Brake chatter

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Model T Ford Forum: Forum 2012: Brake chatter
Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Wednesday, May 09, 2012 - 07:57 pm:

I just rebuilt the transmission in my '14 and now when I step on the brake it chatters at the very end as you let up slightly on the pedal. If I keep holding the pedal all the way down until the car stops there is no chatter. The transmission has all new bushings reamed to spec and Kevlar bands. The transmission is quiet and works perfectly in reverse, low speed and high. Any ideas about what is causing this problem.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bud Holzschuh - Panama City, FL on Wednesday, May 09, 2012 - 08:10 pm:

Val

Never rebuilt a tranny so take this with a grain of salt!

Is there any chance the band is still somewhat dry and has not been thouroughly impregnated with oil yet ?

Cheers
schuh


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Wednesday, May 09, 2012 - 08:14 pm:

Shoulda used Guinn's wood bands. They don't chatter, or crack drums...:-). Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Semprez-Templeton, CA on Wednesday, May 09, 2012 - 08:31 pm:

My opinion is: Your brake band is not tight enough. If the pedal stays down it's because there is not enough spring pressure to bring it back. I've had this happen a few times (both wood and cotton). With reference to Jim Patrick's comment, I just removed a reverse drum that was cracked ... never had any linings but cotton. Wood is OK Kevlar is better. IMHO


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Wednesday, May 09, 2012 - 08:38 pm:

Val, I would not recommend that you hold down on the brake until stopped unless you are barely moving especially when running kevlar. Holding down on the brake will overheat the drum and can cause cracks. It will also cause the bands to rapidly wear and oil glazing on the bands which makes the brakes chatter worse and causes them to not work as well as they should. Did you check to make sure that your bands were completely round and make sure that the lining was tight against the steel band? Did you install them with the hogshead on or off? Are your drums smooth or are they pitted or badly grooved?

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Wednesday, May 09, 2012 - 08:45 pm:

John, where did Val say that his pedal is sticking down?

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Wednesday, May 09, 2012 - 08:49 pm:

Val, I should have mentioned earlier that it is best to pump the brake if it must be applied for more than a few seconds. I used to have kevlar bands and they would do the exact same thing. They would chatter if you slightly relaxed pressure when almost completely stopped. Have wood bands in both cars now and they both do it too.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Wednesday, May 09, 2012 - 11:53 pm:

I do not have a problem with the brake pedal sticking down. I installed heavy springs to reduce the chances of lining drag, soaked my linings for a few days before installing and the bands were not out of round. I drive my T very conservatively so I am not talking about hard stops. Unless I am in a panic stop situation I anticipate the need to stop, close the throttle to reduce my speed and use the brake at the last minute to come to a complete stop. I have kevlar bands in my other 5 T's and none of them have this type of chatter.


Top of pagePrevious messageNext messageBottom of page Link to this message  By kep NZ on Thursday, May 10, 2012 - 02:49 am:

Thought chatter was normal? They have made that noise since the '20's apparently so i thought it was nothing to worry about.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ricks - Surf City on Thursday, May 10, 2012 - 07:54 am:

Try a pint of ATF in the oil.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, May 10, 2012 - 08:44 am:

Here's what you need.



Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry Ostbye on Thursday, May 10, 2012 - 12:41 pm:

I have a set of wood bands in my car and they chatter and shake the heck out of the car.
These are old bands on better drums. Thinking it's because they don't match now.
Looking at new bands very soon.
Still not sure of wood or Kevlar.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Thursday, May 10, 2012 - 02:19 pm:

I'm with John Semprez on this one in thinking that your bands need to be tightened. Chatter is caused by the bands trying to grab but being unable to because the pedal cannot be pressed down far enough for the band to take hold of the drum and stop it from revolving. If my bands were chattering, I would tighten them so that when I pressed down on the pedal they would grab the drum hard.

Val, you mention that you drive conservatively and only brake hard in panic stop situations. I was advised on the Forum long ago that brake linings last longer if the drum can be brought to a stop quickly. That is, if one milks the pedal so that the drum almost comes to a stop then is allowed to pick up speed over and over again until it finally stops, in the mistaken notion that milking the pedal will lubricate and cool the band, or, the pedal is applied very lightly and conservatively allowing the revolving drum to drag on the band, it will result in chatter and contribute to the premature deterioration of your bands. The faster that the drum can be brought to a stop, the better for the band. That is what they were designed to do so don't be afraid to apply those pedals. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stephen D Heatherly on Thursday, May 10, 2012 - 03:23 pm:

Jim, he is talking about the brake drum used for stopping the car not the low or reverse. When braking you should slow down as much as possible by engine braking then apply the brake to complete the stop. If the brake must be applied when the car is moving for more that a few seconds it must be pumped to prevent band wear and drum damage. If the brake drum were stopped as soon as possible by mashing on the pedal you would be constantly sliding the wheels.

Stephen


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Thursday, May 10, 2012 - 03:49 pm:

It makes a difference whether you are on level ground or going downhill. If on level ground, and you pump the pedal, it will not increase speed between pumps, but will actually let the oil lubricate the drum and cool it to the oil temperature, however, if you are going downhill, it might pick up speed and negate the slowdown previous to pumping the pedal. Best thing for going downhill, in familiar territory, is to slow down and gear down before descending the hill. I have a hill I would normally go up in Ruckstell. When I am about to approach that hill, I slow down as much as I can and then quickly pull down the throttle and shift into Ruckstell. Interestingly if you have Ruckstell, the transmission brake will stop better than it will in high because the lower gear through which the brake operates. However, that is not the case with Warford or other in driveshaft transmission. With Ruckstell you combine the compression of the engine with the increased brake power to slow down much easier. It is also beneficial to use external rear wheel brakes as well as Ruckstell and transmission brake.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Thursday, May 10, 2012 - 04:02 pm:

Stephen. Whether it's the low, reverse or brake pedal, no matter what pedal I use, when I press the pedal down, I press it to stop the drum from turning, ASAP. Of course I don't try and stop the car at full throttle and full advance and if I feel there is a strain I might pump it once, but I do try and stop the drums from spinning ASAP and don't allow them to endlessly continue to spin and rub against the bands by timidly pressing the pedal partway down.

I was only trying to illustrate to Val that he might be driving too conservatively in pressing down on the pedals too lightly, or milking the pedals, which can be just as harmful to the linings as being too aggressive.

It's a judgement call learned from many years of driving a Model T and what works for some might not work for others. In my 42 years of driving my T, I find that this method works the best for me and my T. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Thursday, May 10, 2012 - 07:25 pm:

My brake is adjusted properly and I get no chatter when it is applied firmly and I keep the pedal down all the way. The chatter occurs at the very last minute only when I let up slightly on the brake at the point where I have almost come to a complete stop. I have always done this to avoid the car rocking back and forth at a stop and have never had any chatter when dong this before on any of my T's. I don't touch the brake when slowing the car as I close the throttle to slow and only apply the brake at the last minute to come to a complete stop.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Patrick on Thursday, May 10, 2012 - 07:40 pm:

Val, as I said, the chatter occurs at a point where the band is trying to hold the drum, but is not tight enough to do so.

I don't understand why you let up slightly on the brake after almost coming to a complete stop. All this does is allow the drum to start turning again after you have almost completed the stop.

Whenever I have brought my T to a complete stop, I hold the pedal down hard until it is safe to go.

It sounds like you have your brake band adjusted right, but it appears that the problem lies with the way you are applying the brake. Always remember that the purpose of the band is to stop the drum from spinning and the sooner that is done the better, but as Stephen warns, anticipate the stop, slow the car as much as possible with the control levers, then bring it to a full stop. Jim Patrick


Top of pagePrevious messageNext messageBottom of page Link to this message  By J Berch on Thursday, May 10, 2012 - 08:10 pm:

I pump my brakes to allow the break band to replenish with oil and cool. The brake drum does not stop until the car stops. holding your brake pedal down continuously for a long period of time is equal, as far as wear, to slipping your low and reverse bands. The low and reverse bands are just the opposite. Do not pump or slip them.

The animation at the bottom of this page illustrates what happens when you apply the different pedals.

http://www.modeltcentral.com/transmission_animation.html


Top of pagePrevious messageNext messageBottom of page Link to this message  By Scott Conger on Friday, May 11, 2012 - 06:29 am:

Hi Val

We met at Crystal River this winter...hope you're doing well. I've seen how you drive and can state to the others that you know how to drive your car.

My $.02 worth. Having done many bands, I've never taken out bands that were round when compressed, but have always installed bands which were round when compressed (after forming and checking on a scrap drum). I only install bands by pulling the hog's head first, to ensure that the bands aren't re-distorted by working them through the hog's head door.

Now to my point: Many bands have the ears "tipped in" from fatigue/use. They are no longer perpendicular to the casting in the hog's head. Also, many bands are bent "down" at the very ends. I believe that either or both of these conditions together contribute to the leading edge of the band trying to be forced down into the drum with much higher localized pressure than the remaining area of the band. Under moderate braking, the band is set and operates smoothly...when just easing up, only the small area of the very end of the band (leading edge) is still in forced contact with the drum and drive train goes into a brief but violent stick/slip situation. I suspect that a worn u-joint or front drive shaft bushing would likely contribute to this chatter once it starts.

I'd try one or two things: verify that the removable ear is truly vertical/square to the casting (if not, remove and correct), and also consider placing several washers over the brake shaft to effectively extend the length of the hog's head casting boss inside. This will rotate the band's installed position slightly clockwise (when viewed from driver's seat) and reduce the tendency to self-energize when pedal pressure is low.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Saturday, May 12, 2012 - 12:25 am:

Hi Scott
I think you may well have hit on the problem and I am going to try the washers and see if that helps. I do not have removable ears but I expect that the problem you are talking about could also occur with standard bands as well. I did check my bands on a junk drum and I installed the bands with the hogs head off but I must admit that I have never really paid much attention to the ends of the bands other than to check the rivets. I installed a badly needed u-joint and front drive shaft bushing while I had the motor out so I assume the problem does not lie there. Thanks for the suggestion! I just hope I can get those washers in there without dropping one! I think I will try the old dental floss method.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Saturday, May 12, 2012 - 01:41 am:

Val,

Dental floss works great, just remember to leave the leads long enough and maybe tie it off somewhere even if it is to your pinky!

Just saying, no need to explain :-)


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