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MG MGA - Pedal Spindle Binding

My pedal spindle is almost solid with the pedals, but not quite. I remember this one from many years ago : the more you work the pedals, the more the bushes bind.

I can just about turn the bolt, so there's hope, but I cannot think how I might tap or turn it out - no room anywhere around, and I don't want to dismantle the entire master cylinder assembly.

And to think I was happy when I walked into the garage this morning. Driving home yesterday I'd noticed there was no slack on the clutch pedal, and I thought it would entail simply adjusting the pushrod.

Anybody done this recently? If I don't get it sorted out by noon tomorrow, I cannot get to the golf course!
Nick and Cherry Scoop

Nick

Probably a silly question but I presume you have already removed the rubber boot and undone the nut at the other end of the bolt?

I had no issues a couple of months ago removing the bolt and replacing a missing missing shim between the pedals with the MC and bracket assembly in situ.

Steve
Steve Gyles

I always use a good coating of anti-seize compound when assembling any bolt into a metal sleeve, makes for a much longer MTBF

dominic clancy

Thanks Steve.

Panic over - sort of. The bolt is out, after a struggle. I managed to lever against the threaded end while spannering the bolt back and forth, and in the end it capitulated.

Now I'm faced with pedal bosses that look bi- or tri-metallic. I assume that the inner (steel) cylinder is the bolt sleeve, the larger bronze cylinder is the bush, and the dark line between them is the unknown material of seizure.

So, the pedal movements have been bearing on the bolt shank. Lovely.

Tonight I will search my conscience, and then tomorrow I will (i) try drifting the sleeves out, see what's what, and order some parts, OR (ii) sling it back together for now and play golf tomorrow - knowing that today's pain must all be borne again.

(AND it will mean asking my wife to hold a spanner again, not once, but twice - not her favourite thing)
Nick and Cherry Scoop

Dominic - what is anti-seize compound?

(and what is MTBF?)
Nick and Cherry Scoop

Parts ordered, and hoping the bushes will not need reaming (Barney says not).

So, what do we lubricate with?
Nick and Cherry Scoop

MTBF = Mean Time Between Failures

From a quick google search (easier than explaining myself :-) .......
Anti-seize compound is used for the threads of fasteners in some applications. The purpose of the compound is depend upon the application and it can prevent galling of mating surfaces in such that compounds are frequently used with stainless steel fasteners to prevent this effect from occurring. In applications, they are used to improve the corrosion resistance to allow the parts to be subsequently disassembled. And thirdly, this can provide a barrier to water penetration since the threads are sealed by the use of compound.
These anti-seize compounds are used on screws and bolts to prevent galling. When galling occurs at a microscopic level, the local high spots between the two rubs will and weld together. If attempts to move the parts cause of these microscopic welds to tear, it will further roughening the surfaces of the parts and increase the roughing surfaces that continue to weld together in more and locations until the two parts are frozen together. The galling commonly occurs when the parts are of identical materials such as stainless steel bolts and nuts.
The anti-seize compounds act as a lubricant and it also lubricates the parts whereby it is between the inserted sections of tubing to ease assembly and disassembly. This is to prevent the formation of a non-conductive oxide layer on the freshly cleaned metal that includes copper and aluminum. This application base is grease like that prevents the oxygen in the air from reaching into the clean metal surface. This application is very important for cable connections and antennas especially those that used to carry receive level signals whose voltages are too low to punch through the oxide layers.
It also will reduce the galvanic corrosion in a joint of dissimilar metals. This application of the anti-seize compound will actually prevent the water from penetrating into the joint. An example: the anti-seize is used between the stainless steel flat washer or stainless steel bolt head and an aluminum plate. This is to increase the conductivity between the two parts of a joint under pressure. For this application, it requires small aluminum or copper particles in the grease like base that should be included in the anti-seize compound and when the joint in tightened these particles bridge will remain in the microscopic gaps between the parts.

Coppaslip is one brand, I use this one from Loctite, and a copper grease spray on more awkwardly shaped items

dominic clancy

This morning I have drifted out the spacers, using a ⅜" bolt with the shank as guide and the head ground circular (I know that sounds a bit "aren't I clever", but it's so unusual that I thought I'd mention it).

Cleaning off the crud, I find that the spacer/bush fit feels perfect - probably within Barney's 1-2 thou. I could just about reassemble and drive up the hill to the golf club. But I won't, because the spacers are the same length as the bushes, which is probable cause of their rotation with the bush in the first place. Plus, I haven't any Coppaslip.

I will see what the B&G parts look like when they arrive.

Thanks for your help.
Nick and Cherry Scoop

All done.

The only annoying thing now is that the brake pedal will not return the last little bit without hooking my foot under it and pulling. I can adjust this out by reducing the free play to nil. Further investigation needed.

Two things about the pedal job :-

1. Put the return springs on the pedals before you refit them - preferably lightly taping the springs upwards along the pedal.

2. Do up the two rear bolts on the rubber boot retaining plate - the ones without captive nuts - before you hook up the springs.

Simple things, but at my age I can't spend too long twisted out of shape in the footwell.
Nick and Cherry Scoop

You could reduce the bush length by sanding it down on a piece of emery cloth on a glass sheet to give it a bit more clearance or you can just use it until it wears a bit.
Mike
Mike Ellsmore

When I had my pedal assembly apart recently I was a little surprised that there are no shim washers at both ends. Instead the assembly bolts straight against the brackets. Works okay though.

Steve
Steve Gyles

I agree, Steve. No particular sign of wear there, but given the soft metal thrust washer in the middle, you would have thought . . .

Mike, I did slightly grind down the pedal face and bush to achieve a difference between bush and distance piece. On the inside, facing the thrust washer.
Nick and Cherry Scoop

This thread was discussed between 23/06/2014 and 30/06/2014

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This thread is from the archive. The Live MG MGA BBS is active now.