FAQ’s: Reversing Gear

Any good quality automotive medium viscosity (50 to 90) gear oil works fine in the v-drive gear box. I have never heard any reports of any additive being beneficial. – Updated: February 5, 2004

So sorry to hear of your plight!

The short answer to your question is that you have to drill and tap a 1/4 X 20 hole in one of the other two “boss” areas in the cast iron pressure plate.

Access problems on most boats (“V” drive engines are the easiest to work on in this case) make it necessary to move the engine front into the cabin area so that this drilling and tapping can be accomplished. I’ve heard of quite a few folks who have successfully made this repair by having a second person hold a vacuum cleaner directly at the hole so that drillings from the “drilling and tapping” operation won’t fall down into the area below the reversing gear, and eventually into the crank case. I would also spray the area with carburetor cleaner, so that the chips will suck up easier.

You could also remove the aft housing and replace the reversing gear itself with one of our rebuilt units. They are shown in our online catalog with a product number of: OREV_01_226. Just search on “226” (without the quotes). – Updated: February 5, 2004

It’s entirely possible that your customer’s forward clutch adjustment is needlessly tight, although this would have nothing to do with worn clutch disks.

I would rotate the forward adjusting collar one notch in a counter-clockwise direction (as you would face the engine from behind). One notch should make a very noticeable change in the amount of force required to engage the forward clutch “detent”, and as long as the forward clutch assembly does not slip at high power settings, you can leave the adjustment in that new setting.

When reseating the threaded forward adjusting collar retaining pin, be very sure that the tip of the pin is definitely in the next notch. If the pin contacts the outer diameter of the collar, you run a great risk of breaking out a piece of the threaded hole in the fragile pressure plate. – Updated: February 5, 2004

It’s not uncommon for a prop shaft to turn slowly with the engine in neutral. Both forward and reverse are clutch functions, and neutral is nothing more than the space between the two.

Here are some suggestions that might enable you to minimize the degree to which your prop shaft turns:

1) Be sure that your shifting lever is positioned in the very center of the neutral range. The best neutral point might not be in the straight up position. With the engine off, place the shifting lever where you currently think the neutral zone is located. Then grab the prop shaft and try to turn it by hand. You may find that the shaft becomes easier to turn when you move the shifting lever slightly fore or aft from where you originally thought it should be for neutral. This position would be the neutral position for your particular boat.

2) Your neutral range might be needlessly small, which will make finding the best neutral zone more difficult. In this case, you might be able to enlarge the zone by simply backing off a bit on your reverse adjustment. You can find the complete adjustment procedure in Chapter 6 of our service and overhaul manual; but basically, you would have to turn the 3/4″ nut on the left end of the reversing brake band a half turn or so in the counter-clockwise direction (just like loosening a nut on a bolt).

3) The adjustment on your boat’s cable system might be such that your neutral zone is not centered well in terms of fore and aft travel. This can be especially troublesome in the case of pedestal mounted shifting levers where travel is somewhat limited compared to levers mounted on the side of the cockpit. – Updated: February 5, 2004

The slots on the cross shaft are to accommodate Woodruff keys (1/8″ X 1/2″), which are intended to keep the shifting lever from rotating on the shaft. Your keys must have fallen out when your lever came off of the shaft.

If the hole in your lever itself is somewhat enlarged, you may be better off to purchase one of our new shifting levers. They are made with a compression hub that makes them quite a bit more secure than the original levers.

If you order a new lever, ask our sales representative (Ken) at 610-421-4436 to have our warehouse tape a new Woodruff key to its handle; otherwise, the keys are available at most auto parts stores. – Updated: August 3, 2010

Your symptoms are much more indicative of a brace pin that has slipped out of the starboard ear of the brake band. You may remember that the only thing which holds the brake band in place, with respect to fore and aft positioning, is an arm called the “brace”. The brace, in turn, is attached to the brake band by the small tapered pin that is pressed into the starboard ear of the band.

Fortunately, you should be able to install one of our new brace pins without the need to remove the entire reversing gear from the engine. The pins are shown in the Kits and Accessories section of our online catalog, and carry a product number of KTAS_02_87.

The brace itself (in case yours might be broken) is shown in the Overhaul section under Reversing Gear and Drive Train. The brace has a product number of OREV_17_161. Unfortunately, the brace cannot be replaced without removing the shifting yoke and shaft, which means that the reversing gear will probably have to be removed from the engine.

You can order these parts online or by calling our telephone sales representative at (610) 421-4436. – Updated: August 4, 2010

FORWARD MODE ADJUSTING PROCEDURE

1) Place the cockpit shifting lever in neutral.

2) Recheck to be sure the reversing gear is in neutral by turning the prop shaft. The neutral position is at the point where the prop shaft turns most freely.

NOTE: If the forward clutch assembly is not in a good neutral position prior to adjustment, it will be very difficult to rotate the staked adjusting collar in step 6.

3) Remove the access plate on top of the reversing gear assembly.

4) Rotate the gear case cluster until the retaining pin of the adjusting collar is facing upward.

5) Loosen the retaining pin until the staked collar can be turned on its threads. It is not necessary to completely remove the retaining pin from its threads to turn the adjusting collar.

6) Turning the adjusting collar clockwise (as you would be facing the engine from the rear) will tighten the clutch disks when in forward. As a frame of reference, one notch on the adjusting collar makes a large difference and is usually sufficient to prevent slippage.

7) Retighten the retaining pin.

CAUTION: It is very important that the end of the retaining pin extends into one of the notches on the adjusting collar before final tightening. If the end of the pin presses on the collar itself (between notches), or if the pin is simply over-tightened, it is extremely easy to break the cast iron pressure plate.

8) Place the cockpit lever in and out of the forward detent several times to insure a proper “feel”. A solid detent should be felt while going in and out of forward, but the adjustment should not be so tight as to cause any concern that the ship’s cable and levers may be overstressed.

9) If, after readjusting the forward clutch assembly, the neutral position of the shifting lever in the cockpit is in an awkward location, you can adjust the cable shackle at the engine, or cockpit shifting lever, until the cockpit lever is in a more natural neutral location.

REVERSE MODE ADJUSTING PROCEDURE

1) When the forward mode adjustment is correct, recheck the reverse mode for proper adjustment. There should be a well defined neutral range when coming out of the forward detent, and reverse mode should be felt comfortably before the shifting lever in the cockpit reaches the limits of its rearward travel.

NOTE: There is no “detent” in the reverse mode.

2) If the shifting lever in the cockpit reaches the limits of its travel before reverse mode is securely established, turn the 3/4″ hex-headed nut of the reversing brake band clockwise.

3) If the reverse mode is reached too soon, and/or the neutral zone is so small that it is difficult to find a spot where the prop is not turning (one way or the other), turn the adjusting nut counter-clockwise.

NOTE: It is not necessary to remove the retaining spring in order to turn the nut on the reversing band adjusting bolt. – Updated: November 4, 2003

Both forward and reverse are achieved through clutch functions. Neutral is simply the space in the shifting lever’s travel between forward and reverse.

If it is difficult for you to find a neutral place in your shifting lever’s travel, it probably means that your reverse adjustment is set needlessly tight. If the adjustment on the reversing band is a bit tight, it will frequently appear even more tight as the mechanism heats up and expands. Proper adjusting procedure calls for setting up the forward mode first, using the adjusting collar just behind the pressure plate next to the forward clutch disks. Assuming that your forward mode is OK (meaning that it goes into a solid “forward detent” and does not slip under full power), you may be able to loosen the reverse mode a bit by loosening the 3/4” nut in the upper left corner of the reversing gear opening. This is the nut held loosely in place by a spring clip. You can turn the nut within this clip without removing it.

There is no need to have the reversing adjustment very tight. As long as you encounter reverse comfortably before running out of travel on the shifting lever, you’re OK. Remember that there is no “reversing detent,” so you have to hold the lever back to keep the reversing gear assembly in reverse.

After you have the reverse mode adjusted satisfactorily, you should be able to find a neutral place without too much difficulty. Do not expect to necessarily find the best neutral position with the lever straight up, or any other particular place in its travel. Once you find the neutral position on the engine’s shifting lever, you may have to adjust the boat’s cable system to have the lever in the cockpit be straight up. – Updated: November 4, 2003

While there are two sets of small pinion gears within the reversing gear assembly, neither forward nor reverse are achieved through the meshing or unmeshing of these gears. Instead, the functions of both forward and reverse are obtained through the engaging and disengaging of two separate clutch mechanisms.

The forward clutch assembly consists of six steel disks (three plain, and three bronze-faced) which are locked together when the shifting lever is moved into the forward detent. If the adjustment of the forward clutch assembly becomes slightly loose (meaning that the shifting lever goes into the forward detent a bit too easily), the clutch will begin to slip at higher power settings.

Remember that power delivered by the engine increases as RPM increases, so the instant that the clutch begins to slip, engine speed increases and the engine delivers more power. Increasing power with increasing RPM means that the more the clutch slips, the more it is going to slip. The resulting rapid increase in RPM gives the impression that the reversing gear has somehow “slipped out of gear”.

All that is necessary when the forward clutch begins to slip is to tighten the forward adjusting collar one or two notches. You can find the notched adjusting collar just behind the forward clutch disk assembly, near the center of the reversing gear. When adjusting the forward adjusting collar, pretend that you are standing behind the engine, facing forward. From this vantage point, you would turn the collar in a clockwise direction to tighten it (just like a regular nut). If you have the Moyer Marine Service and Overhaul Manual, Chapter 6 contains detailed instructions (with pictures) for adjusting the reversing gear.

Basically, the forward adjusting collar is like a large round nut with notches all around its circumference. It is kept from turning by a 1/2” hex-headed retaining bolt. When adjusting the clutch mechanism, loosen this retaining bolt just enough so that you can turn the adjusting collar, and then retighten the retaining pin. When retightening the retaining pin, be sure that the tip of the pin is definitely in one of the notches before applying any significant force. If the end of the pin contacts the collar between the notches, it is very easy to break the cast iron part into which it is threaded. – Updated: November 4, 2003

Grinding sounds in reverse are normal. There are two sets of pinion gears that are giving you reverse, and they are rather crude gears (not intended for continuous service). As long as you are able to engage reverse, you don’t even need an adjustment. – Updated: November 4, 2003

Unlike the forward mode of operation, the reverse clutch assembly has no detent arrangement to hold it in reverse. Sorry about that!

There is usually enough friction within the cables and levers on the boat (adding to whatever friction there is in the linkage within the reversing gear itself) to cause the reversing gear to hold in the reverse mode for a short while. This gives many people the idea that the reversing gear is somehow designed to stay in reverse once you place the lever to the rear, but this is not the case.

If you don’t keep pushing the lever back now and then, it will soon creep out of reverse. – Updated: November 4, 2003

Indefinitely. The forward clutch disks are faced with a very durable bronze material instead of the asbestos material used on automotive type of clutches (with which most of us are much more familiar). The forward clutch assembly is lubricated by a constant supply of engine oil flowing through, and around, the disks.

The in-service life of the forward clutch assembly is more like an industrial application (engage and stay engaged for long periods of time) than it is an automotive application (engage and disengage at every street corner). – Updated: November 4, 2003

The reversing gear is supplied with a constant flow of engine oil from the main pressured oil system of the engine. The oil flows out through a small hole in the aft end of the crankshaft (under pressure), directly into the gear cage assembly.

The gear cage assembly contains all of the major parts of the reversing gear, including the small pinion gears that provide reverse, the forward clutch disks and the operating cone which contains the “throw out bearing” used to engage the forward clutch assembly. – Updated: November 4, 2003

Pedestal-mounted shifting systems typically have somewhat less cable travel than those which are mounted on the side of the cockpit, which makes them very prone to problems associated with being able to reach both forward and reverse and still have a reasonable neutral zone.

It’s very important that the cable assembly is adjusted so that you’re able to engage the forward detent near the end of the travel in the forward direction. This adjustment is necessary so that you will have sufficient travel in the rearward direction to accommodate reverse, and still have a reasonable neutral zone between forward and reverse.

In the past, we have seen several pedestal-mounted systems where the range of cable travel had shifted so far in the forward direction that there was barely sufficient travel remaining to reach the forward detent before encountering stops within the cable system. In this configuration, whenever the forward adjusting collar is set to provide a “stiffer” adjustment, the additional force required to get the reversing gear into the forward detent results in the cable system reaching the limits of its travel before the detent is reached.

Universal apparently recognized that the notches on their adjusting collars were too far apart for accurate adjustment, and by the late seventies, they had redesigned the forward adjusting collars on their very latest engines so that they had notches considerably closer together for smaller adjustments. We now have adjusting collars manufactured which are modeled after these late collars from Universal. We offer these collars in our online catalog, and we install them in the reversing gears that we rebuild to sell on the catalog. Unfortunately, it is difficult to install these new collars in engines already installed in boats, due to limited access. – Updated: November 4, 2003