So I stripped a hole with thread pitch m10x1.25 on the crossmember that holds the steering rack on my 05 sti steering rack setup. I dont want to helicoil it because it would require me to take the whole rack and pinion off. I am replacing the crossmember when it gets a little warmer so i need a bolt to hold temporarily until the weather warms up. What size tap would you guys recommend me use? The hole is stripped almost smooth (bolt was rubbing it for a while now). I was thinking a standard size thread pitch close to m10x1.25 but what? Any help or suggestion would be great! Thanks in advance.
Not to ask the obvious, but did you already try to re-tap it at m10-1.25? If you can't get that to go, a different thread pitch won't help you. You will have to drill it out larger and either retap or helicoil if it is really that buggered. -Steve
Drilling out the hole slightly bigger and taping it is essentially what helicoiling is. A helicoil tap is a non standard size that is slightly larger than the hole that was previously tapped, followed by the coil which bring it back down to the original size. If you were to skip the helicoil and go just one size up, like M11, then it would be too big to helicoil later on. Tapping one size larger than the original hole without helicoil will likely result in having to drill out the through hole in the steering rack to accept the larger diameter bolt. ~Dan
would you guys just recommend me trying to rethread first? crossmember is just sitting there and i dont have a garage to do the swap right now. just a driveway so i wanna wait till it warms up...
he said he's already planning on replacing the crossmember. So he's just looking for a temporary fix. if the hole is essentially stripped smooth, than it's essentially the same as going after it with a 10mm drill bit. and you won't have any material to cut threads in for the stock size. 10mm = 0.3937 inches. a 13/32 drill bit would be 0.4062. Thread taps say what size drill bit to use. So I'd say, go to the hardware store, and buy a tap that says for a 13/32 drill bit (probably 3/8, 15/32 or so), and a matching bolt, and call it a day. If you felt that that 2/100 of an inch was too much of a difference, you could grab that sized drill bit too and clean it up first, but I don't think you'd need to.
I have a M10X1.25 Heli-Coil kit so if you want it fixed for an OEM bolt, let me know. I'll be in the garage all Friday night.
10mm bolt has a major diameter (diameter over the threads) of ~0.3937". So if it is stripped clean you should be left with a hole around that size, ~0.3937". A 7/16-28 thread has a minor diameter(diameter at the base of the threads) of 0.3937". IE: you should be able to run a 7/16-28 tap in your existing "stripped" hole and have full usable threads when done. Honestly I would take piddster up on the offer to heli-coil it. There is no difference in taping it out to a larger thread vs taping it for a heli-coil. Other then with the heli-coil you will be able to keep the right size bolt in there. Here is a handy chart. http://www.physics.ncsu.edu/pearl/Tap_Drill_Chart.html Should be cheaper(and have) then a hardware store for the tap.... http://www.walterhammond.com/storefrontCommerce/ 3601 29th Avenue NE Minneapolis, MN 55418 612-781-7441
^ This. Stainless steel Heli-Coils typically are stronger than the original threads. I'm not going to get into it here, but it is what it is.
I would helicoil but i would have to drop the rack and pinion. If I have to do that, I would rather just swap out the crossmember...
I'm confused why adding a heli coil would require more work than rethreading it? Essentially it's the same thing, just re-thread it, and put in the heli coil. Done. Better than new. I did 2 of them in about 10 minutes a couple of weeks ago.
^ You make a good point. Re-tapping for a larger bolt and using the heli-coil method involve the same amount of work, and access to said threads.
The hole that is stripped is under the steering rack (looking from under the car). A bolt just goes through the steering rack bushing(larger diameter hole) and into the hole. If I was to helicoil, I would have to drop the rack to make sure the helicoil is inserted nice and sits tight. But if I was to just to tap, I could just tap the hole and clear the bushing, even if the bushing gets ruined, its cheap. Sorry if this didnt make any sense...
