The Mk1 ABF Project

[Preen59]

First type is pretty pointless really. There's plenty of metal in those towers to support option 2 although I'd be putting a plate on the inside of the tower. Something with a diagonal brace would be better again.

Pete

Anything with a bend in it is pointless if you ask me. As soon as you bend them, you've lost the strength.

[thestu]

i only just read your thread simon! forgot you changed your screen name

good stuff man!!!

if ya need a hand i've done my share of mk1's in my short life

[Peter Jones]

Anything with a bend in it is pointless if you ask me. As soon as you bend them, you've lost the strength.

Bending isn't the issue though here. All this style of bar does is tie the tops of the shocks together. Unlike the front, the position of the top of the shocks doesn't affect the tracking geometry.

It won't stop chassis flex because of the rubber mounts either.

Think about what sideways forces are you trying to control here. There's not a lot of horizontal thrust vectors at play at the top of the shock itself.

Even option 2 is dubious. What does it matter if the towers move sideways? The suspension pivots from further forward underneath the car.

Controlling the chassis flex should lead to some improvements in weight transfer as you throw the car from side to side, hopefully that pays off in more predictable handing.

Tying the rear towers together should stiffen the back up a bit but without the diagonal there's still potential for parallelogram distortion of the rear box area.

The distortion you're trying to control can only come from the vertical motion of the shocks pushing up harder on one side than the other.

Shiney shock tower braces are pretty cool though.

Pete

[dado]

this is the way vw aproach this in the case with the convertible

[Oneofthegreats]

Thats the money shot right there!

The cabbys also had bigger sills & front inner guard extension along with various other strengthening devices to make up for the lack of roof support

[Preen59]

Bending isn't the issue though here. All this style of bar does is tie the tops of the shocks together. Unlike the front, the position of the top of the shocks doesn't affect the tracking geometry.

It won't stop chassis flex because of the rubber mounts either.

Think about what sideways forces are you trying to control here. There's not a lot of horizontal thrust vectors at play at the top of the shock itself.

Even option 2 is dubious. What does it matter if the towers move sideways? The suspension pivots from further forward underneath the car.

Controlling the chassis flex should lead to some improvements in weight transfer as you throw the car from side to side, hopefully that pays off in more predictable handing.

Tying the rear towers together should stiffen the back up a bit but without the diagonal there's still potential for parallelogram distortion of the rear box area.

The distortion you're trying to control can only come from the vertical motion of the shocks pushing up harder on one side than the other.

Shiney shock tower braces are pretty cool though.

Pete

I do agree partly Pete, but..

You also are trying to stop the shock towers pushing together. This happens through cornering and under brakes. Tieing the strust towers together prevents this and makes the car point far better and stops the front wallowing and wandering under hard braking. It makes it more stable and more predictable.

The year before last i made a tubular front strut brace for my mate's MK1 escort track car (bit of a weapon- 200hp Pinto engine, sierra 5 speed, mexico guards, half cage.. The whole nine yards). You wouldn't believe the difference it made to thr front end.. It was like night and day. And that was without tieing it in to the firewall.

[Antonvs]

Would love to follow this thread as i would be considereing something like this in the future!
Good Luck with the conversion.

[Peter Jones]

I do agree partly Pete, but..

You also are trying to stop the shock towers pushing together. This happens through cornering and under brakes.

Absolutely agree on the front towers, they bend inwards under load and the suspension geometry changes causing undesirable camber changes.

On the back though? Even if the towers do get closer to each other it's not going to affect the rear tracking geometry, just the way the springs work and mess with the weight transfer as the twisting coach work is providing it's own spring rate.

Generally though, getting the car as stiff as possible is the way to go.

If you wanted to control rear camber changes due to corner loading you'd do it more like this.

[Preen59]

Absolutely agree on the front towers, they bend inwards under load and the suspension geometry changes causing undesirable camber changes.

On the back though? Even if the towers do get closer to each other it's not going to affect the rear tracking geometry, just the way the springs work and mess with the weight transfer as the twisting coach work is providing it's own spring rate.

Generally though, getting the car as stiff as possible is the way to go.

If you wanted to control rear camber changes due to corner loading you'd do it more like this.

Oh, sorry.. I was only talking about the front end. Totally agree with you on the rear..

[Peter Jones]

Rear doesn't matter much really, if you're doing it right you've got one wheel in the air anyway