Changing From Reduction to No Reduction

[wclanin]

I recently purchased a used A4 from an associate who had replaced it with a new diesel. The A4 was removed from a mid 80's Islander 36. I plan to replace the frozen A4 in my 1976 Catalina 27. There are some differences between the installations, most of which I believe I can handle. The major difference in the set-up is the reversing gear. The A4 from the Islander has a reduction unit attached. The A4 in my Catalina does not. So, I plan to swap the reversing gears. I have read the earlier forums on this subject. It is pretty clear what needs to be done. My questions are as follows:

What gaskets should I plan to replace?
Aside from those mentioned in previous postings, what are potential pitfalls?
Has anyone developed special techniques that make the job less risky or easier?

I would also appreciate any general comments on the engine change process.


Thanks in advance,

Wes

[Don Moyer]

Wes,

In most cases you will need the following gaskets to change a reduction gear engine to a direct drive:

1) A set of oil pan gaskets

2) An aft housing gasket

3) A pair of rear flange gaskets

4) A water pump flange gasket

5) An accessory drive gasket

6)A reversing gear cover gasket

I'm also attaching a pdf file to assist in removing your engine and a pdf file to assist in removing your direct drive and replacing it on the engine that now has the reduction unit installed. After the bell housing is removed from the reduction unit (retained by six 9/16" coarse-threaded bolts), the rest of the operation is much the same as removing a direct drive reversing gear, except we do not recommend removing the small gear attached to the tail shaft of the reversing gear unless it is unusually loose.

Don

[wclanin]

RE: Reduction to No Reduction

Don,

Thanks for the rapid reply. This has been my first posting experience and I have to say, the service is great.

As I suspected, it appears that you are suggesting to replace the pan gaskets. I was hoping to avoid this, but I do see the necessity as the instructions call for loosening the pan bolts. I don't think that one can bank on not damaging the gaskets that have been in place for 20 + years.

I have ordered the gaskets you mentioned plus an exhaust flange gasket. I also ordered gaskets for the water jacket cover, the thermostat housing and the waterpump backplate. The engine is new to me and I plan to flush out the water passages. I have seen the info about the side plate, T-connection and the issue of water distribution. Does it make since to go ahead and replace these items considering the age of the engine (mid 80's) and the fact that I'm well into it at this time?

FYI....The engine has registered a little over 700 hours. The top end was reworked at about 450 hours. The previous owner passed along lots of spare parts, the manual, tons of MMI bulletins on the A4 and confidence that it was pretty well maintained. The rust to iron ratio is very low.

Thanks again for your help,

Wes

[Don Moyer]

Wes,

I'm glad you checked back in. The instructions I sent you are copied from our service and overhaul manual and were written within the context of a complete rebuilding operation. Step 2 in the reassembly section can be omitted when you're performing the removal and replacement of the aft housing as a separate operation. In your case, if the aft ends of the oil pan gaskets survive removal of the aft housing, simply leave them in place. If either of the gaskets self-destruct during removal of the housing, take a sharp utility knife and make a sharp cut directly behind the block. Then cut the exact length of gasket you need from one or both of the new gaskets. Put a generous amount of sealer where the new section of gasket meets the old and you should not see any leakage in that area.

How much other work you tack onto a project is always a tough call. I always tend to let my projects grow until I miss half the season, so I'm the worst person to advise you on this matter. Your wife or "significant other"
is the best person to ask.

Don

[wclanin]

What to do? What to do?



Don,

As with most of us, I assume, I've not gotten on to my project as rapidly as hoped (too much time on other boats). I have opened the reversing gear covers and examined the two reversing gears. As it turns out, the unit that is still mounted on the replacement engine appears to be in better shape (it is ~10 years newer). The older unit has had some work done on it that is somewhat jury rigged. Also, the older unit did make some pretty loud noise (whine?) when in reverse. Does is make sense to consider removing the gear reduction from the newer unit and keeping the newer reversing gear on the replacement engine? If so, are there special tool, technique or feasability considerations?

Thanks,

Wes

[wclanin]

Seeing is Believing

Don,

I went forward with the removal of the two reversing gear assemblies as described in the MMI literature. Once I got everything apart and got an eyeball on the works, understanding began to commence. I believe that in order to swap out the reduction gear, one must swap the shafts within the reversing gear assemblies. Upon reaching this conclusion, I decided to perform a good inspection of the reversing gear from the old engine. I found nothing particularly wrong. I did notice that the surface where the brake band rides is a little rough compared to the newer unit. I suspect that this is due to a mis-adjustment of the band and may also have something to do with the whining noise during reverse operation. I have decided to move forward with the original plan to simply swap the reversing gears.

There is no damage to the pan gasket. Do you recommend simply cleaning the surfaces and applying gasket compound?


Regards,

Wes

[Don Moyer]

Wes,

There are two challenges involved in retaining your better reversing gear:

1. You will have to remove the small gear at the end of the tail shaft of the reduction unit. These gears will sometimes slide off rather easily, but most of the time they have been pressed on, to the point that they will require the assistance of a machine shop to remove. This is not usually a big deal for a machine shop (maybe a $25 job), but it will require a puller that most do-it-yourselfers would not have on hand.
   
   
2. You will have to disassemble both reversing gears to exchange the tail shafts. This is also not beyond the services of a good machine shop, but it will require a 12 ton press to remove the tail shaft from the gear cluster inside the gear cage assembly. Instructions for doing this are in Chapter 6 of the MMI Service and Overhaul Manual. Pay particular attention to steps 4 and 5 in the procedure, and give me a call if you have any questions.

Don

[Don Moyer]

Wes,

Yes, you're quite fortunate in finding the gaskets on both sides in good condition.

Don