Anybody have advice for creating chasing tap/die

[QueBota]

Was able to remove the four bolts ( 2 per side) that hold the YPipe to the exhaust flange ears. Wasn't easy, threads on the bolt and the ears took quite a beating removing the fasteners, lots of heat, Kroil, Freeze spray etc.

Need to create a chasing/cleaning tap from a new fastener and perhaps a chasing/cleaning die from a new nut to try to clean up the existing bolts and bores in the manifold ears.

Not sure whats left of the threads in the ears, the threads on the bolts are pretty much gone, except for where they were in the exhaust flange ears. Would have snapped of if Ford hadn't used a M 12 1.75 bolt with a 15mm head, pretty meaty fastener.

Going to try to use the removed bolts if possible, I have each one marked to the bore it came from. I think new bolts will not match up very well with what is left of the threads in the exhaust flange ears. YPipe and flanges were together since 1991.

I know you need to cut a "slot" to give the chips room so they don't gall the threads.

Any advice appreciated.

Thanks,
Q

 

[4570Man]

Why don't you use a real die and tap?

 

[bcp]

When I've HAD to make a thread cleaner instead of making a long trip to town, I've cut 2 grooves in a bolt, using a grinding or cutoff wheel. And for bolt threads, a hacksaw cut through one side of a nut has worked.

Now I have a couple of very cheap import tap and die sets that I only use for thread cleaning.

Bruce

 

[QueBota]

I would like to try to salvage whats left. I believe the rust and pulling the bolts through the ears probably removed enough material to eliminate running a non cleaning/chasing tap through the bore Not enough material left to cut new threads at the original size. Would rather try to clean and dress what is left. My dad would have said we "burned" the fasteners taking them out. We kept them lubricated, it was a struggle for my 1/2" impact gun, 600 lb ft IR. Threads on the removed bolts don't very much resemble the new fasteners. They were hot when they came out, and not from the torch.

Access is poor, don't want to have to pull the exhaust manifolds. Worst case I can use slightly smaller fasteners with "flag" nuts on top. Reason they tapped the ears, very little space above for a wrench or even fingers, especially on the engine (inboard) side.

Thanks,
Q

Why don't you use a real die and tap?

 

[QueBota]

I have a fairly large made in China set of taps and dies, was a gift. Quality not the best, wouldn't use them for anything critical. Need to find a reasonably priced set of quality taps/dies. Was looking at some catalogs, made in USA = $$$.

Thanks,
Q

When I've HAD to make a thread cleaner instead of making a long trip to town, I've cut 2 grooves in a bolt, using a grinding or cutoff wheel. And for bolt threads, a hacksaw cut through one side of a nut has worked.

Now I have a couple of very cheap import tap and die sets that I only use for thread cleaning.

Bruce

 

[bigtiller]

A thread chaser set is cheap enough. Here is one from Sears for $110;

Sears.com

 

[JRobyn]

Might just buy ONE each tap and die of the correct (original) size at your local Ace Hardware?

- Jay

 

[SPYDERLK]

,,,,,,,,,,,,After thorough cleaning use one of these with moly on it to force everything back were its supposed to be.

McMaster-Carr

 

[Sodo]

This is a great tap and die set for only $40 at Harbor Freght. Read the reviews, theres 59 reviews, they seem genuine and overwhelmingly positive. Strangely enough they don't list the thread sizes. I have a set but it's 100 miles away.

 

[DFB]

This is a great tap and die set for only $40 at Harbor Freght. Read the reviews, theres 59 reviews, they seem genuine and overwhelmingly positive. Strangely enough they don't list the thread sizes. I have a set but it's 100 miles away.

It's listed there...but need to scroll bar the specification box

Coarse: SAE 4-40, 6-32, 8-32, 10-24, 12-24, 1/4 in.-20, 5/16 in.-18, 3/8 in.-16, 7/16 in.-14, And 1/2 in.-13, Metric 3-0.5, 4-0.7, 5-0.8, 6-1, 7-1, 8-1.25, 9-1.25, 10-1.5, 12-1.75, Fine: Sae 10-32, 1/4 in.-28, 5/16 in.-24, 3/8 in., 7/16 in.-20, And 1/2 in.-20, Metric 10-1

 

[bigtiller]

I'm not sure a tap or die would work for the OP. It sounds like he still has some threads showing but they are damaged. A thread chaser is basically a worn out tap/die and I think that may be just the ticket for the job.

 

[SPYDERLK]

I'm not sure a tap or die would work for the OP. It sounds like he still has some threads showing but they are damaged. A thread chaser is basically a worn out tap/die and I think that may be just the ticket for the job.

Yes. In a case like that the thread forming taps linked are ideal because they will push the metal of the remaining thread back into correct shape without cutting it.

,,,,,,,,,,,,After thorough cleaning use one of these with moly on it to force everything back were its supposed to be.

McMaster-Carr

 

[QueBota]

Quick update, had some more time to work on this. There were virtually no threads left in the bores of the exhaust manifold ears, just a trace of where they used to be. As I said earlier the bolts came out hot, my father (RIP) and other old timers I know would have said we "burnt" the bolts taking them out. We kept them drenched in Kroil backing them out but the combination of rust and old threads on the bolts wiped the threads from the manifold ear bolts.

We went with slightly under size fasteners with nuts on the bottom. Very little clearance to drop the new fasteners through the bores and into the ears of the Y pipe flange. Difficult to get a wrench on the inside bolt heads to enable torquing. Obvious now why they had threaded the bores on the ears.

Job is done, should last longer than the truck. Just glad the bolts didn't snap off on during removal. Would have been left with the difficult task of trying to remove the broken off studs from the ears, with either a stud remover, drilling them out or burning them out with oxy/acty. Didn't want to pull the exhaust manifolds, I'm sure that would have turned into another project.

Walker sells a replacement fastener kit for about $15.00 a side Amazon.com: Walker 36129 Hardware Spring Bolt Kit: Automotive, looks nice but we just used fasteners from my shop.

Thanks,
Q