Looking for a good shop to diagnose and repair ZF6 clutch issues (too old to DIY). Symptoms are failure to disengage with engine running vehicle stationary (hard to select gear unless rolling). Suspect throwout and/or pilot bearing, might as well do clutch while in there, though no detectable slippage. Master and slave replaced 3 times over 235000 miles, could be an issue, but doubt it.
Suggestions on aftermarket clutch welcomed also. Tow 20,000 lbs regularly. Prefer a rather stiff pedal, have seen a few aftermarket clutches on buddies trucks that produced soft but effective pedals.

 

The only ZF6 guy I know of is a friend of mine that lives in Blairsville GA, sorry.

I had said friend install a South Bend 1939OHD and I have been very impressed with it over the past couple of years. He recommended South Bend and he was right. I tow 12,000 lbs long distance on a regular basis.

Wes444 also has the same clutch and he tows heavy as well.

 

Actually I don't
I have the 1944 60K HD

The difference is Sous' clutch reuses the stock flywheel vs mine uses the slightly different SouthBend flywheel. They do not interchange due to the minute differences in the flywheels. They are both rated to tow 20k

So it really comes down to whether you have a good machinist to resurface your stock flywheel before reinstall or get an all new one so you can put it all in without an extra trip to town and a day or two wait.

I really like the clutch, and it has a firmer pedal stroke than stock. Not grabby on engagement but definitely firm and secure like an off off switch.

 

I always suggest calling Southbend Clutch for clutch recommendations. They’ll give you the best advice, because that’s what they do for a living. They have recommended everything from the 1939HD to their dual disc street clutches for my customers.

Failure to disengage without noise is likely worn/bent fingers on the pressure plate or I’ve also seen the springs in pressure plate get worn and get wedged between PP and clutch disc. (This type of wear is consistent with ‘lugging’ the engine. You never want to lug these trucks. Unless leaving from s stop, don’t try to accelerate with below about 1500 rpms)

The aftermarket hydraulics suck. I’ll only use Motorcraft after toooo many failures of the aftermarket junk. The ‘good stuff’ doesn’t cost much more. (Shop around)

I can’t recommend a shop in your area, but I have a couple suggestions for the shop you choose.

I like to add a piece of tubing to the engine valley drain, directing any liquids that enter the valley to the bottom of the bellhousing. This mitigates the chances of contaminating the clutch with oil/fuel in the event of a leak on top of the engine.





I also have pilot bushings made from oilite bronze to replace the failure-prone Ford design. This material is self-lubricating as it wears, unlike the stock bearing that cannot be lubricated that fails and destroys the transmission input shaft. I also have a repair sleeve and oversized bushing for input shafts that are damaged.




Oilite bronze bushing, Kevlar bushing and OE bearing. In descending order of reliability.




Standard oilite bushing and one with a repair sleeve.

 

SB dual disc street clutch - 650HP rating!!

This clutch is what is currently in my truck.

 

I remember that you bought the flywheel version and thought the clutch was the same at the time when you bought it. I thought the clutch surface area and material (HD-Organic and same ratings) were the same and for the sake of the original question and simplicity, I said you had the same clutch. This statement was right, but also wrong and I thank you for clarifying the differences.

For further clarification, I have pictured the differences below.

Source: https://www.southbendclutch.com/clutches/7878/





All of that said, I echo the thoughts from Wes444 on the performance and results from the clutch. It is confidence inspiring, but it is costly. I am unable to do this job myself due to knowledge and tool inventory, so I took the advice of Jason and went with a known good source.

I think @timmyboy76 and @BBslider001 have different thoughts on clutch choice though from what I remember.

 

Sous..I bombed thru my old threads. Guess, I didn't start one when doing my last clutch, at my bro's shop. For the life of me, I can't think of what I installed however, this last go around, I remember a flywheel being part of the equation. Not sure, if SB is the only company that provides flywheels when using their product...but, the past I've used Valair, which, I'd do again. My main issue up to Jay hooking a brother up with the bronze bushing, was that damn input bearing. Once it let loose, it tore my shaft up resulting in me installing the FITZALL kit. I advise anyone, get the JayBone kit. You'll just need a way to install the sleeve.

 

Thanks Sous. All very good recommendations and you can't go wrong with any of them. I use LUK stock clutches because of the reliability and price. You can't beat it. I tow heavy and have lots of severe use on the current one as the same on past installs. I have 60k on my current clutch and it feels like the day I put it in. I would venture to say about 65% of that is heavy towing, anything form horse trailers fully loaded, my current toyhauler 5th wheel, stock trailers, and all through mountain passes, slow driving in pasture (which I thought would cause an early death for sure). Anyways, can't go wrong with SB or LUK IMO. Their kit with a flywheel replacement is $275.

 

That's what I have now..LUK. Do they come with flywheels?

 

There are two kits, one with and one without if you don't need it.

 

Thanks all for suggestions!
There is one diagnosis I found on the South Bend site that I am able to perform - the hydraulic system test using steering wheel puller. I'm kinda busy at the moment, but will try to do this weekend.
Hydraulic Testing

 

Thanks for chiming in fellas. I responded before my morning coffee was finished and did not want to misquote you or misstate what brand clutch you purchased.

Timmy, I saw pictures of your install with your brother not too long ago. The thread is out there somewhere...

Keep us updated CO Horseman and we are always here for advice and to help you spend your money.

 

For the valley drainpipe mod, I found that there is a convenient hole in the bottom of the block for all the crap to drain out. Seal the bottom of the drainpipe to that hole and none of the crap has a chance to fly around inside the bellhousing.

 

After a few broken tabs at the slave, I found an all aluminum construction m/s asy..been stoked since..p/n pf9021

 

The all aluminum ones are junk. I’ve seen these fail in as little as a couple days (the rod pulls out of master).

My OEM hydraulics lasted over 400k miles. The good stuff doesn’t cost much more and doesn’t need a ‘lifetime warranty’.