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MG MGA - Crankshaft quandary
|I replaced the motor in my 1958 MGA last year that has failed on a run to Concorso Italiano as part of the Autoweek festivites in Monterey, CA last month. The number three and four rod bearings burned out and the crankshaft is 'toast' according to the mechanic who built it reported to me when I trailered into his shop ending my trip. Moss Motors has put a 'hold' on releasing any of their remaining crankshaft inventory due to a machining issue the involves joining the crankshaft to the flywheel. From what I can discern from converstations between them and my mechanic it seems the mounting bolt holes are not lining up and may need to be 'extended'. The pins apparently are lining up and the issue remains the bolt holes. These issues are from a run of 400 made in India and apparently the dies have been damaged to re-manufacture future crankshafts. So these may quickly become very rare to find and replace. The Moss crankshafts include high quality bearings, if and when they will be re-released for sale. |
I have located used crankshafts from another source that require magna-fluxing and polishing and possibly regrinding at potentially .010 and .020.
My quandary is which to proceed with? Any thoughts are welcome and surely any crankshaft that is serviceable would be welcome.
11g73. In stock and fairly priced
|Can you get the damaged bearings metal sprayed and reground?|
|Leacyclassics is Out Of Stock. I sent an email to get information on any back order availability, but these are getting difficult to find that are not 'blems'.|
Art, my mechanic reported that the #3 bearings were probably cracked and down to copper and #4 were burned up. They will be replaced. The bigger issue I have now is finding a serviceable crankshaft because mine is damaged badly from this lubrication failure. Not easy sorting out the cause and responsibilities financially either. We all know how that goes!
Dominic suggested removing the crankshaft from my Magnette motor. That would be my fall back option. I am hoping to keep that motor intact, if I can. So I am still on the hunt for a crankshaft for a 1500 or 1600. One other option I have heard is to have the old cranshaft 'nitrited'. I am not sure what all that involves but it sounds complicated, expensive, and highly technical. Any thoughts on that?
|I believe nitriding is a surface hardening treatment, not a metal-restoring treatment.|
Still not sure why the crank cannot be restored. Is it cracked?
|BE CAREFUL. |
MOSS is out but VB may have some. Just last week a friend of mine purchased one from VB installed it with suppied 10/ 10 bearings. All was well until installing the transmission. It would not pull up the last 3/16". The hole for the pilot bushing was 7/16 shallower that his original.
Why not reinstall your other engine until your present quandry is solved. It may be some time till you get a new or decent crankshaft. This way your still on the road with a good MGA.
|Have you tried APT - they sometimes show as in stock on their web page but are not actually available - they do say they have been crack tested, reground and balanced.|
|Art all the mechanic told me was the crankshaft is 'toast'. I am not sure what the issue is with it unless I take it myself to a machine shop and get a neutral opinion. Maybe I should. |
Mike,the APT option sounds dicey, given the measurements supplied in your post.
Sandy I am going to wait a while longer on this crankshaft solution before deciding to go back to the other mother. It requires an electric tach and I have relinquished that item. So it seems a lot of going backward right now and a lot of extra $$. My goal is to complete an original restoration...so it will take some patience now.
Can you get a crank from a Morris Major or Austin Lancer (1500 or 1600cc)? These cars were very common in Australia (and UK I think). I am sure the cranks from these cars were identical in dimensions to the MGA and so should be ideal as replacements. The only difference was where they were made. I think most Australian Morris and Austin 1500 and 1600 cars had cranks made in Australia. I have a couple in my shed with "Australia" cast into them.
I am only guessing that these cars were not common in the USA but if the quality is OK, perhaps we should be checking out the postage cost and sending them to the USA from UK and Australia?
DOES ANYONE KNOW THE QUALITY OF THE AUSTRALIAN CRANKS COMPARED TO THE ENGLISH CRANKS?
|R L Schapel|
Try this link not sure what happened with original link (didn't quite understand your comment above).
|The link will work if you copy and paste it.|
|Dave O'Neill 2|
|Any 1500 crank should do - Austin Cambridge etc.|
You CAN have your crank metal sprayed to bring it back up if it isn't cracked, but that gets expensive.
I think I have a couple of cranks I use as doorstops. There should be no shortage around.
|About a thousand miles after I rebuilt my whole car my engine developed a strange deep knocking when cruising. Under acceleration or deacceleration no noise. Tore it down in '95 and discovered that when I had the rods rebuilt either they or at other times when the engine was rebuilt,too much from the big end sides making the clearances way over. I think when I measured rod end play I was measuring the bearing insert to crank clearance. Engine was then run, bearing wore down on the sides and I ended up with one at .040,2 at .037 and one at .036 when specs are at .008 to .012. Just try and find rods that over the years have not been touched and who knows what the new specs were/are? John Twist went thru all the rods he had and and got me into the .020's. Then I found out each crank is different too,some journals wider or narrower than each other,no remanufactured crank I found would get me down in clearance. In the end I took the lower end to John and who he uses for his machine work got it down thru welding up my original crank to .008,.010 and .009 side clearance. No problems since. Might be worth giving John a call|
|Is it a 1500 crank you need? If so I may be able to help.|
Your comment that conrods with excessive side clearance making a knocking noise is interesting.
As well as physical contact between the conrod side and the crank you have much reduced lubrication efficiency.
Oil escaping from the sides of a conrod make it difficult for an oil "wedge" to occur.
This oil wedge is necessary to keep the bearing and the journal apart. This cannot be done by oil pressure alone.
Think of a few PSI of oil holding apart forces of tons resulting from engine loads.
|M F Anderson|
This thread was discussed between 26/09/2014 and 01/10/2014
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