loose rivets

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waymon85

loose rivets

#1

Post by waymon85 » Wed Mar 26, 2008 1:11 pm

I was adjusting the chain on my 65 this morning and noticed that the sprocket wasnt tight against drum (AGAIN). This seems to happen way to often and I dont even want to think about what would happen if it let go. Is it a good idea and or acceptable to just go with bolts and nuts? If it is, what size and grade of bolt should I use. Thanks Wick



fourthgear
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#2

Post by fourthgear » Wed Mar 26, 2008 1:32 pm

If the holes for the rivets in the drum are over sized or just out of spec's , new rivets will not last long. Even if you think the assembly is tight , the rivets need a snug fit in the drum and sprocket. I have seen the holes in drum/sprocket in a slight oblong state and in that condition , they don't hold up. Also look for cracks , very small ones. Finding a good NOS/OEM replacement my be difficult. As far as repairing it , others may know a proper way to do that here .

Cotten
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#3

Post by Cotten » Wed Mar 26, 2008 2:01 pm

The clearance between the backing plate and the drum will not allow for anything but a well-pressed rivet to fit.

Rivets that have been peened instead of pressed often do not swell to occupy the eccentricities of worn holes.
Although it looks cheesy, a lot of drums are drilled with the sprocket rotated a few degrees for a fresh start. It would still be safer than some horrible repops.

....Cotten

57pan
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Re: loose rivets

#4

Post by 57pan » Wed Mar 26, 2008 6:26 pm

waymon85 wrote:I was adjusting the chain on my 65 this morning and noticed that the sprocket wasnt tight against drum (AGAIN). This seems to happen way to often and I dont even want to think about what would happen if it let go. Is it a good idea and or acceptable to just go with bolts and nuts? If it is, what size and grade of bolt should I use. Thanks Wick
I can tell you from experience exactly what will happen when the rivits all let go - you let the clutch out and don't go anywhere :?

As others have said - if you don't have the right equipment to smush the rivit enough to expand and completely fill the hole it will very quickly work loose again. (also learned by experience).

I just drilled out the holes slightly and put screws and nuts in instead of rivits. I think they are about #8 stainless socket head cap screws with nyloc nuts.

john HD
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#5

Post by john HD » Wed Mar 26, 2008 10:43 pm

and i would like to add:

cotten is correct, the repops are horrible!

john

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#6

Post by pandit » Wed Mar 26, 2008 11:20 pm

Cotten wrote:The clearance between the backing plate and the drum will not allow for anything but a well-pressed rivet to fit.

Rivets that have been peened instead of pressed often do not swell to occupy the eccentricities of worn holes.
Although it looks cheesy, a lot of drums are drilled with the sprocket rotated a few degrees for a fresh start. It would still be safer than some horrible repops.

....Cotten
There is place for nut and bolt.

Pandit

justdave
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#7

Post by justdave » Thu Mar 27, 2008 1:31 pm

Can anyone show me what kind of tool you use to get the rivets to seat properly without cracking. DaveZ

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#8

Post by Cotten » Fri Mar 28, 2008 1:54 am

Pandit!

Where's the room for a bolt head or nut in the first pic?
The backing plate will hit even riviets if they are not pressed enough.
That's a post '58 assembly of course.

The second pic shows both sides of a mechanical drum, and as you can see, there isn't room on either side, without eliminating the dust ring, and severely compromising the flange.

It should be clear why the Factory used ~3/16" rivets.

....Cotten
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#9

Post by Cotten » Fri Mar 28, 2008 2:06 am

JustDave!

Here's a pic of a 'home-made' press anvil for riveting sprockets; It is very much like the Factory tool in that it has a means of holding the drum down at its center.

The punch on the press ram is a sawn-off motor valve with the stem cut concave on the end. It is held to the ram with a stupidglide fork boot.
The supporting pedestal under the rivet also has a concave dimple in it to accept the rivet head.


....Cotten
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Guest

#10

Post by Guest » Fri Mar 28, 2008 4:19 am

57pan beat me to it, you just don't go. the sprocket spins on and on. i made it home after this happened to me by using nails i got at a farm house and bending them over with a hammer as tightly as i could to hold the sprocket. j

wick5

#11

Post by wick5 » Fri Mar 28, 2008 5:17 am

I did manage to get four 3/16 button head bolts through the sprocket and drum and tighten them down with nylon locking nuts (button head on the anchor plate side). Beat the hell out of the rivets that were left.The drum and srocket doesnt ride against the brake shoe anchor plate on my 65. I dont see how it could with the plate being statoinary and the drum rotating.There is a gap of about 3/16 between the two. The wheel spins freely with this set up and there is still about 1/16 to spare. I will replace all the rivets with bolts if this works long term.

Cotten
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#12

Post by Cotten » Fri Mar 28, 2008 12:13 pm

Wick5!

If you have 3/16" of an inch clearance between the backing plate and the sprocket, Don't ride on gravel!
Sounds like a parts mismatch or a spacing concern.

....Cotten
PS: Most folks call a 3/16" fastener a #12 screw. Unless they were shanked exactly the same as the thickness of the flange and sprocket, the threads will either mush, or tear their way deeper.

1964 pan
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#13

Post by 1964 pan » Fri Mar 28, 2008 1:23 pm

I fasten the sprocket with #12 slotted panhead machine screws and self locking nuts. Never had a problem and sure is alot easier than rivets. Unless some one is going all original. Why hassle with the rivets? With no more horse power than our stock pans put out , sorry but its true, there is no way to shear 20 screws. Is there?

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#14

Post by FlatHeadSix » Fri Mar 28, 2008 3:15 pm

Never say never 64Pan!

Every time I start thinking that there is no way something will happen, "the way" will reveal itself and usually at the worst possible time or place.

mike

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#15

Post by FlatHeadSix » Fri Mar 28, 2008 3:23 pm

Cotten,

Have you got a pic of an end view of your punch? How much did you dish the valve stem? What did you use?, a round stone on a dremmel? Has the ram held up pretty good or have had to refresh the concave surface occasionally?

I've got a drawer full of old valves, I'm making one of those this weekend!

mike

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