Correct pressure plate bolts

4x4M38 · Post by **4x4M38** » Fri Sep 29, 2017 11:10 am

Ok.
My bolts are takeouts.

They are 5/16NC x 1-1/16" with a 3/8" long shoulder.

I just received a package of new bolts from one of our suppliers.

They are 5/16NC x 7/8" with a 3/16" long shoulder.

The manuals show WO-630129 matches my takeouts.

Has anyone else run into this discrepancy?
Do I send these back and try and order Ford 1" long sccews?

What a mess. I may never get this thing back together....

4x4M38 · Post by **4x4M38** » Fri Sep 29, 2017 11:56 am

Well crap.

http://www.speedwaymotors.com/ARP-Faste ... ,7305.html

Same length bolt as the new ones, just a longer shoulder.

4x4M38 · Post by **4x4M38** » Fri Sep 29, 2017 12:29 pm

As I understand it a bolt length is measured from under the head to
the end of the threads.

The factory WO-630129 was 1-1/16" under the head.

The current replacement is 5/16" shorter, with a shorter shoulder.
By the time you install the lockwasher you have very little shoulder left.

Is this what everyone is iinstalling and are okay with it?

Post by **wesk** » Fri Sep 29, 2017 12:54 pm

Shank left with washer on the bolt is not the important issue. The most important issue is overall length. You have a required engagement length of the threads that must be met. It must engage all the threads in the flywheel.This should be the main driving force in your search. Grip length, if a consideration, will equal the combined un-threaded thickness of the parts that will be joined. You will be best off with grade 8 bolts of the proper dimensions with at least a rating of -2 on close dimensional tolerance.

4x4M38 · Post by **4x4M38** » Fri Sep 29, 2017 1:21 pm

I agree with all of that Wes.

The unthreaded shank provides centering of the pressure
plate to some extent, right? I know the alignment tool does
the heavy lifting.

The bolts received are grade 8. Just 5/16" short and a shorter
unthreaded portion. Is that called a shoulder?

4x4M38 · Post by **4x4M38** » Fri Sep 29, 2017 8:45 pm

So,
The Ord 9 G503 shows all the same numbers
as the G740, with the addition of a Ford part number.

Length is 1-1/4" as opposed to the 1-1/16" listed
in both the Ord 9 G740 and Ord 9 G758.

No superseded parts or dimensions other than the
1-1/4" to 1-1/16" from 1946 through the 1955 G740
and the G758 shown on our website.

Does anyone know if the dimension was reduced
further to .77 and have the documentation?

Thanks,

Post by **wesk** » Fri Sep 29, 2017 9:07 pm

What you are calling a shoulder is the grip length. The threads must still use all the threads in the hole. The tolerance -2 I mentioned insures the shank fits the hole in the pressure plate snugly.

4x4M38 · Post by **4x4M38** » Fri Sep 29, 2017 9:21 pm

So the grip length is the unthreaded portion between the head and
the threaded portion?

I understand about using all of the threads in the flywheel.

How can they go from a 1-1/4" to 3/4" long bolt and still use
all the threads in the flywheel?

I don't understand that.

Post by **wesk** » Fri Sep 29, 2017 9:45 pm

How can they go from a 1-1/4" to 3/4" long bolt and still use
all the threads in the flywheel?

Obviously they screwed up on the new bolt selection they are selling you.

This is one of those issues you simply do the math yourself and buy what the math dictates. I don't have a flywheel and pressure plate sitting here tonight but I can explain what needs to be done:

1-measure the depth of the threaded portion of the hole in the flywheel.
This will dictate the threaded length of your new bolt.
2- with the press plate tight against the flywheel use a depth gauge to determine the distance from the top edge of the pressure plate to the beginning of the first thread in the flywheel. Add to that distance the measured thickness of your lock washer.
This will dictate the maximum length of shank or grip length you need.
3-Select a grade 8 bolt with a -2 dimension tolerance and buy them.

4x4M38 · Post by **4x4M38** » Sat Sep 30, 2017 5:38 am

I will do that Wes.

I have a brand new clutch housing as well as an Auburn takeoff.
I also have an unmounted 124 tooth flywheel.

I do not have a depth gauge but will do the best I can.

At minimum, I'll assemble the two and try the two bolts I have
and see what is or is not protruding from the back.

Or what is not making it all the way through.

Thanks,

Post by **wesk** » Sat Sep 30, 2017 10:50 am

We all have a depth gauge!

You take anything even a 12 penny nail can be a depth gauge. You stick it in the hole and draw a line on it then take it out of the hole and measure the tip to your line with a ruler.

The most important dimension will be the shank / grip length. It must NOT hit the threads in the flywheel. With the lock washer installed and tightened flat the shank must end in the pressure plate housing and not in the flywheel hole. If you do make sure of this the shank can bottom out against the first threads in the flywheel and give you a false sense of torque.

Dial calip can use it's tail rod as a depth gauge,

Depth Micrometer is mad for the job

Standard micrometer. Not much use in measuring depth.

Kendall · Post by **Kendall** » Sat Sep 30, 2017 5:07 pm

"I do not have a depth gauge but will do the best I can."
Do you not have a micrometer? I had overlooked the depth gauge of a micrometer until working with a machinist on another project. The "tail" portion of the micrometer is your depth gauge (depending upon the type of micrometer you are using).
Kendall

4x4M38 · Post by **4x4M38** » Sat Sep 30, 2017 6:05 pm

Oh, for crying out loud.

Duh.

Thanks Kendall.

GPA · Post by **GPA** » Sun Oct 01, 2017 2:18 pm

Kendall wrote:"I do not have a depth gauge but will do the best I can."
Do you not have a micrometer? I had overlooked the depth gauge of a micrometer until working with a machinist on another project. The "tail" portion of the micrometer is your depth gauge (depending upon the type of micrometer you are using).
Kendall

There are micrometers made to measure depth, but the ordinary micrometer is not one of them.
The tool with the "tail portion" to measure depth is called a slide caliper.

4x4M38 · Post by **4x4M38** » Tue Oct 03, 2017 8:38 am

Going out to do a little measuring what I have.

I have reached out to the various suppliers for their dimensions.

Just a thought, but I'm beginning to think replacement screws/bolts were
developed with a 1-1/16" overall length instead of under the head length.

We'll see where the queries take us.