Below are probably the three most common sources of rattles and rear-end racket on Early Broncos. Most rattles are the result of something moving that should stay put and striking something that it shouldn’t. And the way these are usually handled in the industry is make sure there is some preload to keep things snug regardless of how things move around. There is no rocket science involved and there are some simple fixes that go a long way toward decreasing the racket. Best of all the fixes are mostly of the “for free” type.
1. Lift gate
The lift gate is arguably the number one source of rattles coming from the rear of the average Early Bronco. Two main causes seem to be at work: (1) the lift gate moves in and out rapidly against the frame with sharp road bumps causing a banging or buzzing rattle. You can see if this is an issue by sharply smacking the butt of your fist against the lower corner of the lift gate when it is closed. If this is the source of the rattle it will sound familiar. Otherwise the problem is (2) the internal latching mechanism, associated rods, and the deadbolt wells. These can be too loose or out of adjustment, letting the lift gate or the mechanism move around too much. Here are some ways to mitigate the racket. It is all about pre-loading:
(1) There are two simple things you can do to keep the lift gate from moving around. First, check to make sure the deadbolts are extending as they should and that they are tight in their respective well. A little grease in the latch holes on the hard top will make sure they move freely. There are two Phillips head screws on the lower latch hole openings of the hardtop lift gate frames that allow a latch hole shim to be loosened allowing some movement and forward adjustment on the deadbolt holes. Move the hole shims as far forward as you can to establish good pre-load on the latch rods when closed yet not so much that you are unable to close the gate handle. You may need to push in slightly on one corner of the lift gate while turning the handle in order to close the lift gate after getting these proper and tight. That’s good. That is just more preload for the forces of racket to work against.
Second, there should be a thumb-sized metal post on the top of the tailgate that fits inside a small opening in the bottom of the lift gate when the lift gate is closed. Some think it is there to keep the tailgate from being dropped when the lift gate is locked, and others think it is to help center and stabilize the lift gate and tailgate with respect to each other. Whatever its purpose originally, this is probably the number one source of the problems and the easiest fix. Either the head of the post, or the hole in the bottom of the lift gate that it fits in when closed, should have just enough cushioning foam or soft rubber to make the lift gate tight against the deadbolts when the whole thing is closed and latched. The best thing to do is experiment with various placements of something that will help cushion the post and its hole and make the lift gate very tight when trying to close it. I prefer to put a replaceable strip of foam rubber inside the hole in the bottom of the lift gate. There is a small stainless steel hole guard that can be unscrewed and used to hold the rubber in place. If you get it too tight, you can’t close the lift gate. But if you don’t get it tight enough, you will not change anything at all and it will still rattle. You have to get it just right. This will last from one to several months until you need to “freshen” it up. Once done, however, it is a matter of two minutes to tighten again. So this is a permanent fix that costs next to nothing and will work until the end of time. At least it has worked for 30 years in my case.
Third, the original (cam-type) lift gate side props can rattle. But this is not too common as a source of noise. There should be a round rubber bumper on the inside of the lift gate on both sides that presses against the props when the lift gate is closed. Along the same lines, the weather-stripping for the lift gate opening can play a small role in making things loose or tight depending on the condition of the weather-stripping. But weather-stripping alone should not be used to isolate rattles. Pre-loads should be something mechanical and something with allowance for adjustment.
2. Tire Carrier
This is probably the number two source of rattles in most Broncos. The main cause is the original tire carrier latch mechanism allowing the tire carrier swing to dither against the latch on rough roads or when hitting a small bump in the road. There is a small rubber bumper on the latch to keep the carrier from contacting the body and there is a stainless steel sleeve that fits over the carrier where the latch grabs the carrier itself. The thing that gets out of adjustment or wears, especially on dusty bumpy roads is the lower, stationary “jaw” of the tailgate-mounted latch mechanism. After a while this gets (a) beaten downwards ever so slightly by the tire carrier jumping up and down on it for mile after mile, and (b) gets egged out or filed down by the carrier rubbing against it with abrasive silt and dirt. The fix is simple. If you have a welder of some sort, just add some more metal to the surface and file it for a smooth operating fit. Or take open the carrier, take a big pair of Vice grips and attaché them to the lower jaw of the stationary part of the latch, and lift upward trying to give the lower latch jaw or perch a very slight upward bending force, kind of like setting the gap on a plug: you can’t see it happen, but you get to where you can guess what force is needed to impart a slight bend to it. Do this until the carrier closes with a solid action. No more rattles, guaranteed. A little white grease helps lubricate the dirt better.
A secondary cause might be worn out bushings at the hinge end. There are nylon bushings similar to the brake and clutch pedal bushings that fit inside the hinge posts. The carrier hinge pins then insert inside of these bushings. This keeps the hinge tight, allows for wear, and gives a smooth hinge friction surface. There are two per hinge post, an upper and a lower one.
This is probably the least likely to be the source of rattles, but can contribute to some loud ones. Two or three things can be a source:
(1) There should be small rubber “dot” bumps on the body opening that pre-load and isolate the tailgate slightly from the body. See a rubber assembly diagram for the tailgate (as for example in any of the vendor lists of rubber parts) to identify these. If these are not present, then the tailgate can vibrate against the body or slap against the body. Start with these rubber dot bumpers first.
(2) When closed and the tailgate hangers are folded up, the hangers should rest against another set of rubber bumpers that are attached to the body inside the tailgate frame opening. If these are missing the hangers can slap around too easily with every bump. Again this is not as a common a problem as it is on some trucks, but it is a potential source.
(3) The tailgate release handle and mechanism can be loose from the linkage components or the “deadbolt” end can be misaligned. From slamming or just age the internal mechanism can get sloppy and lead to all sorts of hidden rattles. Some of the internal rods can be contacting the inside of the tailgate, or the rods can be loose enough to rattle in their respective perches. There are not too many adjustments but, to fix the loose rods, a strategically placed piece of soft rubber or foam rubber can fix the problem for years with little further maintenance.
When you get the combination of latches and bolts snug, you can drive over a washboard type road with no sounds coming from the lift gate, tailgate, or tire carrier. It can be done. It just takes the above fiddling, but mainly, it does not take any money to it.
Last edited by admin; 08/01/06 at 03:14 PM..
Reason: added byline