Bent prop shaft...worth fixing or new lower?

[jthor3277]

Hey guys. My bud bent his prop shaft this weekend and I was just wondering if it's worth re-doing the prop shaft or just replacing the lower? I have some of the special tools to do it minus the shimming tools. Is this a big job and is it that's worth it? Thanks

Mercruiser 4.3L V6
Alpha one Gen 2 (1.81)

 

[achris]

Re: Bent prop shaft...worth fixing or new lower?

How bent? More than about 0.1" is too much (that's most I have successfully straightened)... And when you straighten it, it's got to be better than 6 thou... Even if you put a new propshaft in, you won't need to reshim...

Chris.......

 

[Don S]

Re: Bent prop shaft...worth fixing or new lower?

A new (Aftermarket) propshaft is $515 from here at iboats, the SEI aftermarket lower unit with a 3 year warranty is $835

 

[jthor3277]

Re: Bent prop shaft...worth fixing or new lower?

How bent? More than about 0.1" is too much (that's most I have successfully straightened)... And when you straighten it, it's got to be better than 6 thou... Even if you put a new propshaft in, you won't need to reshim...

Chris.......

Hmm I never even though about straightening it. I'll get the numbers today and see just how badly it's bent. What's your process for straightening it? Thanks for the reply.

Thanks Don. I was just wondering if the schimming process is a bear and labor intensive to replace. But mostly, just want to do it right.

 

[achris]

Re: Bent prop shaft...worth fixing or new lower?

Hmm I never even though about straightening it. I'll get the numbers today and see just how badly it's bent. What's your process for straightening it? Thanks for the reply.

Vee blocks, a press and a dial gauge.

Thanks Don. I was just wondering if the schimming process is a bear and labor intensive to replace. But mostly, just want to do it right.

As I said, it doesn't need to be reshimmed for a new propshaft.... And even if it did, the shimming process it not difficult, just a bit fiddly... and you need the right tools... which you don't... :facepalm:

(Now I'm confused )
Chris....

 

[jthor3277]

Re: Bent prop shaft...worth fixing or new lower?

You're right Chris I don't have the merc shimming tool and it's nice to know that you don't have to shim the new prop shaft. But i do have the dial indicator setup and did a runout this morning of the prop shaft. He hit something good with a .750th of an inch deflection. It was a stainless prop on a gen 2. With that big of a deflection, should I be worried about the drive shaft and upper? The boat does vibrate.

 

[Bondo]

Re: Bent prop shaft...worth fixing or new lower?

You're right Chris I don't have the merc shimming tool and it's nice to know that you don't have to shim the new prop shaft. But i do have the dial indicator setup and did a runout this morning of the prop shaft. He hit something good with a .750th of an inch deflection. It was a stainless prop on a gen 2. With that big of a deflection, should I be worried about the drive shaft and upper? The boat does vibrate.

Ayuh,.... I hope ya missed a decimal point there, that's 3/4"....

The price of SEI lowers beats rebuildin' what ya got....