Hurth transmission questions

Hello All,
I have the Universal 5432 with what I am assuming is a Hurth transmission in my E38. I don't have a manual for the transmission which leaves me with some questions:

1) How high should the oil level be on the dipstick? There is a line on the stick but it is at the very bottom end of the stick and I can't imagine thats the full mark..... Right now the oil level is about 1/4 of the distance up the stick. I changed the oil today, removed 20 oz's, sucking it right out to the bottom of the unit and put 20 oz's back in.

2) Is there a way to tell what ratio the transmission is? I would like to reprop in the near future and need to know.

3) I am assuming the trans is a Hurth. Looks to be original. Is there any way it could be anything else?

Thanks, RT

Hurth Tranny Manual

Take a look at another thread I started on my Hurth Tranny Hurth Noise in Fwd (Tranny Removal ?). I got a deal on my manual which worked good for overhauling a HBW100 (ZF10) which may be the same as yours. If you dig enuf you can find out which Tranny "should" be behind your engine. Also, I could email you what I have. Might help. Email me "griggs@centurytel.net".

Hurth Ratio

There is a 3 ways I know to determine your ratio:
1. Track down the exact model and from online docs you can be pretty sure.
2. Put chalk marks on the engine pully and the tranny output flange. Put the tranny in forward gear and then carefully hand rotate the engine a couple revolutions. Then measure the arc distance on the tranny flange, get out your calculator and you will be right on.
3. Get a hand help optical tachometer, put markers on the pully and flange (mentioned above) then run the engine in forward gear measuring the rpm of both. Divididing one by the other will work.
I did all three on mine (long story) and got the same answer 1.79:1 for a ZF10. Did a reprop and got full fuel rpm right on the money (2960 rpm at hull speed).
All this is not as hard as I make it seem. Go for it.

docs has a Universal Engine Manual scan that has a great section on your trans. I was just reviewing it to change ours... Seems like the line on the dipstick is correct as it is placed, but not threaded, in its hole.
Also seems like there were only 3 Hurth options on these motors...
Chris

Tranny

Interesting that you just changed transmission fluid ... I did also and within an hour's running time after changing the fluid, I lost forward gear. We were about 10 miles from our marina though. The interesting thing is that we still had reverse and we could make about 4 knots backing up ... then I put the dinghy in the water (15hp Yamaha 2 stroke), strapped it alongside and we could make 5.5 knots that way ...

Anyway, I had the same questions as you. The mark on the dipstick is the full mark if you don't screw the stick in, just dip it.

I'm working with my yard manager now to replace the trans. While we're at it, I am replacing the rear main seal (leaking some), replacing the damper plate, replacing the Hurth gear with a new unit (parts will be $1500 or so and 2 yr warranty vs $1000 to rebuild mine and a 90 day warranty), replace the coupling, prop shaft and PSS Shaft Seal with new, new cutlass bearing, zincs, prop keys. I expect the yard bill for the trans to be about $3000-$3500 all up.

I don't know how many hours we actually have on the engine and trans.

We've put 1800 or so on it since we've owned it. Engine still runs fine, still puts out white smoke, oozes a little oil but not much and still starts easily provided I run the glow plugs for 30 seconds first (always has been this way).

Anyway my question is; given that the engine is old, what gear ratio would make sense? Assuming I have a choice, that is. I have a feathering prop that can easily be reset to about any pitch required so I'm thinking that the final drive ratio doesn't matter but maybe a lower gear would be better?

Thanks for all the replies! All good info. Captron, I sure hope that doesn't happen to me! Would be a tough bill to swallow this time of year. Good luck with it. RT

Hurth manual

Rob,

Some of the info on the Hurth tranny is at;
http://www.marinedieseldirect.com/universal/200157/universal-owners-hurth-transmission.html

It shows the gear ratios for various models and links it to whichever engine you have.

good luck,
Keith
E-33

Well today I got to removing the extra ATF from the Hurth. I pulled maybe 6-8oz's out to bring the level down to the mark on the dipstick. It still seems very strange to me that there is so little lube in these transmissions but the line is the line and thats where I left it. Thanks again for the input from everyone. RT

transmission cooler - good investment for ~$200

I would encourage anyone putting time into their transmission to consider a cooler at the same time. It is a thermal heat sink that bolts onto the transmission and is part of the heating circuit. Easy to install and keeps it from overheating. As mentioned, there is not a lot of fluids so it is critical to keep it cool. also, putting it in reverse to keep if from freewheeling is critical to keep the rear bearing from wearing out.

shaun

Okay, I'll bite. Shaun, where do you get this transmission cooler? RT

Good Article about transmissions and cooling. They claim it increases performance of an HBW100 (now ZF10 I believe) to that of a HBW150. Details can be found at:

http://www.foleyengines.com/TechTips/TechTip39.html

I put one on my boat since I know heat and transmissions +$$$$ in repairs.

Shaun,
You know I had noticed that mentioned when I read that link before somewhere. The thing I found strange is they mentioned a product but no link, no price, etc. which IMHO was weird for an internet article. I guess you have to do the old fashioned thing and pick up the phone and ask for one? Thanks, RT

Hurth Makes one

Hurth makes a cooling kit for this as an OEM part, you don't have to go to Foley for it. The issue with this particular cooling kit is that it is ALUMINUM with salt water running through it. There can be corrosion issues, so it needs to be monitored.

That said, I would get one of the real Hurth cooler, and use it on any of their transmissions that I had installed in a boat, heat kills these units faster than anything else (Ok except running them without fluid!)

Guy

Guy Lurking in the Shadows

Guy,

Thanks for the information. Based on what you said, I'm sure mine if the OEM cooler, not the foley. I did a google search and came up with the Foley and never asked the yard which they installed...only that I wanted one. Since it was a new engine and transmission, I'm sure they went OEM. I did see OEM as an option.

As alway, it is good to have you learking in the background to make sure the technical content is the best it can be.

I will refund .01 cents to anyone who asks, but will require a .02 cent handling fee and service charge.

Shaun