Rear crossmember replacement.

Looking for your thoughts i have a defender 90 200 tdi, with a rotten cross member.

Bought the replacement part have a couple of questions on fitting generally and a specific question to my vehicle.

Obviously the replacement cross members with extensions are somewhat oversize to go over the original chassis rails the issue i have is that my defender seems to already have had a replacement historically.

Option 1 - cut off the replacement then try and grind through the welds to get back to the original chasis; this will result in the cleanest fit of old to new but seems like a lot of work.

Option 2 - cut down the replacement by the length of the cut outs, then mate the new replacement over the historic replacement - this seems like the quickest way to fit - is there any reason why this seems like a terrible idea?

On fitting a replacement cross member generally i understand the wiring loom must be pulled back through the chassis after the replacement is welded in - where should i cut the the loom?

Quite hoping to get this done this weekend, strongly favoring option 2 for fitting the replacement at the moment unless we can think of a reason not to do it that way?

Thanks for your help guys

All the best
James.

Replacement should be the right size to fit without chopping bits out. Cut loom where you can easily get access to put it back together but if it has had it done before, it should be cut already. Cut out all the first replacement and it will be ready to go.

Thanks Gmacz for the response - I know chopping all the replacement out in the best and proper course of action - i'm just concerned about the amount of grinding in awkward areas - i would have to cut the old replacement through further back then grind hard through the welds to get to the original chassis that's inside - i recently did my passenger outrigger and although its only 3mm thick, the weld bead made that up to 6mm thick in places. each chassis rail has about twice the amount of grinding as that outrigger to remove the old one then grind it back through to the original - option one looks like a day an a half of hard grinding which just isn't a fun weekend! In my heart i know what i should do, but other than introducing two areas of weaknesses / points of failure / i cant see why the other option wont work?

Do the job properly and just do it once and don't come back to it has always been my motto.

Thanks Mike taken on board! Ill see how the new one measures up as its just crossed my mind that this replacement and the old replacement might not necessarily be the same length extensions. Will keep you posted - pictures after the weekend.

You will only realy be able to see how much of a job you have when you open it up and can see inside. There may be corrosion between the original chassis and the historic replacement,after all it has rotted away again.
I have not bothered running the loom through the chassis on this job,just replace the whole section from the plug in the engine bay with good quality 9 core trailer cable fixed externaly to the top/inside of the chassis rail.

Remember the chassis wiring loom is the same part for 90 and 1110 the excess is tucked in the chassis, so if you have a 90 you will have loads of spare to play with.
I ran my loom down the outside.

As @tottot says ^^^
There could be serious rot between the current 'new' crossmember and the old chassis legs. You really won't be able to decide until you open it up. I would really want to get rid of all the current overlap to do the job properly.

I didn't cut the loom, but pulled it back inside the chassis leg leaving a wire 'mouse' on the end. It was great fun teasing the connectors on the loom through the hole in the new crossmember extension and nearly as bad getting a new grommet on!

There is not reason to cut the loom, just disconnect it in the engine bay and pull it through with some rope attached to it, leave the rope in the chassis as you replace the x member then use the rope to pull the loom back through.

Just dont do what i did and acciently pull the rope through. I had to get some thin pvc piping to push through the chassis, wasnt a fun day.

Or pull it out and then stick it in some conduit and p-clip it down the outside of the chassis.