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Discussion Starter · #1 ·
I'm getting ready to by the PTO to connect to the driveline, and am planning to use a flexplate rather than a flywheel as it is lighter. Any reason I shuold consider using a flywheel?
 

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I'll be interested to hear the replies but I think a flex plate in big hp applications is a no go what are you running hull engine vdrive?
 

· Village Idiot
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We have done flex plates in the past (granted they were on the tail of some tame engines) and have not had issues. Then again we did not use the cheap Hughes or Pioneer flexplates, but stuff like the JW or the ATI units that are much thicker and stronger.

I am interested on what you guys are putting in your Hot Rod/Race boats that have considerable power and run higher RPM's.

Paul
 

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Flex Plates

I have run flex plates for years. Even when I ran TAH I ran them on my Arias. I wouldn't run the stock ones, but the SFI certified ones are thicker and usually better made. Although any more alot of companys are getting them from china and slapping their stickers on them. I ran into trouble trying to find one that wasn't out of round. JW trans. is a local business here and I went through several of theirs before finding one that was true. I run one made by Meziere now and it is a billet piece and is very nice. They are a little pricey but I haven't had any starter issues in four years.
 

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We run flex plates also. I currently have a TCI on my Pontiac.
 

· Lookout I'm Crankin it Baby
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Here's my take...
SFI approved flex plates work great. But I think it really depends on the use of the boat. If you are doing a considerable amount of low speed stuff, skking, tubing, I would consider an aluminum flywheel or even the heavy steel one. It seems to calm the motor down a bit and let's it idle smoother. If your looking for "out of the hole hero status"...probably go with real good flex plate...
 

· Owner/Crew Chief
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I'm getting ready to by the PTO to connect to the driveline, and am planning to use a flexplate rather than a flywheel as it is lighter. Any reason I shuold consider using a flywheel?

After what almost happened to us using a flexplate made by a very reputable manufacturer, I'll never use a flexplate again unless it is used where there is a converter behind it to minimize its 'flexing' .....

When we put our current motor together, we installed a very well known brand of flexplate. The plate was AL with a steel starter ring pressed onto it which was held in place by 9 steel tabs each having 2 small allen heads, head on the AL side with their ends spot welded to the tabs.

When we started putting nitrous to the motor we began to find these small allen heads in the bottom of the boat and couldn't understand where they we coming from as we didn't understand what was happening at the time ....... this went on for a few races before one of our motor guys decided to find out what was happening toward the end of one of the latter races and he pulled the flexplate cover off on a hunch ..... low and behold, all but 2 of the 18 allens had been popped of and had we fired the motor again, or, had it been running on the track and we put a shot of n2o to it, the ring could have come off and done some serious damage to say the least.

We worked with the manufacturer, at no cost to us other than shipping, and had the same thing happen on 2 more of their flexplates. Turns out that the abrupt Tq that comes with nitrous shots was just too much for the design and the manufacturing process (which there's no need to go into here) of these particular flexplates.

Given our above experience we decided to go with a CnC's zero balance AL flywheel with a pressed on steel starter ring ..... net weight difference 5.6 ounces which is fine with me.

I'll come back in a bit and finish this, but, Brendel has just arrived and we need to go over some things.

James is on his way back to Kalifornia so I'll finish .....

Flexplates are named that for a reason ..... they flex ..... the plate flexs and the starter ring doesn't or, at least its far more rigid being steel (we did a through lab analysis of the materials involved and found some things that apply elsewhere, but, that's not the focus here). That being the case, if one is bound and determined to use one in an unconfined or, relatively unconfined application then, they should pay particular attention to how the starter ring is attached to the plate and how durable the connection is ..... in my opinion, it's just far better longterm cost wise and safety wise to use a lightweight AL flywheel ..... just my opinion.
 

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Discussion Starter · #9 · (Edited)
The boat is a 74 Sanger bubbledeck with a 10* Casale v-drive.
I hadn't given any thought to the need for an sfi approved flexplate, since it doesn't really do anything but hold the ring gear. But it makes sense not to spin a patoto chip at high rpm. Even though I'm only putting in a 400 or so hp motor right now (it's sitting on my garage floor), I may pull the motor out of my drag car later ,or build a new one for the boat when the economy picks up. So I guess I will set it up with a flywheel since I already have that too, and it can handle some serious hp later on.The motor in my car that I'm thinking of using is about 750 hp,but I think I better get my feet wet with the wimpy moter first, so I dont kill myself (or someone else)Thanks for all the info.
 

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Here's my take...
SFI approved flex plates work great. But I think it really depends on the use of the boat. If you are doing a considerable amount of low speed stuff, skking, tubing, I would consider an aluminum flywheel or even the heavy steel one. It seems to calm the motor down a bit and let's it idle smoother. If your looking for "out of the hole hero status"...probably go with real good flex plate...
My .02 also, the heavy wheels make a better no wake grocery getter especially with a blower !!!
 
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