tap threads?

[crawlin91]

cleaned up my d35 diff that will soon be under the truck. ran a new bead of rtv and bolted back onto axle arm. one of the bolts (the very bottom one)that holds the chunk on the arm is stripped. Im assuming all I need to do is tap new threads, anyone know what the thread count/size I need.

 

[AllanD]

IF I recall correctly the D35 bolts are 10x1.5mm Metric threads.

Simply cutting new threads won't help, you need someone wiht a helicoil kit
and to drill out the original threads and cut new ones to accept an insert
So that the original bolts can be used.

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[crawlin91]

fawk

 

[swamprat]

It is simple. Just call some industrial supply houses and ask if the carry helicoil. Tell them what size you have and they can get what you need. Kit comes with the proper size drill bit and tap. Drill hole out and retap. I put the tap in the drill and on low speed and plenty of oil tap the hole. Dont tighten the chuck all the way. You want it to slip if it gets too tight. Kit also comes with the tool needed to insert helicoil. Keep the kit because you can order just the inserts later if you need them. I use these at my work and the are great.

 

[MAKG]

You can get Helicoil kits at an auto parts store. They cost quite a bit for what they are, but they do exist.

 

[crawlin91]

Oh, I guess it just sounded worse than that. Dont most taps come with a T handle to turn the threads? Ive only turned threads a few times but I would think a drill would be too much speed and bore it out.

 

[Psychopete]

Oh, I guess it just sounded worse than that. Dont most taps come with a T handle to turn the threads? Ive only turned threads a few times but I would think a drill would be too much speed and bore it out.

I've usually tapped with the t-handle that you're describing. Taps are very brittle, and suck to remove if snapped.

My dad has told me at some point when I was a kid to never to drill with 3 fluted taps, but 2 fluted are ok. Not sure why he did at that time, but oh well, I just remembering him telling me about a guy at his work that was tapping pretty thick steel with a larger dia. 2 fluted tap with some sort of hard core drill.

IMO, No sense in rushing something your not comfortable with though. Do it right the first time, and you won't have to do it again.

Pete

 

[AllanD]

When installing a repair coil you must first remove the original threads to
prepare the hole for the new (oversized) threads to be cut (by hand with a tap)
to accomodate the insert.

genuine Helicoil kits run $25 and up

But there is a common Copy "Save a Thread" insert that is a close copy that are to be found in most chain autoparts stores (or Fastenal)

They aren't too hard to find.

Personally I tend to use a lot more helicoils as "preventive maintainance"
than as "repairs"

Particularly on threaded holes that go into aluminum or for exhaust flanges.

As an example all my exhaust manifold flange bolts (all twelve) on my 4.0
have been helicoiled, as have been the bolts that retain my water pump, and especially the thermostat housing bolts.

Basically all the bolt holes that are EASY to access with the engine on
an engine stand but are an absolute bitch to helicoil with the engine
in the chassis... It is much less annoying to helicoil all those holes
than to have a bolt break off when doing a hurried repair...

then there are the bellhousing bolt holes into the oil pan and the
starter mount holes in the bellhousing and the tranny mount holes
in the tranmission tailshaft...

or the tiny 1/4-28 threads in the front differential flange


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[swamprat]

Oh, I guess it just sounded worse than that. Dont most taps come with a T handle to turn the threads? Ive only turned threads a few times but I would think a drill would be too much speed and bore it out.

variable speed drill. You can do it by hand if you want. Get a cheap T handle at sears. I use a drill on low speed then barely hit the trigger. I can count the revolutions of the tap.

 

[4x4junkie]

I'd do like Allan also, drill out ALL those holes, and stick an insert into each one (it can actually be looked at as an upgrade, not just a repair). The steel insert is far more durable than a hole with aluminum threads.

 

[yyc_tbird_sc]

Alot of the big cylinder head companies will actually put heli-coil inserts for the rockers and other high stress ares. I've also seen them used in aluminum blocks for the head bolts. They help to distribute the load more evenly, to a greater surface area of aluminum. I agree with doing all the threads you can with them.

I'll stick with the heli-coil brand as I've seen some of the cheap ones not install properly or actually be deformed out of the package. Use the full kit unless all you need is a refill.

 

[c_note]

i recommend tapping by hand. if you've never tapped or arent very experienced in tapping holes, you will definitly break it while power tapping. make sure you drill to the proper tap drill size and you shouldnt run to any problems.

the helicoil kit will tell you the tap drill size for aluminum and also steel if it is not included in the kit. theres usually one size in difference between the two metals.

btw, before you go ahead and buy the helicoil kit, buy the actual size bottoming tap and try to clean out the threads. you may be able to save the threads. the tap alone should be around 5 bucks or less.

 

[Dann757]

I have heard it's a good idea to tap in a little, then back the tap off a little to clear the cuttings, keep doing until you have the depth you want. I use cutting oil from alittle bottle, had that bottle for years.