Hurth HBW20 transmission questions

[S/V Selene]

Two questions:
1- How much ATF does the Hurth HBW20 Transmission require?

2- Do I check the fluid level with the motor NOT running or with it running?

Thank you in advance.

[tkeithlu]

2. Not running.

1. To the index mark on the dipstick. It's about 0.3 liters

3. The manual with this information is readily available on the internet. Try

https://c320.org/filemgmt_data/files...p%20Manual.pdf

[S/V Selene]

Thank you I did a search but hadn't found this.

Am I splitting hairs to ask if this manual addresses my HBW20? I do not see that listed on the cover.


I'm very new at this so pardon the (likely) noob questions.

[tkeithlu]

Right. The one I cited is for the larger versions. The one you want I think is available at the bottom of this page.

https://www.marinedieselbasics.com/h...arbox-manuals/

I didn't download it because I didn't feel like giving the source my contact information.

Hey, you're doing just fine. We all have to learn our way through this business. We all started at zero, and I for one am still learning.

[S/V Selene]

Originally Posted by tkeithlu

I didn't download it because I didn't feel like giving the source my contact information.

THIS!!!!! I don't blame you. That stuff has gotten ridiculous.


Thanks for the info!

[FPNC]

The HBW 20 uses .75 liters of ATF.

It is an old design gear. They spec'd 'Type A' ATF back then.

Check fluid with engine not running unscrew dipstick, wipe, insert to threads, do not screw in, pick it back up and check level.

The HBW20 is closest to the HBW 250 / ZF 25m. I would not claim them to be identical.

[S/V Selene]

thank you all for your input. You have answered the exact needs...... and then some.

[surfmachine]

Hi fpnc. I am in Malaysia, Pangkor marina and my Hurth hbw 250 has stripped its reverse gear! Maybe you can please help me with a question?

Do most of the zf gearboxes have the same input shaft dimensions? 10 spline? My gearbox has iA=2.74 iB=2.72. What these numbers mean please?
Cheers from Keith.

[Wotname]

iA is forward gear ratio
iB is reverse gear ratio

[FPNC]

Originally Posted by surfmachine

Hi fpnc. I am in Malaysia, Pangkor marina and my Hurth hbw 250 has stripped its reverse gear! Maybe you can please help me with a question?

Do most of the zf gearboxes have the same input shaft dimensions? 10 spline? My gearbox has iA=2.74 iB=2.72. What these numbers mean please?
Cheers from Keith.

The HBW 250 ( ZF 25M) has a 26 tooth input spline. ZF uses a 10 tooth input spline on transmissions that are rated for a lower HP than the HBW 250 ( ZF 25M).

[surfmachine]

Thanks. My gearbox has 10 tooth input spline, so it must be a zf?
Cheers from Keith.

[FPNC]

10 tooth input splines are common within the marine transmission world. Hurth/ZF, Twin Disc/Technodrive, Newage/ PRM, all use 10 tooth input splines on some of their smaller transmissions. They all use 26 tooth splines on the larger transmissions. This has more to do with the available drive plates.

[surfmachine]

Thanks. I was considering buying a prm125d. But I am unsure if it will fit my adapter plate bolt holes, set up for the hurth.

Does the prm125d have the same bolts holes on the adapter plate as the hurth 250?

Chrome Keith

[FPNC]

Originally Posted by surfmachine

Thanks. I was considering buying a prm125d. But I am unsure if it will fit my adapter plate bolt holes, set up for the hurth.

Does the prm125d have the same bolts holes on the adapter plate as the hurth 250?

Chrome Keith

no. The PRM 125 and Hurth HBW 250 use a slightly different bolt up.