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09-02-2011, 10:21 AM | #1 |
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pressure plate bolt size?
I searched around but came up dry. What is the bolt size for bolting a pressure plate to a 1950 flywheel? I believe it is the long style pressure plate with the 3 pairs of holes.
Thanks, Don |
09-02-2011, 11:26 AM | #2 |
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Re: pressure plate bolt size?
Go to a speed shop; one of the big speed equipment companies like Mr Gasket or Moroso sells them packaged for '60's small block Ford.
book says 5/16-18 x25/64 |
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09-02-2011, 12:10 PM | #3 |
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Re: pressure plate bolt size?
Long style is 5/16 as above. Borg & Beck types for Mercs are 3/8" and they are special shoulder types.
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09-02-2011, 01:26 PM | #4 |
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Re: pressure plate bolt size?
Thanks Guys. I want to pick them up at a local bolt place but wanted to make sure of the size. I want to get things put together this weekend and have all bolts but those.
The original engine seems to have lost a seal last weekend. BIG puddle of oil under the old girl. I guess that was the last drive until I get the new chassis assembled. |
09-02-2011, 02:09 PM | #5 |
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Re: pressure plate bolt size?
The pressure plate clamping bolts are not something you can find at the average bolt store. The earlier suggestion about buying the special bolts supplied by your local Speed Shop was on target.
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09-02-2011, 05:20 PM | #6 |
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Re: pressure plate bolt size?
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torque them properly. Ended up with a new pressure plate and replacement flywheel. Correct bolts are the only way to go in this instance. |
09-02-2011, 05:29 PM | #7 |
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Re: pressure plate bolt size?
I found some Grade 8 bolts of that size. Called the local "Speed Shop" and they said they had some bins of bolts to look through - LOL
Last edited by 37slantback; 09-02-2011 at 05:54 PM. |
09-03-2011, 08:39 AM | #8 |
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Re: pressure plate bolt size?
I had made this suggestion in a previous post (without pic's)
The 3/8"-16 x 3/4" is what the Merc. manual calls for. (suspect same method could be used for Ford bolts) The result is virtually a duplicate of original. Last edited by 51 MERC-CT; 09-03-2011 at 09:44 AM. |
09-03-2011, 09:21 AM | #9 |
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Re: pressure plate bolt size?
See Bruce's answer for the Ford bolt.
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09-03-2011, 09:52 AM | #10 |
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Re: pressure plate bolt size?
Don't spend time cutting and making bolts fit just buy them .
http://www.google.com/#q=pressure+pl...w=1024&bih=623 R |
09-03-2011, 09:52 AM | #11 |
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Re: pressure plate bolt size?
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09-03-2011, 12:29 PM | #12 |
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Re: pressure plate bolt size?
You really MUST use the correct bolts, as mentioned above in few replies, using the incorrect pieces will result in a "vibration" in the flywheel/clutch area!
We see this while balancing the flywheel and cover ass'y, if the "shoulder's" aren't there and the cover isn't centered, it throws off the entire balance! Thanks, Gary in N.Y. P.S. Below is a shot of both sizes. We choose to not use any locking washers, it's one area we use "Loc-tite". Years ago we started drilling all the assemblies for 3/8" only bolts. Not a real big deal, and one specific customer specializing in the Flatheads wanted them done this way!! |
09-03-2011, 02:41 PM | #13 | |
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Re: pressure plate bolt size?
Quote:
not 25/64" R Last edited by Ronnie; 09-03-2011 at 07:20 PM. |
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09-03-2011, 03:02 PM | #14 | |
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Re: pressure plate bolt size?
Quote:
part # 350433-s c&g ford parts shows them ( costly) https://secure435.hostgator.com/~dlv...12&g=90&t=5810 |
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09-03-2011, 03:03 PM | #15 |
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Re: pressure plate bolt size?
It also shows using a lockwasher..
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09-03-2011, 03:43 PM | #16 | |
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Re: pressure plate bolt size?
Quote:
Costly for the 6 correct bolts?? Any idea what it would cost if the Pressure plate came loose?? Thats a hand gernade if it ever sheared off cheap ass bolts. |
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09-03-2011, 04:46 PM | #17 |
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Re: pressure plate bolt size?
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09-03-2011, 05:30 PM | #18 |
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Re: pressure plate bolt size?
I'm wondering if Roy Nacewicz has them? I gathered up two sets (12 bolts) of nice originals that I had with my collection of flathead engines and sent them to a fordbarner in New England. I can't spare any more but maybe one of the several engine gurus who post here would have some extras they could send you.
__________________
John "Never give up on what you really want to do. The person with big dreams is more powerful than one with all the facts". Albert Einstein |
09-03-2011, 05:36 PM | #19 |
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Re: pressure plate bolt size?
Nice avatar, John.
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09-03-2011, 05:46 PM | #20 |
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Re: pressure plate bolt size?
I've bought the correct bolts from Roy Nacewicz and from "Flathead Jack" Schaffer.
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09-04-2011, 06:39 PM | #21 |
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Re: pressure plate bolt size?
I think both you and Bruce are right about the size, I measured an original Ford bolt and came up with a measurement of 0.780". That is the shaft length not the shaft and cap length. The Ford book I have shows 25/64" or 0.390". I belive the 0.390" is only the threaded portion of the shaft. The balance is the shoulder length below the cap.
Hopefully this makes sense! Tom |
09-07-2011, 09:51 AM | #22 |
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Re: pressure plate bolt size?
On the need for shoulder...these bolts have to locate the PP as well as clamp it on, hence the need so that the bolts can also function as dowels to get the thing in the right place. Obviously they are highly stressed items with really bad potential failure modes, so buy something made for the purpose or a bolt from a serious supplier like an industrial supply.
Lines on bolt heads mean very little if bought at the corner dime store...there is no enforcement of SAE grade standards and the Chines have learned we like lines on our bolts! Originals are of course not lined...they predate that system, but Ford made very high standard fasteners. |
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09-07-2011, 10:24 AM | #23 |
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Re: pressure plate bolt size?
Has anyone used these bolts? they seem to be the right size. ARP has a good reputation for high quality bolts. I have always re-used the original Ford p plate bolts. just trying to help...
http://www.summitracing.com/parts/ARP-250-2201/ |
09-07-2011, 12:03 PM | #24 |
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Re: pressure plate bolt size?
[QUOTE=jdl;269480] I have always re-used the original Ford p plate bolts..../QUOTE]
The problem with using old rod, head, main cap and clutch/flywheel bolts, with no known history, is whether they were properly torqued when installed, and how many cycles they have gone through. Better safe than sorry on critical bolts, and ARP bolts are my first choice. IMO. |
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