Technical Ford 260CI Flexplate

No I didn't,
The harmonic balancer looks pretty fresh just by looking at it, no cracks, pretty fresh paint still on it.
IDK maybe it's defective.

I removed the fan belt and pulley to isolate it down to the balancer, still vibrates.

 

It very well could be a repainted original and may have slipped. Have you ever replaced it looking for this vibration?

 

Maybe the plot thickens, maybe not.
Removed the crank bolt and wondering why someone used RTV silicon on back side of washer and inside balancer??? maybe the key-way but this shit was all over the place.

 

You're supposed to put a smear in there to prevent an oil leak, especially around the key way. If I recall correctly, a 260 has a different imbalance vs a 289, something like 25 oz vs. 28.2 oz. A 260 harmonic damper may be required.

 

Yea Captain taytay, there should be alot less RTV there and as Kustom Komet says, to prevent oil leaking. As far as the imbalance weight being 25 Oz. I am not sure and that will take some research.

 

Never heard or seen a 25 ounce harmonic balancer.
There is only two that I know for SBF 28oz. and 50oz. external balance.
The flex plate is 28oz.

I'm going to replace the current HB, it looks pretty new but while I have
it off I'm just going to replace it as this is the last thing to replace.

If that doesn't fix it, (which I kinda of doubt it will) then maybe the crank is f#%ked!
I'm out of options after this.

 

After the replacement of the balancer the only other area could be internal. As you are unaware of the rebuild it could be unmatched pistons (cheap rebuild replaced only what was damaged or they had on hand, 0.40 in one hole and .10 in all of the others) where only a damaged piston or two were replaced. Unmatched rod weights, where a rod or two were replaced or resized and then the rotating assembly not re balanced. Madly machined crankshaft where two different sized rod bearings have been used (.20 0r .40 over on different rod journals on the same crank) without being re balanced. Any way you look at it I hope it is the current balancer. Yes I have seen all of the above from backyard rebuilds to rebuild shop overhauls.

 

I've seen that garbage too. All the rod and piston assemblies must be the same exact same weight in order for the engine to run smoothly. If they are off, then balancing the crank/damper/flex plate with a single rod and piston for a bob weight accomplishes nothing. An overhaul may be in order if a different damper doesn't work, but going through it to see what's in there wouldn't be a bad idea anyway.

 

Without rebalancing the entire rotating assembly (damper to flexplate) you can't expect
much more than the "99%" improvement that you previously noted. The off the shelf flywheel
28.2oz compatible is just a starting point. As an example: the 160t factory flexplate that I've
got hanging around has a major weight but has 4 additional half gram weights spotted around. Internal balance motors aren't as prone to imbalance issues and you can get away with swapping flywheels and pressure plates, etc, but for higher RPM, performance shops want to take everything into account.

 

Of course I have not experienced the vibration. If it's extreme you may have a problem. If it's a minor annoyance, it may just be a trait of some 5 bolt automatic engines. One of the main reasons Ford went to the 6 bolt block in mid year 1965 was a tendency for some of the early 5 bolt SBFs to have a vibration that could not be corrected.
So....It may be "normal" and something you have to live with.

 

Sometimes the simplest explanations are the best. The extra sealer on the damper behind the washer may simply be to hold that washer on during assembly. That's not unlike using grease to hold small screws and nuts in place.

 

Good detail here. Note that imbalance is quoted in oz-in. The imbalance value is the mass of the counterweight multiplied by its distance from the crank centerline. So (using made-up numbers), a 10 oz weight 5 inches out would be 50 oz-in. I ran into this issue several years back with a late model 302 bolted to and early C4. Had to change the 28 oz-in flywheel to 50 oz-in. Did some calculations and welded on an additional weight in the right location. Worked perfectly. Just remember to account for the wight of the weld metal added.

 

Well gentleman,
I was putting on the new HB and it just slipped on.
I tightened it down and torqued it.

I just needed to see if the vibration was gone.
It's a ton better, not completely gone but enough I can live with.

But I know it's not right, it just fitted to loose for my comfort, it just pushed on.
The old one needed a puller and came off with no issue.
Who knows maybe it's a defective HB. I'm going to pull the timing cover because I also
think the woodruff/keyway is bad. It's pretty hard to get to.
I'll let you know what happens next.

 

Make sure that you have an interferrence fit with the crank snout (0.001-0.0015")....its more
than the just a keyway issue. Maybe this is why somebody tried slopping RTV on the snout.

 

If its not a defective HB, then it looks like the snout is worn. I'm at least going to try a new key-way while I have it apart again.

If so I'm just going to put it back together and put a scatter shield around the car.
No really, If the crank snout is junk I'm just going to run it until she blows.
I'm just not equipped to break down motors.

 

That being the case then I would highly recommend replacing it with a later model 302 with a 50 Oz balancer and flexplate and going with an AOD. It would be a much happier car and you with that combination. Regardless of the rear end ratio the lower 1st gear and OD in the AOD will make it more enjoyable.

 

I'd probably just drive the car and enjoy it (above 1500). I doubt if you will ever have any issues
stem from the vibration as you describe it. You might consider machining one of the dampers
with knurling.....might be kinda mousy, but not much downside in trying

 

I'm kinda at the physical and budget limit and just going to try and enjoy what I have while I can.
I've spent enough money that I don't have and don't want to stress anymore about it.

I appreciate all the help you and everyone has given to me.

I'm just going to try and get it the best I can.
The car in my opinion is not worth it anymore.
The new transmission is worth more than the car itself

It is what it is. I' ll try a new key-way and see if it fits better, if so better for me if not oh well. I have beat the shit out of this thread and need to move on.

Thank you and the other guys for your help. The HAMB Family is great!

 

As long as the bolt is torqued properly, go out and have some fun with it.

Not everything can be perfect.

 

My post was in the event that it does let go. Hopefully it doesn't and you can enjoy what you have. It will never be perfect so no harm. If it was perfect you would be afraid to drive it down the road. As it is, enjoy and live as tomorrow is never guaranteed.

 

There was some mention that the vibration could be due to different size pistons.
Not according to Ford.
My reference is from 1968/9, but the 1962 Fairlane manual with 1963 and 64 supplements says the same, I just didn't have it handy:







If we put more weight on anecdotal evidence, I did have a 260 in a 1964 Fairlane many years ago that I did indeed have only two cylinders bored out 0.030" oversize as they had deep scratches.
The engine ran great after overhaul (new rings, bearings, gaskets) and did not vibrate.

 

Interesting Beanscoot. I wonder how that engine was actually balanced then. Does the rubber between the two halves absorb that much vibration? I was always told that it didn't. Since that is a Ford manual and they would most likely be using Ford parts for warranty repairs maybe they were the same weight. Aftermarket pistons may not be the same weight. I don't know. Old Henry's bean counters at work only replacing what was bad and not all pistons.

 

I used cheap rebuilder pistons (Badger, I think), but all stock replacement pistons should be the same weight as OEM ones.

But you had a good point about con rods. Unfortunately I can't find my reference book, but I am pretty certain that the 1962 260s had a lighter con rod, then switched to the heavier 289 piece in '63 or '64.

 

Thank you Sir for the lesson. One would think that a stock sized piston would weigh less than a .30 oversized by at least a Gram or two.

 

Actually guys I didn't listen well to in school. Instesd of just moving on,
I was wondering why the old HB came off like it should , with a puller.
So I pulled the new one and checked the diameter vs the old one.
Old one 1.3845
New one 1.4005

So I went and returned it for a exchange.
Next one 1.3925
It took the install tool to put this on but it still went on with no resistance.
It was a $80.00 HB, you get what you pay for.

All back together now there is a nice improvement and I'm
going to go shake it down for a long drive, I'll tell the wifey
to be ready for a rescue just in case it breaks.

Thanks for the info "Beanscoot" Makes me want to tear it down just for my curiosity.
But I'm just going to drive it now and do another motor when I'm able and can afford it.

 

You're welcome!
Those measurements on the harmonic balancers are crazy - a good reason not to use new parts, if one can find good used parts.
Are those measurements inside or outside diameters?

 

"Inside diameter"



Also took about a 50 mile drive, and no issues.
Just need to adjust the valves now.

Thanks again everybody.

 

All this could semi-explain the home-brew weights welded to the flex plate. They had a problem, took a shot at 'rebalancing' the motor and missed....

 

I've never used goo on the damper/balancer bolt. If the tolerances are sloppy enough to allow oil seepage, then you have other problems.

Rubber elastomer just allows the outer inertia ring to move and dissipate the unwanted vibrations.
As the crank turns it is being twisted by the force of the power strokes and twisted opposite by the crank pulling down the piston/rods on intake strokes.

Harmonic dampers are the shock absorber of the crankshaft. There are adequate shocks, good shocks, and awesome shocks. Just like shocks for your car, a quality shock can transform that sloppy ride into something incredible.

There are some low powered or low rev(non diesel) engines that forgo the damper, but this is usually due to the low speed operation and self dampening of grey cast-iron crank. If your not revving much past 2500 rpm regularly, it's gonna last a long time without any crank issues.

If the rubber elastomer has hardened, cracked, or changed durometer it will not be able to properly transfer those harmonics to the outer inertia ring.

 

The first Ford small block, the 221, did not use a harmonica damper, just a balancer. I guess Ford didn't think it needed one.

Ford also had a technical service bulletin out that said a "certain amount" of cracking of the rubber ring in dampers was acceptable, as it didn't likely go deep in.