Re: Flat washers under flywheel bolts?
[Re: 340Cuda]
#2678496
07/17/19 11:41 PM
07/17/19 11:41 PM
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Posts: 9,102 Rogue River, OR
Jeremiah
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The last ARP flywheel/flexplate bolts I bought specifically said not to use washers with them.
I have no idea why. Yet they sell flywheel bolts with flat washers for the high end HEMI stuff. Hence my question. More of a curiosity than anything I guess.
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Re: Flat washers under flywheel bolts?
[Re: lancer493]
#2678499
07/17/19 11:43 PM
07/17/19 11:43 PM
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Jeremiah
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I 'think' the small amount of distortion created by tightening the hardened bolts,with their specifically sized and machined area under the head, may help to create a locating effect that is normally accomplished with a dowel or tapered cone. Both of the last 2 would add additional machining steps and cost.I think a hard steel washer would elimate that 'freebie' effect mentioned in the beginning,as it 'may' act as a bushing between the 2 mating surfaces. Not sure if a dowel is included in the equation. That spinning flywheel creates some serious energy there,especially when try to move a 4000lb vehicle with sticky tires. Conical lug nuts on a street car comes to mind.Nothing textbook here, purely speculation and observation. Just my thoughts. Bill The bushing example makes good sense. I guess I didn't really think too far into how much heat gets built up in the flywheel.
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Re: Flat washers under flywheel bolts?
[Re: fourgearsavoy]
#2678500
07/17/19 11:46 PM
07/17/19 11:46 PM
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Jeremiah
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If the OP is talking about an actual "flywheel" and not a flex plate you need to be careful the bolt heads don't contact the damper springs of the clutch disc like Cab said. I like the ARP bolts with a flange built in because they are easier on the flywheel. You might be able to get away with some thin hardened AN washers but double check it. Gus You know I'd never have a car with a flex plate! I think I'll stick with the lube under the head, loctite on the threads and torque 'em down. Now instead of being nervous about the lack of washers I am paranoid they will cause problems.
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Re: Flat washers under flywheel bolts?
[Re: FastmOp]
#2678502
07/17/19 11:48 PM
07/17/19 11:48 PM
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Jeremiah
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I sheared grade 8 bolts a few months ago. I noticed on the ARP bolts they have a nice flat land under the head that looks pretty nice and was bigger then the land on the grade 8 bolts ATI sends with their flywheel and spacer kit. Plus the ARP bolts are 41something chrome moly.
ATI has issues with the flex plate they sell. I reused my old one because the converter bolt pattern is wrong on the new one. Always ARP. You should see the bolts that I got from one of the vendors. They are grade 8 with the heads ground down. Very scary especially when I ordered them with all of the face plated 9310 gears. Nothing leaves my shop wearing hardware store bolts, especially on the rotating assembly. ACE is not the place for flywheel bolts.
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Re: Flat washers under flywheel bolts?
[Re: Stanton]
#2678504
07/17/19 11:57 PM
07/17/19 11:57 PM
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Jeremiah
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Millions have been built with no washers. All the flywheel bolt manufacturers DON'T supply washers. Good enough for me !!! Millions have not been built with 750hp moving 3600lbs through a solid disc clutch/aluminum flywheel to plant sticky 10.5" slick tires at 5000 rpm. That begs the question. Some of the flywheel bolt manufactures that cover the entire motorsports spectrum *do* offer flywheel bolts with washers: Example #1Example #2Example #3I though maybe I was missing something.
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Re: Flat washers under flywheel bolts?
[Re: Stanton]
#2678505
07/17/19 11:58 PM
07/17/19 11:58 PM
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Jeremiah
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Millions have been built with no washers. All the flywheel bolt manufacturers DON'T supply washers. Good enough for me !!! When it comes to high performance race parts I want to as safe as possible, especially in the cars I build, drive and race and have pay to for the race parts Don't you think ARP would have tossed the idea around ?!?!? Yes, I actually do think ARP has tossed this idea around lol.
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Re: Flat washers under flywheel bolts?
[Re: Jeremiah]
#3047770
06/03/22 11:06 PM
06/03/22 11:06 PM
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Darkbreeze
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Sorry to necro, but for anybody who might still come across this thread, which they will because I did while looking for something else, I feel like it's important to correct misinformation even though I realize none of it was given intentionally. The bottom line is, none of the answers is actually correct in this thread for about 95%, maybe more, of applications. The reason being, about 95% of manufacturers use PLACE BOLTS, which you can read about at the following link and I guarantee none of you ever heard of them otherwise they'd have been mentioned in this thread, on critical fastener locations like flywheel bolts, oil pump bolts, camshaft retainer bolts, etc. https://www.earnestmachine.com/sites/default/files/products/imported/BHP.pdfYou will be able to identify Place Bolts by the undercut in the bottom of the head and the six cut out lines in the top of the bolt head. This design allows the bolt to create far more clamping power than a standard bolt, even when using a lock washer. If you remove a place bolt on any application that is the ONLY kind of bolt that should go back in that application location. Generally these are used on applications where the bolt is not particularly long, since longer bolt bodies are able to provide their own additional clamping spring tension, and where they are both difficult to get to if a bolt were to come loose AND would be likely to create a catastrophic end result if they did. Did not intend to step on anybody's toes, but sometimes, like I did, you might go half your career AFTER professional schooling, and have never heard of them, until somebody slapped me upside the head with that information. Hopefully, some of you here or others who come along later, will be better informed for the info. Good luck.
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Re: Flat washers under flywheel bolts?
[Re: Jeremiah]
#3047861
06/04/22 01:28 PM
06/04/22 01:28 PM
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rickseeman
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I'm into bolts. Nice article. I've paid for flywheel bolts twice from "Mopar vendors" and received regular Grade 8 bolts at a big price. These guys make me very mad sometimes.
2011 Drag Pak Challenger
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Re: Flat washers under flywheel bolts?
[Re: Cab_Burge]
#3048062
06/05/22 03:00 PM
06/05/22 03:00 PM
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Craig J
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I try to use thin harden flat washers with thin head bolts, make sure the clutch anti chatter springs don't touch the bolt heads after torqueing before using it that way Just adding photos for reference since I am in the middle of trying to undo numerous mistakes on a car I bought last year. Even without washers they bolt heads can hit... the previous owner tried to add clearance by using a hand grinder on the heads of the flywheel bolts, but it was not enough.
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Re: Flat washers under flywheel bolts?
[Re: Craig J]
#3048064
06/05/22 03:13 PM
06/05/22 03:13 PM
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Joined: Dec 2004
Posts: 10,558 Rittman Ohio
fourgearsavoy
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I try to use thin harden flat washers with thin head bolts, make sure the clutch anti chatter springs don't touch the bolt heads after torqueing before using it that way Just adding photos for reference since I am in the middle of trying to undo numerous mistakes on a car I bought last year. Even without washers they bolt heads can hit... the previous owner tried to add clearance by using a hand grinder on the heads of the flywheel bolts, but it was not enough. That happens when people use a flywheel that has been cut a few too many times Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: Flat washers under flywheel bolts?
[Re: Craig J]
#3048169
06/05/22 10:58 PM
06/05/22 10:58 PM
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Joined: Dec 2004
Posts: 10,558 Rittman Ohio
fourgearsavoy
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Yep only good for an engine run stand now. Gus
64 Plymouth Savoy 493 Indy EZ's by Nick at Compu-Flow 5-Speed Richmond faceplate Liberty box Dana 60
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Re: Flat washers under flywheel bolts?
[Re: moparx]
#3048206
06/06/22 08:54 AM
06/06/22 08:54 AM
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360view
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interesting article breeze. thank you sir ! i learned something, so you can say you taught an old dog. Me too. Glad to learn the automotive term “Place Bolts”. In mining they are commonly called “Double A” like the link to earnest machine has typed on the right. I understand the undercut head because in Mech Engr education class time is spent on “Stress Concentration Analysis”. I now am wondering about whether the six cut marks on the upper head surface are “cosmetic” just for human eyes to see or are functional in that they affect either stress concentration or act similar to “toothed lock washers.”
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