Crankshaft replacement help

[Deadeye512xr]

Hey all, I have a 2003 vmax that spun a rod bearing and the crank is now junk. My buddy had a 1989 or around that year vmax and he decided to part it out and let me have the crankshaft out of it in exchange for me taking it apart (I've taken my engine apart before to get my transmission fixed of the second gear issue and get 5th gear overdrive.) Turns out his crank was junk as well... back to square one. So I want to buy a used crank and need some help with bearing selection and that process. My case is still good and the thrust surfaces are showing nearly zero wear (motor has approximately 21000 miles on it and the last 7000 were from me.) I know that the bearings are color coded but i want to get it right. I also will need a new rod and noticed that when I had my buddy's motor apart his rods were different (different stamping) so I dont think I can use one of them in my motor. Do i use a micrometer to measure the rod journals on the big ends of the rod? Plastigauge? Any help would be appreciated.

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[MaxMidnight]

From the way you have phrased your question it sounds like you don't have a Service manual?

Go here to obtain.

Go to the VMX 12H/ HC supplement then Engine Overhaul (pp 7-12) which explains the bearing selection process.

You will see that the bearings are colour coded and the selection is made by using the numbers stamped on the crankcase and crankshaft.

A micrometer would be useful to check that the journals are within spec.
Use the Plastigauges to confirm the correct clearances with the selected bearing installed.

 

[one2dmax]

I have a number of good used cranks or can even sell you a good short block and you just move over your trans, heads, and misc. We quit rebuilding bottom ends that had spun a bearing because engine life never worked out well. The cases get distorted even if the thrust doesn't look bad.

 

[Fire-medic]

That's an interesting problem. I wasn't aware of that. I may have to re-think a rebuild on a engine I was going to put a new, used crank into.

I have a number of good used cranks or can even sell you a good short block and you just move over your trans, heads, and misc. We quit rebuilding bottom ends that had spun a bearing because engine life never worked out well. The cases get distorted even if the thrust doesn't look bad.

 

[Deadeye512xr]

Will the heads go on without any machine work? This is the first time they have been off to my knowledge last time I took my engine apart earlier this year I left the top end intact to fix the transmission.

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[Deadeye512xr]

Will the heads go on without any machine work? This is the first time they have been off to my knowledge last time I took my engine apart earlier this year I left the top end intact to fix the transmission. This would be to put on the short block if I bought one.

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[one2dmax]

Yes, you can manually clean the heads and they will go on fine as is 99% of the time. Just need to check there was no valve contact when it spun the bearing (which contact almost always happens but most of the time the valves aren't damaged). I would suggest you consider our HD ARP head studs which allow more torque to be applied and more consistently hold that torque.

PCW also quit reusing any case parts with spun bearings. I have resurrected some more expensive engines (chain drive big bores) but as a general rule it's just not worth it (way to many engines I had to warranty). I've got a ton of pics o broken stuff and a very large pile of engines out back if you need more proof of our experiences.

By the way, the crank can be repaired but again the cost isn't worth that work (yet) since you can get a used crank for a lot less cost.

 

[Deadeye512xr]

Yes, you can manually clean the heads and they will go on fine as is 99% of the time. Just need to check there was no valve contact when it spun the bearing (which contact almost always happens but most of the time the valves aren't damaged). I would suggest you consider our HD ARP head studs which allow more torque to be applied and more consistently hold that torque.

PCW also quit reusing any case parts with spun bearings. I have resurrected some more expensive engines (chain drive big bores) but as a general rule it's just not worth it (way to many engines I had to warranty). I've got a ton of pics o broken stuff and a very large pile of engines out back if you need more proof of our experiences.

By the way, the crank can be repaired but again the cost isn't worth that work (yet) since you can get a used crank for a lot less cost.

I can get a used crank for around $300 on ebay plus a new rod for like $130 I think and I want to put new rings in it as well. My engine did not sieze or anything but it was knocking very faintly just before I took it apart. How much do you charge for a short block?

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[one2dmax]

$600 for a short block with crank, rods, pistons and upper/lower case. You swap over your heads/cams, trans, and all misc. I can leave heads/cams in place for $200 more and you can just sell your old parts. Swap over your trans and call it a day. These would be good running engines that came in with bad second gear (customer usually upgraded to a big bore build and traded these in).

Rarely do these engines seize. All the pictured cranks came out of "running" engines. So, don't generalize your engine is good because the crank wasn't seized. It's your money so do what you want. Either listen to experience or gather your own.

Sean

 

[42Below]

Deadeye - Sean is a well experienced guy with these motors from stock to wild. Id go with his plan. Up to you.

 

[Deadeye512xr]

$600 for a short block with crank, rods, pistons and upper/lower case. You swap over your heads/cams, trans, and all misc. I can leave heads/cams in place for $200 more and you can just sell your old parts. Swap over your trans and call it a day. These would be good running engines that came in with bad second gear (customer usually upgraded to a big bore build and traded these in).

Rarely do these engines seize. All the pictured cranks came out of "running" engines. So, don't generalize your engine is good because the crank wasn't seized. It's your money so do what you want. Either listen to experience or gather your own.

Sean

Just curious but why don't these engines last after replacing a crankshaft?

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[one2dmax]

The cases become distorted in both fwd/aft as well as bore. The alignments of all surfaces get jacked up. We used to rebuild them but they just don't get the mileage they should before another failure occurs. To extend the life of a good engine you need to make sure that the engine has some temperature in it before running it hard (you won't see me pushing mine up to the starting line without it having been running for some time beforehand). This experience has been learned the hard way from dealing almost exclusively with these engines since 1988.

 

[Fire-medic]

Do you think align boring them would help? I guess that's a case of too-much machining for a doubtful benefit, when blocks are cheap. Do you do any precise measurement before rebuilding a block, other than inspection of the thrust surfaces, deck height for possible warping, and the bores for roundness?

 

[Deadeye512xr]

The cases become distorted in both fwd/aft as well as bore. The alignments of all surfaces get jacked up. We used to rebuild them but they just don't get the mileage they should before another failure occurs. To extend the life of a good engine you need to make sure that the engine has some temperature in it before running it hard (you won't see me pushing mine up to the starting line without it having been running for some time beforehand). This experience has been learned the hard way from dealing almost exclusively with these engines since 1988.

So what your basically saying is you have to be conscientious of your engine more (kinda like if you have an air cooled bike you want to pay attention to it constantly as far as temperature goes) also do you run through the short blocks you sell to make sure they will last?

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[1FK00]

So what your basically saying is you have to be conscientious of your engine more (kinda like if you have an air cooled bike you want to pay attention to it constantly as far as temperature goes) also do you run through the short blocks you sell to make sure they will last?

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It sounds like he is just saying to take it easy until it warms up. That should be easy enough.

 

[COP RUNNER]

Sean is the V-MAX GURU OF GURU'S NO DOUGHT !

100% GREAT HELP AND GREAT PRICES !

GOES OUT OF HIS WAY TO HELP EVERYONE HERE , AS FAR AS I'M CONCERNED , HIS WORD IS GOSPEL !

 

[one2dmax]

So what your basically saying is you have to be conscientious of your engine more (kinda like if you have an air cooled bike you want to pay attention to it constantly as far as temperature goes) also do you run through the short blocks you sell to make sure they will last?

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Just don't run it hard when cold and you'll get a lot longer engine life out of it. The tendency with these bikes is to walk out of the bar and leave a giganticly long burnout as you leave the place. That's cool and all but you may want to start it, B.S. a bit, put on your gear, and make sure the temp gauge shows that the needle is at least 1/8" up from the first line before you do that.

The short blocks I have are either taken apart and inspected or they are known good running engines that have transmission issues. Most are long blocks with heads/cams but those can be removed (or your old ones sent back) to cut down on cost.

 

[Deadeye512xr]

It looks to me like the short block is going to be a more fiscally viable solution to my problem. How do you do this then? Just $600 and you send me the engine (my heads are in great shape and I just checked the valve clearances so I would prefer to keep them. My transmission was upgraded by you so definitely want to use mine.

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[rzubonja]

I have a number of good used cranks or can even sell you a good short block and you just move over your trans, heads, and misc. We quit rebuilding bottom ends that had spun a bearing because engine life never worked out well. The cases get distorted even if the thrust doesn't look bad.

Not sure if I understand this correctly, does this mean that no matter which bearing is spun (on the rod or on the case), the cases are junk?

 

[one2dmax]

Not sure if I understand this correctly, does this mean that no matter which bearing is spun (on the rod or on the case), the cases are junk?

Yes. In our opinion. There isn't going to be a spun main very often (and i've only seen it twice and in both of those cases the rods were completely wiped out and somehow they managed not to break).