Topics

Matco Brake Maintenance


Keith Spreuer
 

David mentioned what a bear the Matco's are to change the pads. They have come out with some items that really help that. First the Nordlock washers on both the 3 disc bolts and the 4 bolts to the caliper. This eliminates the safety wiring altogether which was one of the biggest pains. The other change is to replace the 4 center bushing (on those same 4 bolts) with a single scalloped spacer. Trying to get all that stuff lined up and bolts stared with just 2 hands was really a juggling act. It still is a handful but with the spacer it's much better. The other trick I learned is assemble the caliper and pads with the spacer and 4 bolts before the 2 outside bolts that go all the way thru the caliper are installed. You put the disc up around the axle without those two outside bolts, then start the 4 inside bolts and spacer but leave them slightly loose. That way the two outside bolts and their bushing can fit between the fixed lining plate and the caliper. Then the assembly is completed by inserting the 2 outside bolts and tightening all bolts. Still more difficult than Cleveland but a real improvement.

Keith


Joel Ventura
 

Sometime ago I read about a problem with the Nordlock washers failing to secure the bolts on the Matco brakes.  Does anyone have any more information about what the problem was there?  That is the only Nordlock failure I have heard about.  I am especially interested because I want to experiment with using Nordlocks to secure the propbolts rather than safety wire, and a failure there could be much more significant. 
--Joel  


On Wed, May 27, 2020 at 3:47 PM Keith Spreuer <kspreuer@...> wrote:
David mentioned what a bear the Matco's are to change the pads. They have come out with some items that really help that. First the Nordlock washers on both the 3 disc bolts and the 4 bolts to the caliper. This eliminates the safety wiring altogether which was one of the biggest pains. The other change is to replace the 4 center bushing (on those same 4 bolts) with a single scalloped spacer. Trying to get all that stuff lined up and bolts stared with just 2 hands was really a juggling act. It still is a handful but with the spacer it's much better. The other trick I learned is assemble the caliper and pads with the spacer and 4 bolts before the 2 outside bolts that go all the way thru the caliper are installed. You put the disc up around the axle without those two outside bolts, then start the 4 inside bolts and spacer but leave them slightly loose. That way the two outside bolts and their bushing can fit between the fixed lining plate and the caliper. Then the assembly is completed by inserting the 2 outside bolts and tightening all bolts. Still more difficult than Cleveland but a real improvement.

Keith


Keith Spreuer
 

I would not use the for prop bolts. Issue there is expansion and shrink in would not slippage of the bolts


On Wed, May 27, 2020, 4:54 PM Joel Ventura <ventura@...> wrote:
Sometime ago I read about a problem with the Nordlock washers failing to secure the bolts on the Matco brakes.  Does anyone have any more information about what the problem was there?  That is the only Nordlock failure I have heard about.  I am especially interested because I want to experiment with using Nordlocks to secure the propbolts rather than safety wire, and a failure there could be much more significant. 
--Joel  

On Wed, May 27, 2020 at 3:47 PM Keith Spreuer <kspreuer@...> wrote:
David mentioned what a bear the Matco's are to change the pads. They have come out with some items that really help that. First the Nordlock washers on both the 3 disc bolts and the 4 bolts to the caliper. This eliminates the safety wiring altogether which was one of the biggest pains. The other change is to replace the 4 center bushing (on those same 4 bolts) with a single scalloped spacer. Trying to get all that stuff lined up and bolts stared with just 2 hands was really a juggling act. It still is a handful but with the spacer it's much better. The other trick I learned is assemble the caliper and pads with the spacer and 4 bolts before the 2 outside bolts that go all the way thru the caliper are installed. You put the disc up around the axle without those two outside bolts, then start the 4 inside bolts and spacer but leave them slightly loose. That way the two outside bolts and their bushing can fit between the fixed lining plate and the caliper. Then the assembly is completed by inserting the 2 outside bolts and tightening all bolts. Still more difficult than Cleveland but a real improvement.

Keith


Marc J. Zeitlin
 

Joel Ventura wrote:

I am especially interested because I want to experiment with using Nordlocks to secure the propbolts rather than safety wire, and a failure there could be much more significant.

Nordlock washers might be useful for prop bolts without bellevilles or underlying flat washers, and in those cases would fulfill the same function as the safety wire. But the issue with prop bolts on wood propellers is not that they unscrew themselves - it's that the wood shrinks out from under the compression of the bolts and you lose friction on the drive face. This is the whole reason for using belleville washers - to accommodate the shrinkage and expansion of the wood prop hub and still maintain compression and associated friction. So if you DON'T use Bellevilles, then nordlocks may be reasonable to replace safety wire. However...

Safety wire and nordlocks only prevent rotation, and only if the underlying substrate cannot rotate, and we've already established that bolt rotation is not the main danger with prop bolts on a wood prop.

Now, assuming that you are using bellevilles to both increase safety margin for drive friction loss and reduce maintenance requirements (as well as comply with the recommendations of two of the most respected propeller manufacturers - Craig Catto and Gary Hertzler, whatever you think of my recoomendations for them) then nordlocks are contraindicated.

The nordlock works by pressing against the lower surface of the head of the bolt and the fixed non-rotating substrate under it - the friction against these two surfaces, along with the angle of the ramps on the intermediate nordlock face is what causes it to get TIGHTER as the bolt attempts to unscrew. If the lower surface of the nordlock is pressing on a surface that CAN rotate (a belleville washer, say), then it will rotate with the bolt and be nothing more than a flat washer. This is useless and accomplishes nothing. As much as safety wire is a PITA, in this special case (prop bolts with bellevilles), it's the right answer.

While I wish that we could use nordlocks with bellevilles, as I believe that bellevilles add a substantial amount of safety margin as well as substantial reductions in maintenance requirements, and _IF_ nordlocks could be used, they would add another layer of reduced maintenance requirements (much easier to check torque without having to remove the SW), I think that safety would be reduced by using nordlocks with bellevilles rather than safety wire with bellevilles.

However, since with bellevilles, we only need to check the prop bolt torque once/year, at the CI, rather than every 10 or 25 hours, or four times per year at the change of seasons, the reduction in maintenance needs is already a large positive factor, and well worth the installation even if it prevents the use of nordlocks to replace the safety wire.

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2020                     Burnside Aerospace


David K
 

Marc,
    I don’t know if there’s enough compliance for the shrinkage, but Nordloc does make a spring type called X-series. It’s does not contain the amount of deflection that Belleville’s do but does give two levels of force retention. 

On May 27, 2020, at 5:41 PM, Marc J. Zeitlin <marc.j.zeitlin@...> wrote:

Joel Ventura wrote:

I am especially interested because I want to experiment with using Nordlocks to secure the propbolts rather than safety wire, and a failure there could be much more significant.

Nordlock washers might be useful for prop bolts without bellevilles or underlying flat washers, and in those cases would fulfill the same function as the safety wire. But the issue with prop bolts on wood propellers is not that they unscrew themselves - it's that the wood shrinks out from under the compression of the bolts and you lose friction on the drive face. This is the whole reason for using belleville washers - to accommodate the shrinkage and expansion of the wood prop hub and still maintain compression and associated friction. So if you DON'T use Bellevilles, then nordlocks may be reasonable to replace safety wire. However...

Safety wire and nordlocks only prevent rotation, and only if the underlying substrate cannot rotate, and we've already established that bolt rotation is not the main danger with prop bolts on a wood prop.

Now, assuming that you are using bellevilles to both increase safety margin for drive friction loss and reduce maintenance requirements (as well as comply with the recommendations of two of the most respected propeller manufacturers - Craig Catto and Gary Hertzler, whatever you think of my recoomendations for them) then nordlocks are contraindicated.

The nordlock works by pressing against the lower surface of the head of the bolt and the fixed non-rotating substrate under it - the friction against these two surfaces, along with the angle of the ramps on the intermediate nordlock face is what causes it to get TIGHTER as the bolt attempts to unscrew. If the lower surface of the nordlock is pressing on a surface that CAN rotate (a belleville washer, say), then it will rotate with the bolt and be nothing more than a flat washer. This is useless and accomplishes nothing. As much as safety wire is a PITA, in this special case (prop bolts with bellevilles), it's the right answer.

While I wish that we could use nordlocks with bellevilles, as I believe that bellevilles add a substantial amount of safety margin as well as substantial reductions in maintenance requirements, and _IF_ nordlocks could be used, they would add another layer of reduced maintenance requirements (much easier to check torque without having to remove the SW), I think that safety would be reduced by using nordlocks with bellevilles rather than safety wire with bellevilles.

However, since with bellevilles, we only need to check the prop bolt torque once/year, at the CI, rather than every 10 or 25 hours, or four times per year at the change of seasons, the reduction in maintenance needs is already a large positive factor, and well worth the installation even if it prevents the use of nordlocks to replace the safety wire.

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2020                     Burnside Aerospace


Marc J. Zeitlin
 

David Kissick wrote:
 
  I don’t know if there’s enough compliance for the shrinkage, but Nordloc does make a spring type called X-series. It’s does not contain the amount of deflection that Belleville’s do but does give two levels of force retention. 

Yeah, we've discussed these before, I believe.

The IDEA is perfect. A combination of nordlocks and bellevilles, with appropriate deflection and force capabilities would be great. But as an engineered system, you can't just throw anything on the prop bolts and expect them to work correctly. These are short on both force and deflection, due to their low thickness and diameter. So, not yet, anyway.

Maybe if I get some free time, I'll propose a custom design to them and see what the volume requirements would be to get them to fabricate a lot...

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2020                     Burnside Aerospace


skybob8
 

Question if I may, can the "Nordloc" washers be used over and over again or should the be replaced after a few cycles on and off?

On Wednesday, May 27, 2020, 11:51:30 PM EDT, David K via groups.io <geckoinc99@...> wrote:


Marc,
    I don’t know if there’s enough compliance for the shrinkage, but Nordloc does make a spring type called X-series. It’s does not contain the amount of deflection that Belleville’s do but does give two levels of force retention. 

https://www.nord-lock.com/nord-lock/products/x-series-washers/

David Kissick


On May 27, 2020, at 5:41 PM, Marc J. Zeitlin <marc.j.zeitlin@...> wrote:

Joel Ventura wrote:

I am especially interested because I want to experiment with using Nordlocks to secure the propbolts rather than safety wire, and a failure there could be much more significant.

Nordlock washers might be useful for prop bolts without bellevilles or underlying flat washers, and in those cases would fulfill the same function as the safety wire. But the issue with prop bolts on wood propellers is not that they unscrew themselves - it's that the wood shrinks out from under the compression of the bolts and you lose friction on the drive face. This is the whole reason for using belleville washers - to accommodate the shrinkage and expansion of the wood prop hub and still maintain compression and associated friction. So if you DON'T use Bellevilles, then nordlocks may be reasonable to replace safety wire. However...

Safety wire and nordlocks only prevent rotation, and only if the underlying substrate cannot rotate, and we've already established that bolt rotation is not the main danger with prop bolts on a wood prop.

Now, assuming that you are using bellevilles to both increase safety margin for drive friction loss and reduce maintenance requirements (as well as comply with the recommendations of two of the most respected propeller manufacturers - Craig Catto and Gary Hertzler, whatever you think of my recoomendations for them) then nordlocks are contraindicated.

The nordlock works by pressing against the lower surface of the head of the bolt and the fixed non-rotating substrate under it - the friction against these two surfaces, along with the angle of the ramps on the intermediate nordlock face is what causes it to get TIGHTER as the bolt attempts to unscrew. If the lower surface of the nordlock is pressing on a surface that CAN rotate (a belleville washer, say), then it will rotate with the bolt and be nothing more than a flat washer. This is useless and accomplishes nothing. As much as safety wire is a PITA, in this special case (prop bolts with bellevilles), it's the right answer.

While I wish that we could use nordlocks with bellevilles, as I believe that bellevilles add a substantial amount of safety margin as well as substantial reductions in maintenance requirements, and _IF_ nordlocks could be used, they would add another layer of reduced maintenance requirements (much easier to check torque without having to remove the SW), I think that safety would be reduced by using nordlocks with bellevilles rather than safety wire with bellevilles.

However, since with bellevilles, we only need to check the prop bolt torque once/year, at the CI, rather than every 10 or 25 hours, or four times per year at the change of seasons, the reduction in maintenance needs is already a large positive factor, and well worth the installation even if it prevents the use of nordlocks to replace the safety wire.

--
Marc J. Zeitlin                      marc_zeitlin@...
                                            http://www.cozybuilders.org/
Copyright © 2020                     Burnside Aerospace