Starter Engagement/mesh Issue, Last Straw That Could Break The Camel's Back

[Fox_Gainz]

Hello to all, I new to the forum, hope everyone is having a great day . I am in dire need of the community's guidance and expertise on an issue I am having that has myself and the shop my car is currently at stumped .

My current engine set up
- Ford Racing

302 Block bored 0.30 over for a 347 stroker kit
-Scat 347 stroker kit
- Performance Automatic 28oz AOD Flexpalte, 164 Tooth, SFI approved
- SVE Aluminum heads
- BBK SSI intake
-70mm TB
-30# injectors
-76mm MAF
-B303 cam
-B&M 2200 Stall converter

- Heavy duty Rebuild kit with shift kit for AOD
-Wire Tuck w/Battery relocation in trunk ( Yes I did use welding wire for the battery power cables )

Backstory-
I've built a new engine for my 1991 Ford Mustang LX. Everything engine wise is brand new down to ARP bolts for pretty much everything. The issue I am having is the starter is grinding when attempting to start the car. It all started off with a newer style PMGR starter found on 92' and up fox body mustangs that I rebuilt that came from a donor 93 GT fox with and AOD. That starter worked flawless without issues till the solenoid went out and gave the infamous "Click" on the relay when attempting to crank. I had and extra auto parts store PMGR starter I had laying around for another fox that needed the starter replaced which I used installed on my car instead. With the new Auto Parts store starter everything was great for about a day or so unit the engine killed the starter's gears internally. The starter would engage but once it touched the flex plate it would just grind the gears on the starter internally. That may have been because of my compression ration on the current engine build not sure. Took it back and had it replaced under warranty. Now things get interesting with 2nd Auto Parts store starter, also worked for a day and then started having an awful clanking/ grinding sound when turning the car over as if it was skipping teeth till eventually it just stopped engaging the flex plate ring gears. Thought maybe It was just a defective unit, took that one back in and had it swapped out for another. Now on to the third starter from the auto parts store, also worked for about less than a day and started the same grinding/ clanking sound. Pulled the starter, checked teeth on the flex plate and they looked worn in some areas and not in others. Thought maybe I've ran into bad luck with auto part's store starters and ordered a PA Performance starter, put that sucker in and it also worked for a couple starts and after started the same symptoms as the previous two starters. I was pretty sure my flex plate ring gears were shot from all the starter issue and sure enough after rotating the engine by hand it would engage in certain spots but not others. At this point I was looking at replacing the flex plate, didn't have the equipment or expertise to do it on my own in the garage, so I sent the car off to a shop that works on nothing but mustangs hoping they would be able to resolve this starter issue with a new flex plate . So far after a new replacement 164 tooth SFI flex plate from American muscle that the shop put on, trying with both my old original PMGR starter that I got off another AOD fox and the PA Performance the shop mentioned that the car will start fine on the first start but then on the second or third start it will try to grind and eventually you just hear the starter engaging but not turning the motor over. The mechanic stated the depth of engage meant from the starter to flex plate is good, just the mesh of the flex plate ring gear teeth and the starter pinion aren't deep enough so much that it looks like just the tips are touching. They didn't want to cause anymore damage to the new flex plate so they recommended I try and find a different starter online. I purchased a new B&M 77100 starter that said in the description that it would work fitment wise but the shop attempted to put it in with no success, said that it didn't fit something about clearance issues. Will be calling tomorrow to speak to the actually mechanic about that because the unit is re-clockable. * Also the measurement from the block plate to the beginning of the flex plate is 3/4"
Now Ive been researching out the wazoo about this issue and keep coming up with people with an similar issue usually with a swap. Transmission wise nothing has changed, same AOD, same block plate, just new engine block, new flex plate 28oz because of stroker kit requirements (same tooth count as stock 164) and a stroker kit with the PMGR starter which from what I've read is a direct replacement of the old style starter. Before all this the car ran perfectly and was actually my daily driver.

Couple questions-
- If starter gear mesh between the starter pinion and the ring gear is the problem what can be done to resolve that
- Is there a difference on off-set on the start pinion on the PMGR starer and the old style starter
- Do I continue with the shop I have it at now or bring the car home for now

At this point I'm at a loss here, not sure what else to do, the shop I have it pretty much saying they never encounter an issue like this don't have a solution on what to do next. Only thing they haven't tried is putting the old style starter back in the car and seeing if that works but the bill from just R&R of the transmission and labor hours for the starter issue is already high. Any help is appreciated and any more info that is needed I can do my best to provide it


.

 

[MustangIIMatt]

You need a 157 tooth flexplate.

https://www.summitracing.com/search...tooth/engine-balance/external-28-oz-imbalance

 

[Mustang5L5]

AOD Mustangs are 164 tooth flexplates from the factory. The starter should work on either as when I 5-spd swapped my car, I used the same started from the AOD on the new 157 tooth manual trans flywheel without issue

Balance is 50oz stock however, but it seems that the motor was assembled for 28oz.

http://www.rowand.net/Shop/Tech/FordFlywheeslAndFlexplates.htm


I assume this is a stock AOD transmission? I'd probably try a different flexplate here, but that's a pretty expensive thing to try when you consider cost of the plate plus install. My thought it you should not be having this much trouble with starter engagement if bolting multiple starters in and having the same issue. Short of an alignment issue (which doesn't seem to be based on the pic) I'd probably research and see if anyone else with that brand flexplate is having the same issue.

 

[Fox_Gainz]

Really appreciate the quick response

@Mustang5L5 Yes the AOD is the stock one that came with the car, just has a shift kit and higher stall converter installed.

From your suggestions I should be going with a 157 tooth flex plate instead of the 164 tooth I have now correct ? From the link provided I did see a Scat Flex plate which the stroker kit is also of Scat branding. SCAT Engine Components FP-302-157-SFI - Scat Flexplates
What would be be the difference between the 157 and 164 flex plate besides tooth count, I'm assuming diameter wise the 157 tooth should be smaller ? Correct me if I am wrong?
Will be giving Scat a call later to verify if this is the route to go.
Definitely want to be sure on this before I order this as I can not return the flex plate after install if it doesn't work

 

[Mustang5L5]

You have to use the 164 tooth flexplate. The 157 flex is a smaller diameter, and AOD's are setup from the factory for 164 tooth. 157 is really more for C4 use. 5-spd Mustangs use a 157 flywheel, and the starter is interchangeable because the bellhousing is what locates the starter.

What I was saying is I would research to see if other have had issues with that particular brand flexplate, and if so, may consider swapping to a different brand flex, but remaining 164 tooth. However, that's an expensive suggestion, so I'd see if you can find any other logical explanation first.

 

[General karthief]

Did the engine vibrate when you were driving? Make sure you have the correct balance flywheel, call crank manufacturer, if your teeth are worn down in spots and the engine stops at one of those spots it likely will not engage correctly. That will damage the started drive. Also make sure you are not having a problem with voltage drop at the starter, that can also cause the starter not to engage fully into the flywheel.
I would turn the engine buy hand untill you see good teeth on the flywheel in the starter hole, bolt up a known, good, stock starter and crank it, if it does not engage properly, look for
A voltage drop at starter
B correct tooth count on flywheel
C starter fits in place with no jiggle'n around
You likely are going to have to replace flywheel if teeth are messed up anyway.
Another, less likely scenario would be flex plate is bent, turn engine over by hand and have someone watch flex plate movement

 

[Fox_Gainz]

Thanks for the feed back @Mustang5L5 will look into that today.
@karthief
Sadly the car hasn't had any road time other than running in the garage ironing out idle issue and timing so I am not able to attest to any vibrations. Car currently has new Flex plate installed by said shop & is currently still there. I've verified from scat's website that the 347 stroker kit requires externally balanced 28oz balancer & flex plate.
Spoke to the shop owner who rebuilt my Transmission last year when the car was running, he was very knowledgeable in the ford starters and mentioned that I may have the wrong starter where starter pinion " offset" from the center is not the correct one and that's why it's chewing up the flex plate ring gears. Planning to take the car to his shop Friday. He seemed pretty confident that the issue could be resolved & will keep everyone up to date. I appreciate all the suggestion and replies

 

[Mustang5L5]

I am aware of a different AOD starter for use with 157 flexplates, but it's rather expensive and moves the starter pinion closer.


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[Fox_Gainz]

I am aware of a different AOD starter for use with 157 flexplates, but it's rather expensive and moves the starter pinion closer.


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That's what it's looking like that I may need a different older style starter Already dropped a bit much on just starters alone
Do you know which year or years starter that would bring the pinion closer ?

 

[RaggedGT]

@90sickfox -whaddya think

 

[90sickfox]

@90sickfox -whaddya think

Did anyone else see the lower bolt hole for the starter ?....kinda looks like the threads are worn out.

I've put a few stroker combos together and have never had that issue. Seeing as though all the starters had the same problem I'd assume the problem is with the flex plate, trans, or spacers behind the crank.

The reason I mention spacers is because some people try to set torque converter depth with spacers between the crank and flex plate.

It really shouldn't be so complicated. I've used the same ( parts house ) starters on a lot of different motors. The starter on my car now has been behind a 302, 306, 347, and my current 331.

Edit; its been on both auto and 5speed motors as well.

 

[Mustang5L5]

I agree. It shouldn't be this complicated. Standard AOD and multiple starters...I don't think the starter is the main issue here

 

[General karthief]

I am gonna go out on a lim and say you have a problem with the flex plate or torque converter not seated. Maybe the plate between the motor and trans? I'm guessing engine block and trans worked together before rebuild. Only thing I see is a different flywheel and torgue converter.

 

[Fox_Gainz]

@90sickfox as far as I know the bolt holes threaded in fine without issues, but yes theres something not right with this combo of parts.


I am also suspecting the block spacer plate could be the issue but looked fine when it went all together, man this is very frustrating at the very least.
@karthief @Mustang5L5 Here are a couple pictures I found of the block spacer plate. I took lots of pictures along the way.

 

[Mustang5L5]

Those teeth are definitely not in full contact. I can see them rounding over, and metal flakes on inside of bell.

Index plate alignment seems fine. I'd almost contact the flex manufacturer and see what they have to say about this

Multiple oem starters? I'd say issue is not the starter.

What's the p/n of the flexplate you are using

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[mikestang63]

My guess is something with the flex[late

• warped flexplate
• flexplate hanging up on the crank not tightened down correct
• wrong flexplate

 

[Fox_Gainz]

Those teeth are definitely not in full contact. I can see them rounding over, and metal flakes on inside of bell.

Index plate alignment seems fine. I'd almost contact the flex manufacturer and see what they have to say about this

Multiple oem starters? I'd say issue is not the starter.

What's the p/n of the flexplate you are using

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Yes indeed I agree with you about contacting the Flex plate manufacture which for the first one flex plate(dark grey in color), which you are seeing rounded off in the picture on my last post, is already trashed from the the ring gears. I still have it but its at the shop with the car. https://lmr.com/item/PAI-26467/Mustang-Performance-Automatic-Aod-C4-Flexplate-Sfi-Approved-164T-28Oz is the link for first flex plate that got messed up. Something quite odd to note is that on the website of LMR it says gold finish for the color but I received a grey colored one ?
The second flex plate which is in the car now & at the shop I got from American muscle http://www.americanmuscle.com/sr-flexplate-7993-28oz.html. Will work on getting exact part numbers for both flex plates this Friday

 

[90sickfox]

Have you tried a spacer ? Most parts stores carry a ford starter spacer in stock.

The reason I ask is because I had a similar issue on an f150 once. Truck kept eating starters and flex plates. When it got to my shop an old guy told us to shim it....it worked. Worth a try...its only a couple bucks.

Everything else sea to be I'm good order..... That bolt hole still looks fishy to me. In the new pic its a shard or something in the hole. Threads still look weird.

It could be a combo of poor picture focus ( in that area ), the fact that I'm tired as hell, or the few beers I drank.

Edit; I see the threads when I squint and turn my phone sideways. They don't look too bad. The stuff in the bolt hole looks like Teflon tape or something unrelated to your issue.

I try to help man, that's all I can say.

 

[Fox_Gainz]

Have you tried a spacer ? Most parts stores carry a ford starter spacer in stock.

The reason I ask is because I had a similar issue on an f150 once. Truck kept eating starters and flex plates. When it got to my shop an old guy told us to shim it....it worked. Worth a try...its only a couple bucks.

Everything else sea to be I'm good order..... That bolt hole still looks fishy to me. In the new pic its a shard or something in the hole. Threads still look weird.

It could be a combo of poor picture focus ( in that area ), the fact that I'm tired as hell, or the few beers I drank.

Edit; I see the threads when I squint and turn my phone sideways. They don't look too bad. The stuff in the bolt hole looks like Teflon tape or something unrelated to your issue.

I try to help man, that's all I can say.

Definitely appreciate the help! shimming it was next on my list of solutions before the flexed plate got chewed up. I will be taking the car on friday to another shop where I got my transmission built. He was quite knowledge guy, also an engine builder, over the phone seemed very confident that he could resolved the issue. Will keep everyone up to date for sure.

 

[knuckledragger77]

I've been out of the Mustang scene for a while but there was a company that made a starter called the mean green starter. It was intended for high compression and custom engines. You could order specific gear combos and custom starter gear throws. I.E. you could tell them how far the starter gear needed to move out to contact the flywheel. Hope this helps.

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