Drum/Back-Plate Interference?

LSolheim

Member
Putting things back together after the early spring/post winter maintenance and ran into something unexpected.

The RR drum seemed to go on OK, but as I tightened the drum attachment screws I felt rotational interference. At first I expected brake shoe interference, but that doesn't seem to be the case. She rotates OK with the screws loosened, but tightens up when the screws are tightened. Once the wheel is attached @ 87ft-lb things do not improve.

Went for a short test drive to see if it would fall into place, but the drum heated up unacceptably.

I don't recall this from last year. Certainly the axle couldn't have moved or be too far to the inside or it wouldn't fit properly into the tranny.

Any ideas out there?

Thanks,
--Larry
 

Ken Chambers

Platinum Subscriber
Brake shoes rubbing? Chalk may help to see where shoe is contacting.
Assemble without shoes to test.
Bent backing plate or plate not seated properly on swing arm, drum
contacting backing plate.
Loose backing plate, loose wheel cylinder, defective cylinder piston
end so brake shoe doesn't locate in center.
Axle castle nut tight for proper compression of disc washers.
Drum seats on hub and wheel seats on drum without any improper
deflection or interference.
Was the hub disassembled? Proper stack-up of spacers, disc washers,
bearings and locking rings?

Good luck Larry. Let us know what you find.

Ken Chambers, CA
'64 Red


On Mar 22, 2008, at 6:08 PM, LSolheim wrote:


> Putting things back together after the early spring/post winter
> maintenance and ran into something unexpected.
>
> The RR drum seemed to go on OK, but as I tightened the drum
> attachment screws I felt rotational interference. At first I
> expected brake shoe interference, but that doesn't seem to be the
> case. She rotates OK with the screws loosened, but tightens up when
> the screws are tightened. Once the wheel is attached @ 87ft-lb
> things do not improve.
>
> Went for a short test drive to see if it would fall into place, but
> the drum heated up unacceptably.
>
> I don't recall this from last year. Certainly the axle couldn't have
> moved or be too far to the inside or it wouldn't fit properly into
> the tranny.
>
> Any ideas out there?
>
> Thanks,
> --Larry
>
>
 

LSolheim

Member
Thanks for the prompt responses, Ken & Dave.

Checking the records, I replaced the bearings in 2005 and certainly don't
recall having this happen last 2 years.

Taking the wheel & drum back off this AM, I MIGHT be seeing a mark at the
very outer edge of the inside of the drum (hard to tell), but I don't see a
comparative mark on the edge of the shoe. No actual shiny spots anywhere.

Since everything turns freely with the 3 screws loose I figure it must be a
tolerance stack somewhere. Certainly not a lining/drum issue (adjustment or
emergency brake). I'll try some chalk on the outside edges of the shoes and
inside edges of the drum. Brake springs are relatively new (2005) - no
bends or defects.

--Larry
-----Original Message-----
From: Ken Chambers [mailto:]
Sent: Saturday, March 22, 2008 9:08 PM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-19910] Drum/Back-Plate
Interference?


Brake shoes rubbing? Chalk may help to see where shoe is contacting.
Assemble without shoes to test.
Bent backing plate or plate not seated properly on swing arm, drum
contacting backing plate.
Loose backing plate, loose wheel cylinder, defective cylinder piston
end so brake shoe doesn't locate in center.
Axle castle nut tight for proper compression of disc washers.
Drum seats on hub and wheel seats on drum without any improper
deflection or interference.
Was the hub disassembled? Proper stack-up of spacers, disc washers,
bearings and locking rings?

Good luck Larry. Let us know what you find.

Ken Chambers, CA
'64 Red


On Mar 22, 2008, at 6:08 PM, LSolheim wrote:



Quote:
> Putting things back together after the early spring/post winter
> maintenance and ran into something unexpected.
>
> The RR drum seemed to go on OK, but as I tightened the drum
> attachment screws I felt rotational interference. At first I
> expected brake shoe interference, but that doesn't seem to be the
> case. She rotates OK with the screws loosened, but tightens up
when
> the screws are tightened. Once the wheel is attached @ 87ft-lb
> things do not improve.
>
> Went for a short test drive to see if it would fall into place,
but
> the drum heated up unacceptably.
>
> I don't recall this from last year. Certainly the axle couldn't
have
> moved or be too far to the inside or it wouldn't fit properly into
> the tranny.
>
> Any ideas out there?
>
> Thanks,
> --Larry
>
>
 

LSolheim

Member
I guess the chalk doesn't lie . . . hard to believe, but it looks as if
it is the bottom end of the rear shoe dragging. Why only when the drum is
tightened, I don't know.

Guess it's time for the biennial cleaning/honing of the cylinders. Does
anyone have a good source for silicone fluid, brake resistant grease
(although the fluid should not actually "see" the grease)?

--Larry


-----Original Message-----
From: Ken Chambers [mailto:]
Sent: Saturday, March 22, 2008 9:08 PM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-19910] Drum/Back-Plate
Interference?


Brake shoes rubbing? Chalk may help to see where shoe is contacting.
Assemble without shoes to test.
Bent backing plate or plate not seated properly on swing arm, drum
contacting backing plate.
Loose backing plate, loose wheel cylinder, defective cylinder piston
end so brake shoe doesn't locate in center.
Axle castle nut tight for proper compression of disc washers.
Drum seats on hub and wheel seats on drum without any improper
deflection or interference.
Was the hub disassembled? Proper stack-up of spacers, disc washers,
bearings and locking rings?

Good luck Larry. Let us know what you find.

Ken Chambers, CA
'64 Red


On Mar 22, 2008, at 6:08 PM, LSolheim wrote:



Quote:
> Putting things back together after the early spring/post winter
> maintenance and ran into something unexpected.
>
> The RR drum seemed to go on OK, but as I tightened the drum
> attachment screws I felt rotational interference. At first I
> expected brake shoe interference, but that doesn't seem to be the
> case. She rotates OK with the screws loosened, but tightens up
when
> the screws are tightened. Once the wheel is attached @ 87ft-lb
> things do not improve.
>
> Went for a short test drive to see if it would fall into place,
but
> the drum heated up unacceptably.
>
> I don't recall this from last year. Certainly the axle couldn't
have
> moved or be too far to the inside or it wouldn't fit properly into
> the tranny.
>
> Any ideas out there?
>
> Thanks,
> --Larry
>
>
 

Ken Chambers

Platinum Subscriber
Larry,

Permatex Ultra Disc Brake Caliper Lube is what you're looking for.

http://www.permatex.com/products/Automotive/lubricants/specialty_lubricants/auto_Permatex_Ultra_Disc_Brake_Caliper_Lube_1.htm

Water and corrosion resistant and compatible with rubber. Pack the
dust caps full of it to keep water away from the pistons.


---Ken Chambers



>
> Guess it's time for the biennial cleaning/honing of the cylinders.
> Does
> anyone have a good source for silicone fluid, brake resistant grease
 

LSolheim

Member
Thanks, Ken. I had also found a listing for CRC Synthetic Brake & Caliper
Grease at Kragen, Schucks, etc.

-----Original Message-----
From: Ken Chambers [mailto:]
Sent: Monday, March 24, 2008 8:49 AM
To: lrsnpark@gmail.com
Subject: RE: [General Amphicar Discussion-t-19910] Drum/Back-Plate
Interference?


Larry,

Permatex Ultra Disc Brake Caliper Lube is what you're looking for.

http://www.permatex.com/products/Aut...per_Lube_1.htm

Water and corrosion resistant and compatible with rubber. Pack the
dust caps full of it to keep water away from the pistons.


---Ken Chambers




Quote:
>
> Guess it's time for the biennial cleaning/honing of the cylinders.
> Does
> anyone have a good source for silicone fluid, brake resistant
grease
 
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