Hi guys,

Pretty soon I'm gonna need to drop the tranny on my car. When I installed the motor in the car I think that some of the bolt holes were going bad. I think that the 3 bolt holes for the halfshaft-to-block are gonna need to be re-done, along with the 2 or 3 bolt holes for the rear mount-to-tranny,

What is the easiest and best way to fix this problem? I'm guessing that drilling it out a bit and rethreading the hole would be best, but I have never had to use a tap and die set. I looked a helicoil kit at a NAPA once and aren't those like coil springs? you just drill out the hole, stick in a helicoil and get a bolt to screw into it?

Can somebody give me a quick run down of how you drill and tap a hole? From what little I know, you drill out the hole to get rid of the bad threads. Then you use a tap and screw it into the smooth hole and it will "cut" new threads for you right?

so what do you guys think I should do?

TIA

 

If it was me I'd probably use HeliCoils or TimeSerts (they're kinda similar).

Be careful - there's a specific drill size for each HeliCoil size. And a special tap that you probably aren't gonna find anywhere else. (It's a bastard size/thread)

Drill carefully, it better be straight & centered. Watch the depth!
Use a T-handle for the tap, if you use a wrench you'll get it tapped crooked.
Clean out all the metal chips.
HeliCoil gives you a tool for inserting the coil, it seems like the instructions were pretty clear.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">Use a T-handle for the tap, if you use a wrench you'll get it tapped crooked.
Clean out all the metal chips.
HeliCoil gives you a tool for inserting the coil, it seems like the instructions were pretty clear.</TD></TR></TABLE>

Cool, thanks for all the tips. I wasn't sure if any special precautions had to be taken before hand to make a good tap job. I'm gonna take to the machine shop guys at the local NAPA and see if they can lend me a hand finding the proper drill size and tap for the helicoil.

 

The package for the HeliCoil kit says exactly what drill size to use. Buy exactly that & you'll be OK. I think the kit comes with the tap & the inserting tool.

If the engine's out of the car, it's much easier to line up the drill & tap so it doesn't go crooked.

If it's in the car, your preparations ahead of time should be remove as much stuff as you can to make plenty of room. Maybe make some fixtures to help hold the drill at the right position so it's straight & square. (Blocks of wood & c-clamps or something??)