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MG TD TF 1500 - Master Brake Cyl Replacemant

I am replacing the Master brake cylinder (MBC) on the TF (the PO used a near, but not like, version with an unremovable lid!).

It is now out (though I am still struggling to remove the floor board for better access).

The nuts which attach to the two bolts securing the MBC to the chassis are located behind a plate with d**n all access from above/below or the side and a only a small slot at the bottom of each end.

Please, what is the trick to get the nuts back on the end of the bolts.

If it helps to know this is a returned LH drive export car which has been made RHD and the pedal box appears to have been welded on, but I suspect that is how it was originally on a RHD car.

IanB
Ian Bowers

IanB, I am pretty sure originally on LH drive cars they are captive nuts welded in the frame, mine are. The switch from left to right is probably why yours are not. You might try holding the nut with a magnet to get it started.

Regards,
Rich
Richard Taylor TD3983

In similar circumstances I have used an open end or box wrench (spanner on your side of the pond?):
Place a small (1" round piece of duct tape to lightly hold the nut in/on the wrench, stick it up into the restricted area.
Have several nuts available - you will (I usually do) drop the first couple.
Bob;
RwB Brown

Not sure if you have room in there, but I have a needle nose vise grip I use for such tasks. Not sure what they're called over there? In some cases I've also been able to use JB Weld to simulate a captive nut. Have fun!
Ed
PS: How is the new shop coming? Any pictures?
efh Haskell

Apologies for the slow response, our ISP has been down so no access to the wider world.

Just to update, there is just NO access behind the plate to hold the nuts in place, the fuel pipe and speedo cable are also threaded through pretty well filling the very small access hole.

My thoughts for now are to drill out the bolt holes in the plate and use a Helicoil through to the chassis plate and cut off flush.

I would welcome any advice on the pro's and con' of this approach.

And, Ed, business progresses but times are a bit harder than for a long time!

IanB
Ian Bowers

Ian, Avation Rivnuts, I'm pretty sure you can get them in the UK. You need to borrow an insertion tool, which fastens them in the hole, creating a set of threads. They come in various sizes. PJ


Paul sr

Paul

Thank you for that thought. They look as though they are either hammered home or fitted into a haxagonal hole. Can you describe the fitting in more detail.
Ian Bowers

ian, rivnuts are fitted into a round hole with a notch..the notch will match a tab on the rivnut. a special tool (that has the appearance of a hand operated tree limb pruning tool) is used to install the rivnut. the rivnut is threaded onto a mandrel on the tool, the rivnut is then inserted into the hole with tab aligning with the notch. the handles are then squeezed together...this draws the mandrel toward the tool compressing and expanding the rivnut. once the squeezing part of the operation is complete the mandrel is unscrewed from the rivnut. regards, tom
tom peterson

Ian, Here's a couple shots of rivnut insertion tools. There's also one that looks like a pop rivet gun. They are pretty expensive, that's why I suggested a rental or borrow one from someone. PJ




Paul sr

Paul

Your help is much appreciated.

I am now trying to work out whether to go down the Rivinut route (we can get them in the UK), which will require recessing the master cylinder to accept the Rivinut heads. If the Rivinut can be cut to just the correct length to lie flush against the chasis side member, the Rivinut head would look to make a very strong fix for essentially only a shear force.

The alternative is Helicoil, which should not require any work on the master cylinder, but the plate into which the holding thread is cut is not overly thick and may not provide enough strength to cope with the shear force if anything is even slightly out of alignment.

Helicoils I have used before very successfully but set in quite deep sections.

If anyone has comparative experience, please do let me know, this is a pretty irreversible piece of engineering!

IanB

Ian Bowers

Ian, I have used Heli-Coils also and totally agree that they are very strong when inserted properly! Not sure what depth your working with, but I wouldn't think they would work very well in anything with a 1/4" or less thickness. There are various rivnuts for various applications, metal thicknesses and made from various materials. Applied properly they will take a lot of stress, usually more than the surrounding material. Personally, I would use the Heli-Coils first, if they'll do the job. PJ
Paul sr

Paul

Many thanks for your advice. In the end I used Rivit Nuts (M10 because those are the only ones available in the UK; 13mm clearance drill). They worked a treat, and I fixed them with the simple use of a M10 nut with the threads drilled out and a washer; the nut against the Rivit Nut held with a spanner to pevent the nut from turning, then a washer and then a M10 bolt through these and screwed in to the Rivit Nut until is cried for mercy.

Thank goodness for the new car lift making working under the car a breeze.
Ian Bowers

This thread was discussed between 12/07/2013 and 22/07/2013

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.