Lotus Elan and Lotus Elan Plus 2 Forums

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

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

handi_andi wrote: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.

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

To protect the Kelvindon rear adjustable wishbones, I use Denso tape (available form Frost etc). It's been the choice for corrosion protection of fasteners for 50+ years. Very heavy gease impregnated stuff. Cut with sharp scissors and use disposable gloves. Also useful for squashing into place for any exposed threads.

Regards

Gerry

I'm with you on the Denso tape Gerry. It is good isn't it. I have it wrapped (smeeered ) it round the exposed threads on my adjustable spring platforms and around the trackrods and ends. I too have used it for years on jobs various. I went looking for it..Found it..

It works..

Alex B....

Where does one source this wonder tape? Does it jsut unwrap off the thread when you need to make an adjustment?

Cheers

Andy

Try googling denso. (I'v not tried this). But it is esy to buy. Its as cheap as chips, and yes it does unwrap for adjustment etc. re wrap it when you are ready. Has it dried out a bit? Then stick on a new piece.

Alex B....

Probably the stickiest product in the world!

http://www.satcure.co.uk/tech/denso_tape.htm

Love this guys explaination.

Roy
'65 S2

Denso tape is available from Frost (in the UK).

Regards

Gerry

Pics of the fracture

http://i727.photobucket.com/albums/ww27 ... G_0128.jpg

http://i727.photobucket.com/albums/ww27 ... G_0129.jpg

http://i727.photobucket.com/albums/ww27 ... G_0131.jpg

http://i727.photobucket.com/albums/ww27 ... G_0130.jpg

http://i727.photobucket.com/albums/ww27 ... G_0132.jpg

gerrym wrote:To protect the Kelvindon rear adjustable wishbones, I use Denso tape (available form Frost etc). It's been the choice for corrosion protection of fasteners for 50+ years. Very heavy gease impregnated stuff. Cut with sharp scissors and use disposable gloves. Also useful for squashing into place for any exposed threads.

Regards

Gerry

That's one of the hottest tips I've seen here for ages.
Just wish I'd known about it when I did my rebuild.

Cheers
John

John,

We used to use it down the mine. Sticks like Sh*t to a blanket. Not that I would know. It is good stuff but as an apprentice I used tons of it. In real wet conditions with all sorts of corrosive nasties in the water that dripped down you neck.

regards M
Hard Life

Hrrm Mike,

perhaps I was a bit too enthusiastic with my "hottest tip" statement, I was so enthused that I forgot about the "Cow Dung" consistancy description.
Your "5hit to a Blanket" description makes you someone else that has put me off wrapping the stuff around the nice mechanical bits.
An occasional good wipe down & a fresh coating of thick grease is what I'll stick to for now.

Cheers
John