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MH
Germany
199 Posts |
 Posted - 29/07/2009 : 16:16:41
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A friendly questions to all those who might know!
All the printed stuff that I have gives next to no information as to the embossed numbers of PA and PB gearboxes.
I wonder whether there is someone who could help me to find out about the two gearboxes that I have by identifying them by their numbers.
Thanks in advance for any advice/help.
Regards
Manfred |
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DickMorbey
United Kingdom
3683 Posts |
Posted - 29/07/2009 : 17:16:23
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Hello Manfred
Maybe you could say what numbers appear on your two gearboxes? That would help folk answer your enquiry!
Regards
Dick Morbey, PA/B 0743 |
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howard r
United Kingdom
19 Posts |
Posted - 29/07/2009 : 18:41:18
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Hello Manfred
There is an excellent article on Triple-M gearboxes by Barry Foster, including an explanation of all the numbers, in the 1997 yearbook if you can obtain a copy.
Regards,
Howard |
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kimber
United Kingdom
1529 Posts |
Posted - 29/07/2009 : 18:44:59
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Easiest way to check what you have is to compare no. of revolutions of 1st motion shaft and output flange through the gears. Ratios are the same except PB has higher 2nd gear. Internally, however, there are many differences and few parts are interchangeable between a PA and a PB gearbox.
The codings were explained in a Yearbook some time ago - in theory they should tell you what the internals are but there must be plenty of examples of gearbox case stampings suggesting one thing and the reality being different e.g my own PA/B which has PB ratios inside a PA gear-case. |
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Peter Green
United Kingdom
1682 Posts |
Posted - 29/07/2009 : 18:55:56
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Kimber forgot to say that 1st gear is also higher in the PB gearbox, the 1st gear ratio's are; 3.58 to 1 in the PB gearbox and 4.18 to 1 in the PA gearbox.
Peter. |
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kimber
United Kingdom
1529 Posts |
Posted - 29/07/2009 : 20:21:48
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| You are, of course, correct Peter - which also gives the PA 4.18 on reverse as well. |
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LewPalmer
USA
3251 Posts |
Posted - 30/07/2009 : 00:06:40
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Gearbox numbers are listed in the front pages of the Triple-M Register listing available from the Triple-M librarian on this site.
Lew Palmer
Registrar, NAMMMR |
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Peter Green
United Kingdom
1682 Posts |
Posted - 30/07/2009 : 10:51:44
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Manfred,
Just to clarify your question, when you say embossed numbers do you mean the raised (embossed) numbers? If so they are all casting numbers and do not relate to the model or gear ratios, these are stamped on the top of the gearbox.
Peter.
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MH
Germany
199 Posts |
Posted - 03/08/2009 : 13:35:59
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Hi,
I am sorry for the irritation that I caused by an incorrect description of the codings when mixing up "embossed" and " stamped" with regard to the codings of the gearbox.
Thanks to your numerous answers I now understand that the raised numbers refer to the casting, the stamped on top the gearbox to the model.
At the moment I have no access to the publications you mentioned, perhaps someone can be of help when I state the stamped numbers of my two gearboxes as follows:
Gearbox 1: 1147 and 135
Gearbox 2: 584 and 165
I would appreciate if anyone of you could help again.
Thanks in advance and best wishes
manfred |
Edited by - MH on 03/08/2009 13:38:03 |
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Peter Green
United Kingdom
1682 Posts |
Posted - 03/08/2009 : 14:43:01
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Manfred,
135 is the code for a single breather PA and 165 is the code for a twin breather PA, 199 is the code for a PB.
The easiest way to find out what ratios are in a gearbox is to put it into first gear and turn the output shaft exactly one revolution, at the same time counting the revolutions of the input shaft, if the input shaft turns 3.58 revolutions it has PB ratios if it turns 4.18 revolutions it has PA ratios.
Peter. |
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Whitworth
USA
135 Posts |
Posted - 03/08/2009 : 18:03:19
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| Are the two gearboxes interchangeable between PA and PB engines? I seem to remember that the clutch housings are different as well. |
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Peter Green
United Kingdom
1682 Posts |
Posted - 03/08/2009 : 18:09:23
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Jack, they are interchangable, the clutch housings are the same.
Peter. |
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Bruce Sutherland
United Kingdom
1580 Posts |
Posted - 04/08/2009 : 21:59:24
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Hello Manfred,
This may help you - a photo of my PB gearbox with the stamped gearbox number and the aluminium casing/housing casting numbers.
Bruce. (PB0564) |
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BobRichards RIP
United Kingdom
238 Posts |
Posted - 05/08/2009 : 14:46:08
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Bruce and/or Peter,
Please could you explain a little more about the relationship between the gearbox and the single and double breather engines.
I would not have expected the engine breather to impinge on the gearbox at all but as my PA is in the process of having a new cylinder block which is single breather in place of the old one which was double breather, I thought I'd better check with the experts! |
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Bruce Sutherland
United Kingdom
1580 Posts |
Posted - 05/08/2009 : 17:09:31
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quote:
Originally posted by BobRichards
Bruce and/or Peter,
Please could you explain a little more about the relationship between the gearbox and the single and double breather engines.
I would not have expected the engine breather to impinge on the gearbox at all but as my PA is in the process of having a new cylinder block which is single breather in place of the old one which was double breather, I thought I'd better check with the experts!
Bob, I'm no expert, just a conscientious amateur, Peter is the man to ask.
I was wondering also why the number of breathers in the crankcase/block should influence the stamped numbers on the aluminium gearbox casing?
Bruce. (PB0564) |
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Peter Green
United Kingdom
1682 Posts |
Posted - 05/08/2009 : 18:09:58
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Bob and Bruce,
Basically it means that if a gearbox is stamped 135 it was originally fitted to an early PA engine (single breather), if it is stamped 165 it was originally fitted to a late PA engine (two breathers) and if it is stamped 199 it was originally fitted to a PB engine. All 135 and 165 gearboxes were PA ratios and all 199 gearboxes were PB ratios. I say 'were' because casings have been known to have been changed over the years and they might not have their original ratios.
Peter. |
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