Tack welding the crank gear?

[Muddin_dude06]

I have heard of people doing this but I have not gotten a straight answer as to why or when it is required? I am rebuilding my engine and because of the money I am putting into it I want this sucker to last until I am ATLEAST finished with school, so would I benefit from putting a couple 1" long welds on it? Thanks for any help!

 

[JerrodGlover]

The Gear is only held in place with friction and a small pin. In high HP builds the gear will want to push through the pin. Weld it with some small welds, heck its cheap if not free.

 

[jtfondy]

http://i926.photobucket.com/albums/ad110/tstpowerd/diesel%20truck/Fondy-3_8.jpg

this is what we have

 

[Rollin Coal]

thats alot of heat into the crank. did you balance it after that?

 

[dieseljunkie]

I just asked about this the other day. I was told by a reputable builder that if it is done done perfectly (preheat, correct rod, & cool down) that the effects of the welding will actually weaken the gear and make it more susceptable to breaking. He said for less than 1000hp it is not necessary.

 

[jtfondy]

this is what it is going in

 

[jtfondy]

the rest of the crank

 

[Rollin Coal]

guess we dont have to worry about putting heat into the crank.

 

[Muddin_dude06]

I just want to take all the preventative steps I can for anything that can go wrong. I am putting to much money in this rebuild to have something I could have addressed compromise it. I got hit by the KDP as well as the cam gear coming partway off the cam, so I got those covered now.

I was thinking if I was going to weld it I would preheat the crank with my torch some and then use an AC 7018 rod set around 120-140 amps. I don't think I need it fully welded as you did jt, but was hoping 3-4 1" long welds would be acceptable.

As of the rebuild my truck will only be spinning 3500rpm or so max and if it was to go any higher than that it would be after finishing school or in someone elses ownership.

 

[Cummalong]

i def wouldnt be stick welding on the crank gear too many sparks that could stick all over that gear

 

[Muddin_dude06]

I would cover the gear with an old piece of leather or somethin so nothin' coud get into the gear teeth. And a 7018 is pretty low spatter anyway.

 

[caveman5656]

I would cover the gear with an old piece of leather or somethin so nothin' coud get into the gear teeth. And a 7018 is pretty low spatter anyway.

your best bet is to find someone to tig it. very low heat input, clean and strong.

 

[caveman5656]

I just asked about this the other day. I was told by a reputable builder that if it is done done perfectly (preheat, correct rod, & cool down) that the effects of the welding will actually weaken the gear and make it more susceptable to breaking. He said for less than 1000hp it is not necessary.

i wouldnt necessarily follow that 1000 horse thing. we recently had a daily driver 12 valve in the shop that had spun the gear on the crank. amazing that it didnt eat itself!