Hurst Transmission Rebuild

[MerryBee]

know this subject has been discussed many times already - both here and on other forums, but I'd like to share our experiences as we undertake our newest adventure!
Last month I started the process of removing the HBW50 transmission from our Morgan 28OI. The fuel tank and exhaust elbow had to go in order for me to gain access without having to remove the engine. Good thing! The raw water inlet to the Barr exhaust elbow is almost completely clogged and the fuel tank had 1/2" of water (bad O-ring on the deck fill).
Current plan is to rebuild the transmission since the replacement, the ZF12, would be physically too long. Many posts about the quality of the HBW50, but I'm hoping I can get this right.



OK folks! Here we go....
I spent MANY HOURS trolling the Interweb for info on parts for this transmission. Looks like most companies offer the ALTA replacement parts; but the 3 rebuilders that I spoke to think they're junk. Maine Sail had some interesting comments about this on the Cruisers Forum about 6 years ago (Thanks for that Maine Sail!). don't recall where I found the reference, but I ended up speaking to Jim at Federal Marine in Illinois. What a wealth of knowledge there! Anyway, it looks like they have a direct line to the ZF company and he's getting us original factory parts: clutch discs, thrust washer, gaskets, shims, etc... It's gonna take a few weeks to get the parts, but since we're on the hard until spring, no worries there.
Getting ready to crack open the case soon, so I'll try to document the progress with pics as we go. Stay tuned!...

[MerryBee]

Added some pics. more to come as we get into the transmission...
The first pic shows that the HX , starter (behind the HX at left in pic), bell housing and rear motor mounts must removed. The 6 bolts fastening the 2 pieces are actually inside the housing. Didn't realize the forward transmission oil seal is actually on the bell housing!

[CHM]

Went through this recently with. HBW150. I found a ZF dealer nearby and it was more cost effective for me to buy a new one. Good luck with it. Consider replacing the damper plate as well.

[MerryBee]

Thanks, CHM! Yes, we're definitely replacing the damper! Getting at the damned thing was so difficult I really don't want to go back in there anytime soon!
In our case, replacement would involve engine removal to re-drill engine mountings. The newer unit - ZF12M - is approx an inch or so longer than the HBW-50, and there's not enough space between the drive hub and the shaft seal. Also, the replacement cost is over $1.2K more than what the parts cost. Hey! what could go wrong??

[Jim Cate]

Out of curiosity: is t he hbw-10 no longer available? IIRC, it was a bit shorter than the 12... could be wrong about that, for it was a long time ago that I was researching this issue.

Jim

[Sailmonkey]

Originally Posted by Jim Cate

Out of curiosity: is t he hbw-10 no longer available? IIRC, it was a bit shorter than the 12... could be wrong about that, for it was a long time ago that I was researching this issue.

Jim

I'm also curious, why not he ZF 10m? Or even the technodrive tmc 40?

[puffcard]

Just rebuilt my Hurth HBW10. The damper plate was a pain in the butt. Mounting bolts striped out. Also had to slide the motor forward two inches to get the transmission out.

[scherzoja]

Jim,

Install the damper plate carefully. When I installed a new damper plate on my Universal 5444, it didn't fit perfectly. The problem is that the new damper plate was slightly warped, not perfectly flat. This caused the plate to become slightly skewed when I tightened the 4mm machine screws that held it to the flywheel adapter.

When I slid the bell housing on (with the Hurth ZF15 transmission attached), it wouldn't go in the last 1/4". The skewed damper plate was binding on the transmission input spline. Tightening the bell housing bolts to seat the bell housing all the way puts inward pressure on the engine's main thrust bearing.

I compared the new and old damper plates by putting a straight edge across them and the old one was perfectly flat, but the new one was slightly warped, but about a skinny 1 mm. This was enough to bind the input spline.

I went to the ALTA distributor here in Alabama (about an hour from the house) and tested 15 damper plates, all were warped.

My fix was to loosely fasten the damper plate, then bell housing would seat easily. Once bell housing was all the way on, I tightened the 4mm damper plate machine screws one-by-one through a hole I drilled in the bell housing just above the transmission, right in line with the damper plate machine screws. I tapped the hole to fit a bronze 3/8" npt plug (drill bit was 9/16").


I'm not saying that all ALTA damper plates are warped or that you'll have problems (I don't even know what kind of engine you have, just made assumption based on paint color), but when you go to slide the bell housing back on, make sure it all slides together easily, with not effort. If you get resistance on the last 1/4 or 1/2", loosen all damper plate fasteners and try again, if it all goes together easily, you have the same problem I had.

Attached is the damper plate I replaced.

FYI: here is a link to Kubota's exploded parts diagrams, if you have a Universal, you can cross-reference and get same part from Kubota without the Universal/Westerbeke price.

http://kubota.com/part/partsList.aspx#

[MerryBee]

many thanks for your input!
Sherzoja: during my studies, I did hear some comments made about the damper. That's why I'm going with the Sachs unit. nevertheless, I certainly will be checking it carefully before installation! And thanks for that link to Kubota!
Jim & Sailmonkey: I was told that the ZF-10 was discontinued by the guys at Eastcoast Marine. Don't know if that's fact or not.

[Sailmonkey]

I'm not the least surprised that the zf10 has been discontinued.

Have you checked the dimensions of the technodrive 40? Supposed to be a drop in replacement for the zf10

[MerryBee]

Yes, I did look at the Technodrive unit. So far, I haven't found any info from users, so I'm leery about trying it.TECHNODRIVE Twin Disc TMC 40 P transmission , NEW | eBay

[Sailmonkey]

Originally Posted by MerryBee

Yes, I did look at the Technodrive unit. So far, I haven't found any info from users, so I'm leery about trying it.TECHNODRIVE Twin Disc TMC 40 P transmission , NEW | eBay

I've had a tmc60 for the last 5 years and it's been flawless. I had ordered a tmc 40 but the 60 shipped by mistake.....my gain I suppose but I needed to lift and move the engine forward to fit the gear.

[puffcard]

One thing I was surprised by was the authorize rebuilder here in Ft Lauderdale says to not use the newer synthetic AT fluid, he recommended the straight Dexton III.

[fish53]

Originally Posted by MerryBee

Yes, I did look at the Technodrive unit. So far, I haven't found any info from users, so I'm leery about trying it.TECHNODRIVE Twin Disc TMC 40 P transmission , NEW | eBay

I have a TMC60A on one of my boats and it's been great for five years, bought it from ASAP supplies in England, way cheaper than US. I have a PRM 120 on another boat that's also been great for 10 years.

[Obi Wan]

What is your engine? I'm in the process of replacing the Hurst transmission on my Universal 5424. I have been planning on getting the TMC40P transmission from Sound Marine Diesel (the ebay seller you mentioned) which is supposed to be a drop-in replacement. I haven't bought it yet because I am still checking out the engine to make sure I don't have any other major problems. My damper plate was also shot so have been shopping around for that. I was quoted a price of $349 for that (apparently not available at the Kubota parts store). Seems kind of steep. I wish I could find an elastomer damper plate - I think that would be a better choice. What price for your damper plate, Scherzoja?
I had problems getting my bell housing off and ended up pulling the whole engine out. I'm glad I did - it was so difficult to work down there - now I have it on an engine stand in my garage and it wasn't that hard to pull out and it sure is easier to work on now. Also allowed me to clean out the bay and get some other work done down there and taking care of some corrosion issues, replacing the engine mounts, etc.