How does your Marine gearbox work ? ZF HURTH

In this video we take a closer look at a common Hurth gearbox.
Any advice or suggestions here are taken at your own risk, no liability for your own actions can be taken.
If in doubt seek professional advice either with us directly or independently.
Thank you.

[@bigKDL]

I have done loads of these gearboxes and have never changed the clutch plates it is nearly always the thrust washers worn so just change them and gearbox as good as new

[@Anthony-rp1qc]

Thanks for your dedication to do these videos. I have a HBW 150v (40 years old now) transmission that is getting more stubborn when shifting into forward (reverse is never a problem). The linkage and cable adjustment seem right on so I'm thinking about rebuilding the transmission myself. Your video has definitely helped me understand what I'm getting myself into. Thanks again.

[@theyard6958]

Sub'ed I purchased my first sailboat and motored almost 100 miles up the Columbia river to Portland Oregon. (almost zero hrs at the helm) As I made it to my new marina I approached very cautiously. I rolled in at idle and just at the slip, I had to make one correction with reverse. when I did, I failed to let the prop stop, and shifting into reverse made a hard connection and then it was stuck in reverse. I said a few choice words and then dropped the outboard (fortunately) and maneuvered into the slip. This is what brings me here. I'm currently researching how to remove the gearbox. This video Helped. Thank you!

[@dhcrouchmarineltd3049]

Glad it's helped, good luck sorting it

[@kevinkimmey8088]

These gearboxes were a mystery to me. After watching your video, they make much more sense. I will, no doubt, use this video while rebuilding my HBW250 transmission. Thank you!

[@zzzsydneyhom1379]

I really appreciate you taking the time to break down the gearbox mate. I learned a lot. Cheers

[@Nerd3927]

This is really good! Thanks so much for these videos!

[@dhcrouchmarineltd3049]

Glad your enjoying them.

[@bborjd]

Great demonstration of the operation of my boat's transmission. Thank you.

[@chrisheath623]

Very, very helpful. Thanks!

[@lausagne4764]

very interesting video!! Learned a lot, thank you

[@omvaren]

Thanks, very informative video. Keep on the good work!

[@markmorgan4837]

I love the educational format of your videos. In my exerience, problems can easily be facilitated by operator ignorance, and in some cases can be a catlyst for component failure. As you rightly touch on, having even a basic awarness of how something works is a fundamental aspect of basic care and maintenance. Cheers Darren.

[@dhcrouchmarineltd3049]

Completely agree. Thanks for that.

[@chuckscheaffer3952]

great details on a Hurth transmission. Thanks.

[@dhcrouchmarineltd3049]

Glad you enjoyed the content.

[@bernigabriello9994]

Thanks for dismounting that gearbox. I hoped that you show rebuilding and adjusting that gearbox, too. We got this Hurth in a Vetus engine in a sailboat. We only get reverse and neutral gear and nearly never forward gear.

[@dhcrouchmarineltd3049]

It is almost impossible to get the bits here. You can easily buy the clutch packs and bearings but the springs, thrust washers, and pins, not yet found a reliable source.

[@SailingMerewether]

Much appreciated for the video. It is perfect for me having trouble with my Hurth ZF 250. I noticed that you didn’t exactly point out a the specific problem but said it’s those disks. If I hope to repair mine would I just order a bunch of those disks new? My ZF is only working in reverse and no forward. Thanks again 🙌🏼

[@dhcrouchmarineltd3049]

All the com

[@tamar5261]

Great video. Thanks. I have the same box. The oil is brown i discovered today.😢 Sometimes when I start the engine with some revs the gearbox is in reverse 😮

[@dhcrouchmarineltd3049]

Ohh brown oil, change it and see how it goes.

[@ralph9987]

Loved this. I have. Zf 25a equivalent and am looking for a video that show the servicing of the control block. I think its the reason why i have loud clunks when i go into fwd or reverse

[@dhcrouchmarineltd3049]

Check the idle speed, you may be running to fast.

[@ralph9987]

@dhcrouchmarineltd3049 I took it down to 650rpm, but it's not much better .

[@lucasdominguezandamoyo6245]

Thankyou.

[@johnbeck2079]

Hello Mr Crouch. I am very much interested in your channel lots of good advise practical how to, just what we need. Thanks very much. Can I ask a question? We have a 1800 BMC - Thornycroft T108 diesel in a boat and we are having problems with the water temperature gauge. The gauge shows the engine overheating when in fact it clearly isn't . The control panel is a Thornycroft and the gauge is electrical, the sender has two blade connectors, The gauge on the panel says VDO as are the other gauges. I think the sender is at fault, have you any idea where I might be able to get a replacement? Thanks in anticipation, John Beck

[@dhcrouchmarineltd3049]

Hi, a two pronged approach here. Well maybe more, Calcutt Boats or ASAP supplies. VDO is a leading brand with most manufacturers so I cant see an issue buying a new vdo sender. However on the sender will be numbers stamped on it and if you Google these, in theory you should get a hit and find one somewhere. Hope that helps.

[@valleyofghosts]

Thanks for the video mate I have been following it . Can you tell me where the 3 springs connect to l can see the top hole where they connect but can't find the bottom location . Thanks

[@dhcrouchmarineltd3049]

Which springs? The three that keep the clutch assembly together

[@valleyofghosts]

@@dhcrouchmarineltd3049 yes mate I can see a top hole where it slots into but can't see bottom hole or location any help would be great thanks

[@iangreenwell6912]

Just watched your video very good information iam put bigger engine in my boat so need bigger prop which is right hand could I put a left hand prop on or not reply would be appreciated David

[@dhcrouchmarineltd3049]

No you need a left handed gearbox. If you run a gearbox in the wrong direction for the ratio its set for you labour the box and engine and the efficiency will be somewhere a billion miles out. Don't do it. Typically the engine would also be an opposite rotation but all said and done it depends on your specific needs.

[@ianmccracken6365]

If ZF are S.A.E boxes does this mean that all ZF boxes only attach to engine's that run CCW as seen looking at the flywheel

[@dhcrouchmarineltd3049]

From what I have seen in the manuals, if there is an R on the data tag which is usually next to the oil filler port its for Right hand use. So it depends on application. Typically I have not seen the same reduction in ahead and astern so it does matter.

[@user-xt2jx1fr1z]

I' interesting a gear ratio please give me thanks

[@gunnara7625]

Thank you for your information! I have a Hurth HBW5 and a 32 HP Watermota Seapanther engine. Occasionally the gearbox will not slip into forward unless I first make it go backwards. Is there a simple way of adjusting this to make it work better?

[@dhcrouchmarineltd3049]

Are you sure its the gearbox and not the morse controller unit?

[@gunnara7625]

@@dhcrouchmarineltd3049 No, I am not sure, I am going to control the angles, the oil level and the controller unit tomorrow.

[@ianmccracken6365]

Hi I just received a new ZF45A Gearbox. I have an issue with it. When I put it in gear either forward or stern and turn the input shaft the propeller shaft is not turning. Surly this is not right It was supplied with no oil in it. Does that make a difference? Any help would be greatly appreciated

[@dhcrouchmarineltd3049]

Have you tried to put power through it. Just turning it by hand may not engage the clutch correctly.

[@chrysdemos7569]

I have a problem I cannot figure out with my HWB50- just had it rebuilt with a standard rebuild kit, clutch plates, seals, bearings, all new. After the rebuild at the transmission shop, turning by hand confirmed everything was fine- fwd, N, rev all evident with normal shift lever travel. Right after being installed back in the boat, where it worked great for 5 minutes it suddenly stalls the engine when shifting into fwd. Reverse is fine. Back at the shop with the transmission removed again, I thought I could recreate the binding problem in fwd, but NO! It moves freely and clutch plates are slipping. What happened? Any guesses? Do you recommend bench testing with drill at 1k RPM?

[@dhcrouchmarineltd3049]

Have the bearings be set up correctly? Once bearings warm they will expand a little.

[@user-vj4ru3le8o]

What modern transmission would you recommend to replace one of these to go on a BMC 1500 still keeping the same ratio. Also would I need to buy some kind of mounting plate to make it marry the engine? Many thanks 🙏

[@dhcrouchmarineltd3049]

The Hurth mounting pattern is the same as a PRM 120/125 mechanical box or PRM 150 for example. The center drop is a bit different, you'll need an oil cooler for the 150 Prm are fabulous bits of kit

[@user-vj4ru3le8o]

@@dhcrouchmarineltd3049 thanks for that, I appreciate your videos.

[@user-ce2sk6km2j]

i'm just rebuilding one now, i managed to press everything onto the shaft ok. i'm just wondering if there is a sequence and torque spec for rebuilding the case?

[@dhcrouchmarineltd3049]

Have you got the workshop manual, always refer to the manual for the tolerances and torque sequences.

[@dhcrouchmarineltd3049]

Have you got the workshop manual, always refer to the manual for the tolerances and torque sequences.

[@James-cr5qx]

Do you happen to know if I can directly replace a hbw 100 for a zf12? Asap says its the closest thing. My question really is about the dimensions and gearing. Is the gear ratio the same? Will the ratio matter? Also will the adaptor plate fit to my bmc 1500? Will I have to lift or lower the bmc to line it up with the shaft? Any advice is much appreciated as I'm a bit lost..

[@dhcrouchmarineltd3049]

If I recall correctly it is a pain and yes you have to re-align everything and pull engine back of shaft forward.

[@drankenkorps]

Hei, i need to learn something.. saildrives have 2.7 or 2.3 times reduction.. or whatever nm is. Where is reduction.. in knee of saildrive where propeller is or inside gear box.

[@dhcrouchmarineltd3049]

The only way to answer that is to ask what sail drive do you have. Propeller size will also make a difference.

[@drankenkorps]

@@dhcrouchmarineltd3049 aaa.. ok I dont have jet.. im calculating to convert to electric motor.. motors that have 16-20k rpm.. which is 5x more rpm than diesel...im studying..before invest.

[@danielchehab9069]

I have a zf30m, very similar to this GB. The gearbox takes approx 30-60 seconds to go ahead, and instantly goes into gear going astern. We've have the gearbox reconditioned many many times but after a few hours of taking it out, the same issue happens. Any suggestions or what may cause this and how to fix?

[@dhcrouchmarineltd3049]

Probably not a good selection of the ahead drive and it slips in slowly. Check the morse controller adjustments.

[@oleskjold9307]

Hi Super Movie where buy new bits have an HBW125 I am missing the pieces for 2: 1 link please

[@dhcrouchmarineltd3049]

www.asap-supplies.com/

[@yannisvlisidis1889]

Can you please inform me which is the right oil for ZF HURTH 45a ? The boat manual recommend oil 15-40 and the ZF manual ATF .

[@dhcrouchmarineltd3049]

What engine is It? Some manufacturers may have had a PRM hydraulic box in mind. If the ZF manual states ATF use that. Typically that's what they use. 15W40 is an engine oil and very thick compared to ATF. ATF is very thin and helps with heat management.

[@yannisvlisidis1889]

Gasoline engine GM V8 6.000 cc 375 hp. Usually working at 3.900 revs.Waterski boat Mastercraft. No hydraulic box.

[@depthsounderdave]

Can the cam plates be swapped around for reverse rotation engines?

[@dhcrouchmarineltd3049]

Not something I have ever done. That being said my reasoning is the gear ratios are set for each respective direction. So not so much a clutch concern more a gear sets being appropriate for the input forces and output rotation. Otherwise you'll thrash the engine and gearbox. The clutch and plates ect are symetrical.

[@depthsounderdave]

@@dhcrouchmarineltd3049Thanks for taking the time to reply! I suppose I'll have to get a hydraulic clutch model with reversible oil pump. I just don't know how the hydraulics will behave when the shifting will all be done with the input shaft at 0 RPM (clutched motorcycle transmission).

[@84Rabbitz]

I have that transmission. I have to get it to stop slipping in forward. Can I make a shim just to add to the clutch pack?

[@dhcrouchmarineltd3049]

Hi, you need to refer to the workshop manual and work withing the design tolerances. Adding something that was not intended is experimental and is questionable.

[@84Rabbitz]

Ps, I'm also a machinist. Honestly it seems that there is too much slack In the forward position. Or the springs on the slide Carrier are too weak. My thoughts where to have a shim laser cut to take up the play in the forward clutch pack. Or add a another disk from my spare transmission

[@84Rabbitz]

@@dhcrouchmarineltd3049 do you have a pdf of the transmission manual?

[@romakayak]

What's the difference between ATF and Dexron 3

[@dhcrouchmarineltd3049]

ATF means Automatic Transmission Fluid. Dextron 2 or 3 defines the chemical composition of that particular ATF mix if you like. There are varying types if ATF and its used a lot in the states for all manner of transmissions. Dextron is an old term from around the 1970s so relevant to older boxes. I would suggest to stick to the oil type the original manufacturer states. Unless the manufacturer says otherwise as all to often people get sold on an "upgraded" oil type.

[@andrewdoble7973]

What’s the drop in replacement?

[@dhcrouchmarineltd3049]

What do you mean. As in an alternative engine system?

[@andrewdoble7973]

He said they are throw away gear boxes. What is the drop in replacement

[@dhcrouchmarineltd3049]

@@andrewdoble7973 I see. Nothing is exact but the PRM 120 / 125 use the same mount registration pattern. You have to realign the engine. Technodrive again use the same mount registration pattern. Again a slight remount and alignment. The PRM Hydraulic box the 150 fits but again you'll have to realign the engine and add an oil cooler for this. This is an example and for guidance only.

[@mikemmx]

I have an oil leak from the coupling. I can't figure out how to remove it to replace the oil seal. Do I need that press machine you used to remove the coupling?

[@dhcrouchmarineltd3049]

Yes, the shaft coupling is part of the output shaft and you have to take the whole box apart and remove the clutches and bearings. You will need a press.

[@mikemmx]

@@dhcrouchmarineltd3049 Thank you for the info! What a god forsaken engeneiring design...

[@Mechone11]

Sorry to disagree its well known that the bronze thrust washers at both ends wear and cause the slipping not the clutch plates and many have just replaced the washers and are good to go. Also as per the manual it is only rated at 17hp and limited use and must have a cooler installed for constant use and moves the HP to 34hp double. It only holds 350ml of dextron 2 which is hard to find mineral oil based .Never use semi or sythetic oil or it will fail ,its too slipppery and causes plates to slip. Also as per manual it must be kept in reverse direction during sailing as the prop spins and wears the bronze washers ,thus causing slipping. Oh and as a Millwright i have personally built 100's of complex gearboxes epicyclic in the printing industry ,even ones made in UK on Baker Perkins G16 .G14, G12 printing presses. I have reashearched this box to death and machined my own cooler and have 1500 hrs on my box (no failures ) in my beneteau

[@dhcrouchmarineltd3049]

Thanks for your input, you clearly have some experience there. As for an oil cooler its not done on inland craft bit I can of course see it being a good idea for sea use. As for slipping clutches, again i appreciate your perspective but they are just not economical to repair for most cases. Also what I have found is damage cause by improper selection of the transmission due to a very old lazy morse controller. This box is not know in terms of which HP it rated too. However it was fitted to a small 30 hp machine. Again no need for an oil cooler. I know the manual states how to fit an oil cooler but ive yet to see that requires or have been done inland. Thanks

[@Mechone11]

Mine engine is 30 hp perkins ,and I can tell you after an hour on the engine you could fry an egg on the box .After install of cooler the box was warm after an hour and when I first got the boat the fluid came out dark red with yearly fluid change ,after cooler bright red every year like new fluid. These boxes should never be installed without a cooler ,look at the graph in the manual

[@dhcrouchmarineltd3049]

@@Mechone11 I think you are again right for sea work. Inland boats just don't do that much work. I have a thermal imaging camera. This has given me some thought in another video.