Flex Plate Question
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 895
Likes: 4
From: whitman massachusetts
Flex Plate Question
Have a GMPP ZZ383 and getting ready to bolt up transmission(Turbo 400) and drop into frame. Happen to be looking at the GMPP flexplate
12.75"X152 tooth. Has 3 raised ears spaced evenly around the plate that I am assuming I am bolting the torque converter to. My question is two of the holes are exactly same 1/2" but the third hole is way smaller and oblong shaped, maybe 3/16" with a tiny hole above it. What am I missing here? Does the converter bolt to a different set of holes on the flexplate? Rookie here, so bear with me. Any info is appreciated.
12.75"X152 tooth. Has 3 raised ears spaced evenly around the plate that I am assuming I am bolting the torque converter to. My question is two of the holes are exactly same 1/2" but the third hole is way smaller and oblong shaped, maybe 3/16" with a tiny hole above it. What am I missing here? Does the converter bolt to a different set of holes on the flexplate? Rookie here, so bear with me. Any info is appreciated.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Suggest you first verify diameter of the bolt circle on YOUR TH400 convertor ... then verify YOUR 153T flexplate has same diameter bolt circle.
I suspect you will need another flexplate or convertor. Unless you have mini-starter, straight-pattern etc requiring a small 153T flexplate, I suggest you use the larger 168T flexplate.
I suspect you will need another flexplate or convertor. Unless you have mini-starter, straight-pattern etc requiring a small 153T flexplate, I suggest you use the larger 168T flexplate.
Melting Slicks
Joined: Apr 2005
Posts: 2,045
Likes: 4
From: Yorktown VA
NCM Sinkhole Donor
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Why? ... Not all mini's are adaptable/clockable & staggered/straight 153T or 168T ... maybe yours is but others are not. Neither do all blocks have two pair of straight holes. I dunno which starter WW has. Also, I dunno, but have a sneaking suspicion WW's small GMPP flexplate may not have the large bolt circle to match his TH400 convertor.
Last edited by jackson; Jun 30, 2009 at 10:31 PM.
Melting Slicks
Joined: Apr 2005
Posts: 2,045
Likes: 4
From: Yorktown VA
NCM Sinkhole Donor
Why? ... Not all mini's are adaptable/clockable & staggered/straight 153T or 168T ... maybe yours is but others are not. Neither do all blocks have two pair of straight holes. I dunno which starter WW has. Also, I dunno, but have a sneaking suspicion WW's small GMPP flexplate may not have the large bolt circle to match his TH400 convertor.
Thread Starter
Burning Brakes
Joined: Sep 2005
Posts: 895
Likes: 4
From: whitman massachusetts
Torque Converter
Torque converters for both the t-350 and t-400 come in two different bolt patterns, 10.75" and 11.50". My 12.75" 153 tooth flexplate, takes the 10.75" converter. None of this has anything to do with my original question. 
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Your original issue is moot if your convertor has typical larger 11.5 bc. Do you know YOUR 400 convertor has the smaller 10.75 bc ? Perhaps it does but you haven't said. Was simply trying to (potentially) save you a step or two. Never mind & good luck.
