|
| 275 outdrive upper gear housing |
| Author |
Message |
    
Justin
Member
Username: thisjustin
Post Number: 8
Registered: 10-2009
| | Posted on Friday, November 06, 2009 - 05:02 pm: | 
|
Hey everybody,
I have an aq131 with a 275 outdrive and the bearing on the reverse gear siezed up. I got it all apart and replaced the bearing, sleeve, and got new shims that were on the parts list I have. In the manual I have it gets very specific about finding the proper measurements for the shim packs during reassembly. With all of the numbers I have it should be .27 mm on one side and I think .28 mm on the other. I'm wondering how critical this actually is since they do not sell shims thin enough to add up to these numbers. Has anyone ever taken one of these apart and put it back together?
Thanks in advance for any help.
Justin |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 748
Registered: 03-2009
| | Posted on Friday, November 06, 2009 - 11:10 pm: |
|
Justin, if you are running a Duo Prop or a LH single prop, you are driving from the lower "driven" gear.
The upper driven gear would then be your reverse gear as you describe.
You really need to find out why you lost this upper bearing!}
I've found that these bearings are manufactured with such precision, that you could most likely start out with the same shim under the bearing retainer (the shim between the retainer and the gear case) if you re-used the same retainer!
In many cases, this is a .008" shim. (start with what you removed)
You can check this if you know how to read a hypoid gear pattern and set back-lash!
The top cap shimming should be checked. It is critical!
One of the easiest methods is to "over-shim" and install the cap minus the gasket.
Just snug it down..... firmly, but not tight as you will for the final tightening!
Take a feeler gauge reading between the case and the cap in several areas around the perimeter.
Now reduce the entire shim pack by an amount that will still give you a .003" squeeze on the bearing/retainer when you re-assemble for the final time.
Example:
*If your feeler gauge reading is .020", reduce the over-shimming by .017"
*If your feeler gauge reading is .018", reduce the over-shimming by .015"
This (in theory) brings the cap/case clearnace to ZERO with a squeeze of approximately .003" on the bearing.
The squeeze is to simply lock/hold/prevent the bearing from spinning while under reversing load.
Very simple and gets you where you want to be.
(btw, this is the exact same procedure that will work when shimming a different transmission to an Intermediate housing)
Be sure to check the vertical shaft brass spit ring keeper for any expansion.
If the sides of it are not parallel to one another......., it needs to be replaced..... especially on a drive running the Duo Prop or LH single prop! (has to do with up-lift on the vertical shaft when under load)
BTW, this large driven gear bearing is an "Angular Contact" bearing...... it is directional.
IOW's, there is an UP side and a DOWN side to it. |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 751
Registered: 03-2009
| | Posted on Saturday, November 07, 2009 - 10:03 am: |
|
Justin, just to be clear on this.... Volvo provides us with a code number on each of the parts to be used in a forumla to calculate and determine the correct shimming.
Through calculations, this gives us a factory setting.
However, and regarding the top cap shimming, this is OK ONLY if no one has been in there before you and made changes to a new gear set, etc.
This is why I use the over-shim-and-deduct method.
The end result is the same, but the method to reach this is different.
One other thing that you may want to do (very cautiously, I may add) would be to mildly lap your brass sliding sleeve to each driven gear "cup" in order to break any glazing that may have occured.
It must be done using a very fine lapping compound and it must be thoroughly cleaned afterwards.
Again, there is a top side to the sliding sleeve when you re-assemble!
. |
Justin
Member
Username: thisjustin
Post Number: 9
Registered: 10-2009
| | Posted on Saturday, November 07, 2009 - 04:48 pm: |
|
Okay Ricardo, bear with me a little bit. I'm new at this. I bought the boat as a project. The guy I bought it from didn't have it for very long. The story I got was that it had sat for a long time before he bought it and the upper bearing rusted a little bit as a result of water/condensation in the outdrive because it wasn't properly taken care of before it was left to sit. When he bought the boat he just went and stuck it in the water without checking it out. The bearing seized up in very short order. When it seized it apparently spun the retaining ring that it sits in and trashed the ring and the shims. So re-using the retainer and shims is out of the question.
With that said here is a link to an exploded view for reference to make sure I'm on the same page.
http://www.volvopentastore.com/Upper_Gear_Unit_Drive_275/dm/cart_id.072715226--s ession_id.141777819--store_id.366--view_id.324030
Now by the top cap do you mean the retaining nut that goes on the end of the vertical shaft with the brass spacer ring? Number 53 in the picture. If that's the case then I understand that part. Thank you.
Now you said to check the "vertical shaft brass spit ring keeper for any expansion." I'm assuming this is a typo and you are talking about the brass ring (number 51) and the split ring (number 52) that go on the bottom end of the shaft. If that is so then those are in excellent shape.
You also said that the large bearing is directional. How do I know which way is which? There is a small curved notch in the outer race on one side of the bearing. I am assuming that goes out (or up away from the gear itself) just like the bearing on the lower gear. That is the only thing on the bearing that distinguishes one side from the other.
In regards to what you said about the code numbers and formula, that is where I came up with the .27mm for the shim pack between the upper bearing retainer and the housing. I cannot be positive but I am pretty certain that this is the first time this box has been taken apart. I believe I have the original gear set. This brings me back to my original question and I thank you for showing me that it's not that simple. It kind of makes my original question irrelevant. We are talking about just over a quarter of a millimeter and I was wondering what kind of tolerances I have to work with if I don't hit that number exactly. From what you are telling me it is my understanding that I'm just going to have to put it together and take it apart making adjustments according to the end result (the .003 gap under the top cap).
I'm sorry about writing a book here but I want to make sure that I get this right so that I don't ever have to do it again. I appreciate your help so much.
Thanks,
Justin |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 754
Registered: 03-2009
| | Posted on Saturday, November 07, 2009 - 06:13 pm: |
|
What I have called the top cap, the Volvo site is calling the gear case cover, # 4. Sorry, I could have used the V/P language on that! (most of us call this the top cap!)
What I am calling a "split ring" keeper is just that.... a brass split ring keeper that the Volvo site calls a "washer" #51.
It is indeed a keeper that captures a split ring on the vertical shaft. It takes a heavy vertical up-lift load against it. They do expand and require replacement.
To test one, you would place it in the jaws of a dial indicator caliper, hold it up to a light source, and see if the jaws make full and parallel contact with the perimeter! If you see any taper, it is starting to expand and needs to be replaced, IMO! (when these let go, the resulting damage is severe!)
BTW, I'm sure that you have by now realized that the top nut (# 53) is reverse thread!
Loc-Tite must be used when re-assembling this nut.
There is also a min/max clearance dimension for the "gap" under this nut. This clearance is directly affected by how much, or little, the brass split ring keeper has worn.
This nut is also available in several thicknesses to accommodate different over-all gear/bearing shimming conditions.
Hypoid gear experience is a real plus when working on these.
You are correct on the large double row angular contact bearing..... the ball relief's aim away from the gear..... this way the apposing thrust is placed against the opposite side of the bearing that does not have these relief's...... hence, they are directional!
When installed correctly, you will not be able to see the bearing number!
As for your last concern, you can obtain the correct shim value in one shot if you follow the method that I suggested for the top cap (gear case cover)
As for the shimming under the bearing retainer..........., well, again, this is where Hypoid Gear experience would benefit you. All shimming is critical! Toss a .008" shim in there to start out with! Use the gear pattern die of your choice and read the contact pattern.... see what you come up with.
The good part is, if you are running a LH prop, this upper most driven gear is your REVERSE gear, and the shimming (while still critical) is not as much so as if you were running a RH prop making this your FWD gear. Right now, this is your REV gear, and when in FWD, it is basically going along for the ride!
If I were working on this, I'd install the brand new bearing on the lower driven gear, and move the lower driven gear bearing up to the top gear.
If you want to email me, we could set up a phone call!
Maybe Morten and Mr. El P have some suggestions as well.
. |
Justin
Member
Username: thisjustin
Post Number: 10
Registered: 10-2009
| | Posted on Monday, November 09, 2009 - 07:39 pm: |
|
Okay, after reading everything you have told me and all of the documentation I have it all makes alot more sense now. The only other question I have now might change things a bit. When I got the boat the prop was not attached. I assumed that the upper gear was the reverse gear because that is what the book said. I double checked and it is a RH prop.
When you switch from a LH to a RH prop or vice versa does anything else have to be changed other than the shift linkage? It seems to me that the direction of the spiral splines on the vertical shaft and inside the sliding sleeve would make a difference, but maybe not. Would it be better to change back to a LH prop since I planned on buying a new prop anyway? |
Ricardo E.
Advanced Member
Username: ricardomarine_vp
Post Number: 763
Registered: 03-2009
| | Posted on Monday, November 09, 2009 - 10:20 pm: |
|
Justin, you had a question of sorts re; switching props and the dynamics of the spiral splined shaft;
Let me see if or how well I can explain this... sort of a test for me! 
We have three gears in the transmission.... agreed?
One is a "drive" gear......... two are identical "driven" gears with conical cups attached to them!
We have a spiral splined vertical shaft that drives the lower unit gear set!
We have an internally spiral splined Conical Sliding Sleeve that glides UP/DOWN on this shaft!
*Since both drive and driven gears rotate simultaneously (and continuously when the engine is running)........
*And since all Volvo Penta I/O engines turn only one direction (std LH rotation)............
*To spin the vertical shaft (and the lower unit vertical shaft) we engage the sliding sleeve with one of the rotating gear cups!
*We do this via the shift mechanism "shifting shoe"!
*The sliding sleeve is then pushed into a rotating gear cup...........
*As friction builds, the spiral splines force the sleeve further into the rotating cup........
*The sliding sleeve fights against the spiral splines until a limit is reached..........
* When the limit is reached, the cup and sleeve lock-up and then start to rotate at a 1:1 ratio.......
*Once fully engaged, the sleeve is the means of spining the vertical shaft!
Then when a prop hand is selected and linkage adjusted, our FWD and REV selection is a simple result of which gear cup the operator (via shifter/cable/linkage) selects!
So;
**Move the shift shoe UP, and we spin the propeller shaft for a RH prop.
**Move the shift shoe DOWN, and we spin the propeller shaft for a LH prop (or a Duo Prop drive).
*It is the same for moving the boat forward or reverse once a prop is selected and being used!
(The transmission doesn't know the difference, so to speak!)
It was very ingenious of the Volvo Penta engineers all those years ago! It makes setting these drives up for a twin engine application very simple and easy. And it's the only reason a Duo Prop is able to work as an I/O and yet have reversing capability!
NOTE on correct cable/linkage connection:
Yes, to change prop hands, we swap sides of the little vertical linkage piece..... nothing else!
It is important that we only swap the vertical linkage rod to make this change.... leave the shift cable as is!
(I say that because you'd be surprised at what some owners will do to swap prop hand!)
**A FWD shift (regardless of prop hand) is always a result of an "Extended" Shift cable at the drive.
**A REV shift (regardless of prop hand) is always a result of a "Retracted" shift cable at the drive!
As for which is better...... the LH or RH prop...??????
The 270/275 torque tab is not a good design. Not enough area, and it shares position with the exhaust outlet.
Some have better luck with the adjustment being more effective if running a LH prop.
I believe that most of these in a single engine boat were sent out with LH props!
Your call on that! |
Justin
Member
Username: thisjustin
Post Number: 11
Registered: 10-2009
| | Posted on Tuesday, November 10, 2009 - 10:52 pm: |
|
Thank you for all of your help. I didn't want to put any of it together until I was sure about all of it. It is so greatly appreciated.
Thanks,
Justin |
|
|
