I broke mine after aprox. 5000 miles. and another guy I know had his break about the same mileage. how many have broke?
how many are still out there in 1 piece? with how many miles?
I am very upset about this inferior product and DO NOT RECOMEND IT!
Sorry for your loss. Never seen one of those, so can't answer anything, but have questions:
Is it standard T size journals, or larger?
Are you running an aux tranny?
Thanks.
I had it explained to me by a Model T engine rebuilder in my part of the world, that the construction of this crank was not suited to a Model T. Essentially, it can't cope with the constant flexing. Breakages are certainly not unknown.
Of course, there are a multitude of other factors that will hasten the demise of a crankshaft in a Model T. I must say 5000 miles isn't much and at a guess I'd say there'd be many Ford crankshafts with cracks already in them that have done more mileage than that - my previous one included.
It's cast. Model T cranks were forged. Forgings usually takes fatigue stress better than cast parts. Now we all know original cranks breaks too, so the best cure would be a new forged crank with larger journals.
SCAT offers a larger journal version of their forged crank, but the costs getting it in place scares me - I'll wait until all my originals has broken, I guess..
Doug,
what number is/was the crankshaft ?
The earlier ones were prone to breaking but the later ones seem to be OK. I have one in my speedster, have done in excess of 10000 miles and travel at 50mph on the open road.
I have another one (still in the box) ready for my next restoration.
So how about the SCAT crank with standard journals? With all the talk about Ford cranks needing to be magnafluxed and still breaking, would a factory balanced SCAT crank be a better option? The expense of boring out the journals to 1.5, and new rods at 1.5 would bring the cost, I'm guessing only, to over 2K.
IMHO, if you are running a fairly stock car, not a speedster, and nothing more stressful than a Z head on the top of the crank, there is little reason to go to the expense of inch and a half journals. The standard 1.25 journals combined with a good babbitt job and today's modern oils should make that crank good for all of our lifetimes and beyond.
I took a good look at John Steele's new Scat crank and I can see nothing whatsoever to criticise other than it isn't mine. I've also seen Bill Dubat's cranks and they appear to be above reproach. Neither one of them costs one dime more for the babbitt to install it than an old worn and unknown quality T crank.
I will check the # on the crank and post it.it broke at the #4 rod
If I remember correctly, Ben Hardeman (Texas T Parts) was one of the first to break one of the New Zealand cranks.
From all that I've heard, (heresay I'll admit), the NZ cranks pop at 5000 miles.
Don't the T-100's have NZ Cranks in them and have done 100,000 miles? I think I read that in the Vintage Ford magazine.
I have also heard that they are prone to breaking...
If the T-100 cars have Bumac cranks and haven't suffered a failure, chalk it up to the fact that they are drive slow and and on level ground.
It is not clear whether Doug's broken crankshaft was an original or a new replacement. He seems to allude to it being a new replacement crankshaft by saying "I broke mine after approx. 5,000 miles...". By now, most original crankshafts have probably been driven more than 5,000 miles.
Moreover, if Doug is talking about an original crankshaft that is about 100 years old, then one would not necessarily say "...DO NOT RECOMMEND IT".
So, is Doug referring to an original or a new replacement crankshaft?
Doug is talking about a New Zealand made crankshaft, so not an original.
http://bumac.co.nz/products.html
So, after digging into all the oblique and tangential messages posted on this Forum on this particular and specific subject, it appears that one should be wary of purchasing, or not purchase, a new Model T crankshaft manufactured by Bu-Mac Engineering in New Zealand. Right?
Are Bu-Mac Engineering crankshafts the ones that are sold in the USA by the major Model T vendors in the USA?
Gavin,
What is early or late s/n's ??
Thanx-
W
Wayne,
The only broken ones that I have seen or heard tell of were all single digits. (not a big sample I know). I have not recorded the number of the crank in my speedster (purchased approx 2001) but I do have a photo which looks like it might be "111". My new crank still in the box and purchased in approx 2008 is number 289 so they did not (don't know if they are still making them) make many of them in that time.
I must take note of the serial Nos of those known to have broken.
The cranks in the T-100 cars were made by Bumac Engineering in NZ.
Mine broke on No 4 throw going about 15mph in a parade. It had several thousand miles on it at the time.
Jim,
do you still have it or do you know what serial number your crank was ?
Yes, the Bu Mac T cranks often broke early. Their chemical composition had too little nickel and copper, and too high of a carbon % in the base iron. While they were "ductile iron" (A.K.A. nodular iron or malleable iron),they were not X rayed before machining, and not properly heat treated.
I X rayed and probe spectrometered both the Bu Mac and SCAT T cranks. The Bu Mac showed quite a bit of shrink based porosity, esp. near the 4th crank throw. A sure prescription for stress concentration and breakage.
The SCAT showed sulphr strings in X ray, and way too little nickel to be the 4340 it claims to be in the spectro. The SCAT (a China blank)was also he "dirtiest" steel I have ever seen in a spectrometer test.
Don't be quick to blame Bu Mac's breakage problem on being "cast iron". Ductile iron is much different than grey iron in composition, metalurgical analysis, and physical characteristics. With the right melt analysis and a complex heat treating process called Austempering, ductile iron can out preform many steel alloys. Witness it's use in Catepillar bucket ripping teeth, truck ring gears, John Deere high stress brackets etc.
I have pulled the plug on my Made in USA Model T cranks after shipping over 200 cranks. Max, most of the ductile iron cranks sold through the major Model T parts suppliers since late 2008 have been my Made in USA ones, and we have not had a failure, even in modified engines.
I published an article on "Why Model T Crankshafts Break" a few years back. I anyone wants a copy, I can e-mail it to you. Out of town until Nov 9. 2012.
From a NZ member of the BuMac two piece crank club:-
Gavin my crank was No. 10. I have read the thread on the forum and the last fellow had a number of good points but no one has mentioned the machining of the cranks especially at the No.4 site.(Where mine broke also.) (Engineering Company's name removed) down here looked at mine and said the machining of the radius at the 4 site was totally inadequate ie there was hardly any radius there at all. When I had mine replaced (free of charge) they intimated that the machining was inferior but was subsequently improved (they sacked the machinist.) The main reasons they gave me for the breakage were 1) Machining & 2.) the 'mix' of the metal. I was told that the first 12 were these inferior products.The 'mix' was improved from No13 onward.
I'm not registered for the forum so I have passed this info on to you to forward to them if you wish.
Cheers
John
Gavin, I still have it, could not find a number on it, all it has is BU.MAC in raised letters on one of the throws. I was wrong about where it broke, had it confused with another crank, it broke on the front throw.
Jim...look at pic above...BuMac embossed on left between 3 & 4 and the s/n on the right in the ground off area between 1 & 2 on that crank.
W
this BU MAC NZ crank is garbage. do not purchase it, and if you have one, only install it on a trailer queen, not a driver.
my NZ crank serial # BM0296 broke with aprox 5000 miles on it. i broke on the #4 rod journal. this was a waste of money for a product that was offered to the model T community. i will not buy any cheaply made import products for my T. other than tires which is disgusting that they are made in vietnam!! how many of this cheaply made inferior product was sold to unaware model T collectors??? shame on this company!!! vendors should ban any of this garbage from being offered!! there! i feel better, but upset about the wasted money on the complete engine rebuild that i had spent, only to end up with a block with a broken crank!!!
As far as the tires are concerned Doug your kind of stuck since (apparently) they are the only one's out there. Cranks are available from a number of people but running out and buying one from a new company would not be my first choice any way. I completely understand that shipping costs are prohibitive and some thing local is tempting for that reason but this is the place to find out what's what as far as parts go.
i thought i read on the forum that they were breaking because they were case hardened and original ones were not.
I had a few cranks made by Crower to my design. They are billet steel cranks and are about as close to bullet proof as you can get. They are not cheap so most T guys won't buy them. They prefer to buy something cheaper and then complain when it doesn't stand up. I have learned you may not get what you pay for, but you will pay for what you get!!