460 Starter Grinding Problems

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Back in July 2017 I installed a new engine. When mating up the C6 transmission to the engine block, I ommitted reinstallation of the engine backplate to make things easier. That turned out to be a terrible decision. Without the engine backplate installed, the starter drive gear will extend 1/8" further backward than designed as it meshes with the teeth on the flex plate. Within 8 months, my brand new Summit Denso-style starter started to grind during startup. The grinding quickly (within a week) deteriorated into a free wheeling starter that wouldn't turn the engine.

The obvious solution was to replace both the flex plate and the starter, and this time, reinstall the engine backplate. So, I did that.

The problem went away for almost a year, but it's back. I heard a little grind upon startup yesterday. This morning the grinding was a little worse. I know where this is going.

I have a new starter on order with Summit. I know I'll be taking a chance by installing a new starter without also addressing the flex plate, which could be damaged. I may end up ruining another starter drive gear (which can easily be replaced, but it's not cheap). My biggest concern is having to repeat the flex plate replacement. What a PIA!

I really thought the root cause of the problem was the lack of an engine backplate, but after this second failure, I have my doubts.

Anyway, I just wanted to post this here to document a relatively unusual issue I've been having with my starter. Has anyone else heard of 429/460 owners who have been running into similar problems?

[Tom Wells]

Todd,

Yes! It's one of the 385 engine's dirty little secrets. The starter can sit a little too deep into the bell housing and cause interference with the ring gear.

The problem seems to vary with the brand and type of starter. Some seem to extend a little further toward the rear than others.

What I don't understand yet is why yours took a while to develop the noise - mine, if it did happen, was there from the first start.

The solution to the interference problem is a shim that goes between the bell housing and the starter. Takes just a few minutes to insert if you can readily get to both starter bolts. I seem to recall they're about 1/16" thick, give or take, but thick enough to solve the problem.

The shims are available; it has been so long I forgot where mine came from. DuckDuckGo is your friend

Hope this helps,

Tom

[Joey.S]

Doorman makes the starter spacers I have bought a few in the past, the shim will solve your problem like Tom said.

Joey.S

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Thanks, Tom and Joey.

If I simply install a new starter without changing something else, this will happen again. That's guaranteed at this point. The geometry has to change.

I have a couple of different starter shims. They're widely available at all the big auto parts chains (CarQuest, AutoZone, NAPA, O'Reilly, etc) in varying thicknesses -- 1/16", 3/32", 1/8". I didn't use either of them the last time because I was convinced that installing the engine backplate would fix the gear alignment problem.

My plan is to install the new starter with the thinner of the shims. I'll hook up a temporary solenoid voltage source, engage the solenoid, and inspect the starter throw relative to the location of the flex plate ring gear. If it looks well aligned, I'll finish the installation and give it a try.

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One thing I failed to mention was that all the damage to the first starter was isolated to the leading edge and first 1/8" of teeth on the starter drive gear. It looks to be crashing into the ring gear teeth before engaging.

[Tom Wells]

Todd,

It's been a while since I had this problem...

The symptom I had was a loud squeal, not grinding, so your problem may be different!

Another thought: There are two different starter drive gears if my recall is accurate. One is for a flywheel and the other for a flexplate which - I think - have different numbers of teeth.

BTW, is there anything behind the ring gear that the starter drive gear could make contact with after it is (too) fully engaged?

More possibilities?

Tom

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The symptom I had was a loud squeal, not grinding, so your problem may be different!

Sounds very different. My problem is definitely caused by gear teeth clashing resulting in progressively worsening damage.

BTW, is there anything behind the ring gear that the starter drive gear could make contact with after it is (too) fully engaged?

No.

Another thought: There are two different starter drive gears if my recall is accurate. One is for a flywheel and the other for a flexplate which - I think - have different numbers of teeth.

The one I've been ordering says that it's compatible with a 1974 Thunderbird 7.5L. Those all came with C6 3-speed automatic transmissions (which is what I'm using).

[Tom Wells]

Todd,

Interesting observations.

I looked on the RockAuto site and found no simple way to tell the automatic starter from the stick shift. They each appeared to have ten teeth.

I wonder if there's something else going on, as in whether the depth of engagement isn't deep enough for some mysterious reason? It looks like the starter drive gear is restrained by the nose housing, so that's what appears to keep it from going too far toward the flywheel.

Here are two threads from 460Ford.com with what might be some good info:

https://www.460ford.com/forum/37-eng...ter-motor.html

and

https://www.460ford.com/forum/37-eng...ifference.html

If you really want your head to spin, do a search for "460 starter" on the 460Ford site

Maybe one of these will give you the clue you need to get it sorted out, as in "stick shift starters are shorter throw than automatics" and stuff like that!

Tom

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I've double checked with Summit each time I bought that starter, just for piece of mind. My question: "Is this starter compatible with a 164 tooth flex plate?" Each time, the answer was "Yes".

[Large Arbor]

Just to add to what others have said, some aftermarket starters have no shaft support and over time move out of alignment if they have no pinion support. Robb Mc Starters do, but I did not see any for the 385 series. You may want to check with them.

If all else fails, I took my Bellhousing off and bolted the started to the block plate to check alignment and fit.

Phil

[Tom Wells]

Todd,

Pretty sure I have this starter on both the 521 and the 557: https://www.rockauto.com/en/moreinfo...sn=491&jsn=491

I don't know where they came from but they were supposed to be OEM for a 1996 F250 7.5; in other words a stock Ford truck starter. That seems to be where the 460Ford guys ended up with their strokers.

All the fancy aftermarket starters I tried failed, but not in the same way you described yours...

I wonder if yours just got tired and couldn't pull all the way in?

Phil, I think you can see from the illustrations that the pinion seems to be well supported.

Tom

[Large Arbor]

Yes, pinion support looks fine. On my FE, I had a mix of issues. Wrong bellhousing which allowed to much slop in alignment, no pinion support, and wrong size starter bolts.

If all else fails, the only solution is to get eyes on the engagement.

Phil

[hauss]

only one person said ring gear!

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I'll be taking the car to a shop on Tuesday to have both the starter and the flexplate changed out. It really makes no sense to change one without changing the other. If they're grinding, they're both damaged. The starter I can do on my own. I'm not equipped to remove/reinstall a C6 transmission.

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The shop just called me with news of a show stopper. The engine backplate between the engine block and the bell housing is too thick. The starter is not reaching far enough into the bell housing to mate the gears properly. Can't get one within two days, so we're going to Plan B.

There's a big auto show coming up this weekend sponsored by MotorTrend (The First Hawaiian Bank International Auto Show at the Hawaii Convention Center). I'll end up leaving the slightly damaged flexplate in there, and install a used starter having a brand new starter drive gear on it. It'll cause more damage to the flexplate and it'll start to damage the new starter drive gear, but it should work for now. Both components need to be replaced anyway once the new engine backplate arrives from Summit.

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All ready for the car show.