Brake cams: Uh-oh, another senior moment

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Model T Ford Forum: Forum 2014: Brake cams: Uh-oh, another senior moment
Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, October 16, 2014 - 11:53 am:

And I thought I was being so careful to get them in right.


Hand lever forward.


Hand lever straight up.


Hand lever back.

The hint that told me I must have put them in backwards? The brake rods seemed to have shrunk. They were too short to reach the clevises. Fortunately I have new cams to replace these worn ones. I can correct this when I install them.


Until I get to that I'm using some longer home-made "clevises".


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Thursday, October 16, 2014 - 12:06 pm:

Actually, Steve, the brake cam lever looks perfect. I'll bet that someone has shortened your brake rods to make up for shot cams


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Cascisa - Poulsbo, Washington on Thursday, October 16, 2014 - 12:08 pm:

Oh Steve ...

Be_Zero_Be in VA


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Thursday, October 16, 2014 - 12:11 pm:

I agree with Scott, the rear brake levers should point towards the rear of the car, just as you have them.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Hood on Thursday, October 16, 2014 - 12:12 pm:

That looks right to me. The cam lever to brake rod angle should not go past 90 degrees when applied. Over 90 degrees and you are just pulling the lever toward the front of the car and you you have lost your leverage.

Not sure why your rods are too short now. Are they for a "big drum" axle?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, October 16, 2014 - 01:03 pm:

Well, now I'm really up a row of stumps, as Mr.Lincoln would say. These are the same rods that were in the car before I had the rear axle out. I doubt that they have shrunk, so the apparent shortness is a mystery. I'll have to study this some more.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Whelihan on Thursday, October 16, 2014 - 01:37 pm:

Don't feel bad. I did the same thing two weeks ago. What is really unbelievable is that I looked at a correct stock rear end that I had laying there in the garage...twice, before putting in the brake cams backwards on the wrong sides. Would have been nice had I caught the error before riveting them too. However, after much sweat, swearing, and even some blood, I managed to correct the issue. Lesson learned.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Bohlen, Severn MD on Thursday, October 16, 2014 - 02:24 pm:

Steve,

They are correct.
Don't mess with the cams make sure you are using the correct rods.

Good luck,
Larry


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Thursday, October 16, 2014 - 03:37 pm:

You also have the oiler on the wrong end of the shackle.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, October 16, 2014 - 04:15 pm:

Stan, the figure 8 shackles have oilers on both ends. Do you mean the one facing the front of the car should be on top? I installed them this way to get the hole for the oil facing up. I guess I can turn them 180 with the forward facing oilers on on top if that's correct.

Larry, what has me mystified is that these are the same rods that were on the car before. Maybe the cams were backwards before and I didn't notice. Maybe I should just make some new rods that will fit.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange on Thursday, October 16, 2014 - 04:43 pm:

It's unfortunate that you didn't know about the situation with the rods before Hershey, I wonder if somebody there had the correct rods.

From the Encyclopedia:

BRAKE RODS

1909-1910
Forged fork ends had a built-in bend in the forged clevis to compensate for the angle of the brake rod.

1911-1920
Forged fork ends now straight; the rod had the bend.

1920-1925
In August 1920 the forged ends were eliminated and the rod was split to make the fork at the rear end.

1926-1927
Similar to the 1925, rods were shorter and shaped differently for the new larger brake drums.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Thursday, October 16, 2014 - 06:00 pm:

I'm messing witcha, Steve.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Wayne Sheldon, Grass Valley, CA on Thursday, October 16, 2014 - 06:26 pm:

First. As others have said, I think your cam levers are on correctly. At the point of locking the brakes, the cam lever should be straight up.
Second. You did replace the brake shoes when you rebuilt everything. I know you did. How worn were the old brakes? I have seen a lot of them that were worn so much that the cam lever was leaning forward a bunch when the brakes were (sort of) locked. It was common for people faced with that problem to cut the brake rod to clear the cross-shaft lever, rather than fixing the real problem. After you replace the worn cam and brakes, your lever returned to a proper "straight up" for locking the wheels. Now, your rods are too short (because they had been cut). Anytime that the cam lever goes more than a few degrees past straight up with the wheel locked, the only repair is to properly adjust the brakes inside the drum. This can be accomplished several ways.
Standard small drum model T brakes do not have any adjustment. Some after-market shoes do have an adjusting wedge. These are nice. New and/or thicker shoes or linings can help a lot. New cams can help a lot. A well-fit thin-wall sleeve on the pivoting bolt (rear of backing plate) can help a little.
I usually use new cast iron lined shoes and braze a steel shim around the brake cam to enlarge it (provided the shaft and other parts are good). I usually do this on the car. I first fit the wheel and drum with the new shoes onto the axle. Then pulling the cam lever forward to determine roughly how much wear must be eliminated. Then I can choose the thickness of the material to make the shim from. I carefully shape the shim around the cam (sometimes, depending on the wear, it is necessary to oval the ends over the cam a bit). Once shaped, the shim is brazed onto the cam.
After all that, usually, I am lucky enough that the cam lever is right where it needs to be. All my estimating I do on the high side however. Sometimes I need to dress down the cam surface (the shim) with a small grinder and a sharp file to bring the angle right where I want it. Remember, the surface of the shoe ends that rub on the cam also do need to be smooth to reduce wear during use. They should be made smooth before any final fitting. Those surfaces can also be ground to final fit onto the cams.

Another not-so-minor consideration. Both the top and bottom shoes need to contact the drum, and fairly evenly, for best braking. A cursory examination should be made. Usually, careful application of the brake handle and just feeling the wheel sliding the drum around the shoes will be enough. If this is off only a little bit? the shoes will usually wear in and fit themselves shortly. I have never had a problem from one not fitting in this way, not even that horribly damaged 1913 backing plate that required a lot of repair. I checked it closely afterwards. But this is something that should be checked. A mis-matched shoe, tweaked backing plate, or bent bolt or cam could cause one shoe only to make contact.

In short, Steve, I think all you need now is a pair of slightly longer (not cut) brake rods. For this part of the project.
Drive carefully, and enjoy, W2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Tomaso - Milton,WA on Thursday, October 16, 2014 - 06:34 pm:

Steve - the oiler facing towards the rear should be on the lower shackle and the inside one on the top to ease in getting the oil can spout back in there !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jeff Hood on Thursday, October 16, 2014 - 06:38 pm:

You can also get longer shackles at the hardware store.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jack Daron - Brownsburg IN on Thursday, October 16, 2014 - 06:38 pm:

If that is your 15 ,you don't have the correct rods on it.The rod is 5/16 and can easily be made longer.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Larry Smith on Friday, October 17, 2014 - 10:52 am:

Steve and Uncle Stan have it right, but I will re-phrase it here. The shackle is correct, but you need to flip it over so the oiler toward the front of the car is on top. The actual brake cams come in a left and a right, and are a bitch to change. When I redo a rear end I like to replace them, because the cams are usually worn.


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