Collapsing Rear suspension - Not a good day.

T

timj

New Member
Today I decided to meet a mate of mine at the pub for a civilised lunch. As I was having a day off I thought I would take my 3500s. I spent many days in the winter getting it to run correctly and lots of little bits for the MOT. It passed its MOT about a fortnight ago and is not a rust bucket. Its quite solid really. I even treated it to a nice new set of Dunlop Sports so It should be being nice to me.

About a hundred yards from the pub there was a wierd rubbing noise from the back of the car followed by an almighty bang and then the soud of metal grinding against tarmac. "Bugger" thought I if I can just make it to the pub car park I will be out of everyones way and can sort it out from there. No. It ground to a halt right in the middle of the entrange from the pub. and even 5 of us couldnt bump the car out of the way. The landlady wasnt happy!...

Long story short. Got the car home on the back of a recovery lorry. Dragged pushed shoved kicked it to its parking space, and took the N/S rear off to have a look. the mountings for the bottom link had sheared off the de dion elbow.

Yesterday I was on the motorway in this car and I am quite glad this didnt happen at speed.

Can I just change the elbow from the axle? It doesnt look too involved if I can do it without dropping the axle. Any hints and or tips would be greatly appreciated. I was going to rebush the rear suspension this year, and may as well do this at the same time. How much should I be paying for an elbow? or should I buy a complete car and strip it?

Back to driving the van all the time for the moment then!

Everyone go and check how rusty their back axles are at once!!
 
Just thought you might like to know. I did get my pub lunch while I was waiting for recovery so that was quite nice! I could even have a drink!
 
Hi Tim,

The exact samething happened to me around this time last year, I had went to Glasgow on the motorway doing 70 plus my 10 percent. Did my message and was heading home and it went whilst pulling away from the lights. Lucky boy yes.

Any way there was a good thread on this and had an article published in the p6 news.

De dion failure thread


I looked at J R Wadhams, although advertised at 75 +vat+delivery. When I phoned I was told that the price had gone up due to rarity. I also asked about what was done to them, seems that they are cleaned up and sent out.

What I did was get a good condition elbow. I then got the eyes strengthend and galvanised.

I am not afraid to say that after the elbow went I was weary about taking the car out on the road.

I would advise that you take the whole thing off and strip it down. the elbow also goes where the hub bolt on so well worth the effort. There are pictures on the thread which shows this.

Colin
 
Mine did break off at 70mph, new trousers called for! luckily the car steered perfectly and I made it to the hard shoulder but it did wear half the bottom link away!
 
Thanks for your help and emails everybody. I am going to look at a spares car. get its elbows sand blasted and weld some nice thick strengthening gussets into them both. before repainting. (Unless galvanising can be done at a reasonable price)

I have now changed my underpants, and dont want it to happen again, but If I find the right donor car at least I should be able to get some of my money back!
 
Just had a thought. Presumably the mounting where the top link goes into the elbow could shear too? Strengthening plated for that too?
 
Corrosion obviously weakens these parts, but given that yours had only been MOTd a few weeks before as had mine, they must not appear excessively corroded, and that mine actualy sheared with bright shiny steel visible I think metal fatigue is partly to blame and I have reinforced that area, I have never heard of the top link mounting shearing but I guess it is just as possible although it usually pulls the other end out of the boot side!
 
You`ve got to chuckle havent you! No one seems to have had a nasty accident as a result. I think God must like Rover drivers!

I now seem to have committed myself to the rear half of the full suspension rebuild I had promised the car by buying all new bushes for the back end. I think Metal fatigue must be to blame a bit as mine to showed bright shiny steel. suspect if your bushes are knackered it doesnt help.

If I weld 2mm thick steel to each lug will I be able to use the standard bolts? If not does anyone know a good nuts and bolts supplier in the bristol area as the one I used to use no longer trades?
 
Thats what I did and shaped the reinforcement so it went up the side of the elbow. The standard bolt sufficed as the originals have a washer spot welded on to strengthen the area.
 
I've had no trouble with mine (touch wood) on my 73 3500S
When I waxoyled the car I did spray some all round the inside of the hub carrier. I think from memory there's a hole in the housing into which I inserted the flexible wand of my undersealing gun and I gave it a good blast
I'm not sure about the MOT test rules on welding suspension components- I thought it wasn't permitted
Dave
 
I believe that welding of some suspesion components is not allowed but not sure they can complain about the elbow as it was a welded component in the manufacture. Anyway you can't tell mine has been welded by visual inspection.
 
They obviously don't look closely at the components anyway or they would pick up on the fact that they are nearing failure...

90% of MOT testers haven't got a clue what a P6 is, never mind what each bit SHOULD look like. I'm yet to see one check the suspension joints properly (i.e. lever the right bits to check for play)

I was under the impression that repairs were not allowed to removeable suspension components, but having read the manual the only reference I can find is -

2. Deliberate modification which
significantly reduces the original strength, excessive corrosion, severe distortion, a fracture or an Inadequate repair of a load bearing member or its supporting structure or supporting panelling within 30cm of any sub-frame, spring or a suspension component mounting, that is, within a 'prescribed area', see Appendix C.

This basically means that as long as the components is "adequately repaired" then it is ok.

Whilst I was at it I also noticed that a missing bump stop is NOT a reason for failure !

For MOT info see - http://www.motuk.co.uk/manual/contents.htm
Richard



Edited By webmaster on April 07 2005 at 11:31
 
I know about the bump stop one. My old car failed on corroded bump stop mounts so we drove home cut them off and returned later for a pass certificate.

Re: The galvanising of elbows mentioned earlier: I don't think electrolytic coating processes tend to coat very well on the inside of curved surfaces (look at the back of your bumpers for evidence) so may not be as good protection as you think for the elbows.

I think chemically de-rusting and painting (or powder coating if you wish but same problem as galvanising on inside surfaces) followed by wax protection to inside is best bet.

I have said before but watch out for elbows that have been re-condition by sandblasting. I had a pair fitted like this that were still very heavily rusted inside where the blaster couldn't reach.
 
Funnily enough, when I first MOT'd my P6 some 13 years ago, it failed for missing bump stops !!!, I used some Capri ones stuck on with arraldite to get a pass.

Had I known I would have complained and got them to check the manual. I've done it several times since on other issues, when I know they are wrong !

Richard
 
This series has changed my rebuild plans for this summer. I think I'll take all that suspension out and have a good look.
Thanks for the warning, I would not like to be the first to have a serious accident.
 
Absolutely, during my current mini restoration, I too will be removing, checking and repairing the rear suspension. Might as well re-bush it while i'm there too, and of course might as well do the front at the same time...... Oh dear I can see this getting expensive !

Looking at the nature of the failure you can see why luckily nobody has nad a bad accident yet, the wheel still stays reasonably well located by the top arm and the drive shaft, the main problem is if the wheel gets stuck in the arch and starts brake, this would swing the car round quite violently at speed.

Richard
 
Well.... I decided to have a quick poke at the rear suspension tonight, unbolted the top and bottom links to have a look at the state of the mountings on the elbow.... Oh dear !

sus1.jpg


Circled area shows a very small looking hole, which I wasn't sure was supposed to be there or not, until I gave it a little poke with the screwdriver and .....

sus2.jpg


I certainly didn't use much force at all, and it just opened up easier than a tin of beans !

A little bit more prodding and ......

sus3.jpg


Yes the mounting broke off completely ! now I am really glad I took the time to check this, because I couldn't see any of the damage until I took the link off and cleaned the area up with a drill mounted wire wheel.

On the plus side, the inner side of the mounting was sound, but still I have just managed to avoid a failure in-use.

I can also confirm the damage was purely down to corrosion, there was no fatigue damage visible, no cracking etc, just a very small hole.

I suggest that all members should pay carefull attention to these areas, it only takes a few minutes to jack the car up, remove the wheel and have a good look, plus give it a little poke with a screwdriver if it looks at all rotten.

Richard
 
P.s. have you seen the state of that bottom link bush !, looks like I'll definately be re-bushing the rear end.
 
Check the ones on the crossmember ends of the bottom links before ordering. Mine were in almost perfect condition despite the rest of the suspension looking pretty much as yours did.

BB
 
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