hurth zf gearbox

[chrishelen]

Hi I have a zf5 box on my Perkins perama, the engine is fine but I get a whining noise at 1500 revs but this clears at 2000 revs,seems to be coming from the gearbox. Originally I thought it was harmonics from the prop, but now I am not too sure.
A friend of mine mentioned that the zf5 had a high failure rate, so I am considering putting the next one up in, the zf10, it is an inch longer and I have the space to push the propshaft back to facilitate this.
Has anyone experience of this change over?

 

[chrishelen]

Anyone?

 

[Paul1962]

Have a chat with Jez or Mike at Pilkington Marine in Devon, they are ZF agents but appear to know the earlier Hurth boxes as well.

Hope this helps


Paul

PS - No relation or interest

 

[chrishelen]

Thanks Paul.

 

[Caer Urfa]

Hi I have a zf5 box on my Perkins perama, the engine is fine but I get a whining noise at 1500 revs but this clears at 2000 revs,seems to be coming from the gearbox. Originally I thought it was harmonics from the prop, but now I am not too sure.
A friend of mine mentioned that the zf5 had a high failure rate, so I am considering putting the next one up in, the zf10, it is an inch longer and I have the space to push the propshaft back to facilitate this.
Has anyone experience of this change over?

I suggest you look at the drive plate when you remove the existing gearbox box, changed my Hurth 100 box two years ago for a ZF10 box (straight swop) ZF recommended to change gearbox oil every 100 hrs or year whichever the sooner, so far so good.

Mike

 

[chrishelen]

Thanks mike, I think the plate would have been updated as it has a zf5 box at the moment, I just want to know if its a straight swop...looking at the plans the only difference is the 10 is an inch longer, but you know what these things are like when you come to do the job.

 

[theoldsalt]

....... changed my Hurth 100 box two years ago for a ZF10 box (straight swop) .......

Physically interchangeable but different reduction ratios so often a different prop is needed.

 

[chrishelen]

The zf 10 is the same ratio as the zf 5, A position = 2.045... B position1.864....so same prop i guess.

 

[ffiill]

Problem is is that Hurth hbw 50/zf5 which is no longer produced was designed for little engines but was invariably bolted onto engines at the gearboxes maximum hp rating.
This combined with relying on poorly aligned flexible drives runs out the output shaft bearing with associated destruction of oil seal and no oil!
This was info.given to me from another HurthZF agents who also repair rebuild and replace boxes.

 

[Caer Urfa]

Physically interchangeable but different reduction ratios so often a different prop is needed.

Yes you are correct there is a 'slight' difference in the gear ratio of the Hurth100/ZF10, but I have not found there is a need to change the prop.
My 27.5 HP engine has a RH 15"(380mm) dia x 3 blade fixed -pitch bronze prop and run the engine at slightly less RPM than before,at 5 knots I use one litre/hr.

Chrishelen
Not sure if you have a flexible coupling after the gearbox, if you have make sure you know how it goes back together BEFORE you unbolt it as the spacers in it only fit one way.

Mike

View attachment 44616

 

[chrishelen]

Thanks mike, I have a flexible coupling just like yours, is your box cooled?it looks like...I run a small commercial passenger boat that carries 12 people, so the box and engine are worked hard and it would be good to have a cooled transmission.

 

[chrishelen]

Have a chat with Jez or Mike at Pilkington Marine in Devon, they are ZF agents but appear to know the earlier Hurth boxes as well.

Hope this helps


Paul

PS - No relation or interest

Spoke to jez today, very knowledgeable...he seems to think engine mounts or cutlessbearing. Thanks

 

[Caer Urfa]

Thanks mike, I have a flexible coupling just like yours, is your box cooled?it looks like...I run a small commercial passenger boat that carries 12 people, so the box and engine are worked hard and it would be good to have a cooled transmission.

Hi Chris

No gearbox is standard ZF issue purchased new from ASAP, I had a long chat with ZF on the phone about reliability as I sail offshore single handed, 'they say' the secret is to renew the gearbox oil every 100 hrs, maybe time will tell.

I also looked at fitting an equivalent PRM box, the swop of the gearbox would be straight forward, BUT, due to the difference in gearbox input /output shaft height alignment I would need to lift engine 10 mm.

My friend at the same time fitted a second hand refurbished Hurth gearbox, again he is also changing gearbox oil every 100 hrs (or 12 month), so far his is also ok.

Good luck
Mike

 

[cmedsailor]

Just for the records, the MS10L made by ZF only for Volvo Penta is exactly the same in dimensions as the ZF10M, except the MS10L having a different ratio (2.35:1 vs 2.05:1) and costing triple the price.....