Crankshaft End Float - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans Advertise
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 08-19-2019, 08:18 AM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
Crankshaft End Float

I'm getting about .003" float on my 351W crank but I can get up to .007" if I press harder in both directions. However, when I relieve the pressure the gauge comes back to .003". In other words, it seems like something (the thrust bearing?) is flexing acting like a spring. The crank spins smoothly with no effort. Is this normal?

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 08-19-2019, 09:11 AM
johnsongrass1's Avatar
Race it, Don't rice it!
 
Join Date: Jul 2002
Location: Columbia, Mo
Age: 43
Posts: 7,047
Wiki Edits: 0

Thanks: 108
Thanked 738 Times in 605 Posts
Did you tighten the cap before seating the thrust?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 08-19-2019, 10:08 AM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
Please define "seating the thrust."
Reply With Quote Quick reply to this message
 
  #4 (permalink)  
Old 08-19-2019, 10:42 AM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
Ok, I know what you mean now. No, I didn't seat the thrust. Going out to the garage to try that now.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 08-19-2019, 01:45 PM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
I loosened the bolts on all caps and rapped the crank back and forth with a large rubber mallet. Re-torqued the bolts and nothing changed. I've disassembled everything, removed the assembly lube from everything (STP) and inspected the parts. Nothing seems out of order. The bearings fit snug on the cap and block such that I really had to tug pretty hard to pull them back out.
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 08-19-2019, 07:59 PM
johnsongrass1's Avatar
Race it, Don't rice it!
 
Join Date: Jul 2002
Location: Columbia, Mo
Age: 43
Posts: 7,047
Wiki Edits: 0

Thanks: 108
Thanked 738 Times in 605 Posts
Sure sounds like something is amiss. Crank should move pretty easily with just a 8” screw driver.
You sure you have the DI set up stiff enough?
You might try removing all the caps except the thrust, leaving the upper bearings in place, and checking it again. If it’s the same I’d say the thrust is messing with ya. If it’s okay, then installing each cap one at a time along with the thrust, might give a clue as to the align hone.
If you don’t get anywhere there. Might try honing the thrust by placing both thrusts together by using a hose clamp to hold them snugly together. Lay the thrust on a flat plate and snug the hose clamp down just enough to hold it together. Rub the sides on 600 wet/dry aluminum oxide paper and WD40 or lightweight machine oil.
On the flat plate, do about 5 strokes or full figure 8’s and take note of the pattern left. If you see high spots or other irregularities I’d say the thrust is off and/or needs further attention.
Reply With Quote Quick reply to this message
The Following User Says Thank You to johnsongrass1 For This Useful Post:
Molon Labe (08-19-2019)
  #7 (permalink)  
Old 08-19-2019, 09:00 PM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
The DI was set up properly. I was wondering if the thick STP was acting like a hydraulic cushion so I cleaned the STP off the bearings and journal, cleaned the cap and block and looked for any imperfections. Found nothing. I put the bearings back in with no lube on the thrust bearing but still on the other four. I laid the crank in and with no caps on any bearings I still get about .003" but more if I press harder but it springs back to .003". It takes no effort at all to move the crank the .003". The inside of the thrust bearings measures about .003" wider than the cap and block so I'm wondering why they go on and off so hard. They could be sprung so I'm going to try putting them together and sanding them and look for high spots. Should they be so tight on the cap and saddle that I can barely pull them off with my fingers?
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 08-19-2019, 09:29 PM
techinspector1's Avatar
Member
 
Last wiki edit: DynoSim combinations
Join Date: Oct 2005
Location: Zephyrhills, Florida, USA
Age: 77
Posts: 16,954
Wiki Edits: 326

Thanks: 1,915
Thanked 2,813 Times in 2,107 Posts
I'd be taking the bearings back for an exchange. If the same thing happens with another set of bearings, I'd begin to suspect that the block has been dropped.
Reply With Quote Quick reply to this message
The Following User Says Thank You to techinspector1 For This Useful Post:
Molon Labe (08-20-2019)
  #9 (permalink)  
Old 08-20-2019, 12:28 PM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
Doing nothing differently, I laid the crank back in with no thrust bearing in the block and put the cap on with the bearing. It was perfect giving me about .0055" and no spring back. I found a very slight taper down the face of the other block side half. So, I applied the "Johnsongrass1 bearing face alignment procedure" removing about .001" from each face. All assembled again and getting .0055" with no spring back. I think I can move on.

Thanks again to everyone who responded.
Reply With Quote Quick reply to this message
The Following 4 Users Say Thank You to Molon Labe For This Useful Post:
123pugsy (08-20-2019), johnsongrass1 (08-20-2019), Rip VW (08-20-2019), techinspector1 (08-20-2019)
  #10 (permalink)  
Old 08-20-2019, 03:09 PM
johnsongrass1's Avatar
Race it, Don't rice it!
 
Join Date: Jul 2002
Location: Columbia, Mo
Age: 43
Posts: 7,047
Wiki Edits: 0

Thanks: 108
Thanked 738 Times in 605 Posts
Works most of the time!
You can PM your credit card number later. Thanks!
Reply With Quote Quick reply to this message
The Following 2 Users Say Thank You to johnsongrass1 For This Useful Post:
Molon Labe (08-20-2019), techinspector1 (08-20-2019)
  #11 (permalink)  
Old 08-20-2019, 03:53 PM
Molon Labe's Avatar
Registered User
 

Last journal entry: Floors
Join Date: Sep 2017
Location: Hoosick Falls, NY
Age: 71
Posts: 177
Wiki Edits: 0

Thanks: 75
Thanked 34 Times in 23 Posts
Uhhhhhhhhhhhhhh..................The check is in the mail.
Reply With Quote Quick reply to this message

Tags
crank, end float

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Insurance
Please select your insurance company (Optional)

Log-in



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -6. The time now is 08:22 AM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.