I have been working with a local fellow 66 F100 owner resolve some issues the PO blessed the truck with.

While doing a compression test a couple weeks ago, we hear a solid loud knock every revolution of the engine using the starter, not heard when running.

He sent a photo last night of the flexplate with damaged section of teeth, one broken off, some chipped.

1st what causes this? 2nd Can he wait a bit to replace the FP or is it gonna chew up the starter?

thanks

John

 

Hi John,

I would venture to say that a loose starter would be my first guess as to the what can cause chipping of flexplate teeth. My second guess would be using the wrong starter for the flexplate/engine combo.

If someone files/grinds down the damaged teeth so as not to allow the starter bendix gear from being hung up on them, he may be able to get by for a while. But know that he may need to roll the truck a bit (while in gear) to get past the bad spot in the flexplate when needing to re-start the engine. I guess as long as he can stop/park on a slight hill to allow this action, it wouldn't be a big deal. Parked in a garage/building would be a different story...... Lastly, yes, by doing this, it likely could be tough on the starter... I wouldn't postpone changing the flexplate ring gear too long.

I would also suggest you double check that the starter and flexplate are correct for each other. If I recall correctly, a COM transmission takes a different tooth count flexplate than a C6 transmission. I wouldn't be surprised if there was even differences between years of the same type of transmission. We know there are different types of starters, throw in, throw out, long snout, short snout, etc.

I hope you keep us posted on your progress - we can all learn from your work...

BarnieTrk

 

C5AZ-6375-D .. Flexplate-184 teeth / Obsolete - Available from auto parts stores.

1965/67 F100/350 352 MX C-O-M / 1968/76 F100/350 360/390 C6.

1965/67 Galaxie/LTD 352/390 FX/MX C-O-M / 1968/71 Galaxie/LTD 390 C6.
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There are two different FE starters, both have 3 mounting holes, A/T/M/T makes no difference.

1958/62's use the HUGE Bendix 'gear reduction' starter drive. 1963/76's use a different starter drive that is much smaller.

This same starter drive was also used with 289/302/351M/351W/400/429 and some 460's.

1958/64 Passenger Car FE flexplate has 153 teeth.

Upper pic (from 1949/59 car catalog) shows the HUGE 11350 Bendix gear reduction starter drive.

Lower pic (from 1964/72 truck catalog) shows the much smaller 11350 starter drive.

 

Sorry about the extra work Mr. Wilson, this truck is a mutt, I believe it has a 289/C4.

The C4 is leaking pretty bad at the shift arm, whats an easy fix for that?


John

 

There's a seal on the arm, but the pan has to be dropped, then the filter and the valve body to R&R the arm to replace the seal. The fellow should take it to a trans shop.

289: 1963/68 Falcon/Fairlane, 1965/68 Mustang C4 flexplate has 157 teeth. 1965/68 Galaxie/LTD C4 flexplate has 164 teeth.

But 1962/64 221/260, 1965 Mustang 260 (before 8/23/64) use a different C4 flexplate that has 160 teeth.

Who knows if the engine is a 260 or 289? Who knows what it came from? Who knows which flexplate it has?

Lower pic: 7A256 is the selector lever arm, 7B498 is the seal. Upper pic shows the 7A100 valve body.

btw: Notice in my sig that the Escape has gone bye bye.

 

Hey folks it is my 66 jowilker is helping out with. If the PO can be believed, which so far he has no lied to me just done some weird stuff, the engine is from a 66 Mustang my research said there are two possible seals that leak. The shift shaft seal and an o-ring by the kickdown lever. I cleaned it up tonight and will look for the drip. Kickdown is a 2 minute fix. As ND said, shaft seal is more complex and have to drop the pan and valve body to get it out.

For the flex plate, can it do any damage other than premature wear to starter?

 

If the starter drive lands on the chipped/missing flexplate teeth, the starter will make a whirring noise, the engine will not start.

If you had a M/T, you could crank the engine in gear for a couple of seconds, which would turn the flywheel just enough to avoid the stripped teeth, but you cannot do this with a A/T

C3AZ-6375-L .. C4 Flexplate-157 Teeth / Obsolete ~ Available from auto parts stores.

1963/68 Fairlane/Comet 289 / 1965/68 Falcon/Mustang 289 / 1967/68 Cougar 289.

 

NUMBERDUMMY would a starter off a 300 6 with a 164tooth flexplate work on a 351w with same type flexplate dont have part number on hand but will check later

 

i have an A/T, with the same issue, it will not start, the flex plate has a broken teeth, so how can I turn the motor so then bendix lands on a “good” portion of the flex plate?

 

You can turn the motor with a wrench on the front crank bolt

 

Sometimes you can just grab the fan and turn it enough, if your belts tight enuff. If not, tension the belt with your other hand. Dont need to turn it far.