Chassis Repairs

[gazelle]

As I understand it, there are three ways of repairing the chassis:

1 - fill small holes with weld (very temporary)

2 - crop and patch

3 - replace sections (such as cross members)

At what point do you move from one to the other? If hammer sounding reveals a, say, 1cm x 1cm hole and dull section in the cross member, should it be re-plated or filled. At what point do you move from plating to replacement bits?

My question is being asked as I have a small hole from hammer sounding the rear x-member (at the kink on the bottom) and the lower inclined plates are a bit thinner than I would like.

Best regards

Martin

[wozza35]

I had the same thing last month ,in prep for the mot i decided to have a poke around the truck and yes like you found holes in the rear crossmember that could of been plated BUT i also noticed that a few more bits would need attention before the next one so it just seemed a waste of time patching it and so i chopped the whole thing off and put a new one on which in the long run was the least amount of work .

You are the only one who can really answer your question but if its going to need patching now and there are a few other ropey bits i would just go for it and fit a new one then its done for a good few years and you wont have to worry again

[gazelle]

Thanks Wozza,

I have only one small hole at present and the rest of the x member hammer tests ok so replacement is not yet what I am contemplating.

Now on to the reasons for the question.......

There are lots of threads around here on the subject of "Here is my rusty x-member - should I replace it". The answers are specific to the individual case and any general stuff is well embedded. I did not want to ask another similar question that would help just me. That is why there was no picture of my little rust area.

What I was after was to ask if anyone has good general guidelines on what the different cross over points are for chassis repairs, the intent being that there could be a reference to point people towards for a replacement of steel in a number of locations.

So for example:

Do you ever just weld fill a rust hole?

Is overplating acceptable or will it just last 5 minutes?

At what point is it worth calling it quits on cropping and plating and moving to member replacement?

Hence by asking for guidelines I was looking to make up my own mind based upon general principles given by the combined (and considerable) knowledge of this forum. The question was deliberately made general to make the thread more useful in the long term.

Cheers

Martin

[Les Henson]

The best repair would be to cut the rust out, then a plate of suitable thickness (2.2mm or more), overlapping the hole by an inch or more. You ca\n of course just wire brush it up, then weld a plate over it - I doubt there would be much difference in the length of time the repair lasts. Whichever way you do it, you will have other corrosion problems long before you need to look at it again. Filling with weld is ok, but difficult and untidy, so needs to be dressed-up with an angle grinder afterwards.

The corrosion will have come from the inside, so at least cut the rust out in order to be able to see inside and determine possible future problems.

Les.

[reb78]

In my limited experience, i have found that holes that look like they can be filled with weld are generally surrounded by so much more rot that you will find it hard to actually fill them and would have been better off cutting out/plating or patching over. So i dobt suppose 1 is always much of an option.

[wozza35]

I started with a hole that looked small enough to be filled with a bit of weld (about 5p size)and when i started to investigate further it was big enough to put my hand through and that( coupled with a few ropey looking bits that might of cleaned up and been ok for a little while )is what made me think about the time and energy involved in putting it right for the short term and led me to the conclusion that i could replace the whole thing in less time and not have to sort it again in 12 months time .

The same reason i didnt put a couple of patches on the 2 holes the mot man found but cut the lot out and welded in new metal so i will never have to do that bit again either

[Retroanaconda]

1. Enlarge hole as far as it will go

2. Cut repair piece oversize to hole

3. Place over hole and draw round

4. Cut out along the lines (on the inner edge)

5. Place patch within new hole, file to fit if necessary

6. Tack in place

7. Seam weld all the way around

8. Dress the weld back

9. Add corrosion protection

That's my plan for any holes on flat bits of my 110's chassis.

[LandyManLuke]

I much prefer to cut out a bigger hole, and let in a repair plate, flush with the chassis rail. pretty much as described above.

Generally, if you find a small area of corrosion, 30 seconds with a flap disc will tell you if it really is localised, or as mentioned above, is in fact a much bigger problem.

Normally its a case of the latter, rather than the former.