I Put a new flexplate and starter on my engine 632 BBC. It cranks for a second or 2 then kicks out and grinds. If I look at the starter when cranking it the starter drive is bouncing in and out like a pogo stick and finally completely disengages and grinds. Any idea what would cause this? The starter is new but been in the trailer for close to 2 years. It only engages about 3/4 of the way into the flexplate. There is a shim between the nose of the starter and the mount of the starter I can remove to get further engagement but don't think this could be the issue.

Here is an odd twist. It has a 14v battery and it was down to 12.8 when I started it the first several times after putting the engine back in. It started perfectly fine every time. I put the charger on it and the next morning I went to start it and it was grinding.

sounds like you've already wiped out the spring on the pinion gear and possible the bearing too. pull the starter down and remove to the drive assembly to verify.

Bendix or solenoid issues. Mine has been doing the same thing. Got a new solenoid for it....I'll let you know if that fixed it...

quote:

Originally posted by inferno camaro:
I Put a new flexplate and starter on my engine 632 BBC. It cranks for a second or 2 then kicks out and grinds. If I look at the starter when cranking it the starter drive is bouncing in and out like a pogo stick and finally completely disengages and grinds. Any idea what would cause this? The starter is new but been in the trailer for close to 2 years. It only engages about 3/4 of the way into the flexplate. There is a shim between the nose of the starter and the mount of the starter I can remove to get further engagement but don't think this could be the issue.

Here is an odd twist. It has a 14v battery and it was down to 12.8 when I started it the first several times after putting the engine back in. It started perfectly fine every time. I put the charger on it and the next morning I went to start it and it was grinding.

Start with the basics, check the distance from the pinion to the face of the flexplate in three locations, and the shimming if any. A 035 paper clip works.

Remove the spacer if you don't need it, you want a minimum of 060 clearance.

Remake (clean) all your connections including grounds to engine and frame.

If the spring were bad the pinion would be hanging up and knocking teeth off the flexplate.

Check the voltage at the starter when cranking. It needs to be better than 10 v when cranking to keep starter solenoid engaged. If under 9.5v it can cause exactly what you describe. You have a voltage drop from the battery to disconnect and/or disconnect to starter. I’ve seen failed disconnects cause this scenario.

To eliminate the disconnect for possible cause, land the battery and cable to starter on the same disconnect lug bypassing the disconnect completely.

This message has been edited. Last edited by: markemark,

Starter drive teeth drive depth incorrect? If you can put more than a straightened out thick paper clip between them you have too much. I have had starters that the mounting block had to be milled down to get it right.

quote:

Originally posted by markemark:
Check the voltage at the starter when cranking. It needs to be better than 10 v when cranking to keep starter solenoid engaged. If under 9.5v it can cause exactly what you describe. You have a voltage drop from the battery to disconnect and/or disconnect to starter. I’ve seen failed disconnects cause this scenario.

You can guess and buy parts or use a DVOM and do a voltage drop test of each part of the circuit and see if you have a voltage problem first. I don't mean just measuring voltage at certain points, I mean do a voltage drop test where you are actually measuring how much voltage is dropping across each section.

To eliminate the disconnect for possible cause, land the battery and cable to starter on the same disconnect lug bypassing the disconnect completely. Do you have a Ford solenoid wired before the starter?

I put my old starter on and it wasn't grinding but the drive is still bouncing. I checked voltage at rest and cranking at the starter and it was 9 cranking and 14.5 at rest. I cleaned all grounds and check connections now its 11.4 when cranking but drive still bounces. The drive only engages slightly more than 1/2 way into the teeth with the old starter. I never checked this before but can't imagine it had lasted 4 years with no issues with that engagement. Starting to wonder if the new flexplate is built slightly different.
No ford solenoid. Checked clearance and is around .045. The new starter engages about 90% into the fleplate. I need to put the new one back on and see if the higher cranking voltage since cleaning grounds makes any difference. Didn't seem to change the way way the old starter acted.

This message has been edited. Last edited by: inferno camaro,

^^^^^ Check the voltage drop at the main disconnect when cranking like Eman wrote, or bypass it completely. Try Adding a ground wire to the starter bolt if possible

Is 11.4v while cranking still too low?

quote:

Originally posted by markemark:
^^^^^ Check the voltage drop at the main disconnect when cranking like Eman wrote, or bypass it completely. Try Adding a ground wire to the starter bolt if possible

quote:

Originally posted by inferno camaro:
Is 11.4v while cranking still too low?

quote:

Originally posted by markemark:
^^^^^ Check the voltage drop at the main disconnect when cranking like Eman wrote, or bypass it completely. Try Adding a ground wire to the starter bolt if possible

If you have 11.4 v not fluctuating measured at the STARTER SOLENOID while cranking this is good.
I would still do voltage drop test on the main disconnect to verify ok.

Check the voltage at the starter solenoid coil from the relay panel start PB also.

If you have a car battery jumper cable try clamping it to the starter plate and other end to ground.

I borrowed a spare starter from a buddy of mine and it seems to work fine. So I'm guessing my new 2 year old starter needs work. Thanks for the help and suggestions.

As I stated, you've already wiped out the spring on the pinion gear and possible the bearing too. Your description is the giveway...

quote:

Originally posted by inferno camaro:
If I look at the starter when cranking it the starter drive is bouncing in and out like a pogo stick and finally completely disengages and grinds.

The one way clutch was seized up. Swapped that with an old one and it works great now.

It’s not a “one way clutch”, it’s the bendix…

“A Bendix drive is a type of engagement mechanism used in starter motors of internal combustion engines. The device allows the pinion gear of the starter motor to engage or disengage the ring gear (which is attached to the flywheel or flexplate of the engine) automatically when the starter is powered or when the engine fires, respectively. It is named after its inventor, Vincent Hugo Bendix”

aka pinion drive assembly and they don’t seize, the bearing and/or the spring breaks which is what I told you in the first reply.

A simple thanks Ed was all that you needed to say.

Thanks Ed. When I purchased a new starter from HOP I had Mark send a spare drive and 2 springs. Easy to change either in the event of a failure.I've experience a failure with both items in the past using a different brand starter.

and

I re-used the spring and the bearings. Only thing changed was the one way clutch or what ever you want to call it. I took it apart and with out bearings or anything on it, it would barely turn. (seized) I posted the results so if anyone else has a similar issue it may help find the cause.

Part # 255602
Powermaster 602 Starter Clutch Assembly, For Mini Starter

quote:

Originally posted by inferno camaro:
I re-used the spring and the bearings. Only thing changed was the one way clutch or what ever you want to call it. I took it apart and with out bearings or anything on it, it would barely turn. (seized) I posted the results so if anyone else has a similar issue it may help find the cause.

Part # 255602
Powermaster 602 Starter Clutch Assembly, For Mini Starter

It is effectively a sprag, it turns one way but not the the other. When you put power to the starter it engages the sprag and spins the motor over, when motor fires it spins starter faster than the starter motor is running and it disengages the sprag. It will turn one way hard but shouldn’t turn the other way at all. I have tore them completely apart to see how they worked.
The spring is only there to return the pinion gear back to non energized position. If you keep starter engaged too long the spring will get messed up and enlarge the coils which will get in the way of pinion fully engaging. I have seen springs messed up bad and not cause issue other than pinion will pop out on a hard launching car and hit flexplate on the launch hence the sparks you sometimes see coming out from that area on the launch.
If you hear grinding but see the pinion is engaged but not turning that is most likely because the sprag in the clutch is tore up.

It’s not what I want to call it, it’s what it is and you’ll be replacing it again because the bearing and or the spring is hurt, it’s why they sell the entire assembly. Bendix failure is common starter issue with race engines due to kickback, regardless of who built the starter. The root cause of which is low cranking voltage at the starter

You’re welcome!