EB Cadillac Eldorado Rear eBrake Fix

[RonJones]

I replaced the foot pedal eBrake with a Lokar floor mount lever. Unfortunately, it doesn’t have mechanical advantage to lock the rear wheels. Here’s the stock equalizer setuup:

I lengthened a new stock lever arm 1-1/4” by welding on 3/16” x 1” mild steel stock, and drilled new pivot and equalizer rod attach points:

Equal distance between the lever pivot point vs. the equalizer shaft to the actuator pull point results in 2:1 mechanical advantage. Any change that moves the equalizer shaft towards the pivot point or lengthening the actuation distance will improve the mechanical advantage. At the same time, that will decrease the travel of the equalizer rod and bar.

The original mechanical advantage is: 5.125/2.75 ‎ = 1.864: 1

Using the hole nearest the pivot point, the mechanical advantage is 6.375/1.375 ‎ = 4.636: 1

1” further away from the pivot point gives an mechanical advantage of 6.375/2.375 ‎ = 2.684 : 1

I jacked up the right rear wheel by placing a hydraulic floor jack under the rear end pumpkin. Because of all the friction in the system, it’s hard to tell when the rear brake is nearly touching the disc. I put a 3 x 5” card between the brake pad and the disc, and adjusted the e-brake until I felt the card start dragging when I pulled on it.

The 2.7:1 mechanical advantage hole provided the right amount of force and travel to enable brake lock while not having detectable friction when the eBrake was not employed:

 

[toddz69]

I love to see fixes like this!

Todd Z.

 

[DirtDonk]

Yay, finally!
I know we’ve spoken of it occasionally in the past, but I don’t remember anyone ever fiddling around with it until now.
Thanks for the good detailed write up.

 

[SteveL]

With the added travel of the pivot would it still give the improvement with the stock e-brake pedal? Or does the lokar floor lever have a longer pull?

 

[ntsqd]

I had to do something similar to use the Fiero hand p-brake lever.

 

[RonJones]

This mod diminishes travel while increasing mechanical advantage when compared to the stock lever arm and equalizer rod location. I haven’t actually measured it, but my impression is that the Lokar floor lever has a shorter pull or travel in comparison to the OEM foot pedal.

 

[ksagis]

@RonJones, nicely done.

Question for you, when you had the foot pedal ebrake, did you have enough mechanical advantage? Or was this only needed when you made change to Lokar.

Edit: when you mention adjusting the ebrake, were you adjusting the arm on the caliper, or adjusting the nut on the lever and maybe keeping tension on the cables downstream? (If the latter, not sure if that affects how the caliper self adjusts, maybe somebody else does)

 

[RonJones]

ksagis, I never had trouble with the foot eBrake with rear drums, but my hand-welded cage got in the way. So the foot pedal had to go. Enter the Lokar floor-mounted hand lever. At the same time I put the cage in, I also added the Cadillac Eldorado rear brakes.

With the Lokar hand lever and using the OEM 1.9 mechanical advantage didn’t develop enough force on the disc to stop the car from rolling. When you think about it, the drum brakes linings have a lot of surface area in comparison to disc brakes pads. So more force is needed. More mechanical advantage to the rescue. When I write about adjusting the eBrake, I’m referring to tightening or loosening the equalizer threaded rod that is double-nuted in the pictures.

The idea of the 3 x 5 card, is to get enough tension on the cables going to the brakes so that the pads are almost touching the disc when the Lokar lever is down and when the card is removed. The card basically acts like a feeler gage, but gives a good tactile sense of tight or not tight. I wanted the eBrake adjusted so that the pads are very close to the disc when not engaged. That makes the travel required in order to develop the force minimal.

HTH

 

[ksagis]

All makes sense, thanks.

I’ve got Caddy brakes (still have foot pedal) and haven’t been super happy with parking brake performance.

I’m a little surprised you can get a 3x5 card (maybe 0.015”) under the pad if you adjusted the caliper. I pretty much have very little daylight between my pads and rotor which took a fair bit of fiddling with that adjustment process tho.

Thanks for sharing the mod.

 

[ksagis]

I thought about this some more on flight home. One needs to include the mechanical advantage in foot pedal or hand lever as well as foot / arm force.

i.e. simply mirroring what RonJames did for a foot pedal application may or may not work out as well.