I have a rod change box that was reconditioned approximately 12 months ago. The gear changes in the car are fine until the car has been driven for 20 minutes or so. At this point the clutch has to be pushed closer to the floor and all gears are more difficult to select. I'm thinking it is a fluid issue of some sort but seeking guidance from the brains trust as to how to solve the issue.

A mate had this problem once, it turned out to be not enough endfloat on the idler gear. Clearance there reduces as the box heats up.
He had under .002" clearance, was not quite enough.
Minimum is .0035" (3-1/2 thou) I think without looking it up.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Doc. If that is the cause then my mini specialist can look at it as he reconditioned the box.

Hi, pretty unusual problem in a rod change. something bent or tight ! always difficult to find as its not hot when recoing, and then all sorts of gearshift get bolted or pinned up !
I have also seen the lower selector shaft bent, the one that goes inside the gearbox from the rod change sleeve.
The easiest first try imho is to borrow a known gearlever/ rod change system and bolt it on... then you can identify internal or external...remember the sleeve has to be able to move a bit too
cheers Lindsay Siebler

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1967 EX works rally mini restoration virtually complete OBL45F
1965 Mk1 Cooper S
1970 Colt 1100F SS
2014 Mitsubishi Imiev fully electric daily driver
1948 Allard M coupe Olds 215 v8 project
1971 Twin cam Escort ex Uk championship winning rally car project

I would start with the basic clutch adjustment first before getting too carried away.
Firstly loosen the small 1/4 " clutch adjusting bolt lock nut and unscrew (anti clockwise) the 1/4" bolt 1 full turn and re tighten the lock nut.
Secondly unlock the 2 large throw out plunger stop nuts and loosen them 3/4 to 1 full turn.then Re lock them together.
Once you have done this, try it and see if the situation has improved. From your description, if it is simply a clutch adjustment problem this should correct it.
Alternatively get someone who is familiar with mini clutch adjustment to check it for you.

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I agree with Sitnlo62 on clutch. Just another thought, what grade oil are you using.
Penrith HPR30 20W60 high zinc will also assist with better gear shifting.

Thanks guys. I'll have a play with the clutch adjustment on the weekend and go from there.

The Penrite Mini is meant to be the high zinc oil.

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http://www.youtube.com/user/Hanras

Quick update. Completed a clutch adjustment on the weekend but the clutch pedal still had way too much free play. Upon closer inspection, the clutch pedal clovis pin was nowhere to be found. I searched under the floor carpet and located one R-clip and one clovis pin. The R-clip had bent so would not stay in situ. One new R-clip, replaced the clovis pin and now have a clutch peddle with no free play. Always amazes me what an old car will throw at you.

Mark

Its variable. Penrite Mini isn't as high as standard Penrite oils surprisingly. I've always wondered what Penrite mini brings to the table for the extra cost. I don't believe its anything actually.

http://www.penriteoil.com.au/assets/pis_pdfs/HPR%2030%2020W-60%20(Mineral).pdf

Versus:

http://www.penriteoil.com.au/assets/pis_pdfs/HPR%2030%2020W-60%20(Mineral).pdf

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Mine did the same thing! But mine was bad all the time, not just after the engine heated up

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The Penrite HPR range is their high Detergent Range whereas the Classic range is low detergent-. Low detergent oils increase the effectiveness of film formation ( a good thing). Hi detergent oils tend to clean away the film as well as varnish etc -not so good on the film bit, but their formulation is generally much higher Zc and Boron to allow for this.( they can achieve higher service intervals with this model) so the 10 10ths Race oil Modern could have 2200 ppm zn/boron etc in a high detergent base, where the classic formula has maybe 1600ppm in a low detergent base- and both offer good protection levels. Edit THIS IS MY INTERPRETATION ONLY so please do your own research. PS Break in oils tend to be LOW detergent oils

Thanks for taking the time to spell this out. I figured there was a trade-off with zinc levels somewhere, as each and every formulation of mineral viscosity have specifically different levels of each.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I would ditch the R clips (Especially if you have them on the brake pedal ) and re-fit split pins, simply because the current type of R clips are nowhere as good as the old type that you used to be able to buy , IE: they are a different length and profile to the ones that will suit , plus the metal doesn't have anywhere near the spring tension of the old type .

How do I know this , because I changed both my Clevis pins out some years ago and instead of using split pins , (simply because they were harder to fit ) I thought i'd use R clips only because they were easier and quicker to install (WRONG ) , twice now I have found the R clip has dislodged from the brake pedal , the pin has moved out , but not completely
so that was enough for me to revert back to split pins .

I've had this.

When the R-Clip points down, the pedal when released will push the R-Clip down against the car body, pushing them out. I changed back to split pins and was a little easier going in how I bent them over so I could geth them out agin without too much stress.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.