15 replies to this topic

[Gavroche]

Hey, 

 

Two months ago, a noise appeared in the car while driving with gear 1, 2 or 3 but not the 4th. Everything pointed out the layshaft in the gearbox, and here we are, working on the gearbox. After having disassemble every piece of the gearbox, we have noted that the layshaft does not fit properly in the gearbox case. At first we thought it was the layshaft that was damaged, and we bought a new one. But this new layshaft is even looser in the case than the old one (the thinnest part of the layshaft in the gearbox case got some loose) !

 

We thought that our case was the problem because of this article, and bought a new one on the internet, but still the same loose between the layshaft and the case.

 

Testing a third used layshaft from a third gearbox, and the loose disappear in the new case, and nearly in our old case.

 

As a result, our old layshaft (knowing that our old layshaft is really damaged on that surface) and the new one have 16mm diameter at the thinnest end (see drawing), whereas the third used one has a 16.1mm diameter. I went to my shop testing out a bunch of other new "reinforced" layshafts (C-22A1739), and all of them were 16mm diameter (I think they all came form the same production series and thus have the same dimensions).

 

Does anyone on the forum has an old layshaft to measure, just to tell me what is the proper diameter to have ? Do I have a chance to get a 16.15mm or even 16.2mm diameter layshaft that fit my old case ?

 

P.S. : My mini is a 1992 British Open with carburettor. So the gearbox is a RodChange A+ with a 3 steps layshaft.

 

Attached Files

•  DAM3187.jpg   28.86K   2 downloads

[Spider]

I'll come back with the dimensions of the factory shaft a little later, however, there are a number of shafts getting about that are warped presumably from the hardening processes and from what I've noticed, this is usually the issues with these shafts. The casings, especially in later years, were poor, but from what I've found, this results in sloppy fits rather than anything tight.

 

I've found the Layshafts from Swiftune to be excellent.

[Spider]

The dia of the little mounted end is 16.00 mm.

 

If your case is worn (and the odd one will wear), I'd suggest boring it bigger, fitting a sleeve and then re-boring it on centre and on size + fitting clearance.

[Gavroche]

Thanks for answering my questions and the measure !

 

But is it normal those 16mm layshafts does not even fit properly in the brand new case we bought ( > new case is badly produced so ?) ?

Do we agree that there should not be any radial loose between the case and the layshaft ?

The sleeve sound like the best option, but I can't do it my self. It should be very precise, isn't it ?

 

I have check the Swiftune layshaft, clearly not in our budget.

Edited by Gavroche, 26 July 2017 - 09:12 AM.

[nicklouse]

what is the part number on the new gearbox?

[Gavroche]

22G2383 small idler bearing and 4 bolt retainer. (written DAM3220 on the case if I remember well)

 

 

P.S. : I know it is not the good case for my Mini. The guy from whom we bought the case did not put the good references on the selling announcement. We are sending it back to him next week.

Edited by Gavroche, 26 July 2017 - 09:24 AM.

[Spider]

There is nearly always some play between the layshaft and the case on the little end, especially with the cases intended for the late 3 step layshafts, as there's less 'meat' to support them.

 

If you were to consider a bore & sleeve operation, it would need to be done in a suitable machine, like a Mill.

 

The very latest 'brand new' gearbox cases (which are debatable if they are 'new') are really bad from the ones I've been through in regards to casting and machining quality. I find I spend 2 - 3 days on correcting them before they can be assembled satisfactorily. The 'new' gearbox cases that I've had my hands one were clearly assembled (possibly as a spare part complete gearbox or maybe even with an engine) but not run, then disassembled and sold off in parts.

 

The DAM3220 from my experience, while reasonably well cast and machined are one of the weakest gearbox cases they ever made. I gave up using them for anything long ago.

[Gavroche]

Does any of you have experience parts that come from MOSS MOTOR ?

We found out they are also producing parts for classic Mini, maybe their layshafts are "bigger" than the Minispare's one.

[Gavroche]

Hey, 

On my usual french forum, one guy confirmed me that the original layshaft was 16.1mm at the little end. He measured 3 old layshafts (one dead) and the results are 16.1, 16.1, and 16.09mm !

I'll try out those MOSS MOTOR parts this week, buying a layshaft just to see if they are produced well.

 

 

The very latest 'brand new' gearbox cases (which are debatable if they are 'new') are really bad from the ones I've been through in regards to casting and machining quality. I find I spend 2 - 3 days on correcting them before they can be assembled satisfactorily. The 'new' gearbox cases that I've had my hands one were clearly assembled (possibly as a spare part complete gearbox or maybe even with an engine) but not run, then disassembled and sold off in parts.

 

 

The gearbox cases from 1980's Mini are better quality ? (the one I have is a big idler bearing + 3 holes only for the retainer).

[Spider]

Curious as the bearings in the Gearbox are either full Metric or Imperial / Metric hybrids. 16.1 mm isn't a typical bearing size in either metric or imperial and while I know we are talking about a 3 step shaft, the little end of these is the same size as the 2 step shafts, upon which the Layshaft bearings ran. The shafts I've measured and gave info on were also factory shafts, not re-made replacements.

 

The Gearbox cases from about 1984 through to about 1992-ish were about the best of the bunch.

[Gavroche]

So, we bought a layshaft from Moss Motor. The seller told us it was from an old stock of original parts, and that it was its last one. Not that expensive (32 euros) compared to what we find in France. We measured it, and it was 16.1mm at the little end. It fits correctly in my old case and the play is really low between the shaft and the case. You can feel the play, but you can't heard any sound coming from it when shaking the shaft on the contrary to the "newly" produced one we bought.

 

We are currently building back the entire gearbox, and it does not seem we have any trouble besides having lost 2 bolts from the right differential gasket !

It seems that those bolts may be used to attach the bottom of exhaust manifold. Can anyone with a STAGE 1 mounted take a picture of the attach ?

 

Some particles may have felt down into the gearbox when assembling it (dust, what so ever ... ). How would you wash the gearbox before running it ? I was thinking of pouring motor oil on it, then filter the oil, and pouring it back and again (basically oil shower). I don't know if it can be a good idea.

[Gavroche]

Good news, we restarted the car. It revives, and the gearbox does not make anymore noise !!! Problem looks solved.

 

Still, we got some vibrations coming from the clutch. The vibrations only appear when the disc goes in contact with the plate (when engaging). It does not vibrate at all when clutch's disc is fully engage or fully disengage. Any idea ? We changed the clutch's disc and the diaphragm with new parts (LUK parts). 

[Rorf]

I have an early 80s A plus box and have just measured the small part of the layshaft and it is 16.1mm. Measuring the diameter on the worn side and it comes in at 16.04mm (2 thou of an inch wear). Strange I would have thought the aluminium casing would have worn first?

[Gavroche]

Well the worn layshaft we had looked like it has been shot-blasted (hammered with little balls to hardened the surface by deforming it). We could see it has been submitted to little shocks that deformed the layshaft's end.

 

I think the case was deformed too (in my case), but not as much as I thought ... The layshaft with good measure fit pretty well without a huge play. It may not last for 20 years or more this time, but I hope it will do the job for 10 .

[mini13]

somthing I heard of recently is using a hydraulic ram to squish a part like this slightly to she hole shuts up and then can be reamed back to size. this was in reference to large steel parts, i wounder if it could be used i this instance.