General Help please..strange suspension issue.

[Marx]

Hi, we have a weird issue with our car. We have toe out on one rear wheel. We have changed the rear arm and shimmed as much as possible....we have also increased the size of the slots in the mounting bracket on a spare bracket to see if we can get near spec....but to no avail. There is no sign of accident damage and the car doesn't seem "twisted". As it's not the arm or mounting bracket it must be an issue of one of the fixed mounts on the car. We are at a bit of a loss to be honest.
Would it be possible for some kind person on here to measure under their car, the distance between the mounting points shown in this image either the blue line (between those bolts).or the red line between the outer edge of the brackets. That would let us know if the mounts there are at fault.
Many thanks. Mark

 

[the hobbler]

Hi, we have a weird issue with our car. We have toe out on one rear wheel. We have changed the rear arm and shimmed as much as possible....we have also increased the size of the slots in the mounting bracket on a spare bracket to see if we can get near spec....but to no avail. There is no sign of accident damage and the car doesn't seem "twisted". As it's not the arm or mounting bracket it must be an issue of one of the fixed mounts on the car. We are at a bit of a loss to be honest.
Would it be possible for some kind person on here to measure under their car, the distance between the mounting points shown in this image either the blue line (between those bolts).or the red line between the outer edge of the brackets. That would let us know if the mounts there are at fault.
Many thanks. Mark

I appreciate that it will be a bit of a 'faff', but I would suggest that you remove the NEW arm, and check it against the ORIGINAL arm--just to make sure that they are identical

 

[Marx]

I appreciate that it will be a bit of a 'faff', but I would suggest that you remove the NEW arm, and check it against the ORIGINAL arm--just to make sure that they are identical

Thank you, yes we lined them up against each other before fitment, thinking the old arm must be bent.

 

[TeleSpeed]

Marx, Can you please upload a higher resolution version of the photo that was attached to the first post?

 

[fiat500]

How are you measuring the toe-in?

 

[Marx]

Marx, Can you please upload a higher resolution version of the photo that was attached to the first post?

This is the best I can get as it's a screen shot fron the Internet...

 

[Marx]

How are you measuring the toe-out?

Gunson trakrite and metal horizontal tracking system and measuring tape.

 

[fiat500]

Gunson trakrite and metal horizontal tracking system and measuring tape.

Do you have the car completely loaded so that the rear wheels are vertical when toe-in is measured? Are there any shims either side of the silentblocs? If so, would it change anything if you placed them to one side of the mounting?

 

[Marx]

Do you have the car completely loaded so that the rear wheels are vertical when toe-in is measured? Are there any shims either side of the silentblocs? If so, would it change anything if you placed them to one side of the mounting?

Thank you for the reply. The car is loaded as best as we can do. The toe is within spec on the other side. Car handles oddly around corners and is very weird in the wet. We also had just that rear wheel locking up under hard braking too.We have gone so far as to test with a spare bracket with the mounting slots extended and also shimmed all on one side to push the arm over more bit still not enough to get in spec. I would be thinking damage to chassis but an measuring and examining all seems okay. Hence my request for someone else's measurements.

 

[fiat500]

Thank you for the reply. The car is loaded as best as we can do. The toe is within spec on the other side. Car handles oddly around corners and is very weird in the wet. We also had just that rear wheel locking up under hard braking too.We have gone so far as to test with a spare bracket with the mounting slots extended and also shimmed all on one side to push the arm over more bit still not enough to get in spec. I would be thinking damage to chassis but an measuring and examining all seems okay. Hence my request for someone else's measurements.

....and I would give them to you if my car wasn't in an inaccessible garage just nor...but if no-one else does, I'll try.

 

[Marx]

....and I would give them to you if my car wasn't in an inaccessible garage just nor...but if no-one else does, I'll try.

Many thanks.

 

[fiat500]

Many thanks.

As a stop-gap, do you have this diagram. If it's useful but not clear enough I will scan properly and get a PDF later.

 

[Marx]

As a stop-gap, do you have this diagram. If it's useful but not clear enough I will scan properly and get a PDF later.

No I do not, that's helpful, thank you. I will see if the 434.5 bears any relation to me car. Thank again.

 

[Marx]

Okay little update, the 434.5 is in mm
and seems to match up perfectly with both sides of the car. I have also measured from the centre of the car to both outer bolts that hold the brackets on and it's the exact same distance. Now it can only be the rear mouting points for the arm? But they look fine. Very, very odd. Anyway couple of rubbish photos attached to show that the toe out can be actually seen. 1st pic is okay side, toe matches up with side of car (and is measured in spec) 2nd picture shows toe out. Please excuse the mess.

 

[fiat500]

What's the history of your car? Has it had serious restoration? Has it been driven by you with the original arm fitted, and if so, what was the state of the tyre?
If the fixed bracket looks like it is as original with regards to spot-welds and lack of damage, I would err towards what @the hobbler said about maybe the new arm is faulty.

 

[fiat500]

Another thought; a new arm must mean new bushes. Can you be certain that the inner tube of these is exactly to Fiat spec? It would only be by luck that they would be installed so that tube protrudes each side at exactly the original amount. Even if the original shims were position exactly as they were previously, that may not be right for a new arm and bushes. By moving the shims from one side to the other on both bushes you might be able to gain some toe-in.

 

[TeleSpeed]

Marx,
The measurement from center of left bracket bolt hole to center of right bracket bolt hole per your blue line in photo is 74.5cm.

Are you using the proper adjustment shims to space on either side of the estendblock? I have them in two thickness sizes, 0.8mm and 0.5mm. Pic attached.

 

[Marx]

Marx,
The measurement from center of left bracket bolt hole to center of right bracket bolt hole per your blue line in photo is 74.5cm.

Thank you.

 

[Marx]

What's the history of your car? Has it had serious restoration? Has it been driven by you with the original arm fitted, and if so, what was the state of the tyre?
If the fixed bracket looks like it is as original with regards to spot-welds and lack of damage, I would err towards what @the hobbler said about maybe the new arm is faulty.

Hi, yes it has had restoration, we dont know how major. We have driven it with the origonal arm on and we had rhe same weird rear handling. Before fitting a replacement arm we used a laser tool and projected a beam then marked the position inon the garage floor and wall. Whe we tried the replacemeny arm the laser lined up perfectly on the markings we had made, making me sure it's not the arms. The front fixings for the arm appear completely undamaged. The resr ones are on the gearbox area and also look fine. We haven't done enough mileage to see if tyre wear is an issue yet...maybe 200 mile but tyre seems okay........its all very strange.

 

[Marx]

Another thought; a new arm must mean new bushes. Can you be certain that the inner tube of these is exactly to Fiat spec? It would only be by luck that they would be installed so that tube protrudes each side at exactly the original amount. Even if the original shims were position exactly as they were previously, that may not be right for a new arm and bushes. By moving the shims from one side to the other on both bushes you might be able to gain some toe-in.

We have moved shims (which are not original and are thicker).all to the one side (bar 1 original thin one on the other side). This was done incase the bushing was not central in order to try to push the arm over to try to get toe correct. That aswell as enlarging the holes on the adjustable bracket.