Forged Crank Journal repair

[blackgn1]

What are you guys thoughts on having a steel forged crank main journal welded up and ground back down to proper clearance? Let's say this was professional done by people that do this on a dailey basis. They say it's as strong as it was before the damage. Most likely couldn't even tell that it has been repaired.

 

[750H.P.V6]

Although the crank might look fine after it's repaired it's really not. All the weld repaired cranks I've seen ended up breaking later. The problem lies in how hot the crank got when it was damaged. Unless you re-heat treat the crank after the fact I wouldn't want to chance it myself. I'm sure you'll get other opinions.

Neal

 

[TNTSNBS]

the crank would have to be cut down then built back up, then cut down to specs, heat treated then cryoed minus 30 degrees and you are good to go, just as long it didn't get damaged from heat too much the 1st time.

 

[Nick Micale]

Here is my opinion:

 

[Grumpy]

junk in junk out. Plus if ya did all the work it wouldn't be cheap.

 

[GARY HARVEY]

+1 for what Grumpy mentioned. Especially concerning a Buick V6 crankshaft.

Keep in mind, when people were typically making this degree of repair,
they were not dealing with the output level potential we subject these units to.
Most of the current crank rebuild applications are for very hi-dollar (read large)
crankshafts, that have a great deal more mass (material) to work with.

I'd use a stock non-turbo crank (and have.. successfully) than deal with
the expense and effort of rebuilding a V6 shaft.

 

[87GN_70GS]

Also impossible for them to reproduce the rolled fillets.

 

[The Radius Kid]

You could try hard Chroming.
That's been done quite successfully by some of the real fast guys.
Not everyone swears by it though.

 

[SuperSix]

I have no idea if it will work.. but I found a cool video while researching machine chops locally.

I smiled when I saw (towards the end of the video) them using a Cen-Tech (Harbor Freight) laser thermometer..

3D Machine shop spray welding.
ut_crank_weld_01.mp4 - YouTube

 

[Nick Micale]

Also impossible for them to reproduce the rolled fillets.

A forged crank does not have rolled fillets.

You may not tell it was damaged, but I could not tell my now broken crank was damaged either.

If it breaks, it will cost you at least 3 times what a new crank will, that is if the block is not damaged.

Also, you did not qualify how the crank/engine/car will be used? For street use only, good chance it will be ok. In a high RPM race application, I would not use it.

In fact, I will not put any used part for the rotating assembly in my race engines. The rods and pistons will only be re-ued on one freshen, then replaced with new parts.

I have seen hundreds of race engines, not only Buicks, destroyed by re-using parts of the rotating assembly, mainly rods.

A local Stage II engine was almost completely trashed when 2 "old" and expensive billet rods let go.

Everyone has their opinion, you have to make the final choice on how you spend your $$$$.

 

[charlief1]

I've seen all the opinions on this and I can tell you one thing. If you decide to get this crank and have it repaired it will have to be sub-arc welded. Very few places have this equipment much less the right operator to do the welding. They can be made to last if done right, but it's really hit or miss. The crank must be kept at a constant temp for the welding, in a jig to keep it from warping to badly. Once welded it has to be stress relieved and straightend. The straghtening can crack the crank by itself and with the offset pins for the rods you don't have a lot that can't crack.

If it was an oddfire crank I wouldn't have an issue doing it but with it being an evenfire crank I really won't even take the chance of doing it.

 

[blackgn1]

Thanks for the replies guys. I was just doing a little research on the subject. I don't think I could every use one. I would drive around thinking I had installed some junk. Thanks again.