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Hawks flexplate has extra drill holes!

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Old 03-03-2022, 10:34 PM
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Hawks flexplate has extra drill holes!

Ok, I need you guy's input/advice. I have a 92 z28 5.7 tpi. The pinion gear on the starter became loose and damage the original flexplate. I just received a new flexplate from hawksmotorsport, I already made plans to install it this weekend. But, as you can see in the pictures someone obviously drilled 4 holes and returned it. Is it save to use? Can I weld up the drilled holes and smooth up the weld surface? Thanks.

Old 03-04-2022, 04:24 AM
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Re: Hawks flexplate has extra drill holes!

Those look like balancing holes to me. Years ago they would have been deburred but as with most aftermarket parts today quality control isn't what it used to be.
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Old 03-04-2022, 08:50 AM
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Re: Hawks flexplate has extra drill holes!

I wouldn't trust that. That flexplate needs to be balanced otherwise you'll get vibrations. And with how difficult it is to remove a transmission move a transmission I would just go and get a new one from GM.

The new ones from the factory come already balanced. There's no reason to be drilling extra holes in the flex plate.
Old 03-04-2022, 12:44 PM
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Re: Hawks flexplate has extra drill holes!

I wouldn't use it. I'd return that and get a GM one.
Old 03-04-2022, 02:11 PM
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Re: Hawks flexplate has extra drill holes!

The thing to be careful with on the GM flexplates is that they seem to be having trouble with their stampings lately.

https://www.summitracing.com/parts/nal-14088765/reviews

The guys who are saying their flexplates don't provide any clearance to the converter are correct. The one that came with my new HT383 had that problem. I ended up using my old one after I took the measurements prior to installing the engine.

If you want though, I'd be willing to sell you mine a lot cheaper than Summit if you want to take some measurements and we see if it'll fit. Seems like it fits on some people's cars but not others.

Basically if you measure on the transmission from the bell housing flange to the mounting pads on the torque converter (with the converter fully seated on the input shaft)...

Then measure from the flexplate mounting surface on the crankshaft to the bell housing flange on the engine...

I can then measure the flex plate.

If the flexplate is going to work, the math should work out that you have a minimum of 1/8" between the fully seated converter and the flex plate before pulling the converter forward to mate to the flex plate. Typically the maximum gap should be .1875 (3/16"), but if you're a little more than 3/16, you can close the gap with a shim/washer to get back into the range of 1/8 to 3/16 gap. Typically one thin shim or washer is ok. More than that and there's probably some wrong somewhere.

Let me know. My flex plate literally has zero miles on it... If the measurements work out, we can PM on price.
Old 03-04-2022, 07:23 PM
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Re: Hawks flexplate has extra drill holes!

I wouldn't risk it, go to your local parts store and pick up a flexplate. Pioneer FRA160 should be the part number, last time I check o'reilly's and autozone stocks them.
Old 03-04-2022, 07:29 PM
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Re: Hawks flexplate has extra drill holes!

Thanks fellas, I'll return it and get a new one.
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Old 03-04-2022, 09:10 PM
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Re: Hawks flexplate has extra drill holes!

Originally Posted by ULTM8Z
The thing to be careful with on the GM flexplates is that they seem to be having trouble with their stampings lately.

https://www.summitracing.com/parts/nal-14088765/reviews

The guys who are saying their flexplates don't provide any clearance to the converter are correct. The one that came with my new HT383 had that problem. I ended up using my old one after I took the measurements prior to installing the engine.

If you want though, I'd be willing to sell you mine a lot cheaper than Summit if you want to take some measurements and we see if it'll fit. Seems like it fits on some people's cars but not others.

Basically if you measure on the transmission from the bell housing flange to the mounting pads on the torque converter (with the converter fully seated on the input shaft)...

Then measure from the flexplate mounting surface on the crankshaft to the bell housing flange on the engine...

I can then measure the flex plate.

If the flexplate is going to work, the math should work out that you have a minimum of 1/8" between the fully seated converter and the flex plate before pulling the converter forward to mate to the flex plate. Typically the maximum gap should be .1875 (3/16"), but if you're a little more than 3/16, you can close the gap with a shim/washer to get back into the range of 1/8 to 3/16 gap. Typically one thin shim or washer is ok. More than that and there's probably some wrong somewhere.

Let me know. My flex plate literally has zero miles on it... If the measurements work out, we can PM on price.
You would be surprised how many people install them backwards, including myself twice over the years.
Old 03-05-2022, 05:39 PM
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Re: Hawks flexplate has extra drill holes!

True. The raised pads go towards the torque converter.
Old 03-05-2022, 05:56 PM
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Re: Hawks flexplate has extra drill holes!

The GM one has "Engine side" stamped on it.
Old 03-07-2022, 12:26 AM
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Re: Hawks flexplate has extra drill holes!

Thanks, EksCelle

I bought the one you recommended, autozone had it the next morning. Installed it and it worked perfectly, I mean direct fit and no vibration or unusual noise.thanks for the help!
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Old 03-07-2022, 12:26 AM
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Re: Hawks flexplate has extra drill holes!

Thanks, EksCelle

I bought the one you recommended, autozone had it the next morning. Installed it and it worked perfectly, I mean direct fit and no vibration or unusual noise.thanks for the help!
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EksCelle (03-19-2022)
Old 03-19-2022, 11:12 PM
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Re: Hawks flexplate has extra drill holes!

Glad to know it worked! Lucky that our cars take a lot of pretty common SBC parts.
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