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Old 05-08-2003, 07:20 PM   #1
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Brakes 'thunk'ing?

We took the rig to my friend's house and he installed the friction sway control, and test drove it to help us get it all set up. I didn't have the spring bars tight enough, so we put them up one more link on the chain and the whole thing rode much better. We drove it around for about an hour, on a busy highway, then took it on the freeway up to the next town and back, trying to see what it felt like when semis went by - didn't really feel anything. I guess that's the whole point of having friction sway control and a heavy, long wheelbase van. Still, I was pretty nervous getting on that freeway with it, but it didn't give us any surprises.

I do have a question about the brakes though. When I slow down and then let off the brakes but we are still moving, I feel a thunk. If I slow to a complete stop and let off the brakes, nothing, no thunk. Any idea what this thunk could be? Our tire/brake guys thought maybe the brakes were grabby from sitting, but he didn't really seem to know. We're using a Surepull Digitrac brake controller, set at about 2.6.

I'm putting new pics of the van & trailer in my photos section as soon as I send this off. They look pretty snazzy together.
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Old 05-08-2003, 08:44 PM   #2
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It sounds like they need a good cleaning. Take off the wheels and service the bearings and check the drum and magnets for wear. There shouldn't be any real wear on the magnets (nice and square) and free moving. Jim
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Old 05-08-2003, 10:09 PM   #3
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Brakes "thunking"?

Greetings Stephanie!

I concur with Jim that a bearing repack and brake inspection would be a good insurance policy.

My suspicion is that what you are experiencing is a characteristic of trailers having the old style magnets in thier brakes. Before having my Overlander's brakes rebuilt, I noticed a distinct "clunking" noise whenever the brakes were released in slow-speed maneuvering. In a humid climate, electric brakes tend to be a bit "grabby" when first applied after a period of inactivity of as little as 72-hours - - with my Overlander this means a period of 7 to 10 miles where each stop produces a "shudder" that might be perceived as a "clunk" under certain conditions as the jerky application results in movement in the hitch components. Another issue that can cause this issue to be noticed is the adjustment of the brake controller - - if the gain is set too high during slow-speed maneuvers, it can result in a distinct "jerking" motion as the trailer brakes release that can be perceived as a "clunk" when the hitch components react to the abrupt movement.

You mention tightening up the spring bars on the hitch - - this can cause a change in the amount of "feedback" that you experience between tow vehicle and trailer as well. Another item, some weight distributing hitches will make their own characteristic noises as road irregularities are encountered, and either of these could be increasing your awareness of the "noise" or "sensation".

Anytime you change tow vehicle or trailer, the natural reaction is to become more acutely aware of any sounds or sensations being transmitted by trailer or tow vehicle. I noticed exactly that when I towed my '78 Minuet home after purchasing it last fall - - every noise or motion became a question of is this natural or unusual. I hope that you find that what you are experiencing is just a part of the learning curve regarding the nuances of your new rig as you get better acquainted with both tow vehicle and trailer.

Kevin
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Old 05-09-2003, 10:29 AM   #4
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While I think that going through the trailer brakes and repacking the wheel bearings is a REALLY good idea and you should take the time to do it, I don't think that's where your noise is coming from.

I think it's play in the hitch, normal and actually somewhat desirable.

When the brakes are set up correctly on the trailer the trailer should start braking just a little bit before the pull vehicle. The noise is the slop in the trailer hitch assembly being taken up or released. When you release the brakes it shifts the load a little. You have several points where slop is going to be present. At the ball and where the draw bar is attached to the tow rig with the pin. You could proably duplicate the noise to some extent by pulling in and out on the draw bar when not connected to the trailer. Have your SO inside and see if he feels it's the same noise.

Hearing the noise lets you know that the trailer is indeed braking.

I recently barrowed a friends car trailer to move a vehicle a 100 miles and I too noticed some occasional thumps an clunks. I know the trailer was well maintained and it had a recent brake service. I called and asked my friend and he assured me that what I described was normal noises when pulling trailers with brakes and it was the hitch not the actuall brakes. Told me to be more worried if I didn't hear that.

There are some hitches with a rubber dampner that will isolate this noise but proably not worth the expense.
Why you didn't hear it before was probably to due with the incorect tension on the leveling bars changed the load on the hitch and reciever. My truck actually rode better with the trailer then without and the PO told me the same thing and he was correct.
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Old 05-09-2003, 11:23 AM   #5
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Some other thoughts on Thunk

Stephanie,
See if you can detected any lateral play in the ball/coupler area while having someone else jumps up and down on the trailer tongue. Sometimes the mechanism that locks the ball into the trailer tongue has some wear and allows the ball to move front to back just a little. Also do a similar test by pulling the trailer breakaway switch pin (which should set the trailer brakes...a good test periodically anyway) and then alternate trying to pull forward just a bit and then reverse just a bit. The idea is NOT to actually move the trailer, but to see what will move and make a thunk.

BTW, if the trailer wheels easily rotate with the breakaway switch pin pulled, then you need to get that fixed IMMEDIATELY (probably corrosion in the breakaway switch). If the break away switch does NOT seem to be locking the trailer brakes, get some spray contact cleaner and spray inside the switch with the pin removed. Insert and remove the plug several times and if still not trailer brakes, the switch may need replacing.

If you find movement in the ball/coupler, the parts to rebuild the latch are available and easily replaced.

I would agree with pulling the wheels and having the bearing inspected and repacked as well as a brake inspection while the wheels are off. My parents had a wheel bearing failure on a new A/S years ago (4th trip out), so it can happen even on a new rig, but older rigs, especially if they have not been moved in awhile, are more likely to need attention.

You mentioned the road test and I am glad to hear that you had a positive experience. Don't know if you have been on a two lane road and had a semi pass going the other direction, but that is a different set of dynamics that you need to experience and understand. If not already experienced, find an appropriately traveled two lane road (ie semi traffic) and learn how the rig feels and reacts. Also practice engaging the trailer brakes using the manual control on the brake controller. This should be something that you can do without taking your eyes off the road. If you ever get into a situation where the trailer begins to sway, the best action is to continue to drive (in fact a bit of acceleration) and at the same time, apply the trailer brakes ONLY. This will tend to "pull" the trailer back into a straightline and stop the sway. Even with sway damping devices, it never hurts to have more than one solution up your sleeve.

I have been meaning to mention the trees in your pics. You really live in a beautiful location.

david

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Old 05-09-2003, 12:01 PM   #6
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We went out on our test drive looking for Semis, but had a hard time finding any, of course! As we drove down one side of the freeway we saw the other side was packed, so we took the next exit and got back on, and then that side was empty! But we did get a few to pass us finally. On the highway we got passed in the opposite direction by some gravel trucks and stuff like that, but in our area it's hard to find a semi on the rural highways, mostly big construction trucks. I'm ready for it though. I remembered the instructions for what to do if the rig starts to sway, so knowing that, having a big van, and a healthy dose of paranoia should be enough to keep us safe :-)

I'll see if I can get someone to teach me to repack the bearings and inspect the brakes before our big trip next week. My friend who sold us the hitch has been pulling trailers since before I was born (or my airstream was made), so I'm sure he can help us out with this.

Thanks for the comment on the trees. It is very beautiful here. We are right across the street from a state park, and it's like being on vacation everyday. I don't think I could go back to living in town!
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Old 05-09-2003, 12:59 PM   #7
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fyi

http://www.timken.com/products/bearings/techtips.asp

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Old 05-09-2003, 10:42 PM   #8
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You can get this tool at any Sears store. It's a real time save and hand saver as well.

http://www.autotoolexpress.com/hapabepa.html
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Old 05-09-2003, 11:26 PM   #9
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Packing the wheel bearings will be very simular to the way you would pack front wheel bearings on our of your Stangs if you have done those before.

You don't need no stinking fancy tool for it. Just a big blob in your cupped palm and drag the wide edge into the grease.

Yeah it's gross and messy.




(shhhhhhhh don't tell anybody but I have a bearing packer that hooks to my grease gun. It would ruin my reputation)
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Old 05-10-2003, 11:49 AM   #10
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I'm not as worried about the bearings as I am the brakes. My only experience with rebuilding my 'stang's drum brakes involved me trying to dissasemble them on the bench, when something slipped and pinched my finger between the shoe and the backing plate. I had to CALMLY find a tool to pry it back up with so I could get my finger back and then ran yelping into the house! Then I boxed the whole mess up and took it to my mechanic and let him do it (he was putting new gears into the diff housing anyway, so he just returned the whole rear end to me completed and ready to bolt on). So whenever I think about messing with brakes..my finger hurts :-)
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Old 05-10-2003, 05:22 PM   #11
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Use the right tool for the right job. Take a look at this link
http://www.lislecorp.com/tools/catalog/brakes/index.htm
You can get them at any Sears store. The right tool may help the finger pain go away .The trailer brakes for some reason are much easyer than a car brakes ( at least I feel that way ). Good luck and do one wheel at a time so, when you forget how to put it back to gether you now have a "cheet sheet" with the other wheel.
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Old 05-11-2003, 09:41 AM   #12
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I agree that would be the first place to look, however, I don't know about the actual brake controller you are using.

I had a Voyager and I got brake grab, thunk too. I went to the Prodigy and it's smooth as a baby's behind!

If the bearings and the brakes don't fix it, I'd start to look at the controller next.

Eric
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Old 05-11-2003, 11:15 AM   #13
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That's a real possibility, because for one thing, the PO said brakes and bearings were good and ready to go, and I trust he was not lying to me. I'll be seeing him next weekend at the ralley, which he insisted we come to so they could see us and their triler again. Also, the thunking noise didn't happen when our friend pulled it home for us. Which would make me think it's in the hitch or the brake controller, not the trailer itself. If it's the brake controller, I've got no problem with returning it to the guys I bought it from and putting in a prodigy. It wasn't that I didn't want one - after all, everyone has high praises for it, I just couldn't find one locally and didn't want to mail order it (wanted it now).
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