Author Topic: Crank shaft end float.  (Read 2645 times)

Vince Caldicott

  • Jr. Member
  • **
  • Posts: 55
    • View Profile
Crank shaft end float.
« on: June 01, 2017, 18:34:31 »
Does anyone know what tolerances are acceptable for crank shaft end float on a 427 side oiler?

minimans

  • Newbie
  • *
  • Posts: 28
    • View Profile
Crank shaft end float.
« Reply #1 on: June 02, 2017, 03:05:20 »
I have .008 to 0012  on a street build

minimans

  • Newbie
  • *
  • Posts: 28
    • View Profile
Crank shaft end float.
« Reply #2 on: June 02, 2017, 03:11:00 »
Factory spec is .004 to .0014

Vince Caldicott

  • Jr. Member
  • **
  • Posts: 55
    • View Profile
Crank shaft end float.
« Reply #3 on: June 02, 2017, 08:56:13 »
Thanks for the reply, I have quite a bit more than that. Is there an easy fix?

rsk289

  • Full Member
  • ***
  • Posts: 154
    • View Profile
Crank shaft end float.
« Reply #4 on: June 03, 2017, 00:06:36 »
'Easy'...
   Well, first you have to identify why you have greater clearance than stock.  Worn bearings (easy to fix, but why are they that badly worn?) or worn crank (not so easy to fix).
   What sizes are your crank journals, and how badly worn are the shell bearing surfaces?  If the whole shebang is worn, a grind and new bearing shells shoud fix it.
   If it's crank damage, you need either a set of shells with oversize thrust faces or a wider crank journal to take up the excess.  I don't know if anyone makes plus sizes in thrust bearings for the FE.  If the crank is worn/damaged, you need to think about either a new crank or metal spraying to build up the lost material and machining back to size.
   How much out are you?
   Never start an engine with your foot on the clutch...

Vince Caldicott

  • Jr. Member
  • **
  • Posts: 55
    • View Profile
Crank shaft end float.
« Reply #5 on: June 03, 2017, 08:17:39 »
The end play is around .057. The engine was  newly installed after a rebuild 6 months ago. Because of issues with the gearbox and selecting 1st gear. I was starting the engine with the clutch depressed and in gear. The gearbox is currently being rebuilt and it was the engineer who noticed the end play.. with the sump off the crank and everything looks perfect, however the thrust bearing is badly worn!

rsk289

  • Full Member
  • ***
  • Posts: 154
    • View Profile
Crank shaft end float.
« Reply #6 on: July 02, 2017, 01:04:55 »
If the thrust bearing's badly worn, hopefully it's done its job and protected the crank sacrificially.  Fit new thrusts and recheck with the dial gauge and the big hefty screwdrivers!
   Starting the engine with the clutch depressed means the crank thrust bearing surfaces are taking load with no oil pressure at start up.  It doesn't sound like a big deal, but several hot Mini cranks have been destroyed by heavy duty clutches being held down at start up.  If it's good for Minis, it's good for us, I reckon...
   
   Roger

Vince Caldicott

  • Jr. Member
  • **
  • Posts: 55
    • View Profile
Crank shaft end float.
« Reply #7 on: July 06, 2017, 20:47:52 »
Hi Roger,  the engine which I had fitted 6 months ago is out and completely stripped down. I think you are correct in saying that the thrust bearing has protected the crank. Unfortunately, where the engine had been stored for so many years with the rocker springs under tension, 2 of them had disintegrated without me realising and  the metal splinters have gone through the engine, hence the rebuild.  New  bits include, camshaft, springs, main and thrust bearings, some valves and rods. Also, the aluminium racing fly wheel had warped and needs replacing.  I am hoping to have it all back together in time for Silverstone later this month, but it's looking unlikely.