How many teeth do I need on a flexiplate

sal37 · September 17, 2012, 12:14:54 AM

Hi I've just purchased a 290HP chev crate motor and want to run a T700R (non electronic) which flexiplate should I run 153 tooth or 168 tooth. Why is there a difference??

Also with the T700 transmission I undertand there are two ways of locking the tansmission up - one is to have a switch on the dash and the other is to have the an internal switch activated by speed/revs ?? (not sure).

There are probably pros and cons to either method but can I get some comments on which is the better system??

Thanks Stephen

GPster · September 17, 2012, 08:58:13 AM

Just guessing, I wouldn't think that the bigger flywheel would not spin inside the 700's bellhousing. Picking up information that is probably in the archives if you could sort it there is more information that you might need to sort this puzzle. Is the "crate motor" of the pre or after '86 design? The flywheel flange on the crankshaft and the rear seal type is different. If it's the earlier style then you will need to know if the starter bolt holes into the engine block are tapped SAE or Metric threads. You should know that to get the correct starter and bolts to fasten it to the block. This information could come from the Hollywood branch but the time difference might have caused him to miss it. GPster

enjenjo · September 17, 2012, 10:37:05 AM

As long as the flexplate and starter are a matching set, either will work.

Charlie Chops 1940 · September 17, 2012, 05:18:21 PM

Preferably...all of them.

Just couldn't resist.

Charlie

Harry · September 17, 2012, 11:53:58 PM

Is the flywheel actually larger or are the teeth smaller. I wonder how a larger flywheel would affect the starter engagement.

phat rat · September 18, 2012, 06:05:51 AM

Quote from: "Harry"Is the flywheel actually larger or are the teeth smaller. I wonder how a larger flywheel would affect the starter engagement.

The flywheels are different size and the starters are matched to them by the way they mount, offset or straight across bolt pattern

moose · September 18, 2012, 08:34:54 AM

Having gone thru starter/fly wheel issues it not simple. I found tha tthere are several different nose pieces for the Chevy starters. They effect the depth that the starter engages the flywheel. As Frank said BE SURE to get a matched set. I went to my local parts house and ordered a flywheel and started for the same vechile. In my case I used 89 Chevy truck. I chose the 89 as that is the year of my block.

Prior to that I had issues with chewing teeth of firts the starter then the flywheel. I had used the correct 89 flywheel BUT used a starter I had on the shelf. It was the correct bolt style but did not extend far enough into the bell housing to fully engage the flywheel. I did not catch this till I was stranded when it cheweh off the edge of the teeth.

Arnold · September 20, 2012, 09:11:47 AM

Quote from: "Charlie Chops 1940"Preferably...all of them.

Just couldn't resist.

Charlie

"Preferably". I am NOT the only member out here that has had
stuff that you had to turn the flywheel to escape a "bald" spot and try again.

Fess up guys..lol.

UGLY OLDS · September 20, 2012, 06:06:06 PM

Quote
Quote"Preferably". I am NOT the only member out here that has had
stuff that you had to turn the flywheel to escape a "bald" spot and try again.

Fess up guys..lol

Gee .... My Kid had to do that a few years back ... :oops:
I 'spained how to turn the balancer a little to get the car home ...

Then I spent Christmas Day on my back in his garage changing the flex plate & starter drive....

I think he won that one ...... :?

Bob.......

Harry · September 20, 2012, 06:54:20 PM

Recently, I bought a PowerMaster starter that said it fits both size flywheels. 153 and 168 teeth. this is on a 350 Chev. Held in place by two bolts that go straight up.

Warpspeed · September 20, 2012, 07:54:17 PM

Quote from: "sal37"Hi I've just purchased a 290HP chev crate motor and want to run a T700R (non electronic) which flexiplate should I run 153 tooth or 168 tooth. Why is there a difference??
Thanks Stephen

Stephen, I am going through this same drama myself right now with a Ford combination.
There are so many years/applications that it probably does not matter as long as the starter and flex plate are a matched pair.
Do some research and find out what models and years had what (??) and buy both starter and flex plate to suit that exact year and application.

You will obviously need a free torque converter when idling and starting off in first gear, and also for full throttle up changes to soften the sudden shock loading when shifting gear.

The torque converter can be locked in top gear, and also maybe in the lower gears at very light throttle for improved fuel economy.
Many ways to do it, the simplest is probably to use a speed sensitive switch, combined with a "full throttle" switch.

Lock up the converter above a certain road speed, but have it unlock when you really nail the throttle at any speed. That would be about the simplest workable system.