12 replies to this topic

[28hodge]

Not in a mini but I’m guessing some on here will have had to do this. The roof on a Peugeot 205 is brazed at the A and C pillars to the rear quarter and the screen pillar.

I am doing a roof swap on my 205. On the car with the knackered roof I could sacrifice the roof to split them, but on the donor shell I need to keep the roof and the rear quarter usable, so can’t trash one to release the other!

What’s the best way to separate the joints, I’m guessing I can’t heat them to sweat them off as it’ll warp the steel, although when done originally it must have been gotten hot to flow the braze into the joint!

[28hodge]

I’ve tried to V out the joint here with a poly strip and clean wheel but the rear of the panels have flanges which is brazed

Attached Files

•  372456D8-285E-48FF-BF8C-85A6D97DBAAA.jpeg   91.71K   1 downloads

[slidehammer]

In my opinion the best way is with either Oxy-acetylene or Oxy-propane they will get up to temp quickly so there is less chance of warping the steel. Some of the Map gas blow lamps can braze but they are much slower and you will have to get the heat to build up for longer and will risk more warping.in the steel.

[Ethel]

The problem is the join will reset unless you get it all molten at once. Perhaps you could do a bit at a  time  & wedge it apart as you go?

[28hodge]

Hmmm I don’t have access to oxy-acetylene or oxy-propane. I do have mapp gas but wasn’t sure it would get hot enough! I think I can get my way into the internal side of the braze and potential trim the flanges off and then re-attach but I’m not sure how I’d then refit either. I could lead load I suppose?

[Tupers]

First you need to check inside and find out if there’s a spot welded flange on the inside with braze sealing it from the out side of if the braze is the only thing holding the two panel together.

A MAP gas torch will melt braze but ideally you need one person running the torch along the seam and watching for it to turn liquid and a second person to pull the two panel apart.
If you’ve got to work alone the you can use a quick-grip style clamp to push the panel apart so that when you heat it and the braze softens.

I wouldn’t get too frightened of the heat. You shouldn’t get more than a little blueing on the steel as you heat it. What ever you do don’t be tempted to quench the steel with water or a damp cloth if you do it will shrink back too fast and cause you all manner of buckling troubles. Let the steel cool on its own and all should be well.

[28hodge]

First you need to check inside and find out if there’s a spot welded flange on the inside with braze sealing it from the out side of if the braze is the only thing holding the two panel together.

A MAP gas torch will melt braze but ideally you need one person running the torch along the seam and watching for it to turn liquid and a second person to pull the two panel apart.
If you’ve got to work alone the you can use a quick-grip style clamp to push the panel apart so that when you heat it and the braze softens.

I wouldn’t get too frightened of the heat. You shouldn’t get more than a little blueing on the steel as you heat it. What ever you do don’t be tempted to quench the steel with water or a damp cloth if you do it will shrink back too fast and cause you all manner of buckling troubles. Let the steel cool on its own and all should be well.

Ta, it’s definitely only brazed in this location and the front pillars. I’ll give it a hit with the mapp gas was wondering if I could blow the molten braze out with the compressor but was also worried about the temp difference and shrinking etc.

I’ll get my brother to give me a hand, the rest of the roof is released, spot welds etc so we should be able to get them hot and break the joint and keep it apart long enough for the brass to go hard again.

[Tupers]

I wouldn’t recommend compressed air to get the braze out but a small wire brush can do quite a good job of getting it off the surface. Just be careful you’re not flinging molten metal at anything flammable or fleshy.

[Cooper Mac]

I didn't realise the roof was brazed on!

 

Have you had a look on the 205gtidrivers forum? I'm sure there will be some info on there about it, usually every job is covered there if you search!

[28hodge]

Yeah I have a thread over on the 205 forum but it’s a pretty quiet forum to be honest and I think most on there aren’t of an age to have really had to do anything with brazed joints before. Most cut through the top of the rear quarter and retain the brazed joint and butt weld the rear quarter back together.

I can do that but thought some members on here will have worked with brazed joints and have more experience with them, so would know the best way to split the joint without damaging one of the panels.

[Gilles1000]

On the Mini there are a few small brazed joints (top of the A-panels, rear assembly...)

I could split the one on the A-panel by drilling it with a small disc on a compressed air tool (like a Dremel, but bigger) and then carefully split it with a cutting tool and hammer.

On the rear there was nothing else to do as go with the big grinder. In fact I had at some places only the brazing left :)

 

But I am not sure if this is applicable on the 205 as the roof panel area seems to be tighter to get too...

 

Gilles

[Cooper Mac]

I've just realised that I didn't look at this on my 205 when I was at the workshop last night, D'oh!

 

I have made brazed joints, but never tried to take them apart. What I do know from soft and silver soldering is that to melt the solder to get the bits apart always takes more heat than to create the joint in the first place, and I assume that the brazing will be the same.

 

As said before, I think it would require 2 people, Oxy-acetylene to get the heat into the joint and then some way of parting/wedging the parts apart as soon as the braze is fluid. Otherwise I would go at it with a dremel with a slotting cutter.

 

by the way, just found your post on the gti drivers forum!  

[28hodge]

yeah the 205 is a bit of a rescue project but in all honestly its not in that bad shape, i think i bought it just in time before any real serious rot and damage set in.

 

Ive also just bought another B reg GTI that is an ex rally car but has been sat inside a agricultural shed since 1997, it was once owned by a guy who i worked for and went to school with his kids, it did the 1994 RAC rally with him and then has done very little since. its got quite a few nice PTS parts on it and is in complete grp n spec so has all the interior.

 

Thing is i dont need 2 so the one in the current thread the C reg one may be going up for sale once i get a roof back on it and the cage etc all bac into it. seems a shame though as its honestly a good car.