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Technical Ford 260CI Flexplate

Discussion in 'The Hokey Ass Message Board' started by captaintaytay, Aug 6, 2020.

  1. So I have been having some issues with my Ranchero 1960 with a 260 and C4 transmission conversion. It vibrates at about 1500 rpm's and wants to lurch forward when stopped at a red light, kinda like it has a radical cam. (It doesn't)

    I was told by a transmission guy that it's a problem with the flexplate and may have to be replaced.
    He also told me that it could be a 157 tooth or 164 and starters are different for each one.

    There is got to be a way to fix this.
    It also has a B&M Megashifter on it and the cable is worn out.
    It shifts early through the gears.
    I usually do most of the work on my cars, but this one is too much for me.

    Any Suggestions, I would like to find old school guy who is familiar with older cars and doesn't use a computer to fix them. I live in Ventura County.
    Last edited: Aug 6, 2020
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 47,179


    I've never heard of a 5 bolt flexplate, but the bellhousing bolt patter on the 260 and early 289 is 5 bolt, they changed to 6 bolt some time in 1965. Perhaps he meant that you need a flexplate for a 5 bolt bellhousing.

    Vibration might be related to the flexplate, or maybe not. The lurching...probably not related to the flexplate. We'd have to have a better description of the symptoms, maybe?
    dana barlow and captaintaytay like this.
  3. I'm sorry I meant to say bellhousing. I will edit it.
    dana barlow likes this.
  4. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,898


    Does not sound like a flexplate issue to me.

    In rare instances, ones with welded-on counterweights can kick off the weight. I have only seen that exactly once, in 40-years.

    More common is a crack, which will scare the crap out of you, because it can be mistaken for rod knock.

    Neither sounds like your issue.
    chickinhauler and captaintaytay like this.

  5. You can feel the vibration at about 1000-1500 rpm's. Not below 1000 and not above 1500
    Real noticeable while sitting in drivers compartment. It's not a steady vibration, it cycles lower then higher. Like something is out of round, lopsided or warped.
  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,898


    Check to make sure that the bell to block bolts, and the bell to transmission case bolts are all tight.

    Check the engine and transmission mounts carefully, as well.
  7. You do have a C4 flexplate, right? Ford never installed the C4 behind the 260 (although the parts existed to do so), all they got was the two-speed Fordomatic. If you're mixing parts, that could be the issue. Tooth count should be 157.
  8. Yes, I will do that, Thanks.

    All I know is that there is a C4 behind the motor, bought it with the conversion. I'm going to check for loose bolts as Gimpy suggested. If that doesn't do it then I'm going to take it to a trans shop which I was hoping to avoid.
  9. RmK57
    Joined: Dec 31, 2008
    Posts: 1,618


    I would put it on jack stands and then run it. Sounds like something could be haywire with the torque converter.
    warhorseracing likes this.
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,898


    I have seen about exactly two 260s in my life.

    Does that have a harmonic damper? If so, check to see if the outer ring is loose.
  11. Tell me what size the bellhousing-to-block bolt head size is....
  12. Aaron65
    Joined: Dec 29, 2005
    Posts: 285

    from Michigan

    Didn't the '64 1/2 Mustang have a C4 with the 260? I don't think Mustangs were ever offered with a 2-speed.
  13. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,028


    All 221, 260, and 289s used 28oz imbalance and in 63 all sizes were used and they all had the same front balancer. The 289 hi po is an exception it is heavier but the same balance the K motors did have a small steel balancer inside the timing cover because the rods had bigger heaver bolts.
  14. F-ONE
    Joined: Mar 27, 2008
    Posts: 2,346

    from Alabama

    Some questions.
    Is this a new problem or has it done this since you bought the car?
    Have you confirmed this is indeed a 260?

    221s, 260s and 63 289s have closer spacing on the motor mount bolt bosses. You'll have to look that up to get the specs.
    The engine could be anything from a '62 221 to a '96 351W. You need to confirm what you have.
    If it is indeed a 5bolt engine, that narrows it down to a 221,260 or 289.
    1962 the first year for the small block 221and 260.
    '63 and '64 260s show to use the same imbalance as a 289 and 302. They had a 160 tooth flywheel but the 157 is listed as a replacement.
    If it's a 62 engine or a '63 221 this may be your problem. It seems I remember that something was different about the balance in all 221s and the '62 260. I could be wrong about this.

    I would do a compression test or at least pull the plug wires one at a time at idle to rule out a dead cylinder. Checking the timing with a light is not a bad idea either.
    Check all vacuum lines.
    Jack it up and check the wheels for any abnormality. Spin the wheels to check for warped drums or loose bearings.
    Of course.....check the transmission fluid!!!

    Lastly, you may have a early Green Dot C4. The Dual Range Cruiseomatic aka Green Dot C4 ( Ford called all their 3 speeds Cruiseomatics in '64) had a unique shift pattern.
    small white dot (starts in 2nd)
    Big Green Dot (standard or 123 drive)
    You may be running around in the wrong gear especially if the shift linkage is funky. It was quite common to burn up or damage the Green Dot C4 as folks would run it in white dot drive by mistake, thus damaging the transmission.
    Last edited: Aug 7, 2020
    captaintaytay likes this.
  15. I will this weekend

    Ok, this weekend, Sunday probably.

    This one is brand new.

    My son bought this car for me about a year ago.
    I didn't see it until it arrived at my house.
    It was doing this before he purchased it.
    I managed to find one of owners previous to the one my son bought it from.
    He said it vibrated also and had it looked at thought to be a trans problem.

    It has a 260 with 289 stock heads and a C4 behind it.
    It has a B&M MegaShifter on it. The shifter cable needs to be replaced.
    The harmonic balancer is new.
    It was a restored back in the 90's and changed hands a number of times.

    I have checked the fluid levels, vacuum lines, just about everything you can.
    I have had a few heart surgery's and getting under it has not been easy, so my brother
    is coming over this weekend to help me try and get some more info. Thanks Gentleman. I will let you know.
    Texas57 and F-ONE like this.
  16. paleot
    Joined: Aug 29, 2011
    Posts: 220

    from louisiana

    Not specific to your motor, I had an aftermarket bracket to install alternator on my239 flathead (same vibration) Installed cast iron bracket and a stiffener went away totally.I would take the belts off of it and see if it goes away.
    anothercarguy likes this.
  17. I just went back through all of the posts from yesterday to today. Was the driveshaft balanced or checked prior to installation? You never make clear if it does this while sitting still or driving down the road and it does the vibration thing. Please clarify this a little more as it does sound alot like an imbalance problem that is either coming from the engine or drivetrain. Putting it on jack stands and putting it in gear would help to isolate the drivetrain or the engine.
  18. I don't know if the driveshaft was balanced, I received the car with the engine/trans swap already done.

    I notice the vibration when in park at about 1000 to 1500 RPM's, not at idle or above 1500 RPM's.
    I don't notice anything when I'm actually driving, seems to cruise without noticeable issue.

    Also like I have mentioned when stopped at a stop sign/stop light it will sometimes want to lurch forward like it has a big lift cam in it and will stall sometimes also. so I have to double pedal it to keep the R's up. It sounds stupid :confused: but this is what it is doing.
  19. Vibration in Park eliminates the drivetrain from the tailshaft of the trans back, so not the driveshaft. Leads back to the engine trans combo. Is the Harmonic balancer correct even if it is new? As has been mentioned, check the bellhousing bolts flywheel bolts, torque convertor nuts, and flywheel for cracks or missing balance weights. Then get back.
  20. How would I determine if it is the wrong harmonic balancer?

    As for flywheel and torque converter nut's and bolts I would need to pull back the transmission
    and I'am just not capable at this this time to do that. Thanks for your help.
  21. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,028


  22. Marty Strode
    Joined: Apr 28, 2011
    Posts: 5,332

    Marty Strode

    64 -260 with pulley for power steering. IMG_5238.JPG IMG_5239.JPG
    captaintaytay likes this.
  23. They are very different, you just have to know which one you are looking at. If it only has three bolts that secure the lower pulley to it then it is correct for the 260 or early 289, 28 Oz. Google will be your friend to determine which one it is there if four bolts secure the pulley to the balancer, 28 VS 50 Oz. But if there are four bolts instead of the three it is not a 260 or early 289.
    captaintaytay likes this.
  24. Here is some pics, looks right to me.

    008.JPG 011.JPG
  25. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,898


    Baumi and sunbeam like this.
  26. greybeard360
    Joined: Feb 28, 2008
    Posts: 1,543


    C20E 6312 casting number on pulley is correct for 62.

    A vibration at that low of rpm and lurching in gear sounds like a cylinder with a misfire or a dead cylinder.

    I would do as suggested and pull the plug wires at the distributor cap one at a time to isolate a dead or weak cylinder. Check the plug and wire on that cylinder, maybe do a compression test if those look ok.
  27. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 571

    from 94577

    Looks like camera angle to me. you can see the flats on the lower side of the damper bolt head. That would indicate a shot looking up. Thus bolt would appear to be 'down' in the hole.

    I would check flexplate design, 28oz usually has a few holes around the perimeter for bolts, but the 50oz will have large slots cut into the disc. Counter weights are similar in size so it is hard to tell that when under the car unless you have clear access.

    Worst case, someone retrofitted a 50oz crank into an early block, but that would take some work due to the differences in rear main seal.

    As for the surging, even if there is something wrong with the engine, it should not be so great that it overcomes the brakes. Might want to verify no leaky/blown wheel cylinders. Unless the Ranchero is still sporting 4 lug wheels, then you will want to look into fixing the brakes first.
  28. Actually, the 50oz crank goes right in. I put one into a '64 block, had no issues. The only difference is the late crank lacks the 'splash flange' the early crank has.
    Beanscoot likes this.
  29. It is the correct balancer and pulley but I think you hit it on the head. It does not appear to be the camera angle as it is too great of a difference. Captaintaytay, can you get a picture more square on to the center as it appears it could way off. Did you install the new balancer or have you had this pulley off? Possible someone drilled a newer 4 hole balancer and got the new three holes off. That would cause an intermittent vibration. 011 marked.jpg
  30. I must have taken 50 pics. It's like a monkey inter-coursing a football!
    Horrible angle, fricken fan in the way!

    I'll put up a few shots. I just couldn't get a clean shot. And yes Mad Mike taken from underneath.

    Then I got too close to the magnets on my work light and set off my pace maker.
    Scared the crap outta me, didn't know where the beep was coming from.:eek::oops:
    I also pulled plug wires and got spark from all 8 cylinders.
    030.JPG 029.JPG 024.JPG
    Last edited: Aug 7, 2020

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