Crankshaft Thread Repair???

Reply Subscribe

Thread Tools

Search this Thread

May 7, 2006 | 11:13 PM

wro87

Thread Starter

Burning Brakes

Joined: May 2006

Posts: 857

Likes: 1

From: Morrisonville Illinios

Crankshaft Thread Repair???

We have a L98 block that while my son was removing the harmonic balancer he runined the threads in the crankshaft

( with the puller(forgot to use the nose piece on the puller). Does anyone have any suggestions for repair I hate to pull it all apart.

I have thought about using a Heli-coil or cleaning the threads out and using a little longer bolt. I am open to suggestions!! We aready to get this runnig for the summer and now have a minor set back. Thanks WRO

May 7, 2006 | 11:15 PM

STL94LT1

Race Director

Joined: Jan 2002

Posts: 12,261

Likes: 85

From: O'Fallon Missouri

First, I would try to retap the threads.

May 7, 2006 | 11:19 PM

Pete K

Race Director

Joined: Feb 2004

Posts: 12,517

Likes: 19

I had the same thing happen on a brand new crank. Run a tap through, and buy a grade 8 bolt that is 1/4 inch longer 7/16 20 2 1/2 inches long if I remember correctly will work. Replace the thick washer with a thinner one. That will give you 3/8 inch extra penetration of the bolt that you did not have before.

May 7, 2006 | 11:25 PM

Jay Axson

Melting Slicks

Joined: Jun 2001

Posts: 3,444

Likes: 0

I damaged mine by turning the crank without using washers to compensate for the missing balancer hub. The tip of the bolt squished in the seat of the crank and trashed the crank threads during removal.

I ran to sears and bought a thread repair kit. It looks like a standard tap and die kit, but it's slightly different. Tapered I think. Anyway in one shot it fixed my mangled threads. Add a new OEM crank bolt and all has been well for 4 years.

Seriously, spend the 50 bucks and get the repair taps before resorting to a standard tap. It could save you a ton of trouble.

Jay

May 7, 2006 | 11:34 PM

wro87

Thread Starter

Burning Brakes

Joined: May 2006

Posts: 857

Likes: 1

From: Morrisonville Illinios

Thanks for the help! We were wondering if the bolt was metric or sae theads. We checked it and we thought it was 1.25 pitch. If it is sae let me know size and tpi we have both us and metric tap/die sets but might try to get a better tap to take the tapper better. Thanks wro

May 7, 2006 | 11:37 PM

Pete K

Race Director

Joined: Feb 2004

Posts: 12,517

Likes: 19

Quote:

Originally Posted by Pete K

I already gave that info.
Stock bolt length is 2 1/4 long. 2 1/2 give the extra length

May 7, 2006 | 11:41 PM

wro87

Thread Starter

Burning Brakes

Joined: May 2006

Posts: 857

Likes: 1

From: Morrisonville Illinios

Thanks I am glad for the help.

I will attempt the repair tomorrow and will let all know how it goes. Hopefully it get the kid out of the doghouse

Thanks WRO

May 7, 2006 | 11:48 PM

Aggravated4life

Race Director

Joined: Aug 2000

Posts: 14,130

Likes: 7

Cruise-In II Veteran

I always coat my thread taps with alot of grease before retapping.It traps alot of the metal shavings and makes it much easier to cut against the old bad threads.When its all done,spray it all out of the hole with brake kleen.