What kind of Clutches are there?

[Nilao]

I had 700k on mine before the throw out bearing failed.

[smorgan87]

Replaced mine with a 2050 easy pedal. Feels nice compared to the solo self adjust crap. Cant think of the brand at the moment but american made and 550$.

[dhirocz]

Keep in mind, just because a part has life left in it doesn't mean it should be reused...that's a mega fleet mentality...if it already has to come out to do the clutch, the labor alone to come back and do it later might make it worthwhile to do it now.

If it can reasonably wait, sure...but use your best judgement, because it'll be you footing the bill and the cost of additional avoidable downtime.

[Hammerhead]

There are many brands of clutches, but the design comes down to two basic types;

indirect, has angled springs that you are only pushing against part of. Requires more aggregate actual spring pressure because they also aren't pushing directly against the pressure plate. Most clutches are of this design, Eaton's Easypedal is the best at making a light pedal pressure than the rest, but there are knockoffs of them as well.

direct, as is obvious by the name, the springs push directly against the pressure plate. This means more leg force is required to release the clutch, but 100% of spring force is applied and they can produce more clamping force. The Lipe 1 is the most well known of this type.

The indirect is "smoother" to engage, because the springs are angled so only a portion of the pedal movement is directly acting on the springs/pressure plate, this is why they're easier to slip.
The direct is more aggressive on engagement, and if you're in a hurry or don't have the leg stamina to hold it when required, they can be more driveline abusive.
Every clutch linkage moves the release bearing a percentage of pedal movement. Think of it this way, if the linkage moves the release bearing at 0.10" for every inch of pedal movement then it's a 10:1 ratio and the angled springs further reduce that movement another 25%, then the pressure plate moves 0.075" for every inch of pedal movement on an Easypedal compared to the full 0.10" of pressure plate movement of the Lipe 1.

So it's harder to be smooth with a direct clutch, however they achieve more clamping force with less overall spring pressure. This means if you can be as gentle with a direct as you can with an indirect it should last longer. I've yet to see a Class 8 properly rated clutch wear out, the springs break or the damper plates crack and loose springs long before fiber ever wears out.

The best clutch would be a lock up, but nobody mass produces them. A lock up clutch uses direct springs with less spring pressure for smoother engagement, and has small arms with weights that apply force with centrifugal motion to "lock up" the clutch. For example, they would use 1500 ft/lbs of spring pressure, and 2000 ft/lbs of centrifugal pressure (or more) and this can be adjusted for aggression. They're higher maintenance and very expensive ($3k), but I do know someone that builds them.
I've used single, dual, and triple stage lockup clutches when I drag raced. If you can get them figured out, they're amazing. But it's not easy to properly harness their potential.

[Evotrucker]

I try to be as easy on the truck and clutch as much as possible when the environment is proper but today it was all kinds of fucked up. Man..... all day today the damn clutch was clamping so fucking hard, the entire truck was shaking. I wasnt even hard on or dumping the clutch, nothing stupid. lol jesus christ it was biting down so hard in almost every shift and gear that i didnt wanna work today because of how it was acting up.....

since i rebuilt the motor to the best of my ability and with the financial means i had to work with i am pleased. At this point guys, i am figuring getting a reman transmission and new clutch would save me a ton of heart ache and money/time.

[Evotrucker]

(09-07-2018 )Hammerhead Wrote:  There are many brands of clutches, but the design comes down to two basic types;

indirect, has angled springs that you are only pushing against part of. Requires more aggregate actual spring pressure because they also aren't pushing directly against the pressure plate. Most clutches are of this design, Eaton's Easypedal is the best at making a light pedal pressure than the rest, but there are knockoffs of them as well.

direct, as is obvious by the name, the springs push directly against the pressure plate. This means more leg force is required to release the clutch, but 100% of spring force is applied and they can produce more clamping force. The Lipe 1 is the most well known of this type.

The indirect is "smoother" to engage, because the springs are angled so only a portion of the pedal movement is directly acting on the springs/pressure plate, this is why they're easier to slip.
The direct is more aggressive on engagement, and if you're in a hurry or don't have the leg stamina to hold it when required, they can be more driveline abusive.
Every clutch linkage moves the release bearing a percentage of pedal movement. Think of it this way, if the linkage moves the release bearing at 0.10" for every inch of pedal movement then it's a 10:1 ratio and the angled springs further reduce that movement another 25%, then the pressure plate moves 0.075" for every inch of pedal movement on an Easypedal compared to the full 0.10" of pressure plate movement of the Lipe 1.

So it's harder to be smooth with a direct clutch, however they achieve more clamping force with less overall spring pressure. This means if you can be as gentle with a direct as you can with an indirect it should last longer. I've yet to see a Class 8 properly rated clutch wear out, the springs break or the damper plates crack and loose springs long before fiber ever wears out.

The best clutch would be a lock up, but nobody mass produces them. A lock up clutch uses direct springs with less spring pressure for smoother engagement, and has small arms with weights that apply force with centrifugal motion to "lock up" the clutch. For example, they would use 1500 ft/lbs of spring pressure, and 2000 ft/lbs of centrifugal pressure (or more) and this can be adjusted for aggression. They're higher maintenance and very expensive ($3k), but I do know someone that builds them.
I've used single, dual, and triple stage lockup clutches when I drag raced. If you can get them figured out, they're amazing. But it's not easy to properly harness their potential.

I have a feeling you are trying to tell me that it doesnt matter about rather the clutch wearing out but the springs, damper plates wear out or break on indirect or direct clutchs? So it all comes down personal preference? Correct me if i am wrong.

[Hammerhead]

(09-07-2018 )Evotrucker Wrote:  I have a feeling you are trying to tell me that it doesnt matter about rather the clutch wearing out but the springs, damper plates wear out or break on indirect or direct clutchs? So it all comes down personal preference? Correct me if i am wrong.

Depends what your job and demands are?
If you’re just running standard 80k (even 100k) freight, then yes it’s personal preference essentially. I would advise putting in a higher torque rated clutch, because then in demanding circumstances you’re not operating near its limit.
The other thing to consider is ease of adjustment. Because most people don’t adjust their clutch nearly often enough. If it’s easy, you’re more apt to do it.

For me, having a clutch slip on a very steep grade dragging 200k could be catastrophic, so I will only run a direct. I have had an Eaton slip in such conditions, NOT COOL! I saved it, but it scared the bejesus out of me.
Pulling the weight I do, I have never had a new clutch with a resurfaced flywheel NOT slip until they’re scuffed in...until I put this Lipe in.
It takes me longer to put my coveralls on and get my tools than it does to adjust my clutch. And I never need to bump the starter or bar the motor over, or jam something against the pedal to hold it while I do it.

[Hammerhead]

(09-07-2018 )Evotrucker Wrote:  I try to be as easy on the truck and clutch as much as possible when the environment is proper but today it was all kinds of fucked up. Man..... all day today the damn clutch was clamping so fucking hard, the entire truck was shaking. I wasnt even hard on or dumping the clutch, nothing stupid. lol jesus christ it was biting down so hard in almost every shift and gear that i didnt wanna work today because of how it was acting up.....

since i rebuilt the motor to the best of my ability and with the financial means i had to work with i am pleased. At this point guys, i am figuring getting a reman transmission and new clutch would save me a ton of heart ache and money/time.

This sounds like it could be another issue. If you do have a Lipe 1 (direct) and you have loose bushings, or worn hiem joints, etc. it is possible that as the clutch starts to engage and pulls itself together, it then pulls the opposite way on the linkage parts and “yanks" the slack out of the worn pieces, exaggerating the "lack of control” of the pedal?

[Chamberpains]

It even sounds like you have broken spring pieces floating in the clutch disc's. Maybe even a broken intermediate plate. You'll see when you get it apart.