Finished My AC Brake Installation Today

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Model T Ford Forum: Forum 2014: Finished My AC Brake Installation Today
Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Wednesday, January 08, 2014 - 04:21 pm:

Folks may recall my earlier 2013 thread on working up a set of original AC Brakes that another member was kind enough to donate to me:

http://www.mtfca.com/discus/messages/331880/403132.html?1387319137

After fiddling around with making a clamp to fit around my original brake pedal, I decided there just wasn't enough room to fit that setup under my floorboards, so I bit the bullet and ordered a Rocky Mountain brake pedal and brake equalizer assembly from Lang's.

Installation of the brake pedal and equalizer assembly went smoothly, except for a temporary interruption to fish the brake pedal band spring back out of the bottom of the transmission:

http://www.mtfca.com/discus/messages/331880/411170.html

I wrapped up the connection of the equalizer to the brake pedal pushrod today. I also hooked up the pull cable from the brake assemblies to an pulley and turnbuckle setup that is attached to an upside-down U-shaped bracket that I made to fit on the bottom of the equalizer assembly. I installed the turnbuckle to make adjustment of the overall cable tension easier. Each brake assembly also has a band tightness adjustment that I plan to use to dial-in the side-to-side brake balance.

Here are some pics of the finished installation. I still have to make some adjustments to make sure that the new brakes and their linkage doesn't interfere with the operation of the transmission and parking brakes. I also need to fine-tune the cable tension to get full clamping pressure on the AC brakes when the pedal is depressed, without the brakes dragging when the pedal is released.

ac01

ac02

ac03

ac04

ac05


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Richard Bennett on Wednesday, January 08, 2014 - 05:38 pm:

Mark/others, I have some misgivings about this installation. To my usual way of over-engineering things, that U shaped piece attached under the equaliser to which the cable adjuster is attached appears to be rather flimsy. The leverage applied by the pedal arrangement looks to me to be likely to bend that piece under load. In addition, all the load is taken on that single bolt which attaches the piece to the equaliser. Is this a result of mixing two different types of brake mechanisms, or am I being overly concerned?

Just wondering.

Allan from down under.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Wednesday, January 08, 2014 - 05:51 pm:

Allan, thanks for your comments and concerns.

The single bolt on the bottom is the same bolt that comes with the equalizer assembly - it normally attaches the "whiffle tree" bar that the brake rods attach to to the bottom of the equalizer. From the markings on the head of the bolt, it appears to be grade 8.

The "U" bracket is actually pretty stout, but I'll keep an eye on it to see if it bends with use. I intentionally made the ears of the "U" long because I wanted to make sure I had enough linear travel to fully actuate the AC brakes. If it turns out that the "ears" of the "U" are longer than they need to be, I can dismount the "U" and drill another set of holes higher up to reduce the moment arm.

I still have my transmission brake adjusted to lock up the brake band with the brake pedal an inch above the floorboards, so if the AC linkage bends the transmission brake will still engage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jay - In Northern California on Wednesday, January 08, 2014 - 06:01 pm:

My first impression of your photos was the same as Allen's. Let us know how it goes as you adjust them in.

BTW: Your photos are superb!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Wednesday, January 08, 2014 - 08:04 pm:

Mark, no comment on the U shaped piece but the return springs on the rear may be over kill for what they need to do. See how it works. Be prepared for some cable stretch. I found I needed to take up the slack a few times till the cable found it's final length. You might want to drill and use a castle nut and cotter pin on the equalizer swivel bolt.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Thursday, January 09, 2014 - 08:58 am:

Thanks for the comments, Mark. I got in the car yesterday and the brake pedal is pretty stiff, I may investigate weaker return springs at some point. I went for the overkill springs because I already had them and I wanted to be sure that the brakes would release fully (no drag).

I can compensate for cable stretch either by tightening the turnbuckle, or back at the brake arms if I run out of adjustment at the turnbuckle.

The nut on the equalizer swivel bolt is an elastic stop nut, so there's no danger of it backing out, but I agree a castle nut and cotter pin would be more period-looking.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Allan Richard Bennett on Thursday, January 09, 2014 - 06:25 pm:

Mark, the 'whifle tree' bar used on the equaliser set-up puts a different load on that grade 8 bolt. Because the bar is almost straight, the load on it is a shear load. In your set-up there is a considerable bending load. Both the bolt and your U piece take that load. If you find you can re-drill the U piece closer to the bolt, the load on both will be reduced.

In OZ we have a saying, "Suck it and see". This might be one of those occasions.

Allan from down under.


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