note....
you should never use the handbrake or e brake after sessions on a course because if you heat the brakes up enough and then set the parking brake, you could easily warp the rotors.
always park it in gear after doing laps.
Show me your emergency / hand brake calipers
- Thread starter weisserheilbronn
- Start date
note....
you should never use the handbrake or e brake after sessions on a course because if you heat the brakes up enough and then set the parking brake, you could easily warp the rotors.
always park it in gear after doing laps.
my right rear parking brake came apart at 70mph on 2103, locking up the right rear hub. I had to get it towed home and Dennis Olthoff came and picked it up and repaired the damage. scary situation
If something fails which should never fail I don't want it anymore! Unfortunately this one of my peculiarity. Attached a few pictures about the problems I experienced....
Regards,
Markus
P.S. Thanks so far for all the responses, please keep going....
Attachments
the metal piece got wedged in my hub at 70mph, locking up the hub.
Hi Markus,
I had to study the pics for a few minutes to get a handle on what happened. Parking brake mechanisms are a big intrest to me as the early CAVs have boat anchors for parking brakes and I'm all about weight saving without weakening parts.
I have seriously considered using the PBR drum/internal shoe parking brake as used in the SPF GT40. It is an OEM component used on regular passenger cars. It should not fail.
Judging by the pics it appears the mount/lever assembly has let go from the upright casting. So the PBR part did not fail.
Since I have a box load of cracked cast or billet CAV uprights on hand I'm skeptical of aluminum or mag parts. Not to say they can't be done right, or that anything is wrong with the SPF upright. I'm sure the quality is top shelf.
The remedy will probably involve some sort of steel bracket spreading the load across the unused caliper mounts to support the PBR lever/mount for the parking brake. Easy to say without having one in the shop to study, but that would be my initial approach.
On the other hand, for the CAVs we've just released our first aluminum brackets for the aforementioned boat anchor parking brake, each one saves over 1lb meeting the objective as a retrofit part, it's also included on all new conversions.
Good luck with sorting out the parking brake, please let us know how it turns out.
Cheers
I had to study the pics for a few minutes to get a handle on what happened. Parking brake mechanisms are a big intrest to me as the early CAVs have boat anchors for parking brakes and I'm all about weight saving without weakening parts.
I have seriously considered using the PBR drum/internal shoe parking brake as used in the SPF GT40. It is an OEM component used on regular passenger cars. It should not fail.
Judging by the pics it appears the mount/lever assembly has let go from the upright casting. So the PBR part did not fail.
Since I have a box load of cracked cast or billet CAV uprights on hand I'm skeptical of aluminum or mag parts. Not to say they can't be done right, or that anything is wrong with the SPF upright. I'm sure the quality is top shelf.
The remedy will probably involve some sort of steel bracket spreading the load across the unused caliper mounts to support the PBR lever/mount for the parking brake. Easy to say without having one in the shop to study, but that would be my initial approach.
On the other hand, for the CAVs we've just released our first aluminum brackets for the aforementioned boat anchor parking brake, each one saves over 1lb meeting the objective as a retrofit part, it's also included on all new conversions.
Good luck with sorting out the parking brake, please let us know how it turns out.
Cheers
Last edited:
Jack Houpe
GT40s Supporter
Mine works great BUT yes it did loosen up and cause the left rear wheel to start to lock up. It was loose and the small drum would hang up while rotating. Lucky I was 1 block from my shop where I took it apart and found the problem of a missing screw and the other loose. Repaired and not a problem since but I can only imagine what would happen doing 150 in a race!
Jack,
Mine works great as well but, you have me concerned about possible failure and wheras I take it out regularly for drives 000's of miles from my shop I'd like to make sure I don't have a failure.
How about more specifics as to what happened, what to look for so I know what to inspect for.
Tx in advance for your response.
Steve P2125
Mine works great as well but, you have me concerned about possible failure and wheras I take it out regularly for drives 000's of miles from my shop I'd like to make sure I don't have a failure.
How about more specifics as to what happened, what to look for so I know what to inspect for.
Tx in advance for your response.
Steve P2125
Attached you find some pic’s of an rear upright (let's say left rear).
The threads in the red circle are for bolting on the PBR brake actuator. The threads in the green circle are for bolting on the disc brake caliper.
Afterwards it's always hard to tell what really happened.
I assume that the bolts became loose and the PBR brake actuator was wedged in-between the drum and the upright putting axial force (see witness marks on attached pic of PBR brake actuator) on the lower ear (pic of earlier post) and broke it off. Then the remaining upper bolt could not take the load and sheared off. Now the brake actuator was only held by the brake cable and the lever broke ……
So Ian, after looking to the upright I think it should be possible to add a metal plate.
But if my root cause analysis is correct a metal plate should not be necessary when I'm able to prevent axial load onto the mounting points (ears).
Therefore I will try to add mechanical calipers (bolting them to the bigger threads next to the red circles), not just to fix the issue also because I like the challenge and also the look.
Thanks for all replies so far and please add some information about your hand brake calipers.
Regards,
Markus
The threads in the red circle are for bolting on the PBR brake actuator. The threads in the green circle are for bolting on the disc brake caliper.
Afterwards it's always hard to tell what really happened.
I assume that the bolts became loose and the PBR brake actuator was wedged in-between the drum and the upright putting axial force (see witness marks on attached pic of PBR brake actuator) on the lower ear (pic of earlier post) and broke it off. Then the remaining upper bolt could not take the load and sheared off. Now the brake actuator was only held by the brake cable and the lever broke ……
So Ian, after looking to the upright I think it should be possible to add a metal plate.
But if my root cause analysis is correct a metal plate should not be necessary when I'm able to prevent axial load onto the mounting points (ears).
Therefore I will try to add mechanical calipers (bolting them to the bigger threads next to the red circles), not just to fix the issue also because I like the challenge and also the look.
Thanks for all replies so far and please add some information about your hand brake calipers.
Regards,
Markus
Attachments
Jack Houpe
GT40s Supporter
I went to take pictures of the two screws (back side of the screw) that are the problem and found that the other side is loose. They are philip head screws that hold the plate for the parking brake. Just as Markus has described. Here are some pictures. sorry for the road grime, I have not cleaned the car since RA. The picture with the small flat head is stuck between the plate and the main spindle upright. Look very closely at the first picture and you can see the head of the philips screw poking out from inside, it has to be a couple treads loose.
I think a good fix it to get longer screws and put nylocks on the back of them.
You are very welcome for the badges, it was an honor.
Attachments
Last edited:
Marcus/Jack,
Thanks!
Understood
Mine are tight but, food for thought. Wonder if problem resulted from emerg not properly adjusted and dragging (maby one side tighter than the other?). Or moving car with emerg engaged sressing the bolts? Ideas? Not withstanding good idea to either add a plate to the larger holes and or through bolt and nut with nylocks.
Steve P2125
Thanks!
Understood
Mine are tight but, food for thought. Wonder if problem resulted from emerg not properly adjusted and dragging (maby one side tighter than the other?). Or moving car with emerg engaged sressing the bolts? Ideas? Not withstanding good idea to either add a plate to the larger holes and or through bolt and nut with nylocks.
Steve P2125
Hi Markus, Jack, Steve, Yep I think you've got it. Thanks for the pics. Would a 12 gauge plate (0.110) cause interferance by moving the brake assembly out the same amount? Also the holes could be drilled out and helicoiled rather than trusting the threads in aluminum.
Longer bolts passing through and retained with nylocs on the inside surface would be fine if the baskside of the casting was machined flat. Any taper in the casting will cock the fastener, if you put a big enough thrust washer on to protect the casting and it's on a tilt you'll never get a correct torque setting. Hmmmmm...
A plate on the machined face side and helicoiled threads is starting to look pretty good.
The plate should be really tough like stainless steel. The plate decouples the parking break mechanism from the casting, protecting the casting from crush and working wear, larger bolts could be used and the helicoils are also protecting the casting. You'll get reliable torque settings, no more pull outs so long as the bolts come loose and permit the brake assembly to bind. A drop of blue locktite ought to do the trick.
What do you think? 1 Stainless Steel base plate, 2 bolts, blue threadlocker and specs for the helicoils to be fitted. A lot simpler than re-inventing the wheel, or in this case - the parking brake mechanism. Hope this helps. Cheers
Longer bolts passing through and retained with nylocs on the inside surface would be fine if the baskside of the casting was machined flat. Any taper in the casting will cock the fastener, if you put a big enough thrust washer on to protect the casting and it's on a tilt you'll never get a correct torque setting. Hmmmmm...
A plate on the machined face side and helicoiled threads is starting to look pretty good.
The plate should be really tough like stainless steel. The plate decouples the parking break mechanism from the casting, protecting the casting from crush and working wear, larger bolts could be used and the helicoils are also protecting the casting. You'll get reliable torque settings, no more pull outs so long as the bolts come loose and permit the brake assembly to bind. A drop of blue locktite ought to do the trick.
What do you think? 1 Stainless Steel base plate, 2 bolts, blue threadlocker and specs for the helicoils to be fitted. A lot simpler than re-inventing the wheel, or in this case - the parking brake mechanism. Hope this helps. Cheers
Jack Houpe
GT40s Supporter
Ian, I think your idea is a good one, but I am not sure if there is enough room to put a plate between the upright and the brake mechanism, I will let you know tomorrow with full pictures as I will take it apart and make some type of fix. I will say that these brakes are only meant to be applied when the car is stopped. As you can see the pieces are pretty light weight and the philip screws that hold that plate are not that big, smaller than 1/4 inch bolt.
Marcus/Jack,
I have inspected mine and after 3,000 miles my bolts are are tight.
I think that problems relate to either improper cable adjustment or using the emergency as a rolling brake (not intended for this).
I note that if the cables aren't slack with the emergency lever in the down/off position there would be drag and stress on the bolts that could eventually loosen them and cause damage.
So is it possible that the emergency was not properly adjusted to allow in off position a relaxed cable and no pull on BOTH of the brake lever arms?
Both cablles can and should be adjusted to insure there full slack when the brake lever is down/off.
Comments?
Steve P2125
I have inspected mine and after 3,000 miles my bolts are are tight.
I think that problems relate to either improper cable adjustment or using the emergency as a rolling brake (not intended for this).
I note that if the cables aren't slack with the emergency lever in the down/off position there would be drag and stress on the bolts that could eventually loosen them and cause damage.
So is it possible that the emergency was not properly adjusted to allow in off position a relaxed cable and no pull on BOTH of the brake lever arms?
Both cablles can and should be adjusted to insure there full slack when the brake lever is down/off.
Comments?
Steve P2125
Jack Houpe
GT40s Supporter
Steve I think the problem is those philip head screws are a poor choice for a fastener. Yes you are correct about the adjustment and VERY MUCH correct about it not being a hand brake that can be applied when rolling, it will shear those screws off PDQ. I plan on taking it apart today. Had honey do's yesterday, I will take pictures.
Jack
Jack
The issue really boils down to fasteners which is where I was going with the steel plate and helicoils idea. The PBR parking brake assembly being used is an OEM part. There cannot be these kinds of failures on hockey mom mini vans or whatever car it's used on.
Granted the chance of ripping out the screws is much better by driving off with the parking brake on. At standstill the present setup properly adjusted and torqued should work fine. But back in the real world, someones going to drive off with the parking brake engaged.
In our world we're driving off with 500+hp so there's no chance for the screws when threaded into aluminum.
I'm quite sure PBR will call for the parking brake mount to be retained by Grade 5 or better fasteners threaded into steel. Most production car uprights are cast or forged steel. If it's aluminum there has to be a steel mounting provision to spread the load or really big screws to prevent the thread pull-out we're seeing.
If you drive off with the parking brake engaged in normal cars, the first thing that happens is you burn up the linings and possibly the drums or shoes. The brake self distructing isn't the first event however any mechanic or brake shop has all kinds of stories about brakes that were totally destroyed. So we're not imune...
Jack, it would be good to know what space is available for a steel plate, that would make a simple fix. If there's no room then the upright could be milled to provide it. The plate could have integral threaded inserts, weldnuts or rivnuts, so there is no need for through bolts and back milling of the upright for the nuts/washers to land on.
In Markus' case with the holes torn up, milling (if required) and clearance holes for the plate/rivnuts would be the extent of restoration required to fit the new bits, although crack testing the upright should be done regardless.
As much as it would be nice to not have to do machine shop work on the uprights, doing so for a plate with new fasteners will be several orders of magnitude simpler, less costly and efficient than cooking up another caliper assembly with attendant cables and hardware.
Cheers
Granted the chance of ripping out the screws is much better by driving off with the parking brake on. At standstill the present setup properly adjusted and torqued should work fine. But back in the real world, someones going to drive off with the parking brake engaged.
In our world we're driving off with 500+hp so there's no chance for the screws when threaded into aluminum.
I'm quite sure PBR will call for the parking brake mount to be retained by Grade 5 or better fasteners threaded into steel. Most production car uprights are cast or forged steel. If it's aluminum there has to be a steel mounting provision to spread the load or really big screws to prevent the thread pull-out we're seeing.
If you drive off with the parking brake engaged in normal cars, the first thing that happens is you burn up the linings and possibly the drums or shoes. The brake self distructing isn't the first event however any mechanic or brake shop has all kinds of stories about brakes that were totally destroyed. So we're not imune...
Jack, it would be good to know what space is available for a steel plate, that would make a simple fix. If there's no room then the upright could be milled to provide it. The plate could have integral threaded inserts, weldnuts or rivnuts, so there is no need for through bolts and back milling of the upright for the nuts/washers to land on.
In Markus' case with the holes torn up, milling (if required) and clearance holes for the plate/rivnuts would be the extent of restoration required to fit the new bits, although crack testing the upright should be done regardless.
As much as it would be nice to not have to do machine shop work on the uprights, doing so for a plate with new fasteners will be several orders of magnitude simpler, less costly and efficient than cooking up another caliper assembly with attendant cables and hardware.
Cheers
Jack Houpe
GT40s Supporter
I apologize, its an allen head screw not philips, not sure why I had that embedded in my brain. Here are the pictures and my fix, I had some mil spec bolts and nylocks that fit perfect so I used them. When I removed the guides for the expandable E brake shoe I put locktite on the small allen screws also. From start to finish it only take 30 minute per wheel. Worth the time to check these items and put locktite or something like I did. Ian I did all this before reading your post, sorry.
Attachments
Hi Jack,
That looks much better! These pics show a flat face for the nyloc nut, wonderful. Best solution for the effort required.
I would recommend a hardened steel washer under the nyloc so it doesn't get sucked into the soft aluminum, trust me - it will happen.
You've repaired the damage but not the root issue. Where the threads simply worked loose, eventually braking away that won't happen now, good. What will happen if you drive off with the parking brake engaged is that the pull out load that previously destroyed threads in the casting will now suck the nyloc into the casting. Hmmmmm.... Then the mount is loose (again), the shoe can get cocked in the drum when driving and BLAMO she's in peices again.
So it's off to a reliable fastener house you go for hardened steel washers, proper size for the fasteners, most likely metric, nothing at the Home Depot will do
.
Cheers
That looks much better! These pics show a flat face for the nyloc nut, wonderful. Best solution for the effort required.
I would recommend a hardened steel washer under the nyloc so it doesn't get sucked into the soft aluminum, trust me - it will happen.
You've repaired the damage but not the root issue. Where the threads simply worked loose, eventually braking away that won't happen now, good. What will happen if you drive off with the parking brake engaged is that the pull out load that previously destroyed threads in the casting will now suck the nyloc into the casting. Hmmmmm.... Then the mount is loose (again), the shoe can get cocked in the drum when driving and BLAMO she's in peices again.
So it's off to a reliable fastener house you go for hardened steel washers, proper size for the fasteners, most likely metric, nothing at the Home Depot will do
.Cheers
Jack,
Although my bolts are tight after 3,000 miles I will do like you and add the washer suggestion per Ian.
How does one remove the brake rotors/emergency drum?
Dumb question here but although I have pulled the half shafts to replace torn CV boots and adjusted the rear wheel bearings I have yet to remove brake rotors.
Thanks in advance for your direction.
Steve P2125
Although my bolts are tight after 3,000 miles I will do like you and add the washer suggestion per Ian.
How does one remove the brake rotors/emergency drum?
Dumb question here but although I have pulled the half shafts to replace torn CV boots and adjusted the rear wheel bearings I have yet to remove brake rotors.
Thanks in advance for your direction.
Steve P2125
Jack Houpe
GT40s Supporter
Ian your right, I will do the washer next weekend, its hot here today and I am done.
Steve, take off the wheel, take off the brake caliper and stick a wedge of wood or something between the disk so the hydraulic cylinders don't ease closed while your working, take off the spacer between the wheel and the rotor, remove the two large allen head screws (see picture) and the rotor will slide right off. (Make sure you E brake is off) Remove the two small allen screws for the alignment guides, rotate the drum brake shoe so it will slide out of the holder. Replace the allen screws with bolts and washer nylocks and put back together, don't forget locktite on the small alignment guide screws. If the adjuster comes apart be sure to put the pin (look at picture) back before replacing. Pretty simple.
Steve, take off the wheel, take off the brake caliper and stick a wedge of wood or something between the disk so the hydraulic cylinders don't ease closed while your working, take off the spacer between the wheel and the rotor, remove the two large allen head screws (see picture) and the rotor will slide right off. (Make sure you E brake is off) Remove the two small allen screws for the alignment guides, rotate the drum brake shoe so it will slide out of the holder. Replace the allen screws with bolts and washer nylocks and put back together, don't forget locktite on the small alignment guide screws. If the adjuster comes apart be sure to put the pin (look at picture) back before replacing. Pretty simple.
