SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: FASTFREDDY on March 28, 2015, 10:47:53 AM

Title: Flexplate wobble?
Post by: FASTFREDDY on March 28, 2015, 10:47:53 AM
What is an max acceptable amount of fore and aft movement ( wobble) for the flexplate when the engine is running. Zero runout is obviously the best. I put two flexplates in and both have about .040 to .050 I ran the engine last year and didn't have any problems. The rev limiter has a 7k chip. I am wondering if this is common with factory plates. And if so is there an rpm where they start to cause problems with harmonics and eventually come apart
Title: Re: Flexplate wobble?
Post by: obnoxious001 on March 28, 2015, 03:30:23 PM
Do yourself a favor and buy an SFI rated flexplate, they are a little thicker and some are not too much money (hint: try Summit brand). 
Title: Re: Flexplate wobble?
Post by: GT Jets on March 28, 2015, 04:32:55 PM
You need to look at a couple of things. One, like obnoxious stated, get a quality plate.

Second, the run out you are seeing does not sound unreasonable, however, are you certain it is seating properly?  Do you have a PTO designed specifically for a flex plate?

Also I will add,it is important to check the crankshaft thrust run out. The harmonics will not come from a flex plate gyration, but it can weaken the flex plate center causing a very unfortunate failure.

GT
Title: Re: Flexplate wobble?
Post by: FASTFREDDY on March 29, 2015, 10:13:50 AM
Thanx for the input.when I replaced the first plate I had a witness to verify my correct install. Both plates are like new. But a SFI unit will definitely but installed in the near future.
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