don,t screw up the crank snout threads

[grumpyvette]

a common problem I see is crank threads that get stripped when the damper is being re-installed, by guys that think the damper can be easily drawn back onto the crank with the retainer bolt.(its too short,, there's not enough threads engaged, and the damper exerts too much resistance too do that successfully in many cases)
yes Ive seen it done a few times successfully...Ive also seen alot of cranks with stripped threads in the snout due to the practice!

having gone thru this several times , Ill point out a few things,

http://www.atiracing.com/products/dampe ... ctions.htm
(1)
the stripped threads are frequently 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 TRANSMISSION
ALMOST EVERY TYPE OF DAMAGE IS NOT SOMETHING THAT SHOWS UP RIGHT AWAY, BUT IT WILL DAMAGE THE PARTS LISTED AND THERE'S THOUSANDS OF GUYS THAT ARE WONDERING WHY THOSE PARTS FAILED 6-24 Months LATER WITH NO CLUE AS TO THE CAUSE!
[ASK YOURSELF THIS QUESTION, IF CRANKSHAFTS THAT ARE A FEW THOUSANDS OUT OF LINE I.E. NOT PERFECTLY STRAIT ARE BENT/ STRAIT WITH A LEAD HAMMER BY CRANK MANUFACTURES (and yes that's 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 DAMAGE 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 EXERT OVER 15 TONS OF PRESSURE TO SLIDE THE DAMPER ON, IF IT WONT SLIDE ON, THERE'S A PROBLEM! FIND IT AND FIX IT .....DON,T BEAT ON THE DAMPER/CRANK
if your having a good deal of a problem, getting a damper to slide onto the crank snout with the correct tool and an oiled crank, you might have the wrong damper so check carefully ,, the next step one is to CAREFULLY measure both the crank snout diam. and damper hub inner diam.in some cases packing the crank in a bag of dry ice and heating the damper in boiling water changes the interference, enough that the crank slides into the damper far easier, and you won,t be the first guy that needs to have a machine shop hone out a damper to allow it to fit
the crank snout should be only about .0005-.001 larger than the hole in the damper


(2) yes if you screw it up you can easily RE-DRILL and RE-THREAD the crank from the 7/16"NF used on the sbc to the 1/2" NF thread used on big block cranks and use a bbc bolt
or if you screw that up there's larger sizes but doing the install correctly avoids the problem

READ THIS THREAD BEFORE TAPING A STRIPPED CRANK

viewtopic.php?f=50&t=902&p=1463&hilit=+puller#p1463

viewtopic.php?f=53&t=1798

 

[grumpyvette]

btw if youve ever tried to draw on a damper with a crank bolt from a local hard ware store this is frequently the result, that or stripped crank threads, ID strongly suggest use of the correct Damper tool, and use of ARP crank bolts once its properly installed

next time BUY AND USE AN ARP BRAND BOLT
I,ve generally found that if you've stripped the SBC crank snout threads the best answer is to drill and re-thread to the standard and larger BBC crank snout bolt threads size

accurately measure the internal damper and the external crank snout diameter

Measure the crank-snout diameter with a micrometer (above left). Ours measured 1.600 inch, which is right on spec. Then use a dial-bore gauge to determine the inside diameter of the Fluidampr damper (below). Ours came in 1.599-inch, resulting in a .001-inch interference fit. This is the right amount of clearance to provide a good snug fit on the crankshaft, but still be able to install and remove without difficulty. Another method of measuring the damper hub ID of your is with a snap gauge (above right). After setting the gauge, the micrometer is used to to determine the final measurement. In this case, the same measurement as the dial bore gage was reached.
http://www.enginebuildermag.com/Article ... stons.aspx
http://www.arp-bolts.com/

http://www.summitracing.com/parts/ARP-134-2501/

http://www.summitracing.com/parts/ARP-234-2503/

viewtopic.php?f=53&t=1798&hilit=damper

viewtopic.php?f=53&t=1480&hilit=+damper

viewtopic.php?f=53&t=1798
if your current crank bolt is an ARP bolt, heres the dimensions,
keep in mind a bolt threaded in steel should have 1.5 times its diam. MINIMUM in the threads before the bolt starts to draw or tighten or clamp and TWICE its diam. in the threads is better as a minimum to prevent stripped threads, and remember the bolt should never be allowed to bottom out in the crank snout threads and tighten against the bottom of the drilled hole either

Summit Racing Part Number ARP-134-2501

Thread Size 7/16-20 RH in.
Underhead Length (in) 2.470 in.
Head Style 12-point
Washer Included Yes
Fastener Yield Strength (psi) 200,000 psi
Fastener Material Chromemoly
Fastener Finish Black oxide
Quantity Sold individually.
Notes Features 5/8 in. socket size.

One tough bolt.

As the crankshaft flexes, the damper absorbs incredible amounts of energy. These damper bolt kits from ARP will ensure that your balancer is locked into position. They feature a 1/4 in. thick wide-area washer and an extra tall 12-point head that accepts a deep socket to eliminate the fear of stripping the head.

http://www.summitracing.com/parts/ARP-134-2501/

now you can probably re-tap the current threads and use a longer bolt and get by for now, but drilling it with the correct larger drill diam. and re-threading for the big block Chevy bolt is the more common route taken once you strip crank threads
viewtopic.php?f=53&t=1480&p=6221&hilit=stripped+crank#p6221

viewtopic.php?f=53&t=1798&p=5680&hilit=stripped+crank#p5680
there is supposed to be about a .0001 -.0002 INTERFERENCE fit! so the damper has far less tendency to spin on the crank snout or work the woodriff key loose, you can generally polish the crank snout, and internal damper hole with a flap wheel and 400 grit sand paper enough to get a smoother surface, then, place the damper in boiling water to heat and expand it and oil its mating surface, use the correct damper installation tool, pick the damper up with oven mitts so you don,t get burned, use the tool to install it

http://www.summitracing.com/parts/otc-6505

I,ve generally found that if you've stripped the SBC crank snout threads the best answer is to drill and re-thread to the standard and larger BBC crank snout bolt threads size

https://www.nookandtranny.com/Info_LT1.html

these tools work well, fit most engines and if you do break off a thread adapter you can order a replacement without needing to pay for the whole new tool, and keep in mind the threads strip or adapters break if the dampers OVER TIGHTENED,ALL TOOLS WILL BREAK IF OVER STRESSED, this CAN generally be avoided with simply taking a few accurate measurements and use of some marvel mystery oil on the damper, crank and the installing tool threads
Yes I busted one thread adapter years back , but it was a P.I.T.A. waiting on a replacement and I learned not to over tighten the tool, and watch carefully on the measurements and have not had that happen for 30 plus years keeping the tool and damper and crank snout well lubed makes it slide on easier
measuring and checking the interference fits correct helps

read thru these threads, for info on seating a damper and re-threading a stripped crank

just a side note,
I spent an hour or so over at a acquaintances home helping him remove an engines damper with a couple gear pullers,
I brought my gear/damper puller set that looked like this

that tool and the damper removal and install with it was flawless, the normally stupidly simple part of the job, where you pull the crank gear off the crank snout is usually a no-brainer, but this guy grabbed a HF
gear puller

one that looks similar to these , he failed to notice (HOW IN HELL CAN ANYONE DO THAT!)
that the tip of the gear puller that generally has a swivel center support that spreads the load and prevents the crank bolt threads from being damaged,
was missing as these CRAP QUALITY HF gear pullers frequently have the swivel support tips fall off,
as a result pulling the crank gear which is generally not even a minor issue resulted in him screwing up the first few crank snout threads
(these were probably already damaged from previous use of that gear puller , as the damage was rather extensive)
as a result we needed to pull a good deal of the radiator support to gain the required clearance to drill and re-tap the crank snout to a slightly larger thread size,
requiring a separate avoidable trip to a local auto parts and a local machine shop to get the correct tool and bolt.

I jokingly suggested he either buy a better quality gear puller,(MANDATORY)
or give up working on cars as his powers of observation seem to be lacking.

gear pullers like these two above, are well known to cause problems with damage crank threads

http://garage.grumpysperformance.com/index.php?threads/harmonic-balancer.3554/#post-53706

Last edited: Yesterday at 6:51 PM


"Grumpy, Question, all my gear pullers did not come with that load spreader tip, and yeah, I've screwed up some crank threads in the past ,
using it, how do you protect the crank threads if you have the far more common type of gear puller with the narrow and sharp point screw center thread?
LIKE THE UPPER TWO GEAR PULLERS YOU POSTED"

http://garage.grumpysperformance.com/index.php?threads/gear-and-damper-pullers.902/

I used too have that issue, good question,
when I was about 16-17 years old,
and I asked one of the guys that were my mentors....
after looking at me like I was brain dead, smiling and saying....
theres no really dumb questions, but theres certainly plenty of people to head strong too think things through...
the answers very simple he simply smiled, and said,...
you simply walk over to the spare bolt bucket or go to the local hard ware store and purchase a couple 1/2", and 7/16"
national fine thread 1.5" long cap screws ,
of the thread matching your engines crank,retention bolts threads (get several you'll loose them occasionally)
I paint the chevy crank thread ones orange
and the Pontiac ones light blue
and the Chrysler ones gold,
too make them easy to locate and keep them in a old snuff box, or similar wide mouth screw top shallow container,

in the drawer with the gear pullers,
you insert and screw them finger tight into the end of the crank,
after adding two washers to protect the end of the crank snout from the cap screw heads under-side
if you don't know what a cap screw is... they come in all the common threads you'll want one thats about