04marauder
(CEG\'er)
08/31/06 10:47 PM
Crank question

I took the crank from my 2.5 to the machine shop to see if it was still useable/salvageable. For those that don't know or recall I spun a bearing a while back and have been working on a 3.0L swap since. I know, its taking me forever.

Anyway, the 2.5 crank was a bit roughed up but it will be fine after all. It just needs to be cut .25mm. But the machine shop also says that not only does it have to be cut but that in one particular spot it has to be welded back UP to meet the -.25 spec.

This particular journal was in worse shape than the others and rather than take everything down to say -.50 they just want to shave everything down and then add material in the one spot and make it all .25 under standard size.

Now I've been reading up a little on people that have had their cranks cut (ouch that sounded painful lol) but I haven't heard of adding girth to one's crank before.

Seriously though. Is this just what it means to having it balanced? Is this a common practice? Safe? According to the shop they do it all the time and I'll have nothing to worry about. Should I be worried if I may want to use this for another project?

And one other thing. Does Clevite make bearings for the 2.5? I already have them for the 3.0L but I'm guessing it would be a different part# for the 2.5. Anyone got that #?

Thanks


todras
(I have no life)
08/31/06 11:48 PM
Re: Crank question

Originally posted by 04marauder:


And one other thing. Does Clevite make bearings for the 2.5? I already have them for the 3.0L but I'm guessing it would be a different part# for the 2.5. Anyone got that #?

Thanks




The 3L and 2.5 have the same cranks.


beyondloadedSE
(Hard-core CEG'er)
09/01/06 01:22 AM
Re: Crank question

Originally posted by todras:
Originally posted by 04marauder:


And one other thing. Does Clevite make bearings for the 2.5? I already have them for the 3.0L but I'm guessing it would be a different part# for the 2.5. Anyone got that #?

Thanks




The 3L and 2.5 have the same cranks.




i dont think they are 'exactly' the same. I believe the counterbalances on the 3.0L are different due to the larger pistons.


Big Jim
(Hard-core CEG'er)
09/01/06 04:51 AM
Re: Crank question

It was once a very common practice to turn cranks. Engines hold up better today so it is not as common.

In high school I worked for an auto parts store that included a machine shop and was involved with helping the machinist. He didn't have a crank grinder, but he delt with a shop that did when he needed that type of service. I've also been involved with hot rod stroker kits that were made from welded cranks.

Yes, it is practicle to build up a crank with welding and then grind it down to size. As with any welding, it must be done correctly, and when done correctly, it is just as good as a non welded crank. Also, there is plenty of strength in the crank to be taken down slightly to the first or even second undersize. You must use bearings that are made for the new diameter. If not ground correctly by leaving a radius at the edges, it can weaken the crank, but your crank grinder should know what is necessary.

Balancing is always nice. It is more critical on an engine that spends a lot of time in the upper rev range. It may not really be necessary if you stay with stock pistons and other recipricating parts. It is essential if you change piston weight and/or rod weight.


04marauder
(CEG\'er)
09/01/06 12:14 PM
Re: Crank question

Thanks Big, that's reassuring.


Originally posted by beyondloadedSE:
Originally posted by todras:
Originally posted by 04marauder:


And one other thing. Does Clevite make bearings for the 2.5? I already have them for the 3.0L but I'm guessing it would be a different part# for the 2.5. Anyone got that #?

Thanks




The 3L and 2.5 have the same cranks.




i dont think they are 'exactly' the same. I believe the counterbalances on the 3.0L are different due to the larger pistons.




Talked to Napa last night and yeah they have the same part #'s listed for the Clevites for both the 3.0 and 2.5. Just wasn't real sure if they were the 'exact' same either.

If they were exactly the same wouldn't you be able to use the cranks interchangeably? I'm thinking not. Because like you say Loaded Jim, the pistons are different, different stroke and bore and whatnot.

If they were the same wouldn't you then be able to use the 2.5 crank in the 3.0 if you wanted to. Instead of grinding down the 3.0 crank to make it work. Maybe I'm way off here and the grinding step has nothing to do with that.


Big Jim
(Hard-core CEG'er)
09/01/06 01:56 PM
Re: Crank question

The 3.0 crank would be preferred because of the difference in the counter balance weights. I would go out of my way to find a 3.0 crank.

Y2KSVT
(Addicted CEG\'er)
09/01/06 06:10 PM
Re: Crank question

What happened to your 3.0L crank that you're doing all of this extra work? My head is hurting from thinking about doing all of that!

Mark


04marauder
(CEG\'er)
09/01/06 09:40 PM
Re: Crank question

Originally posted by Y2KSVT:
What happened to your 3.0L crank that you're doing all of this extra work? My head is hurting from thinking about doing all of that!

Mark




My 3.0 crank is fine. And I'll be using it for the 3.0 rebuild. It just needed to be polished.

I just felt like looking into whether or not I might rebuild the 2.5 too.

It seems like a waste to me to have the 2.5 sitting there or junking it when all it needed was some minor touch ups. By turning the crank, honing the cylinders and getting new rings and bearings I'll have a good as new 2.5 engine and a second project. Nothing else is wrong with it so why not. Seems like its pretty easy to find something worthwhile and affordable to drop it into.

I did the exact same for the 3.0. New rings and bearings, honing, etc and as I did that it just got me to thinking I should do it on the 2.5 too.

Now I just need to get to work.


bnoon
(Redneck Troll)
09/07/06 04:04 PM
Re: Crank question

Originally posted by beyondloadedSE:
Originally posted by todras:
Originally posted by 04marauder:


And one other thing. Does Clevite make bearings for the 2.5? I already have them for the 3.0L but I'm guessing it would be a different part# for the 2.5. Anyone got that #?

Thanks




The 3L and 2.5 have the same cranks.




i dont think they are 'exactly' the same. I believe the counterbalances on the 3.0L are different due to the larger pistons.




You are correct Jim. The crank and rod bearing surfaces are the same diameter (hence the same bearing part numbers), and the stroke is the same. The only difference is the larger/heavier counterbalances.



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