Community Forums

TROONORTH · 09-29-2016, 09:10 PM

I have a Forest River car dolly with surge type breaks, used to tow my 1995 Oldsmobile Cutlass Supreme convertible. Sometimes, when I apply the brakes the surge brakes lock up, unlock, lock up, unlock, lock up and produce a very unpleasant if not terrifying pounding that shakes the whole motor home like one of those machines you used to find attached to the bed in a cheap motel.

Not that I have any first hand experience with these devices of course.

The 'manual' that came with the dolly is long gone, but the one instruction that stuck in my head was that the tongue should be 19 inches off the ground. Mine is almost exactly that.

Does anyone have any idea what to do to stop this cheap motel massage?

Scarab0088 · 09-29-2016, 09:35 PM

The brakes are malfunctioning. There is a spring pre-load mechinism inside the head that is not working properly at moderating the brake engagement...so it is slamming the brakes, releasing, slamming, etc.

The brake master head needs service.

Best luck

twinboat · 09-29-2016, 11:35 PM

If the brakes look OK and there doesn't seem to be any lose parts or bolts, the next time it happens, check the straps that hold the car tires down.

I think, if the car can shift back and forth, in the pan, it can effect the surge hitch and cause an osolation.

Not the same brand of dolly but my Stehl Tow says, if I recall, to have a 14" hitch height.

Waiter21 · 09-30-2016, 04:57 AM

Check tiedowns, as mentioned, the load could be shifting back and forth.

Check brake pads /verify that nothing is binding. (I had an axle leak grease and this was causing one of my calipers to bind.

But it sounds like something in the actuator is broke or out of adjustment. I looked at the Dexter site to see if I could find something. no luck. There should be a spring that has to compress when the brake cylinder is pressed in...

EZE Tow · 09-30-2016, 05:20 AM

I understand this is not our dolly, however what you are describing is commonly referred to as " Chucking " Usually an indication of insufficient brake fluid. Check your fluid level, you probably have air in the brake lines now too. Needs to be bleed and refilled.

TROONORTH · 09-30-2016, 08:14 AM

I'll check that out. Thanks for the hint.

TROONORTH · 09-30-2016, 08:16 AM

Straps are tight, but I'll keep an eye on them. Thanks.

TROONORTH · 09-30-2016, 08:20 AM

THANKS EZE!! I will give that a look-see. Mine is the 'generic' kind of dolly that can be seen with several different names on it. Next time I'll make sure it's an 'EZE' .

ahicks · 10-01-2016, 07:57 AM

Many surge brake actuators (the part on the front of the dolly) use a small shock absorber built into them to dampen the forward/backward movements. If that shock is shot, that damping action is gone, and that could easily account for the slamming action you're describing.

The shock, if yours has one, is easily visible by removing the actuator cover (usually just held in place with a screw or 2). If present, the shock is easily removed to check. It's just held in place with a bolt on each end. Easy DIY repair....

Kiawah · 10-01-2016, 08:22 AM

Mechanically this is pretty straightforward setup. The hitch is a sliding hitch, where the tow dolly can slide forward toward the coach when you put the coach brakes on. As the tow dolly slides forward, the dolly brake cylinder starts to push brake fluid out to the brakes, thereby slowing the dolly and allowing the sliding hitch to start to slide backward (as the rv continues down the road).

Your symptoms are locking and unlocking, so it is not working smoothly. The previous comments are all right on, and there could be a couple different thing wrong with your dolly. I would disassemble everything to determine what is sticking.

- The sliding hitch itself could be binding, and not sliding smoothly. Need to have the shock and master brake cylinder disconnected so you can inspect this movement.
- The shock absorber could be bad, not smoothing out the movement. If you disconnect one end of this, you can move it back and forth by hand to see how smooth it moves.
- The master brake cylinder could be bad, not working smoothly. Would need to have the shock disconnected, and open the wheel cylinder air purge valves to check.
- You don't mention whether you have disc brakes or drum brakes, but one (or both) of those two cylinders at the wheels could have corrosion in them and not working smoothly. These have to be taken apart and manually inspected. When the master cylinder is engaged and pushes fluid out toward the wheels, since hydraulic fluid isn't compressible that causes the brake cylinder pistons to slide and expand out, mechanically applying the brake pads. Moisture collected in the brake fluid tends to collect at the cylinders, causing rust which binds their movement.
- To a lesser degree, you may also have a brake pad problem, either some leakage on the pads or worn excessively because the brakes have been periodically locked up.

It's all easy enough to rebuild with a little TLC from someone who knows how to work on brake systems. If you do a repair to one of the wheels, always do the same repair to the other wheel. (ie. if you have to replace a brake pad due to wear replace them all, if you have to replace a brake cylinder due to corrosion, replace both).

Brockx · 10-01-2016, 08:48 AM

When I was using a Surge Brake Dolly I had the tongue uphill to the hitch about an inch, it was much smoother that way.

Not may of these left, 1995 bought it new, has 29,000 miles, was built in the last 2 weeks of production. I have encountered one other owner on here.

TROONORTH · 10-01-2016, 09:05 AM

THREE CHEERS FOR THE MAN FROM EZE!!!!

:I never would have thought of that one, but after taking the brake drums off and finding everything was OK, I looked into the master cylinder, and low and behold, DRY AS A BONE!

Of course now the question is; "Where did all that fluid go?" I can't see any signs of leakage, no wet spots, no fluid in the brake shoe area, no collected, oily dust at any connectors. It must be going somewhere.

Aliens. That's it! Aliens ( the legal type) have been taking my brake fluid at night!!

Scarab0088 · 10-01-2016, 09:48 AM

Thanks to the OP for the follow-up and thanks to EZE-Tow for the advice and sponsorship of iRV2

Brockx · 10-01-2016, 02:40 PM

Quote:

Originally Posted by TROONORTH

THREE CHEERS FOR THE MAN FROM EZE!!!!

:I never would have thought of that one, but after taking the brake drums off and finding everything was OK, I looked into the master cylinder, and low and behold, DRY AS A BONE!

Of course now the question is; "Where did all that fluid go?" I can't see any signs of leakage, no wet spots, no fluid in the brake shoe area, no collected, oily dust at any connectors. It must be going somewhere.

Aliens. That's it! Aliens ( the legal type) have been taking my brake fluid at night!!

As the pads wear the wheel cylinders fluid requirements increase as they hold more fluid. The master cylinder is fairly small and it is something to be checked and topped off a couple times a year.