Strengthening suspension pickup points

[Bevan-L]

What would the best way be to strengthen the suspension pickup points for the lower control arms where there isnt a subframe to do so?

I can put up some pics if anyone's unsure what I'm on about

[terence]

Knowing what the car is might help

[AU N EGL]

How old is the car?

What is the cars use history?

[Bevan-L]

Originally Posted by terence bower

Knowing what the car is might help

Dont laugh but its a FWD Hyundai X3 Excel/Accent

Originally Posted by AU N EGL

How old is the car?

What is the cars use history?

almost 10 years old. Use history? just a normal road car.

[Bevan-L]

EDIT:

Yes I know it isn't exactly the ultimate car to start off with but I would like to see what I can achieve out of it.

[boyracer]

Some guys over here rallied one for a while. They're not a bad car, decent bang for your buck and reasonably lively with the lack of weight. Don't recall them re-inforcing the points at all. Probably seam welded and the rollcage would have been bought as close to the pickup points as possible and that's about it.

Ideally as with any strengthening you want to tie the point into a more rigid part of the chassis, or spread the load over a greater area. I'd start by laminating the pickup points where possible and plating around the ones you can't. Same in principle as with any composite material car, just try and get the load spread over as much as the chassis as you can.
Just remember that every piece of metal you add is more weight that you not only have to accelerate but stop as well. You can build a sherman tank out of an excel if you went silly and you'd never break the thing, but you're going to struggle for performance. If it's for simple club level racing, I wouldn't worry about strengthening. Plenty of careless people out there on the road clipping curbs and you don't (often) see them stranded on the side of the road with a corner ripped out of the thing.

[ckiesz]

Just as you would "stitch weld" a factoy spot welded seam, try not to weld across the entire width of semi-stuctural sheet metal. Imagine the piece you are welding and the direction of loads on it. Then imagine the welds you are about to make as deep cuts. Many times welding on factory stamped metal will weaked the original metal at the point of the weld, leaving a line for future cracks.
When adding metal, spread the welds out laterally and try to make the new metal large enough to take the welds away from high stress areas. Common practice for welding the factory seams is to leave space between small half to one inch welds like this _ _ _ _ (stitch weld), this can also be used for adding structure. Take your time to keep things cool, as things move when they're hot.
Happy fabricating,
Christian

[SidewaysFeltham]

I would never ever weld for structural modifications.

The core problem with welding is that since the bead has to achieve full penetration, you are in fact re-smelting the added part and the original structure. Which causes crystalline metal either side of the bead.

Always use brazing: for difficult and heavily loaded items (wishbones; locating arms/rods) we always used Manganese Bronze, since its melting point was very low and its tensile strength very high.

For everything else such as seaming saloons body shells, we used a special Eutectic Silicon bronze rod which was used by Fords at Boreham and Avely to build their rally car shells.

Can't remember the spec but it was tested to warranted to circa 42 tonnes tensile strength.

Of course, if you have the skill and the kit, then you can nowadays use TIG; however bad TIG welds would be inferior to good bronze.

MIG will still create weak points of crystalline structures either side of the weld.

[terence]

I understand what you are saying sideways,only problem there is if the car is galvanized,if that is the case,I would not even consider brazing as an option.

[SidewaysFeltham]

If it was galvanised, or any form of plating, I would always remove it prior to any form of heat jointing: otherwise the weld would have included slag and be very weak, whether Gas, Shielded Arc, Spot, High Frequency Resistance, MIG or TIG.

Still, I suppose that leaves Pop Rivets..........................

I once saw an insurance write off (MG 1300) here both wings and the front panel had been popped on in place of spot welds.

When the owner hit something, the whole front end apparently sort of slid off up the road!

The guy didn't even have the brain to use steel or even Mono Metal rivets: just plain old 1/8" ally!

Which, well sort of corroded: as they do.

Made me larf!

[terence]

Not much worse than an Allegro then,the spot welds used to let go on impact,an old dear sat at some lights and was spotted by the driver of the car behind as being an ex next door neighbor,promptly hit/rolled into her at something like 15mph and totalled her two week old car!!

[ckiesz]

Also, factory metal on many of todays cars is pretty low grade and can be hard to work with. The sheet metal on my Nissan is like recycled pot metal.

SidewaysFeltham: You are right about welding in structural locations, that was sort of what I was trying to say. I would be interested in seeing what he is interested in strengthening, I don't know hyundai's well.

If I remember right, it was a Hyundai that a few of my buddies used for a low budget rallye car. They jumped it and rolled it over and it kept going. If finally stopped when they rolled it a second time.

Christian

[SidewaysFeltham]

When I worked for Ford Europe in the mid sixties (on warranty repairs anc claims) the spot welds on many Dagenham cars were so bad that customers used to complain about groaning noises: which were badly made spots on unimportant places like the sill to floor pan..........

Ford's standard "Service Fix" was simply to spray the affected area with silicon lube: to stop the noise of metal rubbing on metal!

Nice.

We often used to puddle braze parts like wings, rather than spot simply drill a 1/4" hole through the top surface and puddle braze onto the prepared inner wing.

Far stronger.

And much neater if your brazing was good.

[Momus]

Originally Posted by SidewaysFeltham

I would never ever weld for structural modifications.

The core problem with welding is that since the bead has to achieve full penetration, you are in fact re-smelting the added part and the original structure. Which causes crystalline metal either side of the bead.

Always use brazing: for difficult and heavily loaded items (wishbones; locating arms/rods) we always used Manganese Bronze, since its melting point was very low and its tensile strength very high.

For everything else such as seaming saloons body shells, we used a special Eutectic Silicon bronze rod which was used by Fords at Boreham and Avely to build their rally car shells.

Can't remember the spec but it was tested to warranted to circa 42 tonnes tensile strength.

Of course, if you have the skill and the kit, then you can nowadays use TIG; however bad TIG welds would be inferior to good bronze.

MIG will still create weak points of crystalline structures either side of the weld.

The worlds moved on a bit from Boreham in 1971 though I still have my copy of their rally preparation guide.
I have been MIG (and TIG) welding brackets, gussets, doublers and roll cages into cars for 25 years and never had a crystalline weld failure. I know what they are but assume that since MIG is the manufacturers preferred weld type it will be OK for us. The material the makers use has bugger all carbon or anything else expensive in it and MIGs beautifully. If there is gal. grind/sand it off and make sure your gussets are clean and bright and off you go.
With regards to bronzing, especially on dirty material or where there are laps and gaps the chances of getting a good join are not that high and the possibility of stewing the metal and 'crystallising' it are considerable.
Cheers

[SidewaysFeltham]

Since the first "Fuel Crunch" in 73/74, cars have become increasingly composite: high Tensile steel has been increasingly used for (e.g.) chassis legs, suspension pick up points and etc.

MIG is not in fact much used in automotive manufacture: robotic spot and high resistance welding and increasingly, laser welding techniques are.

Assuming that most, with the best will in the world, "Amateur" welders can achieve excellent penetration, not overheat the parent metals and are using the correct gas pressure, current, wire feed speed and of course, correct type of wire (as HT Steel is different in composition to other cold rolled strip used to press external body parts), is making a series of assumptions.

Of course one should not try and braze dirty parts: but then a welded joiunt with all that included slag is going to be just as suspect!

I don't know what your welding qualifications are, Momus: perhaps you have , perhaps APPE ASME or EN 287, whatever.

Most amateur race car builders would not.

Personally, for parts under a whole series of strain moment, I'd prefer the amateur to use brazing.

Few would have access to good TIG kit: or the correct gas.

But we're all different!

[boyracer]

Out here in OZ, never seen a race car brazed. Mild steel roll cages are MIG'd in, Chrome Moly cages are generally TIG'd in. Galv is treated by flaming it with the Oxy torch till the spot is cherry red, doesn't lose all the galv, but makes it a damn sight easier to weld. Those worried about that heat affecting the metal...it's a race car people, Roll Cage welds don't get Ultrasonic testing, or even mag particle. The most thorough inspection it comes under is the scruitineer who may or may not know anything about welding.
If you're confident of your MIG skills, go for it. If you like Brazing...go for it. At the end of the day, you're the dude trying to drive it ten-tenths, so make sure you're happy with the process being used.