Vdrive Rebuild Question

[SONIC]

So my Vdrive has a loud-ish whining noise.
I should have rebuilt it while the motor was out but I didn't (forgot about it honestly)

Anyway, how tough is the rebuild? Should I send it to walter or do it myself?

Last question, is it possible to change the gearing while I'm in there? I've got a 1.52:1 now and I know the newer boats come with a 2:1 is that a worthwhile swap if possible?

[Jetdriver]

What fluid are you running in the drive? I know 30 weight is supposed to quiet it down some over ATF.

[SONIC]

What fluid are you running in the drive? I know 30 weight is supposed to quiet it down some over ATF.

It's got 30 weight in it. It's just got a pretty loud whine. When it was out of the boat it would stick after sitting a while and not want to turn until broken loose and when I got the boat the fluid in it was milk.
Fluids nice and clean now but it still has the whine. I'm betting on a bearing.

[chpthril]

Ive rebuilt auto's, manuals, transfer cases and diffs. I can imagine a v-drive would be too tough. Seals and bearings for sure, then maybe a gear set.

[SONIC]

Yeah there are no complicated parts should be fairly simple.
i just ask because I've read the parts for a rebuild are around 1000, but I have seen several threads where walter will rebuild and test for 1200, seems a no brainer to just have them do it.

I suppose I'll reach out and ask them lol

[chpthril]

$1200 could be a good deal. The unknown is how much in hard parts, you actually need.

[SONIC]

So theory question here:
What's better? Dropping the prop down another pitch or swapping the vdrive gears?

Say an equivalent change in ratio, which is more advantageous?

[SONIC]

Spoke with walter, they said roughly 480 in parts and 8hrs labor to rebuild at 96/hr. So 1250 to have them do it. +shipping there and back.
Said roughly 1000 in parts to change gear ratio.

[chpthril]

Lower pitch raises RPM, larger dia wheel lowers pitch, BUT, also takes more power to spin up. So the pug advantage to the lower gear, is running the larger props without robbing all the engine power. The larger props can give us some added prop performance, that we sometimes go down in pitch for. What this does is offset the RPM increase we get from just a pitch drop.

[SONIC]

Lower pitch raises RPM, larger dia wheel lowers pitch, BUT, also takes more power to spin up. So the pug advantage to the lower gear, is running the larger props without robbing all the engine power. The larger props can give us some added prop performance, that we sometimes go down in pitch for. What this does is offset the RPM increase we get from just a pitch drop.

Yeah, in my case though I can't run a larger prop, I'm already topped out.
So is there anything to be gained by having a lower final drive ratio and a higher pitch prop spinning faster?

I guess what I'm asking is should I drop the gear ratio in the walter and go up a pitch in prop, or should I just drop another pitch down on the prop and call it a day.

[Jetdriver]

Sounds like your due for the rebuild then. If it’s the same cost I don’t see any disadvantage of gearing the trans down. It was originally built as a ski/wake boat and intended for higher speeds. If your planning on mostly surfing loaded up then the engine wouldn’t be working as hard if geared properly for that. I’m no expert but that makes sense to me. You may lose more top end than you want but like you guys have said there is still quite a bit of adjustment to be had by switching props out. It’s good to have a couple pitches anyhow to swap out when at different elevations.

[NICKYPOO]

^^^I agree. If you’re going to spend most of your time surfing, why not change the gears.

[chpthril]

It takes less power to drive a lower pitch prop. This is reflected in the improved hole shot and higher RPM as we go down in pitch. I have not done gear calculation in a long time, but if my oldass memory serve me right, going up in ratio, is going to increase rpm, even with the existing pitch prop. Then going down in pitch raises rpm again.

[SONIC]

I don't think I'm asking the question correctly lol. I understand how the rpm and gear changes work, I just don't know how the efficiency of the prop plays into it.

Lets say theoretically we have 2 boats with the same overall final drive ratio.
One achieved this with a 2:1 trans and a higher pitched prop. (say a 14x16 for argument sake)
One achieved the same ultimate gear ratio with a 1.5:1 prop and a low pitch prop (say 14x12)

Is one scenario better than the other?

The boat with the 2:1 trans will have a slower spinning prop with more torque, where the 1.5:1 guy will have less torque from the motor but compensate with the faster spinning prop.

So i guess that breaks it down as far as I can. So the question is:

Is it better to put more torque to a higher pitched prop, or more RPM to a lower pitched prop?


(PS I didn't do the math on the ratio's above they are just examples for theory discussion)

[Zackdogg]

After dealing with a 1.5:1. Knowing the people running 2:1 aren’t struggling like I am with weight and elevation. And knowing all the manufacturers are going to these 1.76:1 and 2:1 drives on boats with this kind of weight, I’m convinced I need a 1.76 or 2:1..

I think you use the gearing to push the weight, and up the prop pitch, if needed to bring the revs down to where you want to be.


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