Grabbing Brakes

74Tradewind · 08-08-2002, 08:08 AM

I just put on new shoes, magnets. drums, bearings and seals. I pulled the trailer 500 miles with no problem but on the return trip the brakes started to grab.

While driving at speeds above about 25 MPH and applying the brakes there is no problem but when I come to a slow speed stop like in traffic the brakes grab hard like a panic stop. Even as I manuevered the TT in my driveway the brakes were either all or nothing. Could it be the controller (Prodigy) or is the problem in the brakes (mechanical)?

I tried to adjust the power knob but to no avail. Anyone have any ideas?

Peace, Brian

**jcanavera** · 08-08-2002, 08:14 AM

You might want to get a meter and measure the voltage that your brake controller is putting out when your tow vehicle's brake pedal is depressed. I would measure with the vehicle dead stopped on level ground. That should be the absolute minimum of voltage being sent to the trailer brakes.

Unfortunately I have never done this measurement so I don't know what is proper but if I were in your shoes I would start my diagnosis here. You might contract the manufacturer of your control. They should be able to give you some numbers.

Jack

Pahaska · 08-08-2002, 08:21 AM

I have a Prodigy, also, and it is very smooth. Your symptoms sound like what I experienced when I was first setting it up.

The Prodigy has 3 modes of applying the brakes. In two of the modes, the brakes get an initial heavy shot of current before going to the deceleration sensor. One mode gives a moderate initial current, the second mode gives a really heavy initial current. I can't use the modes that give the initial heavy current or my brakes grab too hard at slow speeds, just like you describe. These modes are supposed to improve performance with very heavy trailers. I don't need them with my 5000# trailer.

What I am guessing is that you somehow put the controller into either of the heavy initial current modes. You do this with the pushbutton switch on the right side of the controller with the trailer hooked up and, iff I remember right, your foot off the brake. The display shows what mode you are in. if the number is #.1, then you are in the moderate initial current mode. If the display is #.2, you are in the heaviest initial current mode. If there is no decimal number, then there is no initial shot of current.

I hope I described this adequately.

gwsullivan · 08-08-2002, 08:42 AM

I believe after replacing brake components you should readjust the controller.

Pahaska · 08-08-2002, 09:06 AM

If you read the original post again, the brakes were fine for 500 miles, then something changed. This is obviously not an initial adjustnment problem or an initial controller gain problem.

If something changed at 500 miles and the controller has three modes, two of which modes will cause brake grabbing at low speeds, the obvious first place to look is to find out what mode the controller was in when the problem occurred. The mode can be changed by accidentally bumping the button on the controller so it isn't far fetched to guess that the mode changed.

BTW: The Prodegy is normally wired hot to the battery, but can be removed from the mount and unplugged. I don't know the effect of unplugging the Prodegy; whether the mode is reset or changed when this occurs. I leave mine plugged in all of the time. It would probably be prudent to recheck the controller mode whenever the controller is removed and replugged.

James Schmidt · 08-12-2002, 06:03 AM

The advise you have received on checking the prodigy is good and should be the first thing I would check. My prodigy has one, two, or three lights that come on to tell which mode the brake controller is in. I cannot use any mode but one or my brakes will be grabby on light braking. If this does not solve the problem, look for grease on the brake linings. This could happen on a new job if too much grease was applied initially and it got pass the seals after using it for a while.
Good luck.

Pahaska · 08-12-2002, 06:55 AM

Apparently they changed the later Prodigys to have the 3 lights. Mine is one of the earliest ever shipped (I ordered before first shipment) and it has the decimal numbers as I described rather than the lights.

In either case, bets are that the controller ended up accidentally in one of the 2 modes that cause brake grabbing.

83Excella · 08-12-2002, 08:12 AM

Tekonsha has some troubleshooting on their site.

www.tekonsha.com

John

Ray Midgley · 05-25-2004, 01:58 PM

Quote:

Originally Posted by 74Tradewind

I just put on new shoes, magnets. drums, bearings and seals. I pulled the trailer 500 miles with no problem but on the return trip the brakes started to grab.

While driving at speeds above about 25 MPH and applying the brakes there is no problem but when I come to a slow speed stop like in traffic the brakes grab hard like a panic stop. Even as I manuevered the TT in my driveway the brakes were either all or nothing. Could it be the controller (Prodigy) or is the problem in the brakes (mechanical)?

I tried to adjust the power knob but to no avail. Anyone have any ideas?

Peace, Brian

I had this problem with the right front wheel brake on my 97 25ft excella. I was caused by hard spots in the cast iron drum. inferior iron cast in china can contain hard spots and they are actually visible to the eye as a very shinny area. I had to replace the drum and brake assy. youy must also keep the brakes manually adjusted for wear as they kink a little and grab.
I do not believe the controller is involved.
ray midgley

alan · 05-25-2004, 06:57 PM

Another thing to check is contamination of the linings. If there is any stray grease in the brake assembly (following the bearing repack), it may have warmed enough during braking to drip onto the linings.

Over59 · 05-26-2004, 07:36 AM

You can really smoke em with that thing set on 3 by mistake. Thanks
The guy next to the wheels thanks you to, not happy with me and will always remember the day he saw the old airstream.
"What's that honey?"
"Oh my God it's attacking!!!"

74Argosy24MH · 05-26-2004, 08:37 AM

Most vehicle drum brakes have leading and trailing shoes, don't know if this is true on AS. One shoe has more grip and is designed to grab and push both shoes against the drum. Reverse them and you will have problems. If there are different color linings they have a designated location.

John

71_safari · 05-26-2004, 11:17 AM

Actually, after 500 miles, the brake shoes and drums may have finally "bedded in" and are working properly - it takes awhile for them to wear in to each other. And if your controller was set fairly high before when the old brakes were out of adjustment, maybe they are just feeling grabby now that they are working better. Might have to back it off some.

What kind of reading are you getting on the Prodigy display when you come up to a slow speed stop around town? I would first try lowering the voltage with the adjustment knob, in small increments. Mine rarely gets over 2.4 on slow speed stops. If it is set higher mine grab also, especially when cold. At higher speeds they can take a more voltage without feeling grabby. Of course comparing my old brakes to a newer setup is not probably valid anyway.

seaaudio · 05-26-2004, 12:24 PM

I experienced this very same issue with my '57 caravanner and a Prodigy after driving a couple of hours. When moving in stop and go traffic, it would really start to grab. My feeling was the Prodigy was fine...

Scott