesnt hold the LR up on entry.The bad part of a clamped car is that you have more up and down movement and so you have the LR moving front and rear as it goes up and down which makes a car tight on corner entry. In order to help that you have to limit the LR hike to limit the changes in rear steer, and so you cant run as much hike with a clamp as you can a spring behind ( the spring becomes unloaded quicker on the clamp) If you are running round momentum tracks, the LR is easier to keep up, but if you are on stop and go, the LR is hard for even a good trail braker to hold up, and that is where a clamped car is alot easier to drive and adjust.

[pumpkin joe]

A spring behind car is dependent on the attitude of the car.If the LR drops too far you dont have enough bar angle to make traaction. If it too high (topped out), it doesnt develop any upward thrust to make traction.You have to hold it up by trail braking or using a brake floater ( which makes trail braking more important) or by using a stiff LR shock. The better the driver trail brakes, the less compression or gas is needed to hold the LR up. Too stiff of a LR shock and the car is too rigid to go through any roughness and it will skate across the corner.A clamped spring car isnt as dependent on the attitude of the car, because the pinion rotates into the spring and gets the movement and traction started if the driver doesnt hold the LR up on entry.The bad part of a clamped car is that you have more up and down movement and so you have the LR moving front and rear as it goes up and down which makes a car tight on corner entry. In order to help that you have to limit the LR hike to limit the changes in rear steer, and so you cant run as much hike with a clamp as you can a spring behind ( the spring becomes unloaded quicker on the clamp) If you are running round momentum tracks, the LR is easier to keep up, but if you are on stop and go, the LR is hard for even a good trail braker to hold up, and that is where a clamped car is alot easier to drive and adjust.

Would you run a short straight bar or a j-bar with spring behind ?

[JustAddDirt]

Typically a straight panhard bar with a clamped up set up
J-bar with a spring behind.
I have ran a straight bar with a spring behind with success, but track conditions have to be smooth and slick to do so.

[HEAVY DUTY]

Would you run a short straight bar or a j-bar with spring behind ?

You can run either. The straight bar is shorter, so it changes angle quicker and makes things happen earlier in the corner. The j bar being longer doesnt jack up the car as fast nor let the rear end move as far left. General thinking on the straight bar is to use it on tight stop and go tracks and use a j bar on round momentum tracks. I think most guys use what they are comfortable with and dont change back and forth. A straight bar loads the lr more and a j bar loads the rr more assuming the straight bar is on the left of the pinion and a j bar is on the right. One more thing is the j bar being longer will go thru the rough and on the cushion better because it isnt pole vaulting the car as hard as the straight bar. If you are running the straight bar, be careful to not put too much angle in it and cause suspension bind when the car is hiked up. Always simulate body roll and hike in the garage and twist your shocks , springs , 4 link bars and pull bar and make sure that they will move.

[20fan20]

HD
Is it better to run the RR spring on a coil over , slider or on top of the rear end when clamped up?

[HEAVY DUTY]

HD
Is it better to run the RR spring on a coil over , slider or on top of the rear end when clamped up?

It really doesnt matter that much if on a zlink. If you are 4 bar RR , it is better on the birdcage so you can benefit from the indexing. I like the spring and shock together on the front. If you seperate the shock and put it on the back, you need to stiffen the shock because it doesnt move as much ( less control) A spring mounted on top will give up and need replaced because it is twisting the spring in all directions, whereas if it was on a coilover it will only compress it straight up and down with no twisting.