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GT40 Tech - Chassis,Brakes,Tires,&Wheels Chassis and Handling.

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Old 25th September 2017, 11:27 AM   #1
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Parking Brake Woes

I began road testing my car several weeks back to initiate the sorting process and it was not a very good experience. I only drove it through my subdivision at very low speeds (1st and 2nd gear only) to check the basics. Felt like I was dragging a piano behind the car, heard a variety of mechanical noises, etc. Feedback from the drive convinced me to put it back in the garage and start going through the systems that were likely to be causing the poor behavior.


That was just before Irma swept through, so finally had a chance this weekend to start troubleshooting the drivetrain. Pulled the rear wheels and immediately discovered that the Willwood park brake calipers were both dragging on the inboard surface of the wheels. They appear to have been installed and adjusted correctly by the PO, but clearly do not maintain adequate wheel clearance with the standard RCR40 BRM style 15"x10" Vintage Wheels. Have any of you with this configuration seen this occur before? Forum search didn't turn anything up related to this problem.


I've removed the calipers for now, planning to road test it again later this week to see how it drives without them. Not sure what I can do to alleviate the interference short of removing material from the calipers or moving to 17" wheels. The calipers have a fair amount of float in the brackets, so I may have to remove quite a bit of material to account for that.
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Old 25th September 2017, 08:09 PM   #2
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Re: Parking Brake Woes

Mike I believe Don had the same problems on his RCR MK-4, check his build thread. I think he had clearance problems as well and solved it with a small amount of material removal........................m
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Old 25th September 2017, 10:45 PM   #3
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Re: Parking Brake Woes

Thanks mahlon, found a reference to the same issue on page 5 (post #83) of Don's initial build thread. Thanks for pointing me to it, guess I'll be removing material from the calipers as Don has done.
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Old 26th September 2017, 07:16 AM   #4
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Re: Parking Brake Woes

Mike,

I had the same issue on a RCR40 that I built for a customer a year or so ago. I contacted
Fran and he made me a set of replacement brackets which moved the caliper in 3/16" . Worked like a charm.

Ron
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Old 26th September 2017, 09:16 AM   #5
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Re: Parking Brake Woes

Ron,


Thought of doing that mod myself, perhaps I'll give it a try. If I screw it up, I'll reach out to Fran. Thanks for responding and providing a dimension I can shoot for.


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Old 26th September 2017, 11:57 AM   #6
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Re: Parking Brake Woes

Mike,
Unfortunately, these cars can't be slapped together, you have to check for adequate clearances (hot or cold), and worst case scenarios. You now have a telltale mark on your parking calipers which you can clean up and file down to get the adequate clearance going forward. also, swap your rear wheels L to R and check your clearances again as they can vary.

While we're on the rear brake assembly area, check that your caliper is centered over the brake rotor. The mounting bracket may set the caliper alignment to be off-center slightly, which is OK unless you allow your pads to wear down far enough.... If so, add it to your list of inspection items or see if Fran has another bracket that's machined to fix this.
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Old 26th September 2017, 12:47 PM   #7
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Re: Parking Brake Woes

Duly noted Tom, good advice. I agree these cars aren't meant to be slapped together. FWIW, I bought this car already assembled (~90%), but never sorted. I'm going through everything now to finalize the build and make it roadworthy. Thanks for responding.
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Old 26th September 2017, 04:20 PM   #8
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Re: Parking Brake Woes

Also do a check on the wheel bearings.
If loose they may allow the wheel to move enough to touch

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Old 26th September 2017, 04:42 PM   #9
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Re: Parking Brake Woes

Ian,

Good point. Bearings on both sides display zero slop when checked for play, and they rotate smoothly. Thx


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Old 1st October 2017, 08:46 AM   #10
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Re: Parking Brake Woes

I had the same issue. Here is a link to an old post.

I eventually simply removed the parking brake. Its effectiveness was limited. Have not missed it. I carry a nice wheel stop should the need arise. Just dont tell anyone.

http://www.gt40s.com/forum/258860-post486.html

Last edited by CESLAW; 1st October 2017 at 08:51 AM.
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Old 2nd October 2017, 06:32 PM   #11
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Re: Parking Brake Woes

Chuck, thx for posting the link to your build log, definitely the same condition I've encountered. Curious to know why you ultimately removed the calipers, did they continue to contact the wheel after removing the material?

Great build log btw...I've read through it before. ;-)
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Old 2nd October 2017, 09:17 PM   #12
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Re: Parking Brake Woes

Mike:

I removed it for a number of reasons. First it was not really that effective in stopping the car. Second, putting it in gear keeps the car in place when parked 99% of the time. If in doubt, I just put a wheel chock in place. Third, it cleaned up the interior by eliminating that lever on the center section.

It was needed to pass the registration inspection. After that . . . . . . .

Chuck
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Old 2nd October 2017, 11:11 PM   #13
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Re: Parking Brake Woes

I still have the calipers fitted but your are right Chuck the parking brake is not effective. One reason being that there is no balance bar at the lever cable end to evenly distribute the load on the pads.
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Old 3rd October 2017, 07:49 PM   #14
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Re: Parking Brake Woes

Mike, don't feel bad - these cars can come with a number of issues to sort out before they work properly. These are kit cars.....

When I bought my CAV it didn't shift, the A/C was disconnected, the bulkhead rubbed on the water pump pulley, etc..... The PO was a nice enough guy, just not mechanically inclined.

If there's not enough clearance there are some other options for a working parking brake....everything from hydraulic lock to slimmer parking brake caliper (Wilwood makes several types). You'll get it sorted.
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Old 4th October 2017, 06:28 PM   #15
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Re: Parking Brake Woes

Thx Chuck/Jerry, appreciate the responses.

No worries Cliff, I don't feel bad one iota... got my bucket list car for a nice price, built pretty much the way I'd have built it (except for color and a handful of minor items), and now I get to do what I like to do best... who has it better than me?

Btw, not my first or only kit car. Have an E-M cobra that I built from the ground up, so I knew what I was getting into with the GT and I never shy away from interesting projects.
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Parking Brake Woes-imag00924-jpg   Parking Brake Woes-imag00925-jpg   Parking Brake Woes-imag00926-jpg  

Last edited by Cobra; 4th October 2017 at 07:09 PM. Reason: Add pictures...
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