Technical Rear suspension rattle AFTER changing shocks and springs - Any ideas ?

[gforce1]

Hi all,

Had some strange rear end noises from a 2010 1.2 500, only just bought the car 40k on the clock. Sounded like scraping and growning, but only with a rear passenger, around corners, speed bumps and pulling off. So read the threads and figured rear shock bushes, so as shocks are cheap and easy to replace ordered a standard set, and some springs, for both sides, cos I was there…..

Anyway changed the shocks and springs today, but on a subsequent test drive, it basically sounds like the spring is loose ! Proper rattling around type noise, even on a straight flat road, very different then before and doesnt change regardless of rear passengers. I’ve checked and nothing obvious, spring is in the cup and the rubber on top of spring looks happy enough. I’ve emptied the boot, removed parcel shelf etc, and sat in the back, I’m 99% it’s the near side suspension. I’ll strip it back down tomorrow and refit, but given it’s only 2 bolts ( each side ), I’m a little confused. Are the rear shock torques on the bolts critical on these cars or somthing ? Do the springs just need rotation 90 degrees ? Any ideas welcome

 

[John202020]

The lower part of the spring has a stop in the spring cup that the end butts up to but given the weight is on the car the spring should sit still if not quite in the right place, did you compare the old and new spring to see if roughly the same? torque on damper not critical

 

[gforce1]

I didn’t spot the stop in the spring cup ( nor seen it mentioned in any how tops or videos ), so great shout, very much appreciate . The springs are the same size, laid them next to each other to check. So am I looking for a raised part on the cup and rotate the spring till the end hits it ? As I changed both sides at one, removing the lower shock bolt, dropped the whole rear axel, and the springs literally fell out, so didn’t get much chance to see how they were before. Will drop the rear end again tomorrow morning and rotate the spring. Thanks for your reply, other suggestions welcome too incase it’s not that too.

 

[John202020]

Yep a raised area clean the cup with a wire brush for a clear view
Also take a careful look at the spring cups they can snap off here's a picture of ours 09 car
Look for anything else on the rear that could be loose grab the exhaust and rattle round spin the brake hubs pull on the wheel etc for anything "loose"

 

[gforce1]

Wow - ouch !. Cups looked fine, I gave them a wire brush as there was some surface rust. Still can’t recall seeing a stop though. Do you know if it’s at 12 o’clock or anything to aid finding it tomorrow ( looking from the back of the car ) ? ( I’ll just rotate the spring in the cup till it stops, but and extra info would be great )

 

[John202020]

I cant really remember maybe 9 o'clock toward the centre had to replace the whole axle

 

[gforce1]

wow, it didn’t look tooo bad under there on this one. Will take a look tomorrow and report back - thanks for your help

 

[portland_bill]

The shock bolts are nominally 10mm dia, but in reality slightly smaller.
All replacement shocks seem to come with 11mm dia mountings, so too much clearance is there. Torqueing the bolts does not seem to fix this, although they do need to be tight of course.
Some have added a sleeve, made of .5mm shim material, which is a faff, but possibly the only real answer. Could diagnose by putting lots of grease around the bolt. Will be quiet for a few hundred yards, until the grease squeezes out. Messy, but might confirm the problem. Do top and bottom separately to identify which is the issue. New bolts might help, or might not. If replacing, must be high grade 10.9, not standard 8.8 grade.

 

[gforce1]

That would fit with the rattling noise, but doesn’t fit with why it’s only from one side ( near side ). I’ve searched for 0.5mm and shim, but cannot find any more details, and an eBay search didn’t throw much up - maybe this ? https://www.ebay.co.uk/itm/20-Thou-STEEL-SHIM-1-PIECE-6-x-3-INCLUDES-FREE-1ST-CLASS-POST-/264470326859?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=710-127635-2958-0 and some tin snips?. Do you have any other details ( just buy a flat 0.5mm sheet and bend around the bolt ? - feels hacky given it brand new ). Looks like the top and bottom are different diameter threads too M10 and M12, didn’t notice that although they were 15mm and 18mm sockets. https://www.fiatforum.com/threads/rear-shock-bolt-size.459835/

I’m also questioning shocker orientation, I put the fatter end at the top, so the shock compresses into top section ( hard to describe, hope that makes sense )

 

[John202020]

I put the fatter end at the top, so the shock compresses into top section ( hard to describe, hope that makes sense )

This is the correct way up otherwise it would fill up with grime

 

[gforce1]

Stripped the rear end back down this morning, took the spring, shock and bolts from the offside of the car ( quiet side ) and swapped them to the near side of the car, half expecting the noise transfer from one side to the other. I found the spring stops in the cups this time ( thanks @John202020 ). For others the near side is at 4 O’clock, the offside is at 8 O’clock, when viewed from the back of the car, there quite subtle in the darkness just a raised bump in the metal. I compared the bolts in the new shock and old shock, both had plenty of play, non visibly worse than the other. Bolted everything back up, only tightening the lower bolt with the suspension jacked up to normal ride height, test drove and the rattling has gone, bumps, corners, roundabouts all fine. Gave it a bigger test with a rear passenger and it does still “creak” ( possibly rubber on metal sound ? ) for a fraction of a second when pulling off from a dead stop, but fine under acceleration, corners, roundabout and speed bumps its silent. So I’m going to call that a success. Thanks for everyone’s ideas, very much appreciated

 

[jrkitching]

a 2010 1.2 500

2010 was the changeover year for the redesigned rear beam with the stiffening bar. AFAIK both springs and shocks are different, so it's worth checking which beam you've got and if you've fitted the correct parts. Easy enough to see the stiffening bar in the later beams if you look under the car from the rear.

A good rule of thumb, though it's not definitive because of optional extras, is that if your car has S/S, it'll likely have the later type of beam. I also believe the later type of beam was fitted to the 500C from launch.

 

[gforce1]

@jrkitching The car does has start/stop. I got these and they say 2007-> 2021. https://www.ebay.co.uk/itm/For-Fiat...t-or-Right-Shock-Absorber-Strut-/363693758158 and Suplex Coil Spring 09178 Rear Axle FIAT-500,RR C/Spring Original replacement. Do you know what the difference is between the springs and shocks pre and post 2010 models ? Car seems happy enough now, so either the cup stop needed the be observed, or something wasnt quite tightened down on the first attempt.

 

[John202020]

2010 was the changeover year for the redesigned rear beam with the stiffening bar. AFAIK both springs and shocks are different, so it's worth checking which beam you've got and if you've fitted the correct parts. Easy enough to see the stiffening bar in the later beams if you look under the car from the rear.

So which springs and shocks should you buy if we/I have a 2009 car with the new strengthened beam axle ? at present it has (new) 09 spec springs and shocks that I didn't replace as they had already been changed? Seems OK unless there's a weight in the rear speed humps "can" hit the bump stops occasionally ?

 

[chris3234]

So which springs and shocks should you buy if we/I have a 2009 car with the new strengthened beam axle ? at present it has (new) 09 spec springs and shocks that I didn't replace as they had already been changed? Seems OK unless there's a weight in the rear speed humps "can" hit the bump stops occasionally ?

I'd recommend the later springs if you fitted to later model axle

That being said you'd probably not notice a huge difference I'd have thought

 

[John202020]

I'd recommend the later springs if you fitted to later model axle

That being said you'd probably not notice a huge difference I'd have thought

It's fine other than fully loaded ride height looks fine normally, I already had new springs before I found out it needed a new axle, I did message the axle manufacturer as to which springs but they couldn't say

 

[d4zzl3r]

Yep a raised area clean the cup with a wire brush for a clear view
Also take a careful look at the spring cups they can snap off here's a picture of ours 09 car
Look for anything else on the rear that could be loose grab the exhaust and rattle round spin the brake hubs pull on the wheel etc for anything "loose"

Thats a big crack!