Gain extra benefits by becoming a Supporting Member Click here find out how!
Classic Performance Products Classic Parts
Ciadella InteriorsAmerican Auto Wire Classic Industries
Chevs of the 40sDanchuk Catalog
Hellwig Products IncPerformance Rod & CustomEcklers AutoMotive
Nu-Relics Power Windows
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy

Username Post: Stripped Threads on Crank!!        (Topic#97660)
GySgtBigdaddy 
Senior Member
Posts: 344
GySgtBigdaddy
Loc: California
Reg: 02-18-05
04-15-05 04:53 PM - Post#673516    

Any words of wisdom on what to do when after installing the harmonic balancer on my 1977 350 and then mounting the pulley the main bolt that attaches the pulley thru the balancer is not catching on the threads enough to tq down. I tapped the crank and rethreaded the bolt also. It all feels and looks good. So then I installed the balancer and got it all the way down on the crankshaft. The balancer only sticks out 1/2 inch or so from the edge of the timing plate. But when I put the bolt in it acts like its too short and only catches alittle bit!! Then pops out when I put a wrench on it!! What are my options and how bad could this problem get (crank replacement?!!). Any of ya'll ever had this problem and what did you do to fix it? Thanks for any help you could offer..

It's GOD's job to forgive bin Laden...
IT'S OUR JOB TO ARRANGE THE MEETING!
SEMPER FI!
USMC
*70 C20 Longbed 3 spd manual


 




Bruisr 
Senior Member
Posts: 763
Bruisr
Loc: Tonopah, Az.
Reg: 04-08-05
Re: Stripped Threads on Crank!!
04-15-05 05:24 PM - Post#673517    
    In response to GySgtBigdaddy

Several items come to mind: Heli-coil, not certain if it will provide the torque specs. required!?
I ran into a similar problem; I found a longer harmonic balancer bolt, compared the length, and found it to be almost 1/2 inch longer. I use it now and have not had any problems spinning my 350 to 6000 rpms on a regular basis.

SEMPER FI

Loud Pipes Saves Lives
1976 GMC Sprint (My sons 1st. car)
1976 El Camino (73 laguna front end)
1974 Chevelle 454 TH350 3500 stall 4.10 gear
1973 GMC sprint "DECEASED"


 
MikeB 
Ultra Senior Member
Posts: 10058
MikeB
Loc: Plano, TX
Reg: 08-28-03
Re: Stripped Threads on Crank!!
04-15-05 06:04 PM - Post#673518    
    In response to GySgtBigdaddy

Does the bolt thread into the crank snout when the damper is removed? If so, get a longer bolt to start the damper moving backwards, and then substitute the proper bolt and washer. The ideal way, of course, is to use a damper installation tool.

If the threads are hosed, all may not be lost. It just might be possible to renew the threads with a thread restorer or a tap. And if only the first few threads are messed up, try Bruisr's idea of using a longer bolt. That hole is quite deep.

If that doesn't work, maybe a Heli-coil will, assuming you have good access to the crank snout.



 
Robert_May 
Old as Dirt Member
Posts: 6939

Loc: San Marcos, CA USA
Reg: 01-03-02
Re: Stripped Threads on Crank!!
04-15-05 07:46 PM - Post#673519    
    In response to GySgtBigdaddy

The bolt is not intended to pull the balancer onto the crank. It is intended to keep it there.
Use a proper balancer driver to put the balancer onto the crank. The proper design allows you to put the rod fully down into the crank threads and then you use another nut to pull the balancer onto the crank. You then remove the tool and put the bolt in.

Robert May Fat? Eat less and you will get thinner!


 
GySgtBigdaddy 
Senior Member
Posts: 344
GySgtBigdaddy
Loc: California
Reg: 02-18-05
Re: Stripped Threads on Crank!!
04-16-05 12:37 AM - Post#673520    
    In response to Robert_May

I'm going to try the proper installation tool and get a longer bolt. The threads are fine without the balancer/pulley installed and the bolt threads in just fine. I hope I dont have to install a helicoil....no access to that here.
Thanks for the feedback!!

It's GOD's job to forgive bin Laden...
IT'S OUR JOB TO ARRANGE THE MEETING!
SEMPER FI!
USMC
*70 C20 Longbed 3 spd manual


 
strokersix 
Senior Member
Posts: 1041

Reg: 04-05-03
Re: Stripped Threads on Crank!!
04-16-05 02:15 AM - Post#673521    
    In response to GySgtBigdaddy

You can tap the threads deeper, drilling deeper first if needed, and use a longer bolt. Or drill and tap to the next bigger size. 1/2-20 if SB, 9/16-18 if BB.

69 Caprice 454 TH400 (original 427 in storage) 72 Nova 410 big block 3 speed Saginaw (was 306" inline six)


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17109
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
Re: Stripped Threads on Crank!!
04-16-05 02:26 AM - Post#673522    
    In response to strokersix


these tools are cheap(about $30) and well worth the money, Id HIGHLY ADVISE DOING THE JOB CORRECTLY, BUY the TOOL!
but if you insist, an old head stud can be used
most big block cranks are threaded 7/16 nf , most small blocks are threaded 1/2 20 NF youll need to find a fully threaded 7/16" nf or 1/2 20 NF stud about 6" long, install the ballancer by hand as far as it slides on, now thread in the stud untill it bottoms out, slide on the damper retaining washer ,a dozen large fender washers, squirt with oil and install the nut, now tighten the nut slowly to force the washer stack against the damper untill it slides on.

heres a good place to look, or try EBAY
http://www.etoolcart.com/browseproducts/Harmonic-Balancer-Installer-SKT92514.html

http://www.sdpc2000.com/catalog/2899/Moroso-Harmonic-Balancer-Tools.htm



Harmonic Balancer Installer

Item No. - 46040
Don't risk altering the crankshaft end play by pounding the harmonic balancer into place! This tool supplies the steady force needed to correctly mount the Balancer on the crankshaft. The 8 adaptors (7/16"x20", 1/2"x20", 9/16"x18", 5/8"x18, 3/4"x16, 12mmx1.50, 14mmx1.50, 16mmx2.0) will fit both domestic and foreign cars. Requires 1 1/4" capacity wrench. Replacement adapters available (7/16" x 20). Limited 1 year warranty.



Regular Price: $31.99

having gone thru this several times , Ill point out a few things,
(1)
the stripped threads are surely caused by trying to pull the damper in place using the bolt, (bad idea) you NEED to use the correct tool


look at the picture carefully
the small 7/16 thread ,on the tool threads into the crank, the damper slips over the tool, the large washer style bearing slips over the tool followed by the solid washer followed by the large nut that threads on the tool, the back of the tool is normally a 9/16 or 5/8 hex this is held with a box end wrench to keep the engine from turning, the large nut is usually a 1 1/8" nut and it is tightened with an open end 1 1/8" wrench or a adjustable wrench against the two washers drawing the damper onto the crank snout! lube the threads on the tool, the inside of the damper and crank snout with oil before starting. the damper will normally slide on about 1/4 of the way bye hand then the tool is needed to draw the damper on the last 3/4 of the distance, don,t over tighten the tool the 7/16" thread will snap off in the crank after the damper bottoms out on the lower timing gear if you do!,
NEVER USE A HAMMER AND BLOCK OF WOOD TO DRIVE THE DAMPER ON, YES THOUSANDS OF GUYS THINK THEY DID IT WITHOUT ANY PROBLEMS BUT...
IT WILL DAMAGE THE THRUST BEARING CLEARANCES,
IT CAN BREAK THE ELASTOMER TORSION RING ON STOCK DAMPERS
IT CAN CAUSE THE INERTIAL RING ON FLUIDAMPER TO BECOME JAMMED INTERNALLY
IT CAN CAUSE THE DAMPER TO FAIL.
IF THE DAMPER FAILS THE CRANK WILL EVENTUALLY BE DAMMAGED
IT GREATLY STRESSES THE CRANK SHAFT
IT CAN DAMAGE THE CRANKS TRANSMISSION PILOT BEARING
IT CAN DAMAGE THE TRANSNSMISSION
ALMOST EVERY TYPE OF DAMAGE IS NOT SOMETHING THAT SHOWS UP RIGHT AWAY, BUT IT WILL DAMAGE THE PARTS LISTED AND THERES THOUSANDS OF GUYS THAT ARE WONDERING WHY THOSE PARTS FAILED 6-24 MONTHs LATER WITH NO CLUE AS TO THE CAUSE!
[bASK YOURSELF THIS QUESTION, IF CRANKSHAFTS THAT ARE A FEW THOUSANDS OUT OF LINE I.E. NOT PERFECTLY STRAIT ARE BENT/STRAITEND WITH A LEAD HAMMER BY CRANK MANUFACTURES (and yes thats how its done) AND CRANKS THAT ARE DROPPED ON A CONCRETE FLoOR SOMETIMES BEND SLIGHTLY ,(happens all the time) WHAT MAKES YOU THINK THAT BEATING ON THEM WITH A HAMMER AND A BLOCK OF WOOD WONT DAMMAGE THEM?
AND WHILE WERE AT IT WHAT WOULD YOU DO TO SOME GUY YOU CAUGHT BEATING ON YOUR ENGINE BLOCK WITH A HAMMER? WELL WHAT DO YOU THINK THE CRANKS DOING TO YOUR MAIN CAPS WHEN YOU BEAT ON THE CRANK? PROPERLY USED THAT INSTALLATION TOOL CAN EXCERT OVER 15 TONS OF PRESSURE TO SLIDE THE DAMPER ON, IF IT WONT SLIDE ON, THERES A PROBLEM! FIND IT AND FIX IT .....DON,T BEAT ON THE DAMPER/CRANK


(2) you can easily RE-DRILL and RE-THREAD the crank from the 1/2"NF to the 7/16 NF thread used on big block cranks and use a bbc bolt if you strip a sbc crank,AND TO THOSE ASKING WHY THE FIT IS SO TIGHT
first let me point out that theres a DESIGNED CLEARANCE RANGE of manufacturing tollerances and if its not the factory original ballancers theres an excellent chance the ballancers internal dimension does not match the crank snouts outside dia.....next I need to point out its DESIGNED to be a slight interfearance fit, it it just slides on it will not be as effective at absorbing crank harmonics if theres ANY SLACK and only the crank KEY keeps it from turning, it takes a very tight fit to act as DESIGNED, now that being said, theres no reason that it needs to be excessively difficult to install and a BRAKE HONE used to open up the internal dia. slightly is perfectly exceptable, as is placing the damper in hot (not boiling)water top expand the internal dia. and oiling the crank snout before installation. but using the correct tool makes a huge differance in how hard they go on!





 
GySgtBigdaddy 
Senior Member
Posts: 344
GySgtBigdaddy
Loc: California
Reg: 02-18-05
Grumpyvette!!
04-16-05 11:37 AM - Post#673523    
    In response to grumpyvette

An installation tool makes all the sense in the world...just wish I'd ask that question before I beat it on. I thought I asked the right person who said "just put a piece of wood down and go at it"....this learning process stinks!! I've tapped it out to 1/2" 20, and will purchase a new bolt (bbc) tomorrow. If the base autohobby shop doesn't have the installation tool then I'll get one out in town. Time isn't the biggest issue with this as much as keeping the "One shot..One kill" idea going. Thank everyone for going over the BASICS with me time after time...

It's GOD's job to forgive bin Laden...
IT'S OUR JOB TO ARRANGE THE MEETING!
SEMPER FI!
USMC
*70 C20 Longbed 3 spd manual


 
strokersix 
Senior Member
Posts: 1041

Reg: 04-05-03
Re: Grumpyvette!!
04-16-05 02:21 PM - Post#673524    
    In response to GySgtBigdaddy

You really don't need a high dollar tool. A piece of 1/2-20 all-thread will work just fine. Just be sure you have plenty of thread engagement in the crank. Use a longer nut if possible and some heavy washers, preferably hardened. Anti-seize on the thread will help too. The trick is finding the 1/2-20 all thread! One source for 4140 alloy steel all-thread is Green Bay Mfg 920-793-2411. Their catalog says $2.96 for a 1 foot piece of 1/2-20 alloy all-thread. There may be cutting charge, I don't recall. Also I don't think they accept credit cards. I keep some of this stuff on hand because it's useful for all sorts of purposes; pulling dampers on included.

In addition, I altered my damper puller with some alloy acme thread and nut from the same source. Works far better than the vee thread ever did!

69 Caprice 454 TH400 (original 427 in storage) 72 Nova 410 big block 3 speed Saginaw (was 306" inline six)


 
strokersix 
Senior Member
Posts: 1041

Reg: 04-05-03
Re: Stripped Threads on Crank!!
04-16-05 02:28 PM - Post#673525    
    In response to grumpyvette

Grumpy,

I am curious. How did Chevrolet install dampers on early small blocks and six cylinders without threads? I remember reading somewhere that Chevy drove them on. Is that my imagination or is it true?

69 Caprice 454 TH400 (original 427 in storage) 72 Nova 410 big block 3 speed Saginaw (was 306" inline six)


 
GySgtBigdaddy 
Senior Member
Posts: 344
GySgtBigdaddy
Loc: California
Reg: 02-18-05
1/2"-20
04-16-05 04:01 PM - Post#673526    
    In response to strokersix

Oh, if ya'll haven't figured things out so far I'm an idiot. I've tapped it out to 1/2"- 13 NOT 20 . Anyhow, both the bolt and crank threads are clean and seem good. Well, until I put the pulley on and then everything goes south. Gone south or not tomorrow is the day and if it takes all day I have to finish this one bolt. You'll know things didn't work out too good if ya'll don't hear from me for a while.

It's GOD's job to forgive bin Laden...
IT'S OUR JOB TO ARRANGE THE MEETING!
SEMPER FI!
USMC
*70 C20 Longbed 3 spd manual


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17109
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
Re: 1/2"-20
04-17-05 01:07 AM - Post#673527    
    In response to GySgtBigdaddy

"I am curious. How did Chevrolet install dampers on early small blocks and six cylinders without threads? I remember reading somewhere that Chevy drove them on. Is that my imagination or is it true? "

very true, but chevy does NOT beat them on, they use a tool that presses them on, and yeah, there are thousands of engines out there without a threaded crank running after having the dampers beaten into place,(and many with damaged thrust bearings) yet chevy learned, and threads MOST engine cranks to make damper installation outside the factory easier on the bearings
one trick Ive used is to replace on engines without threaded cranks is to place the damper in hot (not boiling )water and to pack the crank snout in DRY ICE, for 15 minutes and coat the crank snout with MOLY spray, you need to be fast,so the temps don,t equalize, but done that way, it takes only one or two good wacks to seat the damper



 
GySgtBigdaddy 
Senior Member
Posts: 344
GySgtBigdaddy
Loc: California
Reg: 02-18-05
Re: 1/2"-20
04-17-05 04:39 PM - Post#673528    
    In response to grumpyvette

Well, a stock length bolt just won't grab enough threads to hold so tomorrow I'm going after a longer one. The installation tool was used (easy as heck) and didn't have to pound anything! I didn't know what to do without a sledge in my hand...Anyway, the threads at the start of the crank are just too thin to provide any good strength. The bolt will tighten down without the washer installed so I'm confident that a 1/2" longer bolt will do the trick. My fingers are crossed for tomorrow!! Besides that I started putting the heads on and installed the water pump. Its beginning to look like a engine now.

It's GOD's job to forgive bin Laden...
IT'S OUR JOB TO ARRANGE THE MEETING!
SEMPER FI!
USMC
*70 C20 Longbed 3 spd manual


 
GySgtBigdaddy 
Senior Member
Posts: 344
GySgtBigdaddy
Loc: California
Reg: 02-18-05
Re: 1/2"-20
04-19-05 02:40 PM - Post#673529    
    In response to GySgtBigdaddy

It only took 2 minutes to stick a longer bolt in! She's looking good now and I do appreciate all the help!!

It's GOD's job to forgive bin Laden...
IT'S OUR JOB TO ARRANGE THE MEETING!
SEMPER FI!
USMC
*70 C20 Longbed 3 spd manual


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 17109
grumpyvette
Age: 69
Loc: FLORIDA USA
Reg: 03-16-01
10-31-17 10:53 AM - Post#2712828    
    In response to GySgtBigdaddy

http://garage.grumpysperformance.com/index.php?thr...

http://garage.grumpysperformance.com/index.php?thr...

IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!


Edited by grumpyvette on 10-31-17 10:55 AM. Reason for edit: No reason given.

 
scrambldcj8 
Senior Member
Posts: 2293

Loc: MA
Reg: 04-06-03
11-01-17 03:02 AM - Post#2712904    
    In response to GySgtBigdaddy

  • GySgtBigdaddy Said:
I started putting the heads on and installed the water pump.




Leave the sledge hammer in the corner of the garage!
Glad it's coming together for you. Remember, there is a certain "precision" used when putting together an engine...for it to last and give expected results.



 
66cayne 
Valued Contributor
Posts: 2697

Reg: 08-06-08
11-01-17 05:13 PM - Post#2712994    
    In response to GySgtBigdaddy

Good to hear you got it working. Another piece of advice, never use a tap to clean or clear threads. Use a thread chaser. A tap will remove a small amount of metal each time you run it in and eventually the threads will fail to hold a proper torque.



 
65_Impala 
Very Senior Member
Posts: 3919

Reg: 12-29-02
11-01-17 05:27 PM - Post#2712997    
    In response to 66cayne

12 year old thread and the OP hasn't been here 2.5 years.



 
IgnitionMan 
Valued Contributor
Posts: 3219

Reg: 04-15-05
11-01-17 06:02 PM - Post#2713005    
    In response to 66cayne

To add to the threading info, there are a few different versions of tap thread cuts.

There is a cut thread,. which has sharp edges at the ends of the flats, and is for making new threads in soft materials, and, these are usually the ones that are in tap and die sets. These are the weakest threads, they can fracture at the ends of the cuts, and literally aren't as strong as other thread types.

If you look very closely at most of the threads in blocks, heads, other engine parts, the flats on the threads to not come to a sharp point at their ends, they either roll over, or end with a flat. These are strong threads, and most are the "roll thread" types.

Using a cut thread tap/die on them, causes metal to be removed from the ends of the cuts, and therefore, makes for the weaker threading of the cut tap.

This is why "cleaning" threads should be done only with a "roll thread" type tap/die, so the ends of the threads aren't cut away, and no issues/problems are caused.

Just FYI on 'cleaning' threads.



 




Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

8463 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.306 seconds.   Total Queries: 13   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 11:49 AM
Top