Help!! Broken rear wisbone mount!!!

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!! :frowning:

Thanks
Vassilis

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

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.

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

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…

Vassilis,

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

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
elantrikbits.com
Australia



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

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

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. :slight_smile:
Learning the hard way! :blush:

Cheers
John

John P Clegg

Have you considered shot blasting and painting ‘POR15’ see Frosts UK for the process its really very good…

Richard

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

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.

Vassilis

Was the failure line parallel to the weld and a couple of millitmetres from it by any chance?

Cheers

Andy

Thanks all

Sorry for pinching the thread ,will give por15 a go later in the year and report back …

John :wink:

Thank you for all your input and support guys!!

I trully am at a loss…

Yes the failure line is parallel to the weld and a couple of millitmetres from it…I wil post pictures tomorow. Also upon furhter inspection we concluded that it has failed and been welded before. The weld from that side is significantly bigger (ie more substantial) then the one on the other side.

My plan is as follows:

  1. remove body - I hope it is a simple procedure although I believe he wiring will be tricky. Any advice there? This will be done in order to also tackle the gearbox which I believe needs roller bearings (I dont know the name of the component in english but the symptom is that when the clutch pedal is pressed and no gear selected there is a very faint whoooosh noise from the box)
  2. Fabricate or order the mounting ‘ear’. I will talk to Paul Matty for that but other then that I dont know where to ask for it. Perhaps at spyder? I beleive my chassis is not the spyder one but how does one tell one apart from the other?
  3. Bring in an expert to attach it after cleaning the area etc…

I must say that I am very concerened by this whole affair!! Any support and or advice is most welcome and very very heartenning and helpfull!

Thaks again
Vassilis

Vassilis

The fracture sounds like it has occcured in the heat affect zone from the weld, because the metal has been heated up then cooled down the structure of the steel in this area changes and tends to becomeslightly harder and brittle than the rest of the metal. Most of the time this isn’t a problem, but if the area has been welded before and with a bigger weld then this means allot more heat has been put in thus increasing the problem. Only solution is to remove the affected component and completely replace by welding and not brazing, as you suggested in an earlier post. Welding provides a joint that should be almost as strong if not as strong as the original metal, depending on the type of weld used. Brazing is only as strong as the brazing material and the connection of it to the parent material. Brazing medium is always substanially weaker than steel.

A spyder chassis is easily identified by the large lightening holes is the rectangular section to the main back bone of the chassis. If you put your head underneath by the door and you can see large circular holes in the chassis it is a spyder one and if you can’t it isn’t.

Given that the component by the sounds of it has failed before then some dimension checks to check for chassis twist and straightness might be in order, plus checking the body for any rear corner accident damage.

As far as I am aware you can remove the gear box from underneath, preferably on a four post lift. If you have a spyder chassis you need to unbolt the gearbox cross member, if a non spyder one then you need to grind off the gearbox cross member and convert it to a bolt on one. Although I am not sure if I would touch the gearbox at the moment if the noise is the only symptom at the moment, as it could just be the clutch release bearing rather than gearbox or just clutch plate drag.

Personally I would leave the body on for all the repairs, but take suitable precautions and maybe disconnect body at rear end so it can be carefully lifted up a bit to allow full access for complete welding. The new lug needs to be welded on the same as it is on the other side.

Hope this helps a bit

Andy

Sorry Andy but I must disagree with you on nearly every point you’ve made there.
Firstly all of the chassis parts are fabricated from “Mild Steel”, a non heat treatable steel; the heating & cooling effect of welding will do no more than “normalise” the material.
It could also act as a “stress reliever” in sheet metal parts that have been heavily manipulated & become “work hardened”.
If the cooling is extended a possible “softening” could occur, hardening never.
Vasselis mentioned a weld repair, something he was also considering & it seems that this was the source of the failure.
I think we can assume that the weld was faulty because a good weld with full penetration in mild steel has similar strength to the parent material if you disrespect grain flow.
He also mentioned a high build up of weld which indicates poor quality welding & would result in a large sudden change of cross sectional area thus causing a stress raiser in an already fairly highly stressed area of the bracket.
Brazing is used mostly on higher quality, higher carbon steels due to the lower melting point of the brazing rod (ok yes there are different varieties with different melting temp. as you say)
Yes the material is weaker than the steel being joined but strength is gained when a large contact area like 2 flat pieces of steel sheet (as in the case being discussed, I think) are being joined & the braze flows all through the joint as opposed to welds being only edge joints. (Load x Cross sectional area)
Brazing is often the “preferred” method of fabricators, but the cost of it is the deciding factor.
Lastly I must admit that it was me that suggested “possibly Brazing”

Cheers
John