crankshaft pulley question
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,036
Likes: 5
From: Raleigh NC
crankshaft pulley question
ok-I am trying to eliminate possibilities as to why my alternator belt(only belt on the car) keeps twisting up. my crankshaft pulley seems to have a slightly erratic spin to it(original pulley-69 vette 350)
my first thought is the pulley is somewhat warped,but I am wondering what it attaches to(harmonic balancer?) and can that "something" be causing it to be jumpy? alternator pulley and water pump pulley are fine and smooth. crankshaft pulley is tight. to remove the crankshaft pulley is it just the 3 bolts in the triangular pattern and one in the center and off it comes?
just trying to dig as deep as I can before I buy a pulley I dont need...and learn something in the process.
best way to describe the pulley is a slight shimmy while engine is running and with hood up I can watch the belt as I give the car gas and when I let off I can see the belt producing a wider vibration for a second or so...any thoughts? thanks! Dave
ps- I put on v-belt 15560 duralast after trying several different sizes and have roughly 1/2" deflection measured with straight edge and tape measure and the belt lines up up pretty straight and even with all pulleys(if it is off it is within a 1/8".
my first thought is the pulley is somewhat warped,but I am wondering what it attaches to(harmonic balancer?) and can that "something" be causing it to be jumpy? alternator pulley and water pump pulley are fine and smooth. crankshaft pulley is tight. to remove the crankshaft pulley is it just the 3 bolts in the triangular pattern and one in the center and off it comes?
just trying to dig as deep as I can before I buy a pulley I dont need...and learn something in the process.
best way to describe the pulley is a slight shimmy while engine is running and with hood up I can watch the belt as I give the car gas and when I let off I can see the belt producing a wider vibration for a second or so...any thoughts? thanks! Dave
ps- I put on v-belt 15560 duralast after trying several different sizes and have roughly 1/2" deflection measured with straight edge and tape measure and the belt lines up up pretty straight and even with all pulleys(if it is off it is within a 1/8".
Team Owner
Joined: Mar 2004
Posts: 24,202
Likes: 17
I am sure you are aware, that the lower pulley should not shimmy at all.
I have seen many where idiots beat the haromonic balancer on with a sledg! This sometimes causes the pulley to not fit all the way flush to the balancer causing your problem. I have filed and reground these areas and corrected these problems. If this is not the case, that pulley may be bent slitghtly, and would warrant replacment. I would also make super sure all the pulleys line up good!
I have seen many where idiots beat the haromonic balancer on with a sledg! This sometimes causes the pulley to not fit all the way flush to the balancer causing your problem. I have filed and reground these areas and corrected these problems. If this is not the case, that pulley may be bent slitghtly, and would warrant replacment. I would also make super sure all the pulleys line up good!
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,036
Likes: 5
From: Raleigh NC
maybe I will yank the pulley off and check the balancer for damage.
little more info...ive had the car a couple months and put 1,000 miles on it with no issues. this problem just showed up with nothing changed or worked on beforehand.the belt I put on last night has'nt twisted yet but I havent taken it out of the garage yet either. only tested it sitting still. motor has about 3,000 on the rebuild(along with the rest of the car) but 3 years time since it was restored if that helps at all.
I really should of watched/worked with my dad more when I was younger. he restores muscle cars for personal enjoyment and while ive always loved cars, at that age I had so many other hobbies(guitar,sports,women!!) that I never got very deep into the fixing side. never too late to learn though
little more info...ive had the car a couple months and put 1,000 miles on it with no issues. this problem just showed up with nothing changed or worked on beforehand.the belt I put on last night has'nt twisted yet but I havent taken it out of the garage yet either. only tested it sitting still. motor has about 3,000 on the rebuild(along with the rest of the car) but 3 years time since it was restored if that helps at all.
I really should of watched/worked with my dad more when I was younger. he restores muscle cars for personal enjoyment and while ive always loved cars, at that age I had so many other hobbies(guitar,sports,women!!) that I never got very deep into the fixing side. never too late to learn though
Race Director
Joined: Oct 2002
Posts: 12,065
Likes: 2
From: Smalltownville Michigan
Cruise-In 5, 6 & 10 Veteran
St. Jude Donor '09
I noticed when I had mine out friday that there are spots that allow for proper installation of the pulleys. They look like a high grommet kinda. I bet that if it isn't installed so those are in the right holes , that you would get a wobble too...
Pro
Joined: Jul 2002
Posts: 723
Likes: 0
From: North Port, FL
One other thing to look for when you check your ballancer pulley, look very closly to see if cracks are radiating out from the bolt holes on the pulley. I have whitnessed this issue on two C3's, a 69 and a 71.
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Team Owner
Joined: Mar 2004
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Originally Posted by 88'Cubka
Why would someone beat on the balancer with a sledge when it slides right on when heated a bit with a propane torch?
Hey bubba grab me that sledge!
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,036
Likes: 5
From: Raleigh NC
after talking to my dad about yanking the pulley I think I will get his help. I didnt realize it was torqued to about 150 lbs lol
is a breaker bar the best way to get this off or has someone used another alternative?
is a breaker bar the best way to get this off or has someone used another alternative?
Racer
Joined: Jan 2005
Posts: 492
Likes: 0
From: Birmingham AL
Originally Posted by Sacredgrooves
after talking to my dad about yanking the pulley I think I will get his help. I didnt realize it was torqued to about 150 lbs lol
is a breaker bar the best way to get this off or has someone used another alternative?
is a breaker bar the best way to get this off or has someone used another alternative?
The manuals I have all looked at specify 65 ft-lbs. That's Haynes and Vizards rebuild book.
Team Owner
Joined: Mar 2004
Posts: 24,202
Likes: 17
I presume were talking about the center bolt here. I would put it in gear, if you have a 4spd and try the breaker bar. If you can get an impact, this may be better! That bolt is real tough, and you shoul be able to get it out. Some people love to over tighten everything they touch. I remember a lug nut some idiot put on my wifes car. I had to stand on the cheater bar, and finally the stud snapped right off!
Intermediate
Joined: Feb 2005
Posts: 37
Likes: 0
From: St. Peters Missouri
I am looking at my 69 assembly manual and it calls for the three bolts that hold the pulleys to the balancer to be torqued to 25-35 ft-lbs and the single bolt holding the balancer onto the crank to be at 60-90 ft-lbs. I like to go to the lighter side when using old parts!
Thread Starter
Melting Slicks
Joined: Jan 2005
Posts: 3,036
Likes: 5
From: Raleigh NC
60-90 thats good to know! alot more manageable. have a few worries about using a breaker bar and it smashing my fender if it comes loose lol. my dad has impact wrenches and I plan on getting his help with it this week. it hasnt twisted the belt I have on there now yet,but it is squealing at higher rpm's...