Chevy Nova Forum banner

Status
Not open for further replies.
81 - 100 of 124 Posts

·
Premium Member
Joined
·
10,210 Posts
thread chasers will NOT remove any metal taps MIGHT remove metal thats about the only real difference as far as I know...personally I have always used taps to clean threads with seemingly no ill effects:)
 

·
Premium Member
Joined
·
11,208 Posts
Taps will remove material and cut threads which is what they were made to do. Chasers straighten and clean threads more than cut. I use taps alot too but say you clean the threads in your motor for the head bolts with a tap instead of a chaser. Much more likely to leak no matter what sealer you use. There's just less material cause the tap cut some more out when you used it. RM
 

·
Premium Member
Joined
·
10,210 Posts
Taps will remove material and cut threads which is what they were made to do. Chasers straighten and clean threads more than cut. I use taps alot too but say you clean the threads in your motor for the head bolts with a tap instead of a chaser. Much more likely to leak no matter what sealer you use. There's just less material cause the tap cut some more out when you used it. RM
yes a tap will remove metal if there is metal to remove, such as when you tap a fresh hole, but if you are using the correct size tap in an already tapped hole IMHO it should not be removing any metal unless the threads are damaged somewhere in the hole...with an undamaged thread all it should normally be removing is the dirt in the threads...again just my two cent on this:)
 

·
Premium Member
Joined
·
2,950 Posts
I guess I'm going to learn something new here...I've always used regular taps for chasing threads...what's the difference between a regular tap and a thread chasing tap?
Thanks
Same here, I will use a bottoming tap vice a taper for existing threads. I am not sure I know or see the difference in using a thread chaser.
 

·
Premium Member
Joined
·
3,257 Posts
Get the opinion of a machinest that you can trust (someone that really knows what he is doing, not someone that just tells you he is a machinest) and i think you will find that the majority will tell you not to use a tap to chase threads because it enlarges the hole too much, a thread chaser just cleans up and reshaped the exsisting threads back to their original shape like Real McCoy said.
 

·
Premium Member
Joined
·
9,228 Posts
I guess I'm having a hard time understanding that if I tap a hole with a 1/4" tap and later come back and run that same tap through the hole again, how's it going to remove any more material (other than dirt or other contamination) when there's no material there? What am I missing? I guess I'd have to look at a set of them and try to see the difference from a regular tap.
 

·
Premium Member
Joined
·
3,257 Posts
I am not expert on this matter but my understanding is that the threads distort slightly when the bolt is tightened and do not completely go back to their original shape even after the bolt is removed. The tap cuts this distortion out but a thread chaser just reshapes the metal back to its original shape. Like I said, not an expert but that is how it was explained to me many years ago.
 

·
Premium Member
Joined
·
31,194 Posts
In 90% of the cases it will do what you need (tap),but if you have a damaged thread it will cut it out with the tap the chasers are designed to realign threads.If you have a thread that is damaged,gone oval (extreme case)and the hole was 3/8" the wide part of the oval is over 3/8" and the narrow part is under the tap will cut the undersize to 3/8" while the larger part of the oval will remain larger you now have a hole that is larger than 3/8" as well as possible head leak as previously mentioned by RM.the chasers are not designed to cut,but push the metal back into the correct shape,and realign threads.

Sorry for the lack of tech terms but that's the simplest way to explain it.;)

For the most part a tap will do the job,but you only need to ruin 1 block to find out the $30 you saved just cost you $3000 cause the wrong part let go.
When you do this for a living the right tools are needed.I'd be P!$$ed to find that my engine build damaged my #'s block for not using the right tool.

You can take a steering wheel of with a hammer too(I've done many without ill affects),but mess it up and you damage the column.I know i have one from the a previous owner.:(

My 2 cents Paul
 

·
Premium Member
Joined
·
10,210 Posts
You can take a steering wheel off with a hammer too(I've many without ill affects),but mess it up and you damage the column.I know i have one from the a previous owner.:(

My 2 cents Paul
Funny stuff there Paul:D ......however I have engine blue printing books that say taps are fine for this purpose but I dont think I have any chasiss dissasembly books that say a hammer is fine for removing a steering wheel.:rolleyes:
 

·
Premium Member
Joined
·
31,194 Posts
I'll have to agree with using the taps as opposed to hammer for steering wheel removal:p ,just trying to show an example and I went to the extreme:eek:.
For the most part taps are fine I've never had any trouble using them.

Does this mean you won't need me to remove your steering wheel? LOL!!!

Paul
 

·
Premium Member
Joined
·
11,208 Posts
I gave you my thoughts and if you have had good success with taps that's fine,Tap the holes. I have done lots of stuff others have told me I shouldn't. I won't argue about it........LOL. The post was how to remove the balancer and then fix the threads. He now has options and for this job either method will do the job. On some BBCs I've used 9/16 bolts so if all else fails go up a size. You still have helicoils and threaded inserts too. Best of luck. RM
 

·
Premium Member
Joined
·
5,858 Posts
Thanks everyone! I think I will try to find a thread chaser first - if I can't find one of them I'll try the tap idea and go from there. I won't be doing it until it warms up a little though ;)
 

·
Registered
Joined
·
950 Posts
I think the point is that taps will clean out (and slightly enlarge) threads that are good to begin with. When the threads are damaged and are moved where they should not be, a tap will just cut them off and leave you with thin or no threads in the damaged area. The chaser will push the threads back where they should be. This leaves the threads stronger and they will not damage the new bolt like sharp or missing threads can.
As a Gunsmith, I tapped and threaded hundreds of holes and repaired damaged ones. Your wise to use the thread chaser, you don't want to launch the balancer thru the radiator at 7000 RPM.
Be sure to clean the hole out well with some brake cleaner and then use some anti seize on the threads of the new bolt. Use a good high sulpher dark tapping oil ( not regular oil ) on the thread chaser will make for nicer threads, don't put in in dry (you should know that from other experiences ;) ). Clean the hole before using the thread chaser also. You are going to want to back the thread chaser out from time to time and spray more brake cleaner in the hole to clean it out. Use lots of threading oil, get a good tap wrench and apply even pressure streight in, do not lean on the wrench. If for any reason the tap stops or binds, stop and carefully back it out. If the tap breaks in the hole, the're murder to get out. Take your time and do it right. Cranks are very hard and tapping new larger threads is not an easy process.

John K
 

·
Registered
Joined
·
3,416 Posts
Hi,

Lots of good advise on this already.

In my opinion there are several types of taps as well as thread chasers. Some are much better at "forming" threads than cutting them. For cast iron I have had good luck with the forming types of tooling, but alloy steel may be a different matter. Some of the tolerances on the chasers leave a lot to be desired, but they generally get the job done. When you are are done I would thread a new bolt in and see how it fits if it feels "loose" I would be kinda sceptical about it.

I have Helicoiled several crank snout threads. I have made a few fixtures to help align the tooling, that makes it simpler and more accurate. I use two helicoils in this application, or you may be able to order 1 long one. The point is you want as much thread contact as possible. I have had excellent luck with using two coils.

How ever you repair it be very careful installing the balancer.

Good Luck
Jeff
 

·
Registered
Joined
·
1,545 Posts
I think i will get the tap situation figured out for yas

First there are two taps, regular and bottoming, a regular tap is tapered and a bottoming tap is the same diameter the whole length...

A thread chaser is not designed to cut new threads, just clean em out and straighten things up....

The problem with a standard tap (most people do not own bottoming taps) is that in a blind hole you can't tap all the way in....you could with a bottoming tap, and if your cleaning threads in a blind hole i would use a chaser over a bottoming tap....and in general the reason i personally use a chaser over a tap is because i don't want to use my good taps just to clean out some raggedy old holes, i use them for good cuts on a fresh hole so the tap cust cleaner and faster with less chance of breaking, the other reason i like to use chasers
 

·
Premium Member
Joined
·
11,208 Posts
I have bottoming taps and starter taps and I don't think the bottoming tap is any different than a starter tap except one makes threads all the way down a blind hole while the other doesn't. Then nobody has mentioned a two, three or four flute tap. Whats the difference and when do you use the different flute types? Then we have taps with different size shanks. I know what the tool reps who use to sell them all to me use to tell me they were for. I doubt any of us know as fact what the differences are for and we all have different thoughts and opinions. I say just do whatever works and makes you happy. RM
 

·
Registered
Joined
·
1,372 Posts
Thanks for the good info, I'll be checking out my crank this weekend - my balancer almost came off a few months ago. It cracked the entire length of the keyway, boogered up the crank snout around the keyway. I was able to file it down a bit and snug another balancer onto it to get it from the trailer into the garage. I have not touched it since Sept. 2, but 'should' have time this weekend. I didn't even get to check the balancer bolt threads, but now I'm armed with info ;)

Anyone ever see a balancer break open like that? Luckily it didn't happen the day before when I was running 7,000 rpm through the traps :eek:
Will keep you posted.
M
 

·
Registered
Joined
·
433 Posts
People may get into some trouble when they use the incorrect tap or die sets.
There are different "class" of thread fit. 1/2/3, A/B/C.
Class 2 fit is a common industrial standard. If you use a class 2 tap (or unknown poor quality import) on a class 1 thread it will remove material.
Taps and dies are ok for cleaning threads as long as the class fit is the same.
And you do not enter vergin/untapped material.
I inspect suppliers hardware threads at work. This is why I have to inspect threads (internal and external), nut and bolt threads with calibrated, and class matched, plug gages and thread gages. I cannot use a nut to check a bolt thread. Nor could I use a tap to check a nut.
It has to do with pitch, angle, pitch diameter and several other characteristics, plated and unplated factors also.
IMO.....Threads/screws is a complicated engeneering discipline. Some people study to get degrees in "thread engeneering". I'm not one of them!!!

Don
 

·
Premium Member
Joined
·
5,858 Posts
I found the correct thread chaser from one of the mechanics at work and ran that in the hole, then took a new bolt and put it in without the balancer. It seemed to tighten up well - so I hope everything is cool. I bought a 2" long bolt along with the stock 1 1/2" - so if I can get away with it I will just add a washer and lock washer to the 2" one to get farther down in the hole when I install the balancer. the hole is 1 1/2" deep, then you have about 3/16" for the main washer, and I'm sure the balancer doesnt fit exactly flush either - so maybe I can use the 2" one to get more of the threads. Hopefully I will get this done in the next couple of days......
 
81 - 100 of 124 Posts
Status
Not open for further replies.
Top