Broke 3 of 6 flywheels bolts off in crank.

[Chicago1]

Long story short dowel pin for flywheel came loose. Checked the flywheel bolts and two of them were loose. Started taking them all off to replace and 3 off them broke off and the other three look nice and shiny at the ends. I have a buddy bringing me reverse tap I believe but what's thw best way to go at it without stripping it to all hell and having to pull the crank? Oh yeah the three that broke off are flush with the crank. I was about to wake her from her spring sleep. /ubbthreads/images/graemlins/frown.gif Can I retap the other three threads or just pray the new bolts go in nice and smooth?

 

[rdomeck]

That's going to be an odd size tap...Maybe a 12X1.0 or 14X1.0 or 14X1.25. Not sure on the tap size, but not something you will find at a hardware store! Your best bet is to drill a small hole and use an easy out. They look like this click

That company would also have a tap of the right size and maybe the bolts, but I would try and get the mitsu ones!

You can sometimes find the easy out's at a Sears tool store or maybe Napa or one of the better auto parts stores. Good luck and take your time as the other option will be costly and time consuming!

 

[Terry Posten]

If you try and cleanthe threads you have to use a thread chase not a tap.

I would just get new factory bolts and thread them in without the flywheel and see how they go.

 

[89Mirageman]

Ouch, those things are hardened too so I'm betting they will not be easy to drill. If you do get them drilled be careful not to break the easy out off in there.

 

[TRBODSM]

If you have access to a welder I would weld some hardware nuts on the head of the flywheel bolts and try again with an impact socket. As mentioned above try to put the new OEM bolts in by hand and if you have troubles doing that chase the threads but I would not re tap unless that is your last option.

 

[curtis]

There hardened bolts. Your going to have to buy a carbide drill bit. Not carbide tipped /cobolt/masonry but a real deal micrograin carbide drill, go slow at the correct speed and don't force it or it will explode but some time spent slow and easy will drill them out. If you can find a 4 flute get that. I've drilled out alot of broken off bolts in turbine housings and a carbide end mill makes easy work out of it but in the car doesn't allow for a few thousandths at a time pushing a key on a keyboard.

like these below be prepared if you find them local to you probably going to be in the 35 to 50 range each.

click me click me
click me

 

[thedsmguy]

That last one is a seriously good looking drill bit. Thanks for the links.

 

If the head is broken off the bolt it shouldnt be to hard to get out of there. The head of the bolt is what holds it in place(if that makes sense)

Anyways good luck. I recently dealt with bad threads for my flywheel, so I know how stressful things like this are.

 

[BrandonEchols]

Quoting fivesfe:
If the head is broken off the bolt it shouldnt be to hard to get out of there. The head of the bolt is what holds it in place(if that makes sense)

Anyways good luck. I recently dealt with bad threads for my flywheel, so I know how stressful things like this are.

 

[Chicago1]

Well boys I tried and tried with no luck I even had a few of the other guys try and no go. They are seized in there. I tried everything you could imagine except the welding part. I'm in the process of just getting a new crank since all the other holes are stripped pretty bad. I'll see what the machine shop can do but for now I'm pulling her out and getting a new crank. /ubbthreads/images/graemlins/frown.gif She's almost out as we speak. Thanks for the help.

 

[ktmrider]

Dang was hoping the broken studs would come out with the extractor.

I know Rabbi has a few 6-bolt cranks laying around, keep me/us posted on the progress.