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Does anyone know ratio for 5432 w Hurth HBW-100

S

Scott Reed

Junior Member
Does anyone know the reduction ratio for M-40/5432 engine /w Hurth HBW-100 transmission. I ordered a new three bladed prop awhile back, and I think I'm slightly overpitched as I can't get tach beyond 2150-2200 rpm. Below is an exchange I had with the prop folks. I guess most succinctly, is the ratio 1.80:1 or 2:1? I'm hauling for some extensive work, and it'd be a good time to pitch the prop correctly. Many thanks.
Scott Reed
Querencia, E38-200
scott.reed@att.net

ps I suppose I could release compression on engine, engage the transmission, crawl into aft cabin, snake into the small space and manually turn the engine shaft exactly one revolution whilst measuring the transmission shaft response. But that's way too hard for a big fella to do all by himself. Far better to ask you Oracles.

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Sorry for the back and forth. I've conflicting information for reliable sources regarding the specs on the Hurth HBW-100 transmission.

The Universal Engine Manual that came with the Ericson says I have engine model #5432 aka #M-40. Further this manual says I have a Hurth transmission, model # HBW-100, and that the reduction ratio is 2:1.


In checking with two engine, transmission shops affiliated with Universal they both say the reduction ratio is 1.8:1 for this engine (5432), transmission HBW-100.

My inclination is to divide the difference and say the reduction is 1.9:1, which'll bring me within 5% on either side. Can you pitch the new prop based on this compromised 1.9:1 ratio? If I'm not dead on, I'll at least be closer to increasing or decreasing pitch if required.
 
footrope

footrope

Contributing Partner
Blogs Author
The PDF that I have of the Marine Diesel Owners Manual that covers the Universal line from the M-12 to the M-50 says the Hurth HBW-100 on the M-40/5432 is 2:1.
 
S

Scott Reed

Junior Member
Craig, thanks for the information...

Craig,
Many thanks for the information. Very much appreciate it. Though I'm still in a quandary - one of the earlier posts I discovered after my post was sent was from a fellow who actually did what I jokingly described - he relieved the compression, engaged the transmission (presumably in forward LOL), turned the engine shaft through one revolution and measured the output side of the transmission shaft. He said for his 38 the ratio was 1:1.79. So go figure. Looks like I'll have to crawl into tight spaces.
Scott Reed
Querencia, 38-200 #309
 
footrope

footrope

Contributing Partner
Blogs Author
Good luck Scott. You have to give some credence to the experts because manuals are wrong all the time.

Since you're doing the measurement I won't add it to my own pre-cruise checklist. But, I think you meant to turn the engine crankshaft one rev and measure the rotation of the transmission output. You can turn the engine from the cabin - all nice and comfy.

I have a three-blade feathering prop and I love it.
 
R

rwthomas1

Sustaining Partner
FWIW, I did exactly what you described to get an idea of the ratio in my Hurth 100. No need to even relieve compression, the engine will turn over easy enough if you just grab the crankshaft pulley firmly and turn it. Had the wife outside watching the prop. I did two complete engine revolutions which "should" have resulted in one full revolution for the prop for 2 to 1. It did not, prop was a good bit past so the ratio is the 1 to 1.8 option instead. This is easy to do on the hard. RT
 
Rocinante33

Rocinante33

Contributing Partner
Scott,

ZF bought out Hurth a few years back. That model is now called a ZF-10. It may have been available in either 1.8 or 2.0, so it does pay to check the rotations for yourself. There is a lot of info available on ZF's web site, like this;
http://www.zf.com/corporate/en/company/organization/divisions_business_units/marine_propulsion_systems/matching_tool/matching_tool_large.html

There is an earlier thread here about my transmission woes...I was converting from the HBW50 to a new ZF 10.

Good Luck
 
G

gregdettmer

Member I
I have a 1981 E38, which I am refitting. The Engine and Transmission separated are sitting in my garage and I finally got around to checking the transmission ratio. Based on Marking the input shaft and the output shaft, then rotating the input shaft I found the following:

In Forward I get a ratio of 2:1
In Reverse I get a ratio of 1.8:1

I was surprised by this finding and retested a number of times, with consistent results. I will be opening the transmission soon for Overhaul, and will be able to report in detail on the gears.
 
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footrope

footrope

Contributing Partner
Blogs Author
gregdettmer said:
I have a 1981 E38, which I am refitting. The Engine and Transmission separated are sitting in my garage and I finally got around to checking the transmission ratio. Based on Marking the input shaft and the output shaft, then rotating the input shaft I found the following:

In Forward I get a ratio of 2:1
In Reverse I get a ratio of 1.8:1

I was surprised by this finding and retested a number of times, with consistent results. I will be opening the transmission soon for Overhaul, and will be able to report in detail on the gears.
Click to expand...

Greg, you are the new transmission expert on the board.

The rest of us were only half right. :thepaw: high four

Welcome to Ericsonville.
 
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P

Pete the Cat

Member III
Ralph Hewitt said:
All good...BUT what should the 3 blade pitch be?
Click to expand...
Great question. Answer: it depends. David Gerr wrote a book called "The Propeller Handbook" which explains the concepts. And the calculations are frequently off--even by the calculations of the prop guys. Depends on many specifics of your boat.. It is quite expensive to haul and repitch to find this. I have an externally adjustable feathering prop on my Tartan which I have tweaked over the years for different loads and conditions. One of the best long term investments that I made 20 years ago. Having said that, my new-to-me Ericson has a fixed two blade prop that someone (I am thinking it was the factory guys) got nearly perfect. So you might be able to get very close if someone has your exact vessel.
 
R

Ralph Hewitt

Member III
What is the size propeller and pitch for a 1982 Ericson 38 with a 5432 Universal.
Any ideas on how to find the specs?
I have asked and surched for 2 days.
THANKS
 
Loren Beach

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
From a quick search on line for the 5432 engine, and finding a couple of used ones for sale, the sites claim the Hurth 100 is a 2.0 to 1 ratio. Interesting that this was the ratio on our former Hurth model 50, on our 23 HP Universal Model M25XP engine.
 
Dave G.

Dave G.

1984 E30+ Ludington, MI
Ralph, If you can't get to or read the stamping on your current prop there are some calculators on line at various prop suppliers. You will need to know the max rpm of your engine and trans ratio. You can also "get a quote" from prop suppliers and they will compute it for you. I am a little surprised that no one with a E38 hasn't responded with factory specs but they still might. From google searches I did it seems Ericson supplied a 16" x 13" 2 blade prop with your engine.
 
R

Ralph Hewitt

Member III
Dave G. said:
Ralph, If you can't get to or read the stamping on your current prop there are some calculators on line at various prop suppliers. You will need to know the max rpm of your engine and trans ratio. You can also "get a quote" from prop suppliers and they will compute it for you. I am a little surprised that no one with a E38 hasn't responded with factory specs but they still might. From google searches I did it seems Ericson supplied a 16" x 13" 2 blade prop with your engine.
Click to expand...
Thanks Dave, that is Most helpful.
Like so many others... over 70 years of sailing never thought much about propeller size or Pitch.
Until something like this happened.
Yes, we call All learn New things every day. Thanks for your help.
 
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