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Discussion Starter · #1 ·
This may be a dumb question,, but why is it that I seldom hear about 100,000+ mile 5.0 cranks eating up thrust bearings, but I see a lot of threads about 331's and 347's eating them up shortly after they get them running? Is it because of the aftermarket crank? Is it more common with a cast steel crank vs a forged steel crank or vice versa? I'd hate to build a new stroker and have it ruin the block and crank!
 

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properly setting and knowing the crank end play is helpful and not hard to do..

I can see over looking something like that in the "excitement" that is assembling a motor but you should always double tap... It can't hurt if you know what I mean LOL
 

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Aftermarket cranks usually have tighter tolerances than OEM cast. I just finished up a Mitsubishi Evo (yeah yeah yeah) that had a Manley forged with some aluminum rods. Crank end play was a whopping .001". A large screwdriver and a dial caliper are your friend when assembling a motah.

Clutches that are set up incorrectly can also destroy a thrust bearing.
 

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Discussion Starter · #11 ·
I do remember a guy saying that the thrust surface on his new stroker crank had a nasty coarse machined surface which he felt might lead to a failure, so he had it polished or something. I have always checked endplay etc. but never really payed particular attention to the surface on the crank itself.
 

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Discussion Starter · #12 · (Edited)
I wish I had a dollar for every time I have asked people that have engine problems.

Hey did you check clearances ?

And they go huh how do you do that ?
That reminds me of my Dad teaching me how to rebuild our first 302 30 years ago. It was time to torq the rods and we set the torq wrench to #15-#20lbs and when it clicked, the next words out of my dad's mouth were: "That can't be right-give me the ratchet" and he proceeded to tighten them to where he felt it was good and tight. Needless to say the first time the engine made it to about 4000, a rod pulled apart. It was a priceless moment when dad looked under the car and I asked: "Do you think we broke anything?" and his reply was; "I think so-there's a big dent in the oil pan". Looking back it was hilarious how we thought we were doing it right. My dad is still living if you'd like him to help assemble your new engine for you. ;)
 

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Someone mentioned it earlier -- but clutch/transmission issues also often eat thrust bearings. Torque converter not seated all the way so when the tranny is cinched up it's pushing too hard on the back of the crank; similar when manual trannies are changed/swapped and there's a difference in input shaft length, etc.
 

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Discussion Starter · #16 ·
Add another one to the list. My brand new 331 just munched the thrust bearing up with less than 200 miles on it...
Sorry for the bad luck. Any idea what caused it? It seems so weird that our old 5.0's go 200,000 miles regardless of clutch adjustment etc. but yet it seems like so many strokers eat em up real quick. It'd be nice if there was a clear cut reason that could totally eliminate the chance of it happening.
 

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Sorry for the bad luck. Any idea what caused it? It seems so weird that our old 5.0's go 200,000 miles regardless of clutch adjustment etc. but yet it seems like so many strokers eat em up real quick. It'd be nice if there was a clear cut reason that could totally eliminate the chance of it happening.

The answer was given already vvv

The factory is not building strokers, guys don't set thrust, guys don't check the vertical face of the crank. It has nothing to do with it being a stroker.
 

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Discussion Starter · #18 · (Edited)
Without having your crank remachined, how do you set thrust? I know that the stroke itself has nothing to do with the thrust getting eatin. I have to assume it is because aftermarket stroker cranks are not consistently machined to the correct tollerances & surface finishs that OEM cranks are and if we don't catch it before we put it together, it's too late? I have a brother-in-law that works in a factory that makes powdered metal gears. He said if the aftermarket finds one of their gears are bad, they have to replace it, but if Ford finds a bad gear, they are required to replace every gear in that shipment. He said that Ford OEM standards are much higher than the aftermarket. I took a tour of B F Goodrich factory and every tire that is made is weighed and checked for balance, the best tires all go to the OEM car companies and we get the rest. That explains why you never see a large wheel weight on a new car , but when we go get new tires the weights are 3" long. OEM standards are pretty high quality for the most part.
 

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Without having your crank remachined, how do you set thrust? I know that the stroke itself has nothing to do with the thrust getting eatin. I have to assume it is because aftermarket stroker cranks are not consistently machined to the correct tollerances & surface finishs that OEM cranks are and if we don't catch it before we put it together, it's too late? I have a brother-in-law that works in a factory that makes powdered metal gears. He said if the aftermarket finds one of their gears are bad, they have to replace it, but if Ford finds a bad gear, they are required to replace every gear in that shipment. He said that Ford OEM standards are much higher than the aftermarket. I took a tour of B F Goodrich factory and every tire that is made is weighed and checked for balance, the best tires all go to the OEM car companies and we get the rest. That explains why you never see a large wheel weight on a new car , but when we go get new tires the weights are 3" long. OEM standards are pretty high quality for the most part.

You make assumptions that people are even checking thrust. Ask Jim how many thrust failures he has shipped out vs the number of self assembled kit thrust failures. Same parts.
 

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I have an in depth video of how and why to set the thrust. Its not optional its mandatory and has nothing to do with machining your crank. It has to be done during assembly. Its not some trick of the week or speed secret. Not to mention its deadly simple. Its done at oem's and done by regular folks building there engines. If you didnt do it and your alright you got lucky is all.
 
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