Sliding joint for torque arm front

[funcars]

Thanks for the ideas. I have a 91 M5 with a similiar part and understand what you are getting at. I have also seen dogbones with two spherical bearings which is similiar in concept as well. I was not entirely clear on what you meant by needing another lateral locating link though. Do you mean that the torque arm could move sideways and down instead of purely front to rear (a twisting motion)?

Thanks again

[exwestracer]

Originally Posted by funcars

Thanks for the ideas. I have a 91 M5 with a similiar part and understand what you are getting at. I have also seen dogbones with two spherical bearings which is similiar in concept as well. I was not entirely clear on what you meant by needing another lateral locating link though. Do you mean that the torque arm could move sideways and down instead of purely front to rear (a twisting motion)?

Thanks again

Exactly. There is nothing preventing it from "folding" over to the limit of the spehricals when you hit the brakes.

[ProTouring442]

Originally Posted by funcars

Thanks for the ideas. I have a 91 M5 with a similar part and understand what you are getting at.

An M5 eh? Nice! I have a '93 M5 in Calypso Red.

Originally Posted by exwestracer

Exactly. There is nothing preventing it from "folding" over to the limit of the spehricals when you hit the brakes.

I'm confused here... why would braking exert a force on the arm other than a downward motion? Obviously there will be twisting of the arm depending on the individual height of the rear wheels, but for the arm to flop over, wouldn't the axle need to be radically off kilter?

Shiny Side Up!
Bill

[exwestracer]

Originally Posted by ProTouring442

An M5 eh? Nice! I have a '93 M5 in Calypso Red.



I'm confused here... why would braking exert a force on the arm other than a downward motion? Obviously there will be twisting of the arm depending on the individual height of the rear wheels, but for the arm to flop over, wouldn't the axle need to be radically off kilter?

Shiny Side Up!
Bill

You're right, braking force is directly the opposite of acceleration, but it's a LOT of force, and with spherical bearings, there is nothing holding them in alignment with the "dog bone". Take 2 big ball bearings, set them one on top of the other, and press down really hard. They will shoot out to the side. Same sort of deal.

[ProTouring442]

Originally Posted by exwestracer

You're right, braking force is directly the opposite of acceleration, but it's a LOT of force, and with spherical bearings, there is nothing holding them in alignment with the "dog bone". Take 2 big ball bearings, set them one on top of the other, and press down really hard. They will shoot out to the side. Same sort of deal.

Ah! Got it! Thanks!!

Shiny Side Up!
Bill

[funcars]

I like the idea of allowing some movement of the front of the torque arm to prevent binding/bending (from the roll axis location). Can you show an example of the second link? I do like the small dogbone from the BMW, but I don't want to over-constrain the torque arm front if it isn't needed either. Another approach would be to use some type of limiters or stops I guess.

[exwestracer]

Originally Posted by funcars

I like the idea of allowing some movement of the front of the torque arm to prevent binding/bending (from the roll axis location). Can you show an example of the second link? I do like the small dogbone from the BMW, but I don't want to over-constrain the torque arm front if it isn't needed either. Another approach would be to use some type of limiters or stops I guess.

Here's an example of the side link. It doesn't restrain the arm in roll at all. Don't mind the coilover...this one is on a dirt late model.

[jake72ss]

what would be wrong with building the end of the torque arm like Griggs does
http://www.howardweb.org/fastgt/docs/griggs_arm2.jpg http://www.griggsracing.com/images/MTA1000RST.jpg

it looks like the hole in the crossmember is a bit larger than the sleeve and that allows the torque arm to slide front to rear and side to side.

Would this have any downsides?