So after trying many different ideas in an attempt to fix the difficult to select 1st gear problem in my Cooper S I have removed the engine to investigate further.
Previously I have checked the float clearance on the primary gear, measurement is OK.
I have replaced the clutch plate and pressure plate, no difference in gear selection.
I have replaced the seals in the clutch master and slave cylinders, still no change.
I have added 20mm to the end of the clutch actuation arm, still no difference to gear selection.
Any way, engine is out now and I have discovered a few different problems from the last engine rebuild. I found one of the split pins on one end of the rocker shaft had broken and the bits were sittiing on top of the head under the valve spring..
I now think my gear selection problem may be traced to the thickness of the gasket between the engine and the flywheel housing which is black and much thinner than the old orange shaped type I hope to dismantle the engine tommorrow to prove my theory, but in the meantime, I a question for the gurus...
Should I try and obtain an orange gasket for the clutch housing or are they no longer available and if this is the case should I use 2 of the black/grey cloured gaskets?
And is this a previously discovered problem, which I assume has severly reduced the clearance of the idler gear which is limiting its ability to spin freeely?. I had noticed that gear selection was OK when the car was cold and became worse as the engine got hotter.
Gearbox is a 4 speed all synchro type and was OK until I removed the engine for a refresh of rings and bearings, gearbox was untouched.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Does it crunch when you go from neutral to reverse?
If so the clutch is dragging, or maybe the primary gear is too tight on the crank.
Either will make it hard to get 1st gear from a standstill.

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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.

Reverse seemed to be OK. It was mainly 1st gear which would not go in when stopped at the lights and in neutral. No matter how hard you pushed on the gear lever. Usually went into 1 gear after a few attempts moving from 2nd to 1st.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

New Mini K and Cooper S often had this problem. It's one reason Issigonis resisted putting synchro on 1st gear way back when.

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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.

Yes but gearbox was quite good prior to engine rebuild.
I expect to know more after I dismantle tommorrow night.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Measure the endfloat on the idler gear (with original gasket) after you get the engine off.
But if it changes other gears OK it's not this.
Also check endfloat of primary gear (gasket thickness does not affect this) and gear rotates freely on crank.

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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.

According to Vizard (page 142) the idler gear end float should be min 3 thou. max 8 thou.
Perhaps you could check the clearance when you dismantle ie re-assemble the clutch housing onto the gear box with the existing gasket. That should answer your gasket question.

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

8 is a bit much, I like 4 to 6.

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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.

As Doc said. 4 synchro boxes can be fickle. Give me the MK 1 S 3 syncro & its sweet ratios anytime.

It your'e gunna split the box n & engine (again) I would be tempted to look further at the 1st/2nd selector fork and the other high wear areas, layshaft bearings and first motion shaft spigot bearing.

Bit of extra work, but think how much $$$'s you save by doing yourself, the extra knowledge, self satisfaction etc.

Besides, there's absolutely squat on TV these days!

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

If, &-or whenever anyone changes the primary case gasket (for whatever reason) the idler gear end float will more than likely have changed , with the difference in thickness of the primary case gasket,,, it`s allway wise to set this idler gear end float up "With" the gasket you`re going to use... just simply swapping one out to a thicker or thinner is neither here nor there & very bad practise "IF" ther end float isn`t checked after the gasket swap

Bur!!!,,,, if the gasket is too thin,,, & therfor the idler gear end float is nil,,, (or near nil),,,then what will happen is it will grab up as it warms up & the car will drive very poorly,,, slow & retarded,,, , it will also feel like there is an engine brake ,,, the whole scenario is quite disasterous actually because most times this "NO-end-float" situation occurs , it causes the gearbox case & primarly case to "shred up" at the idler thrust faces & almost imposible to correct without very very accurte machining & often new (or good 2nd hand cases) are needed to correct the problem

My suggestion with this one is to rip it all apart & have a good look at everything,,, however if the problem only seems to exist with the selection of first gear & everything else seems ok,,, then my bet is that it`s a problem isolated only to first gear assy,,, but hey,,, anything can happen & it usually does

good luck & let us know your findings,,, if you`re keen to sort it properly & happy to spend what`s needed (time & money) to have it sorted then cool,,, you should do whatever it takes to find the problem(s) I know i`d rather only do the job once

I hope it`s not just a knuckle problem or a shifter problem

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

As Matt said re the gasket - Took me ages to get the idler gear clearance right - even had to get a new idler shim washer from Japan of all places ( since found where one is locally ) but ended up with the required clearance of just under 5 thou.

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

[quote="AEG163job"]As Doc said. 4 synchro boxes can be fickle. Give me the MK 1 S 3 syncro & its sweet ratios anytime.

And I was thinking upgrading to a MKII box would be a good idea! Just saved me some money

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Flute - 68 MK I Cooper S
Member: VMCI #2474
Member: International Mini Model Collectors Club

I loved being able to brake, start a slide with the handbrake, change back to first and then nail it all while on the move in the spiro slalom at Hay....

however, my 'box has been difficult to select first at times since my last rebuild - usually when the engine is cold, I was going to check that I hadn't put the lever thingy on the back of the box one spline out.

But I do have a funny feeling the gasket I used was thinner than the previous one where I had been careful to set the end float correctly - it needs to come out again shortly so there's something else to check & correct

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did I tell you that I won a trophy?

I hope to check the gasket tonight.
The gearbox has not had a lot of use since it was rebuilt a few years ago with new bearings, new shafts, new synchros and a new 2nd and 3rd gear. The car only does abot 300 or 400 miles a year as it is on club plates.
I just hpe I havnt stuffed the gearbox case by having the idler gear too tight due to thin gasket.

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

would it be best to set up the clearance at around 5 thou so next time if you need to change the gasket it leaves room for a slight variance in gasket thickness either way

its a pain to pull the engine of the box each time, thats the only real way to check the clearance (they do have a special tool i believe in the manual that allows for checking end float with engine still attached)

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77 Leyland Clubman
1293cc, LCB extractors, pulsar dizzy (recurved), cooper s disc brakes, 40DCOE Weber