Hurth HBW100 problems

[evaneus]

Hi,
My Hurth gear with 300 hours on it slipped the other day, I have a 25hp 2008 Universal. It slipped when going from idle forward to 1500 rpm, it kicked in with a clunk at the higher RPMs. The cables are adjusted correctly and it engages immediately at idle.

I checked the oil and it is dark brown/black and totally opaque.

My understanding is that once it is slipping, it needs to be serviced/replaced. Is that true?
I am in the Bahamas en route to the DR, so I probably will not take any chances and get a new one anyway, but this is the second tranny and I only have 560 hours on the engine.

I didn't foul the prop or anything, but I did notice that the tranny rattled a bit in very low revs, I could adjust my idle up but I don't know if this rattling is the kind of thing that could lead to this slipping. I spoke to Foley who I bought the gear off, and they said the oil being that color and the slipping probably means it had overheated.

Assuming I get a new transmission, any advice on how to keep it in good health would be appreciated. I don't want to have to replace another one.

One thing I was wondering was if I got a gear with a slightly lower ratio then it might go easier on the gear while losing some efficiency. But there's no reason this gear should not be able to handle the 25hp engine and 13000lb boat.

Thanks for any tips...

[joethecobbler]

Welcome to the world of hurth transmissions. I also had a hurth 100 and I can assure you that the slipping is indicative of a failing trans. When it will totaly fail cannot be known.
Oddly, according to the hurth websight out of SW Florida as per their specifications 300 hours behind a 25-30 hp. engine is all they idicate is to be expcted with what they refer to as recratioal use ! rather hard to believe !
After I "re-built" the H-100 the first time it lasted the exected time (about 3-400 hrs behind a 30hp) and began to slip once again.
Rather than re-pair/build a second time I found a H-125 which is only about 1/2" longer than the H100 but is rated for (if I remember) a 50hp engine application. I purchased the H125 used and ran it many hours thus far (I would need to check the engine log ) and it seems to be hoding up.
I'm not a fan of Foley engines as I've read on SN that they utilize inferior aftermrket parts, and charge Waaaaayyy too much.
If you do decide to re-pair your tranny it is relatively easy w/ the failed part usually being the bronze/brass thrust washer (I think it cost me $40) there are 2 ,one for forward-one reverse. you'll probably only need the forward one. This is a designed wear item. when you dis-assemble the unit you can measure the wear of each part and you will find the washer worn beyond spec. and probably little wear on the clutch discs. the spacing upon assembly is the critical measurement. too loose -slippage, to tight - excessive heat and wear leading to earlier failure.
So get a god set of feeler guages,micrometers,and a 2-5 ton press , study the trans. manual and mentaly prepare yourself for the dis-assembly and re-assembly . It's not that daunting a task,really !
Or find a H125 or 150 and shoe-horn it in place of the old H100 .
I did mine while at anchor both times. After changing to the H125 I had to also change the propellor as the ratio of the tranny was different. the saving grace was I found good used R19-11 prop. for $300 and the old one was all done anyway (red,sign of iminent faiure).
Changing the ratio will most likely require a different prop. Unless the prop you currently have is sized improperly which could lead to early tranny failing due to excessive heat, the bain of the hurth tranny.
A heat exchanger is available for these trannies and is a good value due to the fact that the engine comparments on sailboats are often poorly ventilated creating a bad envroment for heat challenged equipment. you indicated you were in the tropics. Also frequent oil changes (only uses about 1/2 quart) and switching to synthetic oil will help disapate the heat better.
good luck.

[evaneus]

Thanks,
I am short for time so I'm not sure if getting it rebuilt here in the Bahamas is going to be an option - I have no idea where around here might have a press, etc to fix it.
I called ZF and Foley, and they both said that this transmission was not really intended for continuous duty. Despite what the brochures appear to say.
When you put the H125 in at anchor, I take it you did not shorten the prop shaft? Is it significantly larger? The space is tight around the back of my engine, but I'd happily put a 125 in if that might last longer, I'm not sure if I have a spare 1/2" behind the prop shaft.
Getting a prop might quickly might be a tall order here too, so if I was to go for a bigger ZF I'd hope to find one with a close ratio.
Apparently there is a PRM one that might be an option.

[evaneus]

It looks like this transmission is just not rated for continuous duty (they don't explain exactly what that means, anyone know?)

Here is the spec sheet:
http://www.marinepartsexpress.com/pr...07/ZF_10_M.pdf

At the top of the document it says it is rated for 37hp continuous duty (which may be a typo) If you look down to the details it looks like at lower RPMs it is only rated for a 14hp at 1800 RPMs continuous duty. 27hp at higher RPMs.

I'm not sure if I'm reading it correctly but if I am I wish someone had told me about this before putting either of my last two ZF10s! I did say I was intending to do 2000 miles or so up and down the ICW.

[joethecobbler]

the h125 is only about a 1/2" longer. same dimension otherwise. I just slid the shaft back a bit then the next time I hauled I pulled it and shortened it.
As far as the duty cycle, yea- they (h100) are ratedfor 300hrs "recreational use" continuous or commercial use is MUCH less,hence your issues.
If you can get a H125 or H150 it would be money well spent.
I would avoid Foley - just search the SN forums and read for yourself.
You can "knock" the H100 apart dockside w/ a wood mallet and knock it back together to replace the bronze washer (I have done this) , but it won't last under your usage and you have to be "Handy" to get it close to right.
But, it'll get you there in a pinch.