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MG TD TF 1500 - Cracked crankshaft - NUTS

Son of a ....

I was inspecting the the crank last night, I was going to send it out for a magnafluxing.... Damned if it isn't cracked on journal #1. Running in the pic from 11:00 to 4:00. Clear as day, I can catch my fingernail on it.

So.... I guess I need a crankshaft. Or a B engine (gasp).

MAndrus

Dam good thing you caught all this before it let go.
At least it is rebuild able as it is( whole engine ).

M Grogan

Someone else was looking for a crank earlier this Spring and I pointed them to OOPS1947@metalfan.com. I got a spare for my TC late last Fall & they had one left at the time. I don't remember it's specs off hand 20/20 or 20/30 comes to mind and they had NOS OEM bearings available also. Sam
SW SAM

Hi, I have several (uncracked) crankshafts that I am selling. Please send me an email message if you are still looking.
Hugh Pite
H.D. Pite

Most common place for them to break. Lucky you found it now. Hit it with a hammer- does it ring like a bell or thunk? George
George Butz

I just found the same, was visible even using dye, rings fine, but the mag test even showed stretch marks on the other webs.
mog

I'm going to strip the block and have a good look to see if the whole shebang is a boat anchor. Still need to ship the head out... might wait a week or so now.

I've already emailed you Hugh.

If this gets any more upside down, I'm going to rebuild an A 1500 and drop it in.

Thanks all.
MAndrus

I've had two go just there. One broke on the road, the other was found by crack checking when the engine was being stripped for another problem.The usual theory is that the cause is the assymetric load from the water pump/generator drive belt. Makes sense, because that's one common way to carry out a fatigue test.

Makes me a little concerned about the much higher load from my supercharger drive belt, although I haven't seen any reports of problems by blower users.

David
DavePro

I cant tell from the photo but it looks like there is no champer(sp)on the shaft/ mine broke right where your crack is and I was told by an engineer that you must have that slight champfer in order to alleviate the problem.
TRM Maine

Don't throw those cranks away yet. Take them to a reputable crank repair shop many can be welded up and made whole again. Mitchell Hugh is a great guy to deal with. But also check out Manley Ford in Wisconsin. I picked up one from him recently that had already been machined for a very reasonable price. He may have more available.


I also recently sold a TD chassis with a 1500 B Series engine that was adapted to the original four speed. The engine did turn over and was complete missing only the air cleaner. Air inlet pipe was there. Engine # came back as being out of a magnette. He is now using the frame to repair a freshly restored TD that was hit from behind and I'm sure he won't likely be using it as it had been intended for another car. Consider it a core but may in fact be good once the carbs are gone through and an attempt at test firing. The engine had been sitting in chassis for at least 7 yrs according to the PO I got the car from as that was the time he had it and again...no attempt was made to start it.


Bill Chasser
TD-4834
W. A. Chasser

See this web site : http://www.crankshaftco.com/journal-radius.html
For crankshaft journal radius information.

Len Fanelli

Bill, I'd like to follow that up just in case my block is no good. If a new engine is in the future, I wont be looking for a 1250.

Thanks for thinking of me.
MAndrus

I'd heard of cranks being welded, I go back to '72 with antique cars. There are zero crankshafts available for 1920's Dodges, thrust me.

I'll be very happy to buy a good original first, repair second. This assumes that's the ONLY crack.
MAndrus

Well, I was afraid to look any closer....

Tonight I did. another crack, smaller though, at #4 journal in about the same place as the front one.

I think I'll take a pass on repairing this crank, magnafluxing will surely show a dozen more. A waste of money even testing it.

Too bad.
MAndrus

Just for my information, what speed did you typically run your engine at? What was your periodic maximum engine speed? Is your car supercharged or have a raised compression ratio?
John Quilter

There are old and new cranks just like early and late cars. Could you tell us the casting number?

Thanks

Joe
JWP Policastro

John,

I can only tell you about the latest 1,500 miles or so that I put on it in 18 months. No high revving, lugging... 3rd gear is my friend. 2,200 to 3,800 rpm's is where I shift. I put in the 4.3 rear end from Dave before hitting the road. The PO might have done just about anything to it back in the 80's 90's before he took it off the road. Those are the chances we take...

I bought the car through a vintage car dealer from a fellow that owned it for 54 years. It isn't the car's original engine. Who knows?

No supercharger. Haven't measured the head, bit doesn't look like it's been cut.
MAndrus

.
W. A. Chasser

As I said above there are two different casting. The early ones were made out of the best they had but it was inferior metal. The newer ones had a casting number of 168557. You may also find that ESF & EM 27.

I have been trying to track a theory that the older type are the majority of ones breaking. It is just a theory and that is why when some ones reports a break I try to find out the number.

Could you please look at the crank and report the number.

Also if any one else has had a break and can find the number it would be greatly appreciated.

Thanks

Joe
JWP Policastro

Second sentence should have read NOT made out of the best materials. Sorry.

Joe
JWP Policastro

Joe, I'm pretty sure both of my broken cranks in my attic are the 168557 numbers. Will be a while until I can check for sure. George
George Butz

Joe, the info I have is that it's the older ones that wear quicker due to softer metal, it's the newer ones that tend to break. The later ones were referred to as the '100 ton crank'.
Cheers
Peter TD 5801
P Hehir

Thanks Peter and George. Maybe a metals expert can shed some light on both of these cranks.

Peter I am not meaning to put you on the spot but what info do you have on this and would you be willing to share it?

Joe
JWP Policastro

Hi guys,

Lots of good comments so far but thought I would add a few of my own.

EARLY (225??) vs LATER (168557)CRANKS:
About 45 years ago I heard the story about early cranks being softer and hence less brittle. However, I think I would still favour the later crank. I think either is good as long as it is not cracked. The amount of fatigue suffered by a crank is the main issue. A pity we can not easily measure that! A crank which has been worn and reground four times, probably has more metal fatigue than a slightly worn standard crank.

WHERE THEY CRACK:
I have collected a lot of "data" and XPAG cranks rarely crack anywhere except #1 and #4 webs. The only exception I recorded was a crank which had thrown a #3 rod. #3 crankpin was damaged and built up with chrome and had no radius ... and broke. My stats show they usually crack/break at #1 (75% of the time) and sometimes at #4 (25% of the time). The crack nearly always starts at the big end journal(not the main).

REPAIRING CRACKED CRANKS:
I once ground out a small crack at #4. It was only about 7mm long and so I calculated (from patterns left on broken cranks) that it was not much more than 1mm deep. That crank went on to do 19 more race meetings and a few other motorsport events. It was "retired" when the supercharger drive crank-pulley came loose and ruined the pulley area at the front of the crank, also cracking it at #1. #4 had not re-cracked! I agree that we shouldn't discard cracked cranks. I have heard of new laser welding techniques and believe that cracked cranks might be repairable. Techniques are always improving.

THE RADIUS:
This area is a CRITICAL area! A large, smooth radius is good. However, since the late 80s I have been trying to improve on that. I grind into the thrust faces of the #1 & #4 webs, trying to create parallel surfaces which merge with the surrounding metal with VERY large, polished radii. (see image) My theory is that even a radius has a "bottom" and I can put my fingernail on the exact point where a crank will eventually crack. After I re-shape an XPAG crank, the fingernail can be slid along about an 8mm area .... "The crank will eventually crack somewhere along here." In other words, the stress area is spread out over about 8mm instead of 1mm.
The down side is that it doesn't remove pre-existing fatigue. It can not be machined but needs an "artistic" approach with a small grinding tool. It is a time consuming job as grind marks need to be polished out. I would NOT recommend it to an inexperienced engine builder. I would be interested to hear comments from metallurgists and engineers. I reckon they might say the area could also be "thinned down" to send more stress out towards the web edges (which should then be polished). Thinning the web (from A to B) might also remove fatigued metal. Any expert engineers out there to advise us "amateurs?"

Bob Schapel

R L Schapel

Interesting comments. Both of my broken ones snapped #1 area. When tap one of them with a hammer, it thunks, indicating another severe crack somewhere. If our engines had harmonic balancers that may minimize the issue? George
George Butz


Mine, (the subject of the post for those who've lost track) 22528 is cast into the crank on one of the counter weights.

My engine number is 28542, so.... I've got an early crank in a newer engine. Makes one wonder what the poor thing's been through?
MAndrus

I think that more information on broken crankshafts is needed IE was the crankshaft reground, and if so what is the journal radius, by checking with a radius gage.
Len Fanelli

Just what I posted Joe. This came from someone here who has more knowledge on these cars than anyone else that I know of anywhere in the world. It may surprise some to learn that Australia was the second largest market for T Types, even bigger than the UK. I'm always willing to share my research with those who aren't trying to make a profit from it. However now I'm just a little wary having had an article ripped off earlier in the year by the editor of a magazine published in the States. I also agree that more research is needed. Cheers
Peter TD 5801
P Hehir

Thanks George, I will add your two cranks and MAndrus to my stats. I agree that harmonic balancers should help. I think that has been discussed on this forum before. I have often wondered if a supercharger drive(with V-belts, pulleys etc.) acts a bit like a harmonic balancer? Only someone who understands all the theory would know. To reduce "leverage" I have my s/c drive pulleys close to the engine and the water pump pulley in front of them.

I think Len is right, more info' is needed, but that is difficult because of the big variety in usage between cars. A database recording crank age, mileage, radius, regrind size, favoured rev-range, etc, might reveal a common element in cracked cranks.

Many years ago I had a friend's broken crank analysed at a Mitsubishi lab. (My neighbour was an engineer there.) Unsurprisingly, the report came back that metal fatigue was the cause of the breakage.

Another theory I heard a long time ago was that cranks which were hotter during the forging process were less likely to have stresses which cause breakage. A pity we never seem to get engineers and metallurgists as interested T-Type owners.

Bob Schapel
R L Schapel

The cracked c/s in my TF 1500 was a later p/n 168557, std size with excellent bearing journals (never reground). The crack was in the #1 rod bearing journal radius, the most common fatigue site from what I've read. (There are MANY entrees in the archives on this subject).
The change to p/n 168557 from p/n 22528 occurred in April '53 at engine XPAG/TD27551, according to the literature.(Clausager, Willmer)). The change was to EN100 steel from EN16. EN100 is a low alloy steel containing nickel, chrome, and molybdenum whereas the EN16 contains only manganese and molybdenum. The EN100 has better fatigue properties than EN16 but falls short of AISI 4340, the low alloy steel of choice for conrods, crankshafts, and other high duty auto and aerospace components.
My conclusion, after extensive reading in the archives, was that the most likely cause of the fatigue was torsional vibration occurring around 4500rpm, as theorized by several threads in the archives.
Since my TF is a 1500 with its scarce head and block, I bought a Phoenix crank from Brown and Gammons. On the other hand, there are several threads in the archives referring to crank failures with almost no secondary damage. What the hell, take a chance if you have an XPAG engine.
If anyone wants to further discuss this interesting subject, my email is thomasw.moore @yahoo.ca (514-946-2445). I'm in Quebec, Canada.
T W Moore

Damn good thread. Not too often we get such a concentration of valuable information all at once; which brings me to my point ...

Just before I sold my TC in 1952, I decided to give the new owner, new crank and rod bearings. I was astounded when I saw a visible crack on the edge of the centre main.

I took the crank to a reputable machine shop which at the time, was also doing work for Pratt & Whitney. They said it could be saved and recommended it be "sweat-welded".

This involves soaking the crank overnight in an oven at a temperature, at the same temperature as the melting point of the weld material that they were going to use. They welded the crank while it was still red and built up the journal which they machined once it had cooled. They did a lovely job and I couldn't even see the weld.

I guess by today's standards, this is old technology, but it sure worked well in 1952.

Gord Clark
Rockburn, Qué.
Gord Clark

Damn good thread. Not too often we get such a concentration of valuable information all at once; which brings me to my point ...

Just before I sold my TC in 1952, I decided to give the new owner, new crank and rod bearings. I was astounded when I saw a visible crack on the edge of the centre main.

I took the crank to a reputable machine shop which at the time, was also doing work for Pratt & Whitney. They said it could be saved and recommended it be "sweat-welded".

This involves soaking the crank overnight in an oven at a temperature, as the same temperature as the melting point of the weld material that they were going to use. They welded the crank while it was still red and built up the journal which they machined once it had cooled. They did a lovely job and I couldn't even see the weld.

I guess by today's standards, this is old technology, but it sure worked well in 1952.

Gord Clark
Rockburn, Qué.
Gord Clark

Fascinating info' Gord. I have never heard of a crack at a centre main. Do you remember if it was across the web, similar to where they crack at # 1&4? Or was it along the main crankpin? Was it a NEW crank or did you mean spare crank? If it was a new crank, the crack would have to be a manufacturing flaw.

I once saw a crack ALONG a big end journal of a 3 bearing MGB crank. I can not imagine how it would be so .... unless there was a forging flaw. Someone told me that it sometimes happens in diesels .... but where does such a crack go to?

Bob
R L Schapel

I have the Moldex crank in my TD. I would not trust a 50 plus year old crank. the modern crank is so much better. I also had custom pistons and rods built. no one can tell if they are in there or not . I have a 4:1 rear end and cruise very comfortable at 3800-4000 RPM at 68-70 miles an hour. also put disc brakes up front from a 1600 A.
TRM Maine

My new crank (magnafluxed, .030/.030) arrived looking lovely.... YAY.

Many thanks to Hugh Pite for helping me keep an original engine in my TD.
MAndrus

.... to add: The journals all have a very well manicured fillet (radius) intact. So.... maybe we won't be seeing any cracks 'til well after I'm dust.
MAndrus

Great thread. As another data point, my car is now on its third crank. My grandfather replaced the orriginal with a NOS from abingdon spares in the 80s and I replaced his with a manley Ford build about 5 years ago. I went with manley's MGB spec journals and custom rods and pistons deleting the pinch bolt at the wrist pin. So far it has been fantastic. I've unfortunately popped a head gasket and she's apart right now to fix that. The bottom end however is solid!

Alex
Alex Waugh

TRM

Could you please comment on the stopping distance with the disc brakes versus the normal shoes?

Thinking of adding them this winter or early Spring.

Thanks

Joe
JWP Policastro

Never really meausured the distance, just know that there is very little fading and it does stop faster, I feel safer what with the 4;1 rear end and driving highway speeds, it does stop shorter. does not in anyway ruin the looks of the car and in todays world driving fast and on the highway it is safer. you do not need to make any mod to the MC. I used parts from a 1600A I did change part 9 the steering arm as the A part is thicker and bigger than the standard TD part. A couple of us have the Disk brakes on our cars and we would not trade them for the old style shoes. it is a good trade up for the cars.
TRM Maine

Thanks for the input.

Joe
JWP Policastro

Bob Schapel,

That was 1952 - some 64 years ago. No way I can remember that far back!

Sorry.

Gord Clark
Gord Clark

This thread was discussed between 28/11/2016 and 12/12/2016

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