Clutch slave threads stripped on RSV Hybrid

[dingy]

Had a rather serious fubar on the motor on RSV/Hybrib. Was replacing clutch slave and stripped the threads on both the tapped holes. I had the slave on this summer, but removed it to help someone out, then got it back. When replacing it Sunday, both bolts stripped when torque was applied to manual spec. These holes are in one of the most hateful places on the block to reach.

 

My day job has it benefits, as there is a model shop machine group that has a lot of specialty tools and equipment. They had a set of tap extension adapters that allowed a standard helicoil tap to reach back in between the stator cover and the middle gear casting on the block. A 6mm helicoil fortunately needs a 1/4" tap drill that I happened to have, 12" long. I made a helicoil insert tool out of a piece of 3/16" rod with a notch on one end. After installing the two helioils, both screws torqued to spec.

 

Another catastrophe narrowly avoided.

 

Could have been a costly setback with time I have put into this motor. Usual pictures attached. Only top hole has helicoil installed in pictures.

 

Gary

[bongobobny]

What do you think caused them to strip out in the first place?? Anything that could have been avoided such as running a tap down the threads? Use new bolts instead of reusing bolts???

[dingy]

I had new cap screws in them, don't like the allen heads that came from factory on the slave. I have seen quite a few people that had problems getting allen heads out. They were the same bolts that had came out of it this summer. Might have been some loctite residue in holes. One thing I did notice was that the screws were recessed in a counter bored hole on both. This could have given me a false feel for them being lined up. I don't know where I messed up on this. I must have got them both cross threaded, not something I do though. I have run a tap in all the threaded holes on the block after I powder coated them, to help clear any sand out from blasting them.

 

Just lucky in this case. Could have been much more expensive.

 

Gary

[skydoc_17]

Hey Gary,

GREAT Save! I have had problems "feeling" weather those bolts are aligned or not when installing them myself. Your Helli-coil install was "genius"! I'm glad you didn't have to tear that block apart again. I bet you were doing the "snoopy dance" after that repair!

Good Job!

Earl

[uncledj]

Whew!!!

Havin' access to the right tools and knowing how to use 'em makes all the difference.

I'd have been in trouble.

Great save !!!

[Flyinfool]

Back when I worked for a military contractor it was absolutely forbidden to ever put a screw directly into aluminum. ALL threaded holes had to have a Helicoil or some other type of thread insert.

 

For future reference, all Helicoils in aluminum had to be installed with a drop of Zinc Chromate prime,r that helped to lock the coil in place and also resisted any galvanic corrosion.

 

Aluminum can only be torqued so many times before it lets go. I stock many sizes of Helicoils and other types of thread inserts in my basement. Eventually I will have at least all of the common sizes.

[paysaw]

Nice save on that one.

[Yammer Dan]

Scary!!