Rear suspension arms bent

[benbeames]

Hi all,

My name is Ben Beames and I'm new to the world of Formula 500.

I wanted to see if anyone here has any insight into what went wrong with my car, so I'll know what all needs to be fixed as like I said, I'm a newbie to this kind of car..

I bought an old KBS Mk V (Chico Breschini's old car) earlier this year that had been hit from behind. The previous owner had replaced or straightened everything before selling it, but I did the final assembly on the rear suspension and aligned it. Before this last weekend, I'd just driven the car around the block at my house to make sure everything was working. Everything seemed to be good, and I took the car to a local autocross meet to give it a better shakedown. Though I'm not sure, I think something went wrong part way through the first lap. The car started off fine but seemed to loose its oomph half way down the back straight (about half way through the course). It finished fine though and I lined up for my second run. Upon starting off though, I floored the car and it refused to get above ten miles an hour. I quickly pulled off and looked for something wrong. Being new to this kind of car I thought maybe the belt was bad so I swapped it out (though it looked fine on closer inspection), but when I was finishing the instillation of the new belt, I noticed the brand new arms on the rear suspension where both bent WAY out of shape, and both in the same direction. Pictures are attached.

They were straight when I started the day. Has anyone ever seen anything like that before? Is there something I did wrong in the suspension alignment? I wondered if the axle (which is the same one it was wrecked with) could be binding inside the casing and caused the axle-casing to torque the arms as this would also explain the car's lack of go. But I really have no idea. I'm just guessing at this point, but I don't want to replace the suspension arms just to have the new ones break.

Thanks for any help,
Ben Beames

[Jnovak]

The bent parts are actually the rocker arms that actuate the rear spring canisters. I suspect that the spring units must be jammed or something similar may be wrong. I also suspect that you have other problems.

Thanks ... Jay Novak

[mmi16]

Hi all,

My name is Ben Beames and I'm new to the world of Formula 500.

I wanted to see if anyone here has any insight into what went wrong with my car, so I'll know what all needs to be fixed as like I said, I'm a newbie to this kind of car..

I bought an old KBS Mk V (Chico Breschini's old car) earlier this year that had been hit from behind. The previous owner had replaced or straightened everything before selling it, but I did the final assembly on the rear suspension and aligned it. Before this last weekend, I'd just driven the car around the block at my house to make sure everything was working. Everything seemed to be good, and I took the car to a local autocross meet to give it a better shakedown. Though I'm not sure, I think something went wrong part way through the first lap. The car started off fine but seemed to loose its oomph half way down the back straight (about half way through the course). It finished fine though and I lined up for my second run. Upon starting off though, I floored the car and it refused to get above ten miles an hour. I quickly pulled off and looked for something wrong. Being new to this kind of car I thought maybe the belt was bad so I swapped it out (though it looked fine on closer inspection), but when I was finishing the instillation of the new belt, I noticed the brand new arms on the rear suspension where both bent WAY out of shape, and both in the same direction. Pictures are attached.

They were straight when I started the day. Has anyone ever seen anything like that before? Is there something I did wrong in the suspension alignment? I wondered if the axle (which is the same one it was wrecked with) could be binding inside the casing and caused the axle-casing to torque the arms as this would also explain the car's lack of go. But I really have no idea. I'm just guessing at this point, but I don't want to replace the suspension arms just to have the new ones break.

Thanks for any help,
Ben Beames

From your pictures it looks like all you have is the aluminum of the rockers. Normally there is a piece of rectangular steel tubing the forms the main strength of the rocker - I don't see this in your pictures. Mike Quadrini sells a aluminum casting that performs this function on the QRE Invader. Your car looks to be a KBS 5, I don't know if the rockers from the KBS 7/QRE Invader have the same dimensions as the Mk 5 ones.

Mike can be reached at 914-469-7067 after 3PM

[lancer360]

MMI16 is correct. The aluminum is not strong enough by itself. There should be a piece of steel square tubing sandwiched between the two arms that provides the strength to keep the aluminum plates from buckling like they did. Contact Quadrini and he can probably hook you up with the correct replacement part.

[iamuwere]

Be sure the lengths on the trailing arms are correct. It is possible to bind up a MK5 suspension if lengths are incorrect. Be sure the spring canisters are not seized and sliding freely. If they are still metal on metal inside, they need to be upgraded now.

[benbeames]

Thanks for the quick responses! The rocker arms do have a square tube down the middle but it ends right where they bent. I have an old pair in my parts bin, I'll see what they look like.

The spring canisters aren't frozen. They moved out freely when I jack it up, and still have some give when I press down on the car though I'm sure the pucks are old and compressed from the car sitting around so much.

What do you mean by metal on metal? The shaft coming out of the can is greased if that's what you mean.

Anybody think this has anything to do with why the car decided not to go very fast its second time out (10 or 15 mph) or is that a completely un related problem?

[benbeames]

If you zoom in on the first image I posted you can see where the square tube ends.

[Dennis McCarthy]

Quit guessing and cut to the chase, call Mike Quadrini @ 914-469-7067

[benbeames]

I will, I will. But I have to put another car back together first so I can swap positions of the two cars before I tear it apart. So I'm just casually gathering information for the next week or two. Then when I've got everything apart and inspected I'll be calling Mike.

In fact my first post was what I originally was writing to Mike in an email before I saw that he doesn't list (or check) an email account.

[lancer360]

I see the tube now. It doesn't go out nearly far enough. It should extend out almost to the connection point and be rivoted to the aluminum plates along the length. Give Quadrini a call.