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phil
United Kingdom
149 Posts |
 Posted - 30/06/2007 : 09:36:05
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I am having much trouble with my PB at the moment, every job that I undertake seems to go wrong. For example, I purchased a new half-shaft+hub which although in stock took almost a month to be 'over nighted' to me. When I got it it was too long. I sent it back and waited. And waited.(almost 6 weeks from order to now)
Now I have my half-shaft the correct length. So naturally I chuck it in the axle only to find that the flange of the hub is wider than the original causing the stepped bolts of the rear bearing carrier to not locate in the brake drum. I have had others look at it and they have said to get the hub flange machined thinner!!!!!!
Does anyone else suffer like me? does everyone else who fits a half shaft go re-machining? The difference in width between new(7/32) and old(5/32). Does anyone think that a 16th would make so much difference?
Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaagh |
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Bob Clare
United Kingdom
278 Posts |
Posted - 30/06/2007 : 11:06:27
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Yes we all have these problems. Many if not most new parts need fettling unless they're matched with another new part by the supplier.
In you case, a halfshaft/hub and a new matching bearing carrier would have been better.
I've only had 1 of 6 new shaft/hub assemblies which fitted first time. The others were oversize on the ring on the rear of the flange which fits into the recess on the bearing carrier. I just stuck them on the lathe and turned down the daimater of the ring to fit the recess. I certainly didn't turn down the thickness on the flange itself. You'd end up with a thin flange connected to the bearing carrier only by the minute overlap of the ring on the endge of the recess!! Not good news.
Good luck
Bob Clare
Registrar, Triple-M Register |
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KevinH
United Kingdom
156 Posts |
Posted - 30/06/2007 : 11:10:17
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Phil,
I know the feeling! The jobs I've done over the years have either been simple or very time consuming, and 50% of new parts fit easily and the other 50% either go back or have to be modified. A typical example was the new clutch thrust bearing carrier for my PA. The old one was very worn, and the new one from a well known supplier was a worse fit than the old one - I eventually re-bushed the old carrier to fit the thrust bearing properly on the outside, and the first motion shaft on the inside. Luckily I have a lathe etc, but a job that should have taken 15 min eventually took a few days.
I had a pair of new half shafts/hubs from John James a couple of years or so ago, and they fitted perfectly. No VAT and I collected from him at Silverstone.
I'd find another supplier who has half shafts/hubs in stock, and get a refund on the one that won't fit properly. I wouldn't get it machined as if you have problems the supplier will blame the machining & not his faulty workmanship.
Good luck!
Kevin |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 30/06/2007 : 11:59:54
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This week I have replaced a broken halfshaft. I discussed with myself long and hard whether I would buy a new hub at the same time or use the existing hub. I chose to use the existing hub for all the reasons stated above. Plus it had been machined to take Roger Furneaux's hub nut/lip seal.
I bought the halfshaft from one of the main suppliers and it was 1/4" longer than the old one and the inner splines were shorter than the old ones (I suspect that the old shaft was not to spec). As a consequence, or really as a result of my incorrect measuring, it was not pressed in quite far enough but the local machine shop who did the job, pressed it in a further 5mm FOC, while I waited. So, all in all, the job went well. But I was lucky this time. Things do not always work out so well. - So remember the maxim "If it 'aint broke don't fix it". 
Peter |
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Mike
United Kingdom
229 Posts |
Posted - 30/06/2007 : 12:06:52
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This is an old problem with suppliers indeed its the buyer who is the inspector as the trader would appear just to order and put into stock without any checking. The word "quality" is one of the most abused words in all sorts of manufacturing products.
One of the problems is small batch runs as when in a few years time you go back to the original supplier for more he says "yes no problem" only that Joe Blogs who made them for the past 40 years has "popped his clogs". The new guy has not had the skill and tweeks passed on to him by his predesseor.
This problem is not limited to the car industry as it was an ongoing problem in the aviation industry.
Regards
Mike Ellis (Aviation Kwality Manager thankfully now retired)
M ELLIS |
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phil
United Kingdom
149 Posts |
Posted - 30/06/2007 : 16:00:57
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Thank you all so very much.
I am so glad to find that my problems are not unique. In fact this news has really cheered me up!! I think it might be worth getting a new rear bearing carrier to match the shaft as the threads which poke through the brake drum are looking very tired plus, only half of the threads are holding the nuts in place. (which I guess is bad).
Thank you all. |
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Rodney Collins
United Kingdom
424 Posts |
Posted - 01/07/2007 : 15:44:03
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Phil Like Peter Scott I used Roger Furneaux's Half shafts and lip seal / hub nut assembley, it all went togeather well, the off side half shaft was a bit tight in the diff, but overall very well engineered. Which is more than I can say for a lot of the stuff you buy from dealers. If you pay top doller it should fit without a day or so extra fettling. I had meny jobs when rebuilding my P type which took days when I thought hours would see it done and dusted.
Best of luck I am sure you will have a lot more of the same just don't rush.
Rodney |
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Bob Stringfield
United Kingdom
854 Posts |
Posted - 01/07/2007 : 20:40:46
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It has long been known that one of the advantages of buying what is usually known as an 'older restoration' - ie. a car rebuilt in the 'sixties, 'seventies or (perhaps) 'eighties - is that it is more likely that the car's replacement parts were genuine.
The motor cycle world is equally plagued by 'approximate engineering'. |
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davies
United Kingdom
699 Posts |
Posted - 02/07/2007 : 09:51:09
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| who supplied the half shaft in question? I think in the interests of "maintaining the breed" it would be nice to know. Rich |
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tholden
United Kingdom
1638 Posts |
Posted - 02/07/2007 : 12:57:19
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Hang on you guys lets not start naming and shaming anyone over such a small matter. It is not unususal to have to machine half shafts to length. Also much depends on whether you are using new hubs and new bearing carriers and other factors.
We must also remember that it was not uncommon for original components to vary in their machining tolerances. MG often changed suppliers and often only ordered components in fairly small batches so variations occurred between different suppliers. There are many examples of this to be found throughout our cars such as with J2 bodies and bonnet catches for example. With items like half shafts how do you know whether you are comparing your new shaft with an original ? Your original may be an incorrectly machined item from the 50,s or 60,s
I believe that half shafts now come from one particular supplier. I think they are excellent and have used them for a long while without a problem but I have had to machine them to length after they are fully pressed home.
Lets not start knocking the suppliers - lets thank them for being there and for helping us keep our cars on the road. They may not be perfect but without them we would be far worse off.
Terry Holden |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 02/07/2007 : 15:12:06
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quote:
Originally posted by tholden
I believe that half shafts now come from one particular supplier. I think they are excellent and have used them for a long while without a problem but I have had to machine them to length after they are fully pressed home.
Terry Holden
Terry
What is the correct length for a PA halfshaft? I cannot find it specified anywhere.
Peter |
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Peter Green
United Kingdom
1682 Posts |
Posted - 02/07/2007 : 16:31:07
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Peter,
I do not know what the correct length of a P type half shaft should be but I have just checked all the second hand ones I have and they vary from 22" to 22.25", the vast majority are 22.25".
Peter. |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 02/07/2007 : 18:30:10
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Peter
Thanks for your reply.
Terry sent me a comprehensive email explaining that you press the shaft all the way into the hub and then check to see if the flanges mate properly. If not, you shorten the halfshaft by an amount which is equal to the gap between the flanges 'plus a bit'. So as with all things MMM you - you trial fit, measure and then machine.
My old shaft was 21.875" and the new one is 22.25". So similar to your samples.
Peter
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phil
United Kingdom
149 Posts |
Posted - 02/07/2007 : 19:07:15
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Hi, thanks again for the input everyone. although I am an inexperienced restorer, I am inclined t agree with theolden on this. There is no proof of originality of previous shaft. Having done my homework, hundreds of satisfied customers cant be wrong. The suppliers have bent over backwards to help me. (fair enough the hub was not pushed in far enough first time around). They have offered to refund the postage costs for returning the item. I now am thinking it is a combination of factors.
A friend of mine had a look today and took the brake drum away with him. When he returned, the inside was nice and shiney where he had whittled (not much) some of the brake drum.(I am no engineer). I on the threaded end of the bearing spigots, the thread should go all the way to the end, mine look like they have lost a tiny bit of the thread on the end (about 1mm) and have been worn round and smooth.
I have now assembled the hub/shaft drum etc. I used a technique called brute force and ignorance. I managed after an hour of hammering!!! to get washers behind all 6 bolts.
So I think maybe I jumped to the wrong conclusion to quickly. As I mentioned I am inexperienced and possibly thought that if the shaft was wrong first time around, then were the suppliers professionals?
Answer, yes they are, Very nice helpful people.
PS. Approximate engineering??? I think that might be me.
Thanks all. |
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davies
United Kingdom
699 Posts |
Posted - 03/07/2007 : 09:33:00
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| I am now watching the "suppliers" list with interest ! R.D |
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Terry Andrews
United Kingdom
546 Posts |
Posted - 04/07/2007 : 09:11:25
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Hi Phil and Everyone below,
Just returned from the excellent Luxemburg Pre War event and read these comments below.
May I endorse Terry HoldenÆs plea and add a few comments of my own.
Please remember with Triple ûM cars parts need to be ôFittedö not assembled. Hence the difference in the job description of ôfitterö and ômechanicö. To fit something you may need to turn, grind, fettle, file, polish etc. Those brought up on more modern machinery where mass production techniques have improved this is not so necessary. So you should not assume that a part will fit directly on your carà.but it may fit another example of the same model. The degree of difficulty on restoring a Triple-M is harder than at T type with is harder than a MGA and so on.
MG used different parts suppliers during their production run. An example of this was the gear cogs within the engine. I have been shown 3 different gear manufactures marks on the front gears for a P type. So when an engine was rebuilt using original but missed matched gears from different manufactures, the dynamo shaft was ruined after 750 miles. A degree of mechanical understanding and sympathy needs to be built up while restoring or running your car. I have only been doing this for 30 years Terry Holden, Mike and Peter even longer but we never stop learning from each other. It is much easer to restore a Triple-M car now than 30 years ago. As there is more new parts available and more imformation out there in books and through technical articles etc. If you are new to this and to get an understanding of the how to go about restoration may I suggest reading TC Forever by Mike Sherrell, page 106 & 107 gives the set up of the hub, axle shims etc.
By the way, I think you may have been sold a TABC rear hub. This is VERY similar but different to the Triple-M hub. Up to a few years ago these were sold as fitting Triple-M cars. When I needed new rear hubs I was very specific with the manufacture so he fully understood the difference. The flange thicknesses are different this is to take into account of the wider TABC hub bearing and carrier but the PCD of the holes in the hub are the same as our cars. When Triple-M hubs were not available TABC ones were tuned down in a lathe to have then ôfittedö to a Triple-M car.
The bearing hub nuts mentioned are a good modern solution to the oil seal problem and they usually fit straight on to an N type axle. BUT to fit on a 3ft 6 in axle you may need to reduce the thickness of the nub nut or turn off some of the depth within the inside of the hub of a combination of both. Remember if you carry a spare half shaft make certain it fits your new set up on both sides of your car.
I fully understand how frustrating this must be for you but we have all been through it at some time. May I suggest that you find a ôBuddyö / mentor near you to help you on your way or the Register does have a Technical Advisor.
Finally, to those who contribute to this site if you recommend a course of action please do not just say ôfit a widgetö. But give a full answer e.g.: Fit a widget but check the clearance of the whatsit as it may fowl the ugmayflip! Otherwise a series of responses quickly follow and sometimes causes more confusion.
Sorry for the long tomeàà regardsà. Terry A
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