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MG TD TF 1500 - Rear Mudguard Hidden Captive Nuts

There are two captive nuts at the bottom of the rear inner guards (one on each side) that secure the bottom 2 mudguard bolts. These captive nuts are hidden & are completely inaccessible. I'm able to shine a flashlight up on one side from below & can just make out what remains of the captive nut holder, although the nut is long gone. I'd like to replace this captive nut but have no idea how to do this without destroying the inner guard. I could cut a section out of the inner guard, repair the captive nut holder, install the nut & re-weld it to the rear of the cut out section, then weld the cut out section back in place, but unfortunately I don't have power where the car is garaged, so welding with my Mig is not an option. This has been sitting in my too hard basket for a while now. Anybody have any other ideas? I'd like the end result to appear original using a 5/16" BSF bolt & washer. Cheers
Peter TD 5801
P Hehir

Peter, As mine are in place, I don't remember how difficult it is to access them. Would a spring nut work sliding over the frame work? They are made in different depths, this one is of the shallow type. PJ


Paul S Jennings

Hi Peter.
there should be a rivnut (self riveting nut) application, although I have only seen metric ones recently. If you have workshop facilities you could probably make one up. We used to make them in the 50's for access panel fasteners in aluminium.
Ray TF 2885
Ray Lee

Just had a rethink.
Only a commercial rivnut will do as it has to go in from the outside.
Sorry
Ray
Ray Lee

PJ a spring nut would only work if I could cut a horizontal slot in the inner guard & then fit it in from behind but that is impossible as there is no access. If my only other option is to use one there would be much less damage & welding however. I'll try to prise the remains of the captive nut holder away today from below in the small gap I've created at the bottom between the sill panel & the inner rear guard. I also thought I could weld a nut to a length of flat bar at home, take it to the car & push it up from below, then fit the bolt through both the inner guard & the guard & tighten it. I could weld it to secure it later when I have the use of my Mig. These two are the only completely inaccessible captive nuts on the whole car!
Cheers
Peter TD 5801
P Hehir

Peter,
I think the captive nut is covered by the body cross brace. did you take this brace out during the restoration of the car? I did with my TF and although the tub is back together I have not riveted the brace to the wheel arches yet. That means at this point I could take the brace out quite easily.

My advice would be to remove the rivets and brace and then put new captive nuts in place. it may be worthwhile buying or hiring a small generator to give you temporary power at your storage garage.
Max Irvine

Did this on the TF a few weeks ago which uses 1/4" square nuts instead of the TD 5/16" square nuts. Will try to explain how I did it knowing well that a drawing would be of more value. Frist I got some square nuts (BSF) from one of the suppliers, Next I made a template of a cage using the parts that were left of the original cage. Using an old bolt and two square nuts thru the hole drilled thru the center of the metal cut from the template. Now here is the answer as to fitting it in place. Slide it up the narrow space to where the hole for the bolt is, using a bolt with a nut run toward the bolt head thread it into the caged square nut from the wheel well. Now back the nut down to pull the caged nut tight to the back of the wheel arch this will hold it in place. Now just drill two 1/8" holes, one in each leg and then weld up the holes, remove the bolt and your done. Or you can skip this last part and find someone with a spot welder. Yup it would have been better to draw a picture.
F. Driver

Hi Max. No mate I didn't remove the cross brace. I'll have a look tomorrow & see what's involved. FD I like the idea of the "running" nut to pull the cage into position. I believe a spot welder would require access from both sides however. May be able to bribe one of the tenants in the units above to provide me with some power. I think we've shifted the problem from the too hard basket to the just might be possible pile. Thanks guys. Cheers
Peter TD 5801
P Hehir

Removing the cross brace seemed way too difficult as the door pillar frame would have to come out first & I wasn't up for that. I was able to remove what was left of the original captive nut from below with a big screwdriver & hammer giving me a clean surface to start with. The holder on the driver's side was missing completely. Fabricated a couple of captive nuts & holders using a gal ant cap, some flat bar & 1/8" metal brace from the local hardware. Assembled it as show in the series of pics below to trap the floating nut in position. I riveted the 1/8" brace to the holder then painted it gloss black & made an inserting tool from scrap timber. I plan to place the captive nut assembly in position from below & then insert the 5/16" BSF bolt with large washer through the inner guard & tighten it. I'll again use a couple of rivets to secure the assembly to the inside of the inner guard, then remove the timber inserting tool & the bolt. These rivets will be hidden by the mudguard & piping. Job done. Cheers
Peter TD 5801

P Hehir

Pic 2

P Hehir

Pic 3

P Hehir

Pic 4

P Hehir

Pic 5

P Hehir

Pic 6

P Hehir

Installed the first of these today. The only change I've made for the other side is to add another rivet. Reason being the ant cap wants to part company with the 1/8" brace when drilling through from the wheel well & riveting the assembly in place. If doing this again I'd make the assembly a bit longer, use construction adhesive to secure the ant cap holder to the brace, (ensuring I don't glue the floating nut), use 2 rivets instead of one on each flap with the final securing rivet fitting between them & introduce a gentle curve into the 1/8" brace to follow the line of the inner guard. However I now have the captive nuts where they should be. No cutting or welding required. Cheers
Peter TD 5801
P Hehir

This thread was discussed between 01/04/2015 and 22/04/2015

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