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Clutch

TrailTamer

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May 26, 2020
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I started the clutch thread on other forum.

I’ll like to make a quick update on LuK’s Cerametallic clutch kit (part# 05181) I used in my truck.

I emailed Schaeffler tech support on what it’s rated at, shockingly they replied quickly, said approximately 740 ft•lbs

almost 2 years now with ~15k miles with this clutch

This cerametallic clutch HATE to slip! More like grabby on/off when hot (stop and go traffic). I need to use the granny low despite when not towing to take off from a stop to keep it happy, not a huge deal. I also use 4low (front hubs unlocked) to maneuver the trailer without slipping the clutch. Towed at over 20,000 lbs GCW locally with no issue. Towed my 18’ car trailer with my XJ (roughly 6,500-7,000 GTW) up 10% grade at full power to grab 4th gear (and just cuz its fun) and the clutch did not slip whatsoever.

Truck info: 12v Cummins with the big stick cam, 17* timing, fuel plate deleted, AFC LIVE tuner, nv4500, 4x4, 3.55 axle ratio, 315/70r17

Valair, south bend, etc. are gimmicks (other than their dual/triple disks) imho. I thought someone here may appreciate to know there’s something off-the-shelf that can work for you and nowhere near a grand to buy and can hold up to normal tow rig use with modest power adders.
 
what problems have you ran across with single disk SB clutch? what causes you to believe they are a rip off?

its pretty rare to come across a negative opinion of SB so im curious whats led you to that opinion
 
My understanding from his post is that he feels you get the same performance maybe marginally less from luk brand than you get from sb. So a $200 clutch(luk) vs a $500 clutch (sb) and having similar performance. That said if you are pushing the envelope in my experience you are better upgrading or going with the name brand.
 
I've actually heard almost all negative things about South bend single disc kits. Not just being over priced, but reliability issues as well.

I put a Sachs in my 97 7.3 a few years ago and have been happy with it. I found out about them on here, I believe someone spend ~$600 on a valair and it was just a $250 Sach unit :homer:
 
rockyota83 I have not personally used SB clutch

My truck dyno’d 400/1000 on LuK OE replacement 12-1/4” clutch. It did eventually start to slip but that’s after 10s of thousands of miles and still work fine as long as I stay below 40psi of boost while towing to not slip at that point when I took it out for LuK’s cerametallic 13” clutch at about 1/4 of cost what SBC want for its similar unit ($1,200).

Looking at SBC products, there are LuK stamping all over.

There are only so many ways to increase torque rating of a single disk clutch set up. Off hand I can think of 3 ways are;
1) increase pressure plate clamping force (undesired stiff clutch pedal)
2) more grabby clutch friction material (cause any slippage is near impossible without the violent shuddering/chattering and unintended tire slippage)
3) larger clutch disc diameter (only 13” available)

The only real answer to increase torque rating without sacrificing drivability is to go dual disks; no stiff clutch pedal with oem clutch feel regards slippage (no shuddering while such as backing up a trailer without dropping it into 2low). SBC do have their place for dual disk clutch stuff, however…

SBC provide zero technical information and hp/tq ratings are all 100% made up bs.
 
I believe someone spend ~$600 on a valair and it was just a $250 Sach unit :homer:
:lmao:

To add the insult, SBC explicitly say there is no warranty if you buy it below msrp. :homer:
4F03AC04-C50D-4C6B-947B-181D76FDBC84.png
 
south bend single clutch, i didnt pay 1200$ though :laughing: iirc it was around 700$ about 8/9yrs ago, bought it because i had heard nothing but good things about them.

havent had any problems with it. im running a stock turbo and injectors, only thing ive done is fuel pin and governor spring

just looked up the order, i paid $725 delivered
 
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Have a single disk SB in my 4BT powered cruiser crawler, close to 100k miles on it and very happy.

Have a dual disk organic valair in my F550 and have been very very happy with that towing ~26k gross all year this year.

I question those torque ratings you're pulling up TrailTamer . My bet is that SB is conservative with their torque ratings to avoid warranty claims, whereas the larger manufacturers don't care as much. No data to back that up with.



That all being said, I have seen threads of guys blowing the springs out of their single disk SB clutches, but it hasn't been an issue for me. My guess is that's people who let the clutch chatter as much as it wants, as opposed to modifying their driving style to avoid the chatter in the first place.
 
I question those torque ratings you're pulling up @TrailTamer . My bet is that SB is conservative with their torque ratings to avoid warranty claims
Actually, I think SB is overambitious on their clutch ratings. And what's more misleading is that they use HP to rate their clutches.

You won't find LUK's clutch with torque rating anywhere. I had to ask their tech support to get this 740 ft-tq number. I did not pull this number out of thin air.

and for AMS's dual disk clutch, the "up to 1,300 ft-tq" rating is believable, considering how the LUK's 13" cerametallic single disk is rated to 740, as the dual disk set up effectively double the torque rating (single disk have 2 steel faces and 2 friction clutch faces vs dual disks have 4 steel faces, 4 friction clutch faces).

whereas the larger manufacturers don't care as much. No data to back that up with.
I think those larger manufacturers (LUK, Sachs, Valeos, etc.) don't exactly "don't care", considering how their aftermarket OE replacement clutch kits is not rated that much higher than manual transmission's manufacturer rating. They know better to not sell you something way over factory rating and those who still want it is a real small market.

Even though, you gotta make an educated decision on what to do with your manual trans equipped truck. Manual trans can only handle so much power for so long before they fall apart. I personally know people who broke their trans, NV4500, NV5600, G56, and myself included. I just broke the 5th gear in the NV4500, still need to get it out to see what took it out and what else I may find. The only guy I know who never broke his G56, because the truck is bone stock all its life lol

IMHO going with clutch set up with significantly higher torque rating over trans's factory rating to handle turned up diesel and expect the trans to have long trouble-free life is idiocy if you ask me.
 
Actually, I think SB is overambitious on their clutch ratings. And what's more misleading is that they use HP to rate their clutches.

You won't find LUK's clutch with torque rating anywhere. I had to ask their tech support to get this 740 ft-tq number. I did not pull this number out of thin air.

and for AMS's dual disk clutch, the "up to 1,300 ft-tq" rating is believable, considering how the LUK's 13" cerametallic single disk is rated to 740, as the dual disk set up effectively double the torque rating (single disk have 2 steel faces and 2 friction clutch faces vs dual disks have 4 steel faces, 4 friction clutch faces).


I think those larger manufacturers (LUK, Sachs, Valeos, etc.) don't exactly "don't care", considering how their aftermarket OE replacement clutch kits is not rated that much higher than manual transmission's manufacturer rating. They know better to not sell you something way over factory rating and those who still want it is a real small market.

Even though, you gotta make an educated decision on what to do with your manual trans equipped truck. Manual trans can only handle so much power for so long before they fall apart. I personally know people who broke their trans, NV4500, NV5600, G56, and myself included. I just broke the 5th gear in the NV4500, still need to get it out to see what took it out and what else I may find. The only guy I know who never broke his G56, because the truck is bone stock all its life lol

IMHO going with clutch set up with significantly higher torque rating over trans's factory rating to handle turned up diesel and expect the trans to have long trouble-free life is idiocy if you ask me.

What do these torque rating signify, rated strength or fail strength? Asking for a friend whos running a zf6 backed to a 12v :flipoff2: (401whp, 902ft lb torque)
 
Burns
Definitely not 'fail strength' lol :flipoff2:.

It should be defined as the rated strength for the given maximum GCVW..... for to have a normal service lifespan and without catastrophic hard part failure (shaft, gear, etc. turn into million pieces)
 
Burns
Definitely not 'fail strength' lol :flipoff2:.

It should be defined as the rated strength for the given maximum GCVW..... for to have a normal service lifespan and without catastrophic hard part failure (shaft, gear, etc. turn into million pieces)

Cool! The "fail strength" was my quick and dirty term to get the point across as you could tell! Guess Ill need to baby my ZF6 some so I dontblow it up too fast :grinpimp:

I am enjoying this thread and am curious to see how long my south bend single disc lasts!
 
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