MOT fail - suspension mounting/sill corroded
MOT fail - suspension mounting/sill corroded
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Discussion

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
Got this failure in an MOT, don't really understand it - before I pick up the car and the guys try to sell me some repairs does this sound like a big job or just something that needs patching up? They mentioned welding on the phone, is this something on the chassis that is corroded or just bodywork?

Nearside Rear Suspension component mounting prescribed area excessively corroded significantly reducing structural strength sill (5.3.6 (a) (i))

montyjohn

219 posts

116 months

Monday 8th November 2021
quotequote all
Sorry but it's quite an involved job.

You haven't said what car you have but it's probably a monocoque chassis, meaning that the body and the chassis are the same thing.

Your suspensions control arms need removing. I assume you have macpherson struts which are pretty common, so it's just one control arm per side (if both sides need attention).
Metal from your body need cutting back to remove the rot. It's usually quite thin stuff but might be doubled up at the suspension mount areas.
New pieces made out of some sheet steel (unless they exist off the shelf) and welded in.
New rust proofing.
Suspension control arms back on.
Undertake suspension alignment.

Any structural issues near things like suspension mount areas or seatbelt mount areas need fixing properly otherwise it won't pass an MOT if they notice.
All welding has to be continuous for example, not just spot welded.

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
Okay, will get ready to bend over - will at least get them to show me what they've found so I understand the problem. First time detecting any kind of corrosion on the car so it either went unnoticed or it's escalated quickly. :-/

CrutyRammers

13,735 posts

228 months

Monday 8th November 2021
quotequote all
Stuff like this can rot from the inside out due to condensation, so won't necessarily show until it comes through. Not so common on modern cars though, but older stuff suffered terribly from it.

steveo3002

11,212 posts

204 months

Monday 8th November 2021
quotequote all
if its a nice keeper car be aware there can be vast differences between a cheap patch up to last another year and a quaility good as new repair that will last a long time

find out what youre being quoted for and what it will look like etc ....unless its a shed

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
CrutyRammers said:
Stuff like this can rot from the inside out due to condensation, so won't necessarily show until it comes through. Not so common on modern cars though, but older stuff suffered terribly from it.
Interesting, we do tend to get a lot of ice on the outside of the windows and steam on the inside, very occasionally even ice on the inside (!) so maybe that's a factor, will ask.

ARHarh

4,892 posts

137 months

Monday 8th November 2021
quotequote all
Another point to remember, if one side has gone this year the other is likely soon as well. As with all MOT failures there will be one point in time when they tip from pass to fail, so you don't always get an advice the year before. Unless its got some real meaning to you, rarity or value don't bother find another car.

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
ARHarh said:
Another point to remember, if one side has gone this year the other is likely soon as well. As with all MOT failures there will be one point in time when they tip from pass to fail, so you don't always get an advice the year before. Unless its got some real meaning to you, rarity or value don't bother find another car.
It has some monetary value to us, we're not just going to ditch a car - what's a ballpark for repair costs?

montyjohn

219 posts

116 months

Monday 8th November 2021
quotequote all
ScotHill said:
what's a ballpark for repair costs?
It's really hard to say without getting under the car with a screwdriver and a hammer to see how extensive it is.
What might look like a small area can soon expand to a pretty large area once you start cutting back the rot.

I do all my own work so I'm not very clued up on garage prices but I'd assume about £400. See any less as being a bonus.

Chris32345

2,141 posts

92 months

Monday 8th November 2021
quotequote all
montyjohn said:
Sorry but it's quite an involved job.

You haven't said what car you have but it's probably a monocoque chassis, meaning that the body and the chassis are the same thing.

Your suspensions control arms need removing. I assume you have macpherson struts which are pretty common, so it's just one control arm per side (if both sides need attention).
Metal from your body need cutting back to remove the rot. It's usually quite thin stuff but might be doubled up at the suspension mount areas.
New pieces made out of some sheet steel (unless they exist off the shelf) and welded in.
New rust proofing.
Suspension control arms back on.
Undertake suspension alignment.

Any structural issues near things like suspension mount areas or seatbelt mount areas need fixing properly otherwise it won't pass an MOT if they notice.
All welding has to be continuous for example, not just spot welded.
Given its a rear unless it's somthing fancy it won't have rear control arms
More likely a heavily rusted rear axle or mounting point

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
I don't think it's as bad as the description sounds - the guy showed me under the edge of the rear door area where there was some corrosion and movement, and thought it needed a clean up and a plate welded onto it. Will look around for a garage to do it.

Which makes me wonder whether it was logged under the correct clause - or is that still the 'suspension component mounting [i]prescribed area[.i]'?

montyjohn

219 posts

116 months

Monday 8th November 2021
quotequote all
ScotHill said:
I don't think it's as bad as the description sounds - the guy showed me under the edge of the rear door area where there was some corrosion and movement, and thought it needed a clean up and a plate welded onto it. Will look around for a garage to do it.

Which makes me wonder whether it was logged under the correct clause - or is that still the 'suspension component mounting [i]prescribed area[.i]'?
Doesn't sound like the right clause. What car/year do you have?
Can't think of any suspension systems that have control points mounted near the edge of a rear door.

Doesn't sound like an MOT failure to me. But I'm guessing what car you have and where the rust is.
Upload a picture and it can go through trial by forum.

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
Honda Jazz 09 - I'll upload a photo tomorrow in the daylight.

Krikkit

27,938 posts

211 months

Monday 8th November 2021
quotequote all
montyjohn said:
Can't think of any suspension systems that have control points mounted near the edge of a rear door.
Anything with trailing arm or torsion beam rear suspension probably will...

anonymous-user

Original Poster:

84 months

Monday 8th November 2021
quotequote all
I'm guessing that this video https://www.youtube.com/watch?v=VaKQFguMxJo#t=1m13... shows how the rear suspension connects close to the rear door - if that's the case I'm happy it failed legitimately. If it's just a quick check and patch up I'm not too worried by it, by the time we end up selling the car no-one's going to care about what it failed on this time, and the guy confirmed there was no sign of corrosion anywhere else, Will get the welder to double-check though.

InitialDave

15,132 posts

149 months

Monday 8th November 2021
quotequote all
Hard to tell without seeing it (or a good photo), but most likely the rear underside of the sill has rusted through. This would be close would to the suspension attachment point to count as the failure described.

If it's just that, and you're happy with "good enough" to get an MOT, a patch over it would likely suffice.

Have they quoted to sort it?

anonymous-user

Original Poster:

84 months

Tuesday 9th November 2021
quotequote all
Ballpark figure of £120 to tidy it up and weld a plate over the top, depending on how much they have to scrap back and what good metal they can weld onto.


E-bmw

13,493 posts

182 months

Tuesday 9th November 2021
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That is one of those welding jobs that could easily grow arms, wings, legs & horns looking at that pic.

ARHarh

4,892 posts

137 months

Tuesday 9th November 2021
quotequote all
You can see the rust breaking through on the top seam of the sill. Looks like it will grow to at least the back 30 cm of sill.

steveo3002

11,212 posts

204 months

Tuesday 9th November 2021
quotequote all
will just be a typical mot plate...they wont chase out every last scrap of rust , just whack a plate over it so their poking tool wont go thru