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Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 11:05 am
by GreekS1
As I was driving along a twisty road I heard two pound bangs one after the other and my steering went all crazy as did the conrtol of the car (very dangerous)

After taking the car to a garage I found out t that the rear mounting point of the rear right wisbone had been completely cut through from top to bottom!!!! On top of that there was some rust there on a supposedly galvanised chassis!!

My question is what to do??? Do I weld it? Will it be the same position for the wishbone as before???? The cut is in the metal not the weld so to weld it exactly where it was before is not guaranteed!! Can I buy the brackets that weld on the chassis independantly???

Please help because Im in a bit stuck!! :-(

Thanks
Vassilis

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 11:28 am
by GrUmPyBoDgEr
Oh that sounds bad.
I've never heard of that happening, possibly the chassis in that area was faulty from new?
If I remember correctly there is a lot of bodywork in that area so welding could start a fire.
Secondly if a welded repair was made the strength could not be guaranteed.
I wouldn't do it.
The best & quickest option is to make a new bracket. Shouldn't be too difficult.
It would take ages to get one from the chassis supplier, if at all.
If you remove all of the body to chassis bolts it should be possible to lift the body away from the chassis enough to be able to grind or file away the remains of the broken bracket & with sufficient protection (heat shields, wet rags etc.) weld or possibly preferably braze the new bracket in place.

Sounds like you've got a lot of work to do but hope that someone can come up with a bit of lateral thinking for you.

Good luck
John

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 12:59 pm
by kstrutt11
Make a new bracket and weld it on they are pretty simple, to ensure alignement make measurements from the other side, you could even make a jig to hold it in place from the front one .

You will need to also ensure all the galvanising is removed before you weld, to protect te body etc use damp rags etc, the biggest fire risk is probably the felt which sits between the chassis and body make sure you soak this as well.

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 4:30 pm
by andyelan
Hi there

Just a note of caution but I believe there can be problems getting good structural welds on steel which has previously been galvanised. I'm not saying it can't be done, just suggesting you get a bit of expert advice first.

Andy

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 7:49 pm
by richardcox_lotus
I'd be very cautious about attempting a weld with the body on in this location. Remember the petrol tank is just above the area you want to weld..........

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 8:23 pm
by 512BB
Vassilis,

Are you able to post a couple of pictures of the failed parts? Then everyone can see exactly what you are talking about.

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Fri Aug 07, 2009 11:09 pm
by ceejay
Crikey, no elan owner wants to experience this kind of thing. What you
need to do before you fix the problem is to ascertain what caused the
failure in the first place, once you know that you can move forward
with confidence.

As to carrying out a repair to the rear tray & brackets...I'm afraid
It?s a body off the chassis job, doing repairs with the body and
everything else still attached is a pain, the results are often less than
satisfactory & ending up with a job that's only half done, sorry, I
don?t mean to be critical, but that's the way it is with these fragile
little lotus cars.

I have retrieved some old photos that I took waaay back in 1982 during
the rebuild of my elan S2, The chassis was in a pretty bad way, but with
a lot re-fabricating and new sheet metal added the chassis is still in
service today.

Image no 1: Shows a rear wishbone in the early stages of fabrication,
being built on a simple jig that I made. Surprisingly when the elan
was put on the laser wheel aligner the rear setting was only out a fraction,
which required a small adjustment. With the current elan s2 rebuild
happening right now, I am installing threaded adjusters (left hand - right hand)
in the rear straight wishbone tubes so that minor adjustment tweaks can be
made if the wishbones are not quite right. I like to have the ability
to adjust the suspension - both front & rear.

Image 2: New wishbone mounting brackets being aligned and tack welded
to the new rear tray, yes, the rear lower part of the chassis was virtually
replaced. The new brackets were upgraded to 14g metal, the original
brackets are far too weak in my opinion.

Image 3: Another shot of the rear tray fabrication work. You might like to
know that over the past twenty odd years the chassis has not developed
any further cracks, or parts that have parted company with the chassis. If
you are skilled at welding and metal fabricating methods, you will be
surprised at how a damaged chassis can be rebuilt back to top condition
again.

A word on welding galvanised sheet metal. You cannot weld on raw galvanised
metal, every trace of the gal has to be removed by grinding with a flap
wheel mounted on a small angle grinder, old brackets will need to be removed
to thoroughly clean the metal. If Welding is done on galvanised metal
the gal will react & burn with the welding heat and create a crystal like
structure in the metal which will only lead to further cracking and fatigue
and probable future failure.

And that is another reason why I would never own a galvanised chassis, I
much prefer a paint primed chassis finished with three or four top coats of
black chassis enamel, at least that can be removed with stripper of sand
blasting before major welding repairs are done. Understand in Australia we
don?t have salt spread on the roads, so corrosion is not the big problem you
may have in the Northern part of the globe.
Anyway I hope the above info has been of some help.
Col
http://www.elantrikbits.com
Australia

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 8:47 am
by GrUmPyBoDgEr
I think the body off option is a bit of an overkill.
OK that will make everything very accessable but all that work just to get at that bracket??
It should be possible to lift the body up from the chassis with the minimun dissconnetion of services to gain working access to the bracket location.
TIG or MIG welding heat can be fairly well contained & even Oxy-Acetelene is a safe option provided sufficient protection is in place.
Having a fire extinguisher close by when welding is not an option.

So far it seems there is no simple solution & I don't think a post mortem will resolve anything but here are a few guesses based on the initial description.
I believe that the "galvanised" chassis are hot dipped in Zink (which is a bit of a missinterpretation of terms).
Nevertheless "Hot dipped" or "Galvanised" the chassis will have probably first have been "Pickled", that meaning immersion in an Acid bath.
That process removes any contaminents from the chassis.
The Acid then needs to be washed off prior to dipping/plating, if this is not done thoroughly acid residue can remain hidden in such areas as the one being discussed.
With the low carbon steel used, weakening through Hydrogen embrittlement is unlikely but a pocket of acid could have caused the accelerated localised rusting as described.
Alternatively that area could have escaped the the process & had no Zink covering; that would have put that area of exposed steel at the "top of the chain" in the corrosion process.

Anyway Vasslis, all the best with the repair.
I hope you've got a nice cool place to do the work?
It's 30?C here & getting hotter; I expect it's over 44?C where you are!!

Cheers
John

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 10:51 am
by john.p.clegg
John
Just as an aside,I am thinking of having my A frames and front arms galvanised (am fed up with powder coating peeling and hammerite is not much better) and as you brought up the subject could you give me some "info" hints and tips etc.etc

P.S. am going to use adjustable A-frames,how does one protect the thread/adjusters?

John :wink:

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 12:06 pm
by GrUmPyBoDgEr
john.p.clegg wrote:John
Just as an aside,I am thinking of having my A frames and front arms galvanised (am fed up with powder coating peeling and hammerite is not much better) and as you brought up the subject could you give me some "info" hints and tips etc.etc

P.S. am going to use adjustable A-frames,how does one protect the thread/adjusters?

John :wink:


I assume you do mean me?
My A frames came new & powder coated from spyder & still apear to be good.
The advice given in my last posting comes from the experience I've gained in my Aero Engine & Automotive powertrain jobs.
If you get your parts "Galvanised", that being an electro plating process, the platers will be able to protect the threads & bush bores by masking them off with a type of wax.
If you get them Zinc dipped then the threads will need re-cutting with taps & dies & the bush bores reamed to correct size.
Hot zink dipping may cause them to distort / twist, depending upon how much fabrication residual stress there is in them.

MikeD has had recent experience with adjustable A Frames & & has also had them plated. He could give you first hand advice on the subject, if he's looking & not too busy.

It's strange how often a mix-up in terminology occurs & can lead to confusion:-
"Galvanising" is a galvanic, otherwise called electro-plating process
The so called "Galvanised" Lotus chassis' are Zink coated by immersion in a molten bath of Zink


Hope I've been of some help?
John

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 1:08 pm
by jkolb
The problem with welding on a galvanized chassis is that the fumes are toxic. Be very careful!

Jerry

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 1:56 pm
by GrUmPyBoDgEr
jkolb wrote:The problem with welding on a galvanized chassis is that the fumes are toxic. Be very careful!

Jerry


The stuff also spits & splatters all over the place as well as producing a very poor weld.
I welded all the way around a home made dry sump that I'd fabricated out of galvanized steel sheet once.
It took ages due to the above happening & half emptied my friend's Oxy-Acetylene cylinders.
I walked home afterwards because I was too "woosy" to drive. :)
Learning the hard way! :oops:

Cheers
John

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 8:07 pm
by richard sprint
John P Clegg

Have you considered shot blasting and painting 'POR15' see Frosts UK for the process its really very good...

Richard

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 9:29 pm
by prezoom
Speaking of getting sick welding, I recently read an article about TIG welding something that had been cleaned with brake clean and the brake clean had not completely evaporated. Apparently the process of welding and the mixture of argon gas with liquid brake clean will produce phosgene gas. The person doing the welding became extremely sick, but recovered. I have been welding with my TIG for over 30 years and usually use acetone to clean parts prior to welding. On rare occasions, I have used brake clean, but the time from cleaning to welding was sufficient to allow evaporation. My welding bench also has good air flow to keep fumes from lingering. From now on the brake clean will now remain on the shelf.

Rob Walker
26-4889

Re: Help!! Broken rear wisbone mount!!!

PostPosted: Sat Aug 08, 2009 10:44 pm
by bcmc33
john.p.clegg wrote:Just as an aside,I am thinking of having my A frames and front arms galvanised (am fed up with powder coating peeling and hammerite is not much better) and as you brought up the subject could you give me some "info" hints and tips etc.etc

P.S. am going to use adjustable A-frames,how does one protect the thread/adjusters?


John, my friend,

Its good advice from Richard - a couple of coats of POR-15 will be more durable than powder coating.

Wow, adjustable A-frames - serious, or what?
To protect the adjusters I would probably use self-amalgamating tape from Screwfix as it can be easily removed and replaced, or for a more permanent solution maybe track rod covers from CBS.

Track Rod Cover.JPG and