4L60E Flex Plate

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jce98

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98 Tahoe 2 Door 2 WD 4L60E. Truck was stolen back in February, and was recovered a couple of weeks ago. The thieves had dropped a new engine 5.7, mine had 300K miles on it. When I was able to make my way beyond the Passlock BS, thankfully I had the original key, I got it started. Good compression, good oil pressure, no knocks. The engine I had in it before it was stolen as on its last leg. Hooked up transmission lines and radiator. BTW 3/4 socket and take the trans adapter lines out, install clips, and then put the adapters back in. I put in transmission fluid, started it, put it in gear and nothing. Pulled the inspection plate and the TQ was not bolted the flywheel. Yes, I am one lucky SOB. Problem now is trying to bolt up the TQ to the flywheel and they do not line up, tried both sets of holes in the flywheel and I am about 1/16" off from being able to get a bolt into the TQ. I read where the block VIN is stamped on the passenger side at the front of the block in order to determine what engine I am working with. It does not appear readable unless I remove the alternator and bracket?

At the point of trying to decide if I want to elongate the holes in the flywheel, or pull the transmission and try to figure the correct flexplate? I'm leaning toward the Dremel and carbide bit.
 

Joe Dirte

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The holes are off alignment or the converter is too fat back? You can pull converter forward some to get bolts in.
 

PlayingWithTBI

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Nope, pulled the converter up to the flywheel. They will not start as is.
Do you still have the 2 alignment dowels from the block to the trans? If not, enlarging the holes in the flex plate will throw it out of balance and tear stuff up.
 

Schurkey

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98 Tahoe 2 Door 2 WD 4L60E... ...new engine 5.7... ...Pulled the inspection plate and the TQ was not bolted the flywheel.... ...Problem now is trying to bolt up the TQ to the flywheel and they do not line up, tried both sets of holes in the flywheel and I am about 1/16" off from being able to get a bolt into the TQ.
I would not have expected a problem with bolt circles. So far as I knew, the 700/4L60/4l60E torque converter bolt circles were all the same, and the same as the TH350/TH400 except with metric threads instead of SAE.

So this is all-new to me.

Does the "new" engine have a one-piece rear main seal, or the old 2-piece rear main? Seems to me that the ancient Powerglide torque converter bolt pattern was different from the 350/400/700/4L60/E, but it's been so long since I've even seen a Potatoglide that I'm not sure any more. Point is, there's no Potatoglide flexplates for a one-piece-seal block unless they're made in the aftermarket, which seems unlikely for thieves to use.

OTOH, I can see them slamming in an old 283/307/327 that they found in the back of someone's garage during a previous thieving session. Heck, I had a '69 Impala with a 350/Glide, until I pulled the 'glide and stuffed a TH400 in place.

I read where the block VIN is stamped on the passenger side at the front of the block in order to determine what engine I am working with. It does not appear readable unless I remove the alternator and bracket?
Probably. And it would be nice to know, but not critical. If the decks of that block have been planed, those numbers are gone anyway.

I'd be more interested in the block casting numbers, which may be on the block below the exhaust manifolds. Potentially on the bellhousing area, visible from above at the rear of the engine.

But what really matters is the torque converter and the flexplate; and block numbers won't tell you that.

At the point of trying to decide if I want to elongate the holes in the flywheel,
NO.

or pull the transmission and try to figure the correct flexplate? I'm leaning toward the Dremel and carbide bit.
Lean AWAY from the Dremel and carbide bit.
 

shovelbill

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My guess is that the wrong flex plate is in there. In a similar circumstance, I had the GM crate 4L70E put in behind the new Vortec 383. The stock 168(?) tooth FP couldn't be used, and I had to get a 153 tooth. Other issues rose their ugly heads for me, but that's a different animal altogether.
Could you check the part number? I think your problem is the reverse of the one I had. It's something to look into anyway.

Here's a page from my thread.

 
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