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Change out drives Volvo

T

trobador

New member
Here's the scenario:

I own a 24 Bayliner Volvo Power with a dual prop out drive 280. Now I bought a 28 Bayliner also Volvo power with a 270-T out drive which is also Volvo. They are both V-8 5.7 and I am wondering how much work it will take to swap the out drives and install the 280 dual prop on the 28 footer, and which is the best way to go about it.

Thanks a lot for your help,
Trobador
 
I'd first verify the over-all gear ratio by removing the prop shaft ring anode and revealing the numbers that will be stamped into the bearing carrier.
If it is the 1.95:1 DP lower, then yes, it will work on your 28 footer with the correct prop set.
Probably a B2.... maybe a B3 set.
(all uppers in this series are of same ratio)

NOTE: Critical shimming adjustment must be done to the vertical shaft bearing race when swapping lower units.
The original race from the DP will need to be carried over to the Intermediate housing of the 28 footer (and visa-versa).
Shim this according to OEM procedure..... it is shown in the OEM service manual!
BTW, this is a negative pre-load!


The Duo Prop drive oil now changes to GL 5, and the smaller boat (with the single prop drive) now goes back to engine oil!

Easiest is to change the lower unit only..... but not at the cost of forgoing upper unit maintenance.... i.e., new Bellows, U-joint bearing crosses, main drive seal, etc.

It takes me almost as much time to properly R & R the drive oil as it does to calculate the shimming.
The install is easy.

To swap both lower units, you will need a total of eleven (11) new O-rings; 2 for pivot tube, 2 for center bearing, 2 for oil drain back tube, 1 hollow bolt O-ring and 2 dip sticks and 2 drain plugs!
Don't forget the one 280 fill plug gasket (270 does not have typical fill plug).


I'm the PDSB (primary drive shaft bearing) NAZI, so if you have not yet replaced these, I'd strongly encourage you to do so!

That DP will make your 28 footer happy! :D

Have fun!
.
 
In short, this is a negative pre-load in-that if we compare it to a pre-load where we can take a rolling torque value reading, the pre-load is normally positive.
(i.e., as we increase the shim value, the rolling torque value increases, or visa-versa.)
With this, the shimming of the angular contact bearing sets the "drive" to "driven" gear contact (or gear back-lash).
(the angular contact bearing is directly beneath this tapered roller bearing)

Volvo wants a shim value above this race to be minus .001" to .0015" from ZERO....... hence what I am calling a negative pre-load.
If we were to shim this on the + side, we are now pre-loading two bearings beyond what Volvo wants.

This goes for both the AQ series DP and single prop lower units since each bore depth in an Intermediate housing is unique!

This is explained in the OEM service manual and shows how to determine the correct shim value above this race!
It's actually quite simple, but requires skills that are in step with any Hypoid gear work!
If not up for the task, it may be best to have this done by a tech.... or have someone walk you though it!
 
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Thanks a lot Ricardo,we will read on and let you know.One more question we have a spare 270 complete and we like to use the tilt motor from the 270 on the 270T can the interchange from the 270 to the 270 T be done
Thanks
Trobador
 
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I'd like to ask if this is correct on shimming.........

I'm in the same boat, so to speak! (swapping lowers)

1- Measure bore depth of intermediate housing.

2- Place cone (of bearing race) on lower bearing and measure height of cone.

3- Utilize shims to achieve the dimension of .001 to .0015.
(clearance, i.e. negative pre-load)

4- Assemble two parts utilizing new o-rings.

I could swear my shop manual states .001 to .003 inches, please advise ,
if that is incorrect.

John
 
John, you are correct.
However, I shoot for the dimensions that I posted.
The .003" is at the high side of the tolerance.
Also, the two cases never quite close the gap to absolute zero.

One thing that I will say, is that taking the dimensions is the tricky part!!!!!
You'll find that no matter how many you have done, no matter how good you are, you will always come up with several readings.
What I do is take about a dozen reading for both the "A" and "B" measurement.
I go with the reading that I come up with more consistantly......... not average...... but more consistantly....... and then I do the math!

I've not had a failure due to this. (knock on wood) :eek:

NOTE: Make sure that the vertical shaft end play (up/down) has been eliminated and is fully DOWN and with the race fully tapped into position before taking this part of the dimension!
If doing this eliminates gear back lash, you will need to check the shimming of the angular contact bearing before proceding!
The angular contact bearing sets the initial control!
 
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