Suspension: Need some expert advice.

[Outrun]

I have a dilema. I have been hearing mixed reviews about how and what to do, so if you know, please enlighten me. I bought a complete polyurethane cushing kit from TurboX2 (thanks dude ). Since I have to take the control arms off of the rear, I was going to buy some for cheap, torch out the old bushings and box the upper and lower control arms, paint them, and install my new bushings. That way, I can take my time welding and painting the arms when I finish. I have heard the following....

1. Do not run poly bushing in the control arms, it's hard on the torque boxes.
2. Hard poly urethane bushings on both ends of your controls arms is BAD for autox. The rear end can not move around as it is forced through corners etc. This is bad. Can cause snap oversteer and other unwanted characteristics.
3. You should run a stock style rubber bushing at least in one end of the uppers to prevent binding while it travels through its up and down extremes.
4. poly bushings in the lowers on both ends but rubber in both ends of the uppers.

I do not really want to spend the money on new control arms since boxing them is free. I figure it's something to do to add strength while they are out. So what is the best thing to do? Should I box Both the upper and lower arms, or just the lowers. I do not want to waste my time boxing the uppers if it is not worth it. Is it a bad idea to run poly bushings in all 4 arms? I am going to box the lowers for sure, and probably the uppers if it is necessary, which I do not see how it can hurt.

http://www.oldwestracing.com/index.html?http://www.oldwestracing.com/articles/armsbox/BCAwo.htm

[93SVT]

your right about the poly in one end only, due to the articulating (sp?) motion of the arms the angles of the bolt must change, poly does not allow for this, a spherical bearing or softer bushing will, the truth is you will not be able to get ideal performance with the stuff you have, but id say with one of each youd have a decent improvment. Not sure on the uppers, never looked into what you would want to do in that case because I just went right to a tourqe arm setup for its handaling asspects.

[bad-speller]

Bills right. If you change to all poly, it is going to feel like the car is tighter, which it will be, but it will be because of the bind created by the bushings and also be very unpredictable.

The control arms are doing three main jobs at once. 1, locating it for verticle movement, 2, locating it for horizontal movement 3, locating it rotationally (Ie: under acceleration and braking)

You want the suspension to be as free as possible since it is operating on more than one axis. Since this it is impossible for the stock 4 link setup to do all at the same time, you are basically screwed, and any changes you make are band-aid fixes at best.

The best setup is to have control arms with heim joints so the axle can pivot freely in all directions, then add a panard bar or watts link to control side to side movement. Then the control arms have one job, and the panard bar has the other. You have a free moving axle that you are basically controling with spring rates rather than some spring and some bind. When you make changes as I mentioned above, you will need to step up substantially in spring rates because the springs are doing more work.

The next step is a torque arm, I won't go that far here, but the torque arm basically comes in to take over the duty of the upper control arms.

Brian

[Mullet Tuner]

I have poly poly LCA's. Im primarily into drag racing though, ill see how they do at the April 17 autoX.

[Outrun]

Bills right. If you change to all poly, it is going to feel like the car is tighter, which it will be, but it will be because of the bind created by the bushings and also be very unpredictable.

The control arms are doing three main jobs at once. 1, locating it for verticle movement, 2, locating it for horizontal movement 3, locating it rotationally (Ie: under acceleration and braking)

You want the suspension to be as free as possible since it is operating on more than one axis. Since this it is impossible for the stock 4 link setup to do all at the same time, you are basically screwed, and any changes you make are band-aid fixes at best.

The best setup is to have control arms with heim joints so the axle can pivot freely in all directions, then add a panard bar or watts link to control side to side movement. Then the control arms have one job, and the panard bar has the other. You have a free moving axle that you are basically controling with spring rates rather than some spring and some bind. When you make changes as I mentioned above, you will need to step up substantially in spring rates because the springs are doing more work.

The next step is a torque arm, I won't go that far here, but the torque arm basically comes in to take over the duty of the upper control arms.

Brian

I would like a Watts link Torque arm setup but do not want to spend a huge amount of money.

I am just trying to figure out what to do with the poly bushings, and control arms, without breaking something.

[WUTUGOT]

I would like a Watts link Torque arm setup but do not want to spend a huge amount of money.

I am just trying to figure out what to do with the poly bushings, and control arms, without breaking something.

As they mentioned with the poly bushings they will cause binding. I think you would be fine with polys in the LCAs and polys in the UCAs...but run the stock style rubber bushings in the axle housing for the UCAs.

[Outrun]

So....

Box both upper and lower arms,
Use poly on the lower arms on both ends
Use rubber in one end of the uppers and poly on the other end.

Sound good?