Hammeriting A Subframe

[Rupertfinch 6]

As part of the celebrating summer season, I shall be getting under the old girl and having a good tweek. But before I do that I may have a go at working on my peugeot! Please make the laughter end!

 

Anyway, Last time I had it up on a ramp I noticed the subframe was looking a little rusty and a little oiley (rust looked cosmetic). Have bought some hammerite to restore it to a MOT inspector pleasing colour and was wonering the best way to go about preparing the subframe.

 

Steam clean? Wire brush? Cillit bang? I'm a bit lost amongst a sea of strange advice. Can anyone out there share with me some sensible Forum knowledge?

 

Cheers, Mark

[welshpug 1,657]

Ideally a steam clean then a sandblast, followed by etch primer and then topcoat, if you've got a welder you could have a go at seam welding it up

 

thats the posh way to do it, DIY way would be half a gallon of gunk, wire brush, red oxide then topcoat

[Richie-Van-GTi 71 2 Cars]

My method was remove from car, jet wash, sun dried then hammerite before refitting. Looked spanking when done

[vern 0]

My advise would be get it sand blasted, then powder coated, only costs about £30 and is a much more durable finish than paint and looks better.

[Rupertfinch 6]

Hadn't actually planned on taking the subframe off, but am now coming round to this idea. How much work is involved? Replacing wishbones anyway it's not a problem removing them, but will I not have to remove a range of other gubbins to get the subframe off?

[vern 0]

2 bolts securing the rack.

4 bolts securing anti rollbar.

2 gear rod brackets

4 bolts on wishbones.

Engine mounting yoke.

6 bolts securing the subframe itself.

I think that is about it, someone else will add anything I have missed, how long it will take you is down to when the bolts were last undone. It would take me about an 1- 1 1/2 hours.

[clifton 0]

sorry to hijack the post abit...but what exactly is seam welding?

[Hilgie 16 2 Cars]

The subframe is spotwelded. That is fine for a road car but not very rigid (like you'd want on a trackcar). To make the subframe more rigid all seams are welded hence the name seam welding.

[Beastie 1]

Pretty much as Hilgie describes - just to add: Most mass - produced fabricated assemblies have metal joints which overlap (seams) and which are electrically spot welded at regular intervals. This is done for 2 reasons: Strength and durability. Spot welding is strong because it minimises the heat affected zone in the join. The heat of welding reduces strength of material so minising the heat prevents excessive weakening. Spot welding is durable because it allows the concealed faces of the join to be treated against rust and painted; the subsequent welding involves such a localised heat that the rust treatment is not significantly compromised.

 

The drawback of spot welding is that it is not as stiff as seam welding.

 

Seam welding involves making a continous run of weld along the join. This stiffens the joint but it's important not to confuse stiffness with strength (a spring is strong but not very stiff, but glass is very stiff and not very strong for example). The seam weld itself is very strong but the material immediately adjacent will be weaker than it was when the seam was just spot welded because the heat affected zone is so large. The heat of seam welding will completely destroy the rust treatment concealed inside the join so the joint will be less durable.

 

It's only sensible to seam weld if you really need the stiffness. If you have a track car then seam welding is probably the way to go. I spend most of my time at work carefully replicating the original spot welded seams on classic cars because apart from any originality issues it's going to be a lot more durable. Additionally when it does need rebuilding again a car or assembly which has been seam welded costs an awful lot more to restore than an original spot welded item.

[Rupertfinch 6]

Excellent Beastie. Good information much appreciated, thanks for the 'hi-jack' Clifton, I've learnt from it!

 

Thanks one and all for your help.

 

Mark

[Guest maxlee]

owning many old cars i have done a fue things like this

 

my tip when it comes to wire brushing is : get down to a pound shop and get a big wire brush that fits in a drill

(not the little ones that you screw on to a rod ect un less you doing little bits)

saves you loads of time and at £1 you can only but try, i have done to transits a land rover, some of my avenger and most cars i have owned using cheap wire brushs all so the waxoil under seal is quite good £10 for 1 or 2L from holfords would easy do a belly of a 205

 

if you can't get rid of all the rust the kurust is good also made by Hammerit works best when you leave it over night tho even if it dose say 3 hours on the tub

 

just my 2 pence worth

Edited July 18, 2007 by maxlee

[brumster 135 1 Cars]

Just to continue the hi-jack/be pedantic ...

 

Seam welding involves making a continuous run of weld along the join.

 

...although I would advise against welding up the WHOLE of the join because of the very reasons Beastie points out; weakening of the metal being joined. More common practise is to do a ~2" run of weld, then leave a 2" gap, then another run of weld, and so on. You get the idea.

 

Anyway, on the painting front, I've had good results in the past with wire brush (or drill attachment, but get some goggle and watch for the flying steel wires!), copious amounts of gunk, and good wash-off and drying session, then prime and paint-up. Just make sure you get every last little bit of greasy, oily buildup off it before you put a paint brush anywhere near it.

Edited July 18, 2007 by brumster

[Rupertfinch 6]

Thanks folks, replaced the wishbones yesterday, so had a good chance to poke around. Reckoned that I wouldn't take the subframe off, so decided to give it a blast with my £15 poundstretcher steam cleaner. Took a while, but it really made the frame come up like new (with the exception of a bit of rust there and there). Going to give it a wipe down to remove any oil reside, then use a can of the hammerite/waxoyl spray. Would I need to prime the frame first if using this product?