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problems with resealed Frankenstein AQ outdrive

T

tedm2

Contributing Member
I have a SP-A upper with a 290DP lower
I had shift problems last year so I pulled apart the upper transmission but ended up resealing the transmission and replaced the u-joints.
I am having to assume that the lower unit oil had degraded enough that the unit had too much friction. Not sure since the oil might have had all of 25 hours of use but everything looked brand new when it came apart.
When I went to put it back on the outdrive one of the trim seals blew so I decided to go ahead and reseal the lower unit as well since it was off.

Now that everything is back together shifting is great and all sounds ok but I am only turning 2900rpms at WOT. I used to get 4400. Top speed is also down 12mph

My engine temp is also running 25 degrees hotter. Not sure if this is from the engine working too hard or something else from removing the outdrive.
Could not look at the oil today rain poured as soon as we pulled the boat out.

Any ideas on what I may have done to cause the loss in rpms?

I figure I'll have to work on the temp problem after I get the outdrive back to where it should be.
 
tedm2 said:
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Now that everything is back together shifting is great and all sounds ok but I am only turning 2900 rpm at WOT. I used to get 4400. Top speed is also down 12mph
Click to expand...

It's doubtful that the work to the drive would have anything to do with this.

By the way, with the [FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]SP-A upper and a 290 DP lower, the gear oil will be GL-5 or equivalent.



.[/FONT]
 
used 80w90 gear oil from NAPA
per label
[FONT=Aileron, Arial, sans-serif]Gear Teeth Wear Protection From Pitting & Scouring. Recommended For Differentials & Non-Synchronized Manual Transmissions Where An API GL-5 Or API GL-4 Fluid Is Specified[/FONT]

[FONT=Aileron, Arial, sans-serif]Could I have over tightened the top plate or something else in the transmission?
Engine will turn 5500rpms in neutral which has no load.

[/FONT]
 
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tedm2 said:
Could I have over tightened the top plate or something else in the transmission?
The top cover will be fully tightened down against the main gear case.
There are shims inside of it that squeeze against the upper gear bearing.

In other words, NO..... it would not have anything to do with your problem.

Engine will turn 5500 rpm in neutral which has no load.
A no-load RPM is rather meaningless.

Click to expand...
 
So I have been mulling over possible reasons for the drop in rpms. Shown the manual to a couple car mechanic friends and the only thing that pops out at all is replacing the front seal at the transmission.
What would be the outcome if the scale was off and I ended up tightening the bearing box a 1/2 pound or more tighter than the manual states for used bearings?
Instead of 2.2lbs what if it was actually 2.75lbs or even more.
I'm trying to get the scale back to test it's accuracy.
Upper has less than 50 hours on it.
 
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