Clutch and brake pedal arm repair made simple By Peter Laidler

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1 Clutch and brake pedal arm repair made simple By Peter Laidler You just know that when I do a repair of any sort, it s going to be simple and true to form, this is just that too. Following from my recent article, the trials and tribulations fighting my clutch refurbishment and soon afterwards, taking the whole thing apart again to replace the bulkhead engine steady bracket (see articles REPAIRING BROKEN ENGINE STEADY BRACKET and REPAIR AND RENEWAL OF THE OUTER CLUTCH OPERATING SYSTEM in THE MINI RELATED HOW-TO PART of the Tech Forum). I mentioned the elongated clevis pin hole (the CPH hereafter) in the brake and clutch pedals. Quite soon afterwards, a couple of forumers asked me if I d elaborate on what I did that appeared so simple in writing that I just glossed over it. Yes, it was simple, made even simpler by a couple of strokes of good fortune which I m going to pass on. Sadly I didn t photograph that sequence of repairs and the rebushed pedals and pedal box have now been replaced in the car. So a couple of apologies are called for. We didn t have the original clutch or brake pedals to show so I ve just fabricated a simple top-half same thickness stainless steel replica of the clutch pedal we were working on in order to illustrate and explain. And secondly an apology for going on about bushes being trimmed, oversize bushes and bushes in general!! And thirdly, later, for the squeamish, for referring to squeezed balls. Phew., eye watering or what? I won t go into the maths and geometry of the pedals except to say that a little bit of unwanted movement at the CPH equals about 5:1 movement at the leverage end of the pedal. This is the last thing that you want, believe me! Personally speaking, I believe that this wear at the CPH in the clutch system (not so much in the brake system I hasten to add) is the main source of clutch trouble in the Mini. It s because owners just refuse to believe or admit that a seemingly small amount of wear at the pedal end is capable of causing the grief at the clutch end in other words, slack movement = no movement! In simple engineering terms clevis pins are nothing more than hinge points and in our clutch pedal, articulate horizontal movement of the pedal into vertical movement at the M/cylinder. Physics lesson over

2 So we ve inspected the pedal and instead of being a nice firm sliding fit, the clevis pin is loose and rocking in the hole or as we say in engineering circles,.its like a sausage in the high street... The ovalised CPH in our facsimile clutch pedal shown against a 5/16 bolt to illustrate the point. Remember that 1/8 slop in the CPH will give you approx 5/8 of slack at your foot Once you have the pedal box out, for whatever reason, you must inspect the CPH s and be honest with yourself about their condition AND about the condition of the cheap CPins too. ANY slop is unnecessary. There s four simple answers a) replace the pedal(s). Perfect solution if you re rich and even better if you re paying someone to do the job for you b) have the oversize holes welded up and re-drilled. A tad more difficult but still a good lasting repair or c) bore through the pedal and push rod CPH s to the next CP diameter, 3/8. But you re really closing your repair options down. d) simply re-bush what you ve got. Part D is what I ve done and is what I m about to show you how. I went to my local model engineering supplier and told him what I wanted and wanted to do. These model engineering blokes are pretty clever because he had, on the shelf, a length of nickel tube with an inside diameter of 5/16 and outside dia of 3/8. If the elongation is less that 3/8, we re quids in. If not it meant machining a new bush on the lathe. Guess what.. Yep, so I bought a 12 length for a couple of quid!

3 The piece of nickel tube and a couple of newly cut bushes on a 5/16 bolt shank. JUST right and ready to go Caption: The 5/16 i/d and 3/8 o/d were just what I needed. If the elongation were any greater I d have had to make from scratch Having got the nickel bush material we parted it off to the width of the clutch pedal PLUS.020 then drilled through the elongated hole with a 3/8 drill to make the old oval hole into a 3/8 round one. Now the new bush was a push fit into the oversize hole. So far, so good and so simple To secure the new bush in the hole you can simply soft solder it in place if you want. It ain t goin nowhere as it s supported at each end by the master cylinder push rod arms. Or you can do what I did and as shown here. By getting two old ball bearings (these came from a knackered hub bearing.), placing one into each end of the slightly over-length bush (.010 each side don t forget ), put the arm into the vice and gently squeeze the balls hard, one in each end, into the new bush.

4 The balls sat into the new slightly proud bush. Sit a ball, one into each end of the new.020 over wide bush and gently squeeze them down in your vice jaws (or a whack with a hammer!) to spread the bush to form a tight fit in the arm Doing this will slight bell-end the new nickel bush, spreading it a tad and securing it into the clutch or brake lever. That way it s secure for good. The saddle or yoke end of the clutch push rod will clear the slightly extra width. The balls have been squeezed and spread the bush. Bush is now bell-ended and a tight fit in the pedal lever. Now the CPH is the correct 5/16 inside diameter as shown by the shank of the bolt and clevis pin. Job done! Now, talking of bushes, while you re down there ooops, apologies again.. what about a close look at the brake pedal CPH

5 too? Same meat, different gravy... I know the next question you re going to ask.. And it s this. Surely, if the clutch pedal hole is elongated, then the same will apply to the clutch (and brake.) master cylinder push-rod. The yoke part is even thinner material and therefore more liable to elongate. Yes, I agree.but! The fact is that by the time the pedal CPH has gone oval, there s every chance that you ve gone through several new master cylinders so it won t (?) be a problem. Or will it? If it was mine I d be doing something similar to that above. First I d overbore the ovalised push rod CPH s round. Then machine a couple of nickel-brass or steel top-hat bushes as shown in the accompanying photo. The INSIDE diameter is 5/16, the diameter of the clevis pin The SMALLER diameter part of the bush is the diameter of the now oversize CPH and the depth of the small diameter is the thickness of the yoke legs. Don t worry, the photographs will show what I mean. The LARGER diameter is close to the width of the yoke part. With me so far? Then simply soft solder the new bush into the holes, to each outer side of the old yoke. Problem solved. (If you re concerned that the soft solder (or hard/silver soldered) heat will affect the rubber boot further up the shaft, then don t worry. If you don t want to peel the boot off just support the rod upright with the rubber boot bit downwards, immersed into a jam jar full of water. Solder it that way. Easy eh!)

6 An example of a top-hat bush for the push-rod The small diameter sits neatly into the oversize yoke hole supported by the large diameter soldered to the outsides of the yoke. All you need to complete this is to use a slightly longer 5/16 CPin available on the web or from any hardware supplier Things you ll need: BUSH MATERIAL. Any 5/16 i/d nickel or other tube. Available from any model engineering supplier or ask me for a short length. I don t get asked very often now!! OR simple to turn up on a lathe from suitable material Make 2x top hat bushes if you re doing the master cylinder CLEVIS PINS; 3x new 5/16 dia. Get stainless, cheap on E-bay and do the upper clutch lever arm while you re there. And the cost. Forget the pleasant couple of hours faffing around in the garage. Just think of the alternative, traipsing around John Lewis with wifey. The cost, a couple of quid for the new clevis pins and a bit of nickel/brass or steel offcut