Retrofitting Velvet Drive In Place Of Hurth

[forsailbyowner]

I'm putting together an offshore 33 that has a universal diesel and hurth gear. After reading about the Hurth looking at parts prices and expected lifespan I don't want anything to do with it. Anyone ever retrofitted a velvet drive in ones place? I can see needing an adapter plate on the bell housing, a damper plate to fit the borg warner spline and possibly drlling flywheel and a cooler. I'm seeing fresh velvet drives for $750, half the price of the pos hurth. Foley diesel mentions hurth as being the 1$ an hour transmission. Generally last 1000 hrs and cost $1000 to rebuild.

[Blue Stocking]

Can you direct me to the site which shows Foley comments about Hurth?
My HBW 150 was installed in 1985 on a westerbeke dated march 1970.
Box has 2500 hrs, about 1500 of which were run when the boat was in the day charter business licensed for 18 passengers.
No maintainance other than fluid changes.
B/ws are good boxes, but heavy and complex IMHO.

[forsailbyowner]

Originally Posted by Blue Stocking

Can you direct me to the site which shows Foley comments about Hurth?
My HBW 150 was installed in 1985 on a westerbeke dated march 1970.
Box has 2500 hrs, about 1500 of which were run when the boat was in the day charter business licensed for 18 passengers.
No maintainance other than fluid changes.
B/ws are good boxes, but heavy and complex IMHO.

ZF/Hurth Marine Transmissions: A Six Step Program | Foley Engines

[forsailbyowner]

places like the engine and trans are where I want heavy. I know of 3 people at this moment who's boats are without power because of failed hurth gearboxes. Maybe yours has the upgrades Foley mentions that prolong life. I've seen 2 recently with holes corroded in the case and the oil pan at the same level isn't corroded at all.

[forsailbyowner]

Anybody? Posed this question to a transmission rebuilder. Will post his reply once it comes in.

[Blue Stocking]

Read the info on Foley site.
Wouldn't give up my Hurth based on the "6 tips"
3 of them, pitching their ATF, their cooler, and their upgrade from 100 to 150, sound too much like a commercial.
Read the other site info extensively, where they state that Hurth boxes are good, if not undersized, overloaded, or abused.
IMHO, same could be said about any transmission.
AAMOI, I have worked on B/Ws where the ATF was cooked like shellac and the plates where heat-blued.
But they are good boxes, the B/ws I mean.

[forsailbyowner]

I just looked again at a friends hurth gear I don't really understand what's going on in there. The transmission corroded through from the inside out. The inside of the case is filled with white powder that used to be the case. A slight tap and the case falls apart. It was never under water and there's no cooleror anything to leak saltwater in. I saw another in the same condition that I thought took a saltwater bath, now I wonder. I've been looking at the 71c with direct drive. It takes up less space for and aft which would become an issue with the addition of the gear reduction. Will be headed to the junkyard to compare cases, mounting bolt patterns, shaft lengths etc when I get back to the Tampa bay area.

[Suijin]

The ZF15MIV in my Valiant is 27 years old, with thousands of hours on it and it's doing great.

The way I read the article that you linked was that if you take good care of your ZF then you won't have a similar experience as the owner cited at the beginning of the story.

I think three friends is not a good sample size. Sounds to me from what you saw in your friend's transmission that it was neglected. I change my ZF fluid when I change the engine oil, and I check the level every 5 operating hours or so.

Of course, only you can put a price on your peace of mind. If you doubt the transmission because you don't know it's history and you have the coin to replace it, go for it.

[oldcal46skipper]

I have been rebuilding gears for about 40 years. I will not work on a Hurth, ZF or Kanzaki. Like Foley's Dr. Diesel says, "They are a dollar an hour gear." I have BW Velvet Drives in two of my boats, my Cal Cruising 46,Perkins 4.236 and BW 71C and my Ski Nautique, Ford 351 and BW 71C. Why? Because I don't need to work on them, just change the oil as directed.