Technical Undertray fixings

[SiloSean]

Dear All,

My 63 plate 4x4 failed the mot the other week, propshaft centre bearing and front lower suspension arm bushs on both sides. Nothing I wasn't really suspecting.

Propshaft was changed without needing to lift the wheels off the floor. Not an easy task that way, access is limited, but possible and safe.

The suspension arms are a right pain, I can't believe how much has to be stripped to get access to two bolts! Front bumper, undertray and subframe support arms.

Anyway, removing the undertray, a couple of bolts sheared, a third one was already rounded and had to be cut off. They seem to screw into rivnuts and I wondered if anyone here has replaced these? I thought was to grind the flange back and knock the rivet through, then fix new rivnuts in their place. I assume someone here has done this, just want yo ask if they are a standard M6 rivnut 8.9mm od through a 9mm hole? Did you use steel or aluminium rivnuts, did to copper grease the bolt when refitting?

Any pointers would be much appreciated!

 

[JayAre]

I trust you’re not working under the car with just the hydraulic jack supporting it..

Plan for Your Floor Jack to FAIL!

toolguyd.com

 

[SiloSean]

I trust you’re not working under the car with just the hydraulic jack supporting it..

Plan for Your Floor Jack to FAIL!

toolguyd.com

No, there's an axle stand behind the jack. If you zoom in you can just see it just to the right of the jack, but it's basically the same colour so difficult to see it. It's a commercial axle stand, not like the pressed ones from halfords.

 

[WitleyPanda]

On the sump guard they are M6 standard fasteners. Instead of removing the rivnuts I carefully drilled out the broken portion of the bolts. This is easier if you can grind square. I also have access to a small lathe so drilled a short piece of bar to act as a guide. Plenty of copper slip on the bolts, then lanolin on the plate and surround.

 

[jackwhoo]

I zoomed in and saw the most important workshop item.....tea pot . Plus a catering size pack of tea bags .
Well done that man

 

[SiloSean]

On the sump guard they are M6 standard fasteners. Instead of removing the rivnuts I carefully drilled out the broken portion of the bolts. This is easier if you can grind square. I also have access to a small lathe so drilled a short piece of bar to act as a guide. Plenty of copper slip on the bolts, then lanolin on the plate and surround.

My brother tried drilling one in the support arm before we refitted it, but the pilot snapped and we couldn't get it out. Now can't drill any further down and can't get the remains of the bolt out. I should have just ground the flange on that one and knocked it through when I had the chance. Unfortunately, didn't think about it at the time.

I wondered if anyone had changed the rivnut complete, guessing it might be easier. If so they may know what size the existing hole was.

 

[WitleyPanda]

My brother tried drilling one in the support arm before we refitted it, but the pilot snapped and we couldn't get it out. Now can't drill any further down and can't get the remains of the bolt out. I should have just ground the flange on that one and knocked it through when I had the chance. Unfortunately, didn't think about it at the time.

I wondered if anyone had changed the rivnut complete, guessing it might be easier. If so they may know what size the existing hole was.

Try a carbide drill? Or a grinding point in a Dremel. That was partially my reason for the guide as well as keeping the drill true, to minimise potential breakage. I did not known that the hole size was standardise, it tends to vary depending on manufacturer and material of the rivnut.

 

[Panda IIs]

Dear All,

My 63 plate 4x4 failed the mot the other week, propshaft centre bearing and front lower suspension arm bushs on both sides. Nothing I wasn't really suspecting.

Propshaft was changed without needing to lift the wheels off the floor. Not an easy task that way, access is limited, but possible and safe.

The suspension arms are a right pain, I can't believe how much has to be stripped to get access to two bolts! Front bumper, undertray and subframe support arms.

Anyway, removing the undertray, a couple of bolts sheared, a third one was already rounded and had to be cut off. They seem to screw into rivnuts and I wondered if anyone here has replaced these? I thought was to grind the flange back and knock the rivet through, then fix new rivnuts in their place. I assume someone here has done this, just want yo ask if they are a standard M6 rivnut 8.9mm od through a 9mm hole? Did you use steel or aluminium rivnuts, did to copper grease the bolt when refitting?

Any pointers would be much appreciated!

That's a proper jack! And a nice space to work in too, definitely jealous!

Bad luck on shearing the bolts, my TA 4x4 has just passed its MOT with advisories (again) on wishbone ball joint pins - this seems to be a two year recurrence so I've done this job a few times now! Bumper removal is at the point of being done blind fold now! It doesn't help you now, but my recollection is that you don't need to remove all the crash bar bolts fully for access but more importantly the undertray bolts (read undertray) do not need to be removed if you are prepared to pry back the corner of the undertray that shields the bolt access, it can be "restored" with a swift hammer tap! It all depends on whether you are prepared to compromise your mechanic's principle's

First time I wasn't so ended up replacing the undertray too (used stainless hex fasteners for the future).

 

[SiloSean]

I zoomed in and saw the most important workshop item.....tea pot . Plus a catering size pack of tea bags

That's a proper jack! And a nice space to work in too, definitely jealous!

Bad luck on shearing the bolts, my TA 4x4 has just passed its MOT with advisories (again) on wishbone ball joint pins - this seems to be a two year recurrence so I've done this job a few times now! Bumper removal is at the point of being done blind fold now! It doesn't help you now, but my recollection is that you don't need to remove all the crash bar bolts fully for access but more importantly the undertray bolts (read undertray) do not need to be removed if you are prepared to pry back the corner of the undertray that shields the bolt access, it can be "restored" with a swift hammer tap! It all depends on whether you are prepared to compromise your mechanic's principle's

First time I wasn't so ended up replacing the undertray too (used stainless hex fasteners for the future).

Don't be jealous, it's the end of an era for us. We had a steel fabbing business, been doing it 30 odd years, but decided to call it a day as things are just getting harder and we're just getting older!

It's now 4000 square foot of emptyness, waiting the sale to go through and back into our pension pot. Just thought we would use it before we no longer own the place. Depressing really, cause it means I need to get a job!

 

[jackwhoo]

I don't know what too say to that........so will say good luck
J

 

[SiloSean]

That's a proper jack! And a nice space to work in too, definitely jealous!

Bad luck on shearing the bolts, my TA 4x4 has just passed its MOT with advisories (again) on wishbone ball joint pins - this seems to be a two year recurrence so I've done this job a few times now! Bumper removal is at the point of being done blind fold now! It doesn't help you now, but my recollection is that you don't need to remove all the crash bar bolts fully for access but more importantly the undertray bolts (read undertray) do not need to be removed if you are prepared to pry back the corner of the undertray that shields the bolt access, it can be "restored" with a swift hammer tap! It all depends on whether you are prepared to compromise your mechanic's principle's

First time I wasn't so ended up replacing the undertray too (used stainless hex fasteners for the future).

I've had the bumper off before, my eldest had a slight altercation with a range rover, so I changed the black quarter trim and fog light. That was a pig to do, has to be plastic welded in the back.

I would advise not putting stainless bolts into mild steel. You get electrolysis and a galvanic reaction between the two different metals. This accelerates corrosion and the mild steel will rot prematurely. Stainless needs to be isolated from mild with plastic or rubber to insulate them against electrolysis. Thus, it's better to use mild steel fixings, like bzp or black bolts, just copper grease them for protection against the wet.

 

[Panda IIs]

Don't be jealous, it's the end of an era for us. We had a steel fabbing business, been doing it 30 odd years, but decided to call it a day as things are just getting harder and we're just getting older!

It's now 4000 square foot of emptyness, waiting the sale to go through and back into our pension pot. Just thought we would use it before we no longer own the place. Depressing really, cause it means I need to get a job!

Well at least with that skill set you will be well placed to fabricate a replacement sump guard! I do however, commiserate re the working environment for small firms.

Re your guidance re materials selection in another post which I fully appreciate. I made a judgement call here based on the fact that the undertray comes off at oil changes and I like to do this regularly (TA ownership experience!) so stainless and some copper grease keeps everything functional. My car is now 10 years young so I figure that it will either self destruct or legislation will see it off before there would be a galvanic corrosion issue!

 

[SiloSean]

Well at least with that skill set you will be well placed to fabricate a replacement sump guard! I do however, commiserate re the working environment for small firms.

Re your guidance re materials selection in another post which I fully appreciate. I made a judgement call here based on the fact that the undertray comes off at oil changes and I like to do this regularly (TA ownership experience!) so stainless and some copper grease keeps everything functional. My car is now 10 years young so I figure that it will either self destruct or legislation will see it off before there would be a galvanic corrosion issue!

Might have the skills, but I don't have the equipment now. I miss the guillotine, the pressbrake, the radial drill and the welders. Week after the guillotine and pressbrake went, I needed some brackets to secure a shelf unit to a wall. I actually had to part with money for them, no longer grab an offcut of plate, cut/drill/fold it to the exact size needed. No, I had to BUY some from Screwfix, then cut them down to suit and redrill. I was gutted, I hadn't bought a bracket ever before. I always just knocked something up out of scrap. That I will miss.

Sump guard was in good condition, the only rust being on the tin plates on the front corners, bit of rust killed and repaint, should last a few more years.

I think your right about legislation, we need a ticket to wipe our backsides, so driving a car with a horrible, dirty, polluting combustion engine car is bound to become illegal. They're certainly making it more expensive. I went Heathrow the other day to drop someone off, £5 for drop off, plus an extra £12.50 to come off the M25 another 4 miles to the airport. How can the Ultra Lower Emissions Zone include an airport, surely jets are not exactly clean? It is just another tax and another reason not to go to London.

 

[Panda IIs]

I think your right about legislation, we need a ticket to wipe our backsides, so driving a car with a horrible, dirty, polluting combustion engine car is bound to become illegal. They're certainly making it more expensive. I went Heathrow the other day to drop someone off, £5 for drop off, plus an extra £12.50 to come off the M25 another 4 miles to the airport. How can the Ultra Lower Emissions Zone include an airport, surely jets are not exactly clean? It is just another tax and another reason not to go to London.

Absolutely; the inclusion of LHR in the ULEZ is a blatant money making exercise. I use the airport fairly regularly and my regular rides (classics) both cop the "tax". There are also implications for the offsite parking Companies where you drop the car off and they then drive them off to remote parking spots, cars have to be paid for when ever they are driven in the zone...