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Technical Can't remove chassis cross-member bolts

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Technical Can't remove chassis cross-member bolts

hymerhobo

hymerhobo

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Whilst removing the old radiator I discovered rust at the bottom of the nearside chassis where the front cross-member bolts on. Having read various accounts of people removing this cross-member to replace it, I thought to myself, 'how hard can it be?' So I tackled the job earlier today. And wouldn't you know it ... 10 minutes later I'd succeeded. Succeeded, that is, in freeing the captive nuts that are presumably welded or tacked in place in the interior of the box chassis section. I used a rachet wrench and a short length of pipe to increase the torque, and after a moderate heave, felt all three bolts give. But then further turning resulted in a grating sound, with the bolt failing to emerge. I can't think this is so very unusual, so has anyone here been in the same situation, and if so, what did you do to remove the cross-member? Incidentally, that cross-member is in good condition. I'd prefer not to have to cut it up.

And now for some smilies:-
:bang: :yuck: and finally :cry:
 
To remove you could grind the bolt heads off, If you're reusing then try replacing the captive nuts using normal nuts and a spanner, It's not going to be easy.
 
If your crossmember is in good condition hammerite and leave it be . You've only just loosened the bolts , so they won't go no where , sounds like a nitemare job. :) Gary
 
garyo said:
If your crossmember is in good condition hammerite and leave it be
Click to expand...

Can't do this I'm afraid. It's the chassis, not the cross-member, that's rusty and needs reinforcing. The cross-member needs to come off to access the chassis.

tommytopgun said:
try replacing the captive nuts using normal nuts and a spanner
Click to expand...

But the captive nuts are inside the box-section chassis. I'm thinking the welder who's coming in a couple of days will only want to weld a reinforcing plate to the bottom of the chassis. IOW there isn't going to be any access to those nuts, unless I decide otherwise.

One way to tackle the problem might be to remove the cross-member (let's call it a c/m) with a bar, lump hammer, and some strong language. I'm guessing (hoping) the bottom of the chassis is rusty enough to give way and allow the bolts to emerge. Having done this I'd cut off the bottom of the chassis with an angle grinder, removing as little as possible. Then, using the c/m as a template, I'd mark the position of the fixing holes on a new bit of steel and drill them. The welder could then tack the nuts onto one side of this plate before welding it on to the chassis. This would be the plan. In practise though there are a few things that could go wrong.

The chassis might be rotten enough to pose a potential road hazard yet strong enough to resist my efforts to remove those bolts. After an hour of violence, I might find myself with an undriveable vehicle and a c/m still in situ!

Why not grind the chassis with the c/m in place? Because there's insufficient access to get the a clean cut on the inside. I suppose I could cut the c/m off with the grinder. That would allow good access to the chassis. I could then cut the chassis bottom off quite cleanly, and the c/m could be welded back together again. It's possible but not very pretty.

Another problem is drilling those holes and fixing the nuts. In the real world it's very hard to do these thing accurately enough to allow reassembly afterwards. It's more than likely one of the bolts will not go back in because the hole is out or the nut is slightly out of plumb.

Hmmn ... what would Harry Potter do?
 
My previous vehicle had two bits of galvanised threded bar welded in where the captive nuts had come free. For anyone else taking it off its worth soaking for a few days with penetrating oil wirebrushing the exposed threads and using an impact to save yourself the hassle
 
It's always the little jobs that turn into a nightmare!
I had a similar problem and ended up grinding the bolt heads off to remove the cross member and then grinding off the threaded stubs in the 'chassis'. This left me with a good idea where the centres of the original captive nuts where. I drilled a hole in the flush threaded stub deep enough to locate a ground down end of some threaded bar about the same dia as the original bolts into the hole then welded the whole lot up. My chassis bottom was sound and weldable. There is a bit of diametral clearance in the 3 short tubes which go through each end of the cross member so you have a bit to play with if you don't get the centres of the threaded bar spot on and can always be persuaded with the FIAT friend in the form of a portable hand operated kinetic energy device!
I discovered that the reason why the cross member and retaining bolts rust up is the drainage water that comes down the two gutters on the wings (from the wind screen scuttle) exiting just above the headlight assembly. This water then drains around the metal pressing behind the grill (which also rusts away) and conveniently drips onto the cross member ends which has a nice lip on it to retain the water and corrode nicely if not properly sealed and painted.
I fixed up a pipe at the bottom of each gutter just above the headlamp which now drains rainwater away from the cross member and seems to have considerably reduced the c/m corrosion problem. The rubber pipe in the scuttle which is supposed to drain the rainwater on the passenger side only works if you are parked on a driver's side kerb and then drains it over the gearbox if you haven't extended the pipe! Maybe they never get rain in Italy!
I don't think the c/m is regarded as a structural component for MOT purposes just an elaborate rusting radiator support so as long as it looks right I don't think anybody will query it's retaining properties.
Hope you get it sorted. Coppercoat is the FIAT dismantlers friend.
 
toyogran said:
It's always the little jobs that turn into a nightmare!
I had a similar problem and ended up grinding the bolt heads off to remove the cross member and then grinding off the threaded stubs in the 'chassis'. This left me with a good idea where the centres of the original captive nuts where. I drilled a hole in the flush threaded stub deep enough to locate a ground down end of some threaded bar about the same dia as the original bolts into the hole then welded the whole lot up. My chassis bottom was sound and weldable. There is a bit of diametral clearance in the 3 short tubes which go through each end of the cross member so you have a bit to play with if you don't get the centres of the threaded bar spot on and can always be persuaded with the FIAT friend in the form of a portable hand operated kinetic energy device!
I discovered that the reason why the cross member and retaining bolts rust up is the drainage water that comes down the two gutters on the wings (from the wind screen scuttle) exiting just above the headlight assembly. This water then drains around the metal pressing behind the grill (which also rusts away) and conveniently drips onto the cross member ends which has a nice lip on it to retain the water and corrode nicely if not properly sealed and painted.
I fixed up a pipe at the bottom of each gutter just above the headlamp which now drains rainwater away from the cross member and seems to have considerably reduced the c/m corrosion problem. The rubber pipe in the scuttle which is supposed to drain the rainwater on the passenger side only works if you are parked on a driver's side kerb and then drains it over the gearbox if you haven't extended the pipe! Maybe they never get rain in Italy!
I don't think the c/m is regarded as a structural component for MOT purposes just an elaborate rusting radiator support so as long as it looks right I don't think anybody will query it's retaining properties.
Hope you get it sorted. Coppercoat is the FIAT dismantlers friend.
Click to expand...

Thanks for the tip re: drainage (y)
 
Remember that if you ever break down, the towing eye is on the crossmember, which is bolted to your (rusty) chassis. i would make sure the repair is beefy enough to take a tow.

I fitted a new crossmember because I got an advisory at MOT time (even though the crossmember is not part of the MOT). When it was off, it looked OK, just a wire brush and bit of paint would have done. The trouble is you cannot take a chance as motorhomes often need to be towed out of soft ground. Mine has a few times and it weighs nearly 5 tonnes when loaded for a trip.
 
Many thanks to all who replied. In the end I took a 9in angle grinder to the problem bolts. Welder's coming next week. Good point about making sure the repair is strong enough to withstand towing, BTW!
 
I tried removing my cross member and experienced similar issues as others on here related to the fixed thread becoming loose within the box section. I decided that the fixed thread can be replaced by a stainless threaded rivet nut. Considering that the cross member has a minimal load exerted on it and it's main task is to support the rads and provide a fix point for a tow rope that this method would be sufficient to the task.

After all is fixed I'm going to fill the horns with waxoil to ensure that nothing is going to rot (hopefully).


TOOGOO(R) Insert 304 Stainless Steel Flat Head Rivet Nut Threaded M12 Amount: 5pcs (Amazon £2.40 ish)

US PRO LONG ARM THREADED NUT RIVETER M3-12 B5434 (Amazon £35 ish)

if you decide that the riveter tool is too expensive the insert can be fixed using a 12mm screw, washer and nut. Screw the nut onto the screw. Screw the nut and screw into the rivet nut ensuring the washer is in place between the nut and flat head of the rivet nut. Insert the rivet nut into the box section. Hold the head of the screw still with a ring spanner and tighten the nut against the flat head of the rivet nut via the washer (to reduce wear between the nut and head). The nut in turn will cause the rivet to compress and fill the hole fixing the nut in place :D


Before you decide to tighten the nut ensure the screw is fully engaged with the thread of the nut to ensure minimal risk of damage to the rivet nut.


The nut is designed to create a threaded hole in sheet metal.


The compression tool is around 12 inches long and needs clearance of around 14 inches to allow its use. Ramps help :)
 
From what I have seen on cars it would seem that a lot of parts like wings etc that just bolt on are all assembled before the shell is dipped in the primer coat so all of these hidden bolts are difficult to remove not because they are rusted but because they have a coat of paint .
 
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