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MG MGA - Layshaft quality?

My car is a 1962 MK-II with the original 1622 engine. I have my transmission apart due to a failure of the new caged layshaft bearing that I installed about 15,000 miles ago. I have obtained a NOS bearing from a local source but am having trouble getting a new layshaft. The first one I purchased from a local Moss distributor was soft. He called Moss and was assured that all of their safts were correct and Rockwelled at 52/53 Rc. That is soft enough that a file easily removes material. (I think they have left off the case hardening process.) My old shaft is hard enough that a file will not mark it at all. After rejecting two more soft shafts sent from Moss in Los Angles I purchased one from Brown and Gammons in the UK. It arrived today and is properly heat treated but the diameter is .642 and my old one is .645. It's a very loose fit in the holes in the case. Can I use it or is that too small?
Ed Bell

Ed, it will also be a loose fit for the bearings.
Art Pearse

It is to small for proper mating with the roller bearings. The shaft should be 0.6455-0.6450 diameter, serving as the inner race for 16.4mm roller bearings. When it is 0.003 too small it will cause excessive loading on a few rollers of the bearing, and accelerated wear on the shaft. If the super hard rollers survive (which they usually do), the shaft will eventually wear down a couple thou on the lead bearing side until it conforms to the working diameter of the roller bearing. This then causes a misalignment of the rotational axis of the laygear, in which case you may get an audible whine from the gear teeth under working load in the lower gears.

Case hardening of the shaft is only a few thousandths of an inch deep. Once it wears through the hard surface the wear rate will accelerate, and end of life is near at hand. I would not install the undersize shaft.
Barney Gaylord

Where can I find the specifications for a layshaft? I am looking for diameter (min. and max.) and hardness specifications if they are available.
Ed Bell

I find it in the "mga twin cam Engineering Technical Data Book", Flywheel, clutch and gearbox section. Look on page 5 of 6 here: http://mgaguru.com/mgtech/books/tdb/tdtc_f_transmission.pdf
The layshaft should be 16.4-mm diameter.
Barney Gaylord


Any word back from Moss Ed ?

As I'm in the market for a layshaft but for a 4 hole - 3 syncro late MKi MGB and may consider Moss UK if they are the correct size and properly hardened. I guess I should take along a file to test the hardness.



Mark Hester

Mark,
Moss sent two more lay shafts to the distributor that I was buying parts from. They were both soft. When called, Moss said that the original specification for hardness was in the low 50s (Rockwell) I was a machinist and Die maker for 39 years and I know that a bearing race (that's what the shaft is) should be 60 to 65 Rockwell. I purchased one from Moss several years ago that was properly hardened. They must have changed suppliers since then. The shaft I bought from Brown and Gammons was properly hardened but was undersize. They e-mailed me that they are investigating the issue and will get back to me. I still have transmission all over my work bench but I am hopefull that I will be able to reassemble it before spring.

Ed Bell

My layshaft came from Scarborough Faire and is the correct diameter. I had it tested and it was 65 rockwell.
M Wellard

Brown and Gammons were unable to furnish a correct size layshaft as all of their shafts in stock were also undersize. They did give me a full refund for the shaft I purchased. I will give Scaroborough Faire a call and see what they can do for me.
Ed Bell

I got a shaft from Moss in the US last year, and it was sufficiently hard (couldn't easily mark it with a file as John Twist shows in his video). Moss says they have corrected the problem, I believe.

JIM in NH
AJ Mail

You guys got me worried now. I rebuilt using a Moss shaft, but this thread was not going so I didn't have it tested. I guess I will just use it and do it over if it wears!
Art Pearse

We have been dancing around this issue for several months now, and I have been keeping tabs on it. The parts from Moss UK were reported to be properly hardened but too small diameter. Moss Motors USA has layshafts that are Rc-49, yes hardened, but not hard enough. A bearing shaft needs to be at least Rc-60. S.F. had some good ones previously, but have been out of stock and recently sourced a couple of pieces from Moss USA, unfortunately not properly hardened.

Today's news is that Lee Simmonds (not a BBS type person) obtained one of the Rc-49 shafts from Moss USA and took it to a local heat treating facility for service. After proper heat treating it came out with Rc-62 hardness. It just wants a little follow up polishing to restore the luster.

So the good news is (after months of fiddling around) the metal is a good alloy that will accept heat treating to the required hardness, and Lee can get his car back together. The bad news is that a customer had to solve the problem at his own expense (while other customers are still waiting), and so far Moss Motors has not even acknowledged that there is a problem with their part (let alone fix it). As always, Let the buyer beware.
Barney Gaylord

We have been dancing around this issue for several months now, and I have been keeping tabs on it. The parts from Moss UK were reported to be properly hardened but too small diameter. Moss Motors USA has layshafts that are Rc-49, yes hardened, but not hard enough. A bearing shaft needs to be at least Rc-60. S.F. had some good ones previously, but have been out of stock and recently sourced a couple of pieces from Moss USA, unfortunately not properly hardened.

Today's news is that Lee Simmonds (not a BBS type person) obtained one of the Rc-49 shafts and took it to a local heat treating facility for service. After proper heat treating it came out with Rc-62 hardness. It just wants a little follow up polishing to restore the luster.

So the good news is (after months of fiddling around) the metal is a good alloy that will accept heat treating to the required hardness, and Lee can get his car back together. The bad news is that a customer had to solve the problem at his own expense (while other customers are still waiting), and so far Moss Motors has not even acknowledged that there is a problem with their part (let alone fix it). As always, Let the buyer beware.
Barney Gaylord

I am reading the UK magazine Practical Classics, and in the May 2013 edition Moss has a full page advert for 3 Synchro Laygears and shafts quote: Manufactured to OE standards and pre-assembled with 20 needle rollers at each end for maximum support. The same advert is visible here

http://content.yudu.com/Library/A248qw/MGCarClubSafetyfastA/resources/6.htm (if you scroll forward a few pages there is also an article on MGA cooling!)

The laygear kit is available in the USA too, part numbers 461-571 or 22H54K

see here for details http://www.mossmotors.com/graphics/products/instructions/461-571_22H54K_INST.pdf

For the price of 210 GBP including sales tax, I would seriously still evaluate the change to a Ford box....
dominic clancy

Sorry about the prior double post. I don't know how that happened. It didn't show up the first time. For additional clarification, the layshaft Lee Simmonds procured came from Scarborough Faire, but is almost certain to be originally sourced from Moss Motors.

That new replacement laygear from Moss (with two long needle roller sets) is a non-standard gear with non-standard bearings. Unless Moss can continue to supply the same non-standard parts forever, next time it needs service you may have to throw it away and procure another original type laygear.

Also there is no specific note on hardness of the shaft, and the current Moss standard layshaft is not hard enough (Rc-49 vs. Rc-60 minimum requirement). This has been a reoccuring problem in recent years (not only Moss). Unless the vendors start publishing certified hardness of Rc-60 or better for these shafts, it would behove every customer to have every piece hardness tested before using it. If it can be scratched with a file it is not Rc-60.
Barney Gaylord

Where should you do the test scratch?
Art Pearse

Sorry Barney I don't agree with your "non standard" part approach to dismiss this new part out of hand

The layshaft shows no sign of any variations in diameter, so it appears to be a straight shaft. If it fits into the gearbox casing without problems, it's a standard layshaft.

The laygear may have a new bearing set, but for ages we have had to deal with a caged bearing set that offered much less support area for the shaft than the original needle bearings. On the basis of your new comment, that would mean that all the bearings available for the last x years are also no good because they are not standard. That leaves no rebuild option at all!

I agree that the layshafts available from most suppliers have been rubbish for years, I personally had two rebuilds for this reason before switching to the Ford box. But before you shunt this into the "unapproved" category, maybe Moss could tell you what the hardness is. Certainly for most users the better bearings and "kit" approach is probably a benefit if the hardness issue has been addressed.
dominic clancy

Do the scratch test on any part of the shaft that does not run the needle rollers. The OD on one end where it fits into the housing is a good place.

I didn't say it was a non-standard shaft, only the laygear and bearings. However, is may well be a non-stndard shaft if it has the oil supply holes are drilled in different location to accommodate the non-standard needle bearings (maybe).

If in fact the matching layshaft is the standard part, then we know the current layshaft from Moss is sub-standard on hardness. As noted, certainly test the shaft hardness before putting it into service.

I an not dismissing the parts out of hand. I suspect they will work okay in service (if you have a good layshaft). I was just shining a light on the idea that they are non-standard and may or may not be available for future maintenance. If the non-standard laygear or bearings are not available next time the gearbox needs parts, then you may have to buy another laygear. These laygears are not interchangeable without the matching parts.

As to the caged bearings with only 11 needle rollers, that is exactly correct that they are also sub-standard parts that will yield shorter life of the bearings and layshaft. This point has been thrashed around for a long time, and I have a couple of web pages covering it.

In recent years I have been scrounging about to find new old stock full compliment needle bearings for my own use. I find them on eBay occasionally, a piece or two at a time. I also like to install four of them in the MGA gearbox, which may (sometimes) require honing the bore of the laygear to slightly enlarge the bore in the area of the extra bearing.

A few years ago I supplied a couple of these original bearings to Moss Motors to be used as samples in an effort to have new ones manufactured. Apparently it hasn't happened yet. I really thought it would be easier to manufacture the correct bearings as opposed to producing a different laygear.

In the process of installing 4 bearings (a personal preference), the standard laygear may need to be modified slightly. Consider that Moss might endeavor to produce a laygear the doesn't need to be modified to do this, and they are well on the way to producing the current non-standard laygear set with two long needle bearings. It's not a bad compromise, just non-standard and single source parts with a questionable future.

Life would be a lot simpler if we only had the correct original type bearings (and suitably hardened layshafts of course).
Barney Gaylord

This thread was discussed between 20/12/2012 and 12/05/2013

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