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Air assist clutch conversion question


Jeff.Sloan

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To all who have done the air assist clutch conversion (Sibernut, any others?): Did you maintain the 1/8" fork to bearing pad (free pedal dimension) clearance? The air assist 'servo' has a fairly strong full extension pre-load tension, so I think that once installed it will push the fork onto the throw-out bearing throughout its entire stroke. Is this OK? All of the clutch adjustment videos I am seeing online spec the 1/8" clearance on the fork but I don't think that will be possible after the conversion.

 

post-8344-0-85152800-1475470232_thumb.jpg

 

Here is one of the clutch adjustment videos I am referring to:



Thanks,

Jeff

2004 Volvo 630, Cummins ISX, Eaton 10 speed (air assist clutch), 3.71 3.07 rear locker, ET jr, 200" WB, GearMaster

2017 Forest River Sierra 372LOK

Full time June 2017

DW, 2 kids, and 2 dogs

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Is that the same servo I used? I left the slack between the retracted piston and the attachment to the clutch shaft arm, shaft of the servo did not preload at all. Possibly when the servo is connected hydraulically, the fluid trapped will stop that

2000 Volvo 635 A/S, N-14 Cummins
"The Phoenix"
'03 KA 38KSWB

http://s918.photobucket.com/user/sibernut/library/?sort=6&page=1
Furkids- Sibe's CH. Sedona & Tseika
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Is that the same servo I used? I left the slack between the retracted piston and the attachment to the clutch shaft arm, shaft of the servo did not preload at all. Possibly when the servo is connected hydraulically, the fluid trapped will stop that

 

Yeah, exact same part. That makes sense. Once the hydraulic system is sealed & bled out, it shouldn't be able to self-extend.

 

OK, thanks for confirming! My application is different (Eaton 10-spd trans) so I will post a couple pics once it's done. Thanks! -Jeff

2004 Volvo 630, Cummins ISX, Eaton 10 speed (air assist clutch), 3.71 3.07 rear locker, ET jr, 200" WB, GearMaster

2017 Forest River Sierra 372LOK

Full time June 2017

DW, 2 kids, and 2 dogs

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The hydraulic forks don't have the 1/8" gap. They touch but they don't put any pressure on. I know I've messed up a rodded style and had it too tight and it made a heck of a racket in the cab under load. Bad things happen over time like that but I never made it too far to get to that point. I've never done a Volvo so I have no idea how you set freepedal.

 

So never doing a Volvo before walk me through it and my ton of questions.... On the right in your pic is the hydraulic release fork that was in the truck? Eaton A7786 (new style) or A7414 (old style) and the Volvo stock slave in the box with it? Can you pull the slave mount studs off the release fork, install in clutch housing, and then just bolt a Volvo air/hyd slave to it? http://www.ebay.com/itm/Volvo-Vn-Gen-2-Wabco-Clutch-Slave-Cylinder-20469695-/122053794962?hash=item1c6af91c92:g:VYoAAOSwe-FU4iUZ&vxp=mtr Is the 2-piece fork even install-able with the trans in the truck?

 

Do you have the bottom mount inspection cover in the clutch housing? Or is it the cover that is clocked around 7:00 with a small clutch adjust hole at 5:00? Just kind of wondering how they set it up. They really don't like a manual adjusting clutch in a hydraulic setup cuz you can't feel it coming out of adjustment (kinda same principle as air brake adjustment) but it is your truck and I'm sure you can feel it when it is time.

 

Only retrofit I've done is a change to the integral release fork setup for T680/T880 (and a couple swaps where PTO and air/hyd actuator wanted to occupy the same spot) but man is air actuated worth it. T680 and T880 clutches are freakin awesome.

 

http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/ct_196611.pdf

 

http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/taib0853.pdf

 

It all looks so easy without a transmission already in the truck. ;) Interesting stuff!

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Yeah, exact same part. That makes sense. Once the hydraulic system is sealed & bled out, it shouldn't be able to self-extend.

 

OK, thanks for confirming! My application is different (Eaton 10-spd trans) so I will post a couple pics once it's done. Thanks! -Jeff

Jeff

Would you be up to building me one. I also have an Eaton 10 speed.

 

Roger

GCTaaehl.jpg

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The hydraulic forks don't have the 1/8" gap. They touch but they don't put any pressure on. I know I've messed up a rodded style and had it too tight and it made a heck of a racket in the cab under load. Bad things happen over time like that but I never made it too far to get to that point. I've never done a Volvo so I have no idea how you set freepedal.

 

So never doing a Volvo before walk me through it and my ton of questions.... On the right in your pic is the hydraulic release fork that was in the truck? Eaton A7786 (new style) or A7414 (old style) and the Volvo stock slave in the box with it? Can you pull the slave mount studs off the release fork, install in clutch housing, and then just bolt a Volvo air/hyd slave to it? http://www.ebay.com/itm/Volvo-Vn-Gen-2-Wabco-Clutch-Slave-Cylinder-20469695-/122053794962?hash=item1c6af91c92:g:VYoAAOSwe-FU4iUZ&vxp=mtr Is the 2-piece fork even install-able with the trans in the truck?

 

Do you have the bottom mount inspection cover in the clutch housing? Or is it the cover that is clocked around 7:00 with a small clutch adjust hole at 5:00? Just kind of wondering how they set it up. They really don't like a manual adjusting clutch in a hydraulic setup cuz you can't feel it coming out of adjustment (kinda same principle as air brake adjustment) but it is your truck and I'm sure you can feel it when it is time.

 

Only retrofit I've done is a change to the integral release fork setup for T680/T880 (and a couple swaps where PTO and air/hyd actuator wanted to occupy the same spot) but man is air actuated worth it. T680 and T880 clutches are freakin awesome.

 

http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/ct_196611.pdf

 

http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/taib0853.pdf

 

It all looks so easy without a transmission already in the truck. ;) Interesting stuff!

 

Thanks for confirming no gap. Great to know. I do have an access cover in addition to the release fork hole itself, so I should be able to reinstall the fork and get everything lined up when the time comes.

 

My clutch is far out of spec. Perhaps 3/8" to the pressure plate, and much more than 1/2" to the clutch brake (Maybe 5/8"-3/4". The clutch break is an older 1 piece and very thin, less than 1/4". I think it needs to be replaced as well. I had another nasty surprise when I opened it up, someone used a generic release bearing grease tube/fitting and the threads were wrong, so the release bearing grease hose had fallen out of the release bearing at some point. There is a lot of nasty grease buildup inside the housing, so I'm afraid it's been the way for a while. The release bearing feels dry inside, rocks about 1/16-1/8" on the shaft. I'm hoping to buy a new tube (Looks like I need the Eaton #A7857) and reload the bearing. I'd sure hate to have to R&R this entire clutch . . .

 

Here is a pick after a lot of cleaning had already been done:

post-8344-0-15531600-1475638244_thumb.jpg

 

I didn't know their was a Volvo air/hyd slave on the market!! Thanks for sharing that! I think I might try that route first before getting to deep into the custom fabrication. Hard to beat stock parts that already work with custom fabricated solutions . . .

 

Thanks also for posting the links to those service bulletins. Great info for me to be aware of! I don't mind adjusting the clutch every 20-25k miles. With the previous owner, the truck only moved 50k miles in the last 8 years . . . I'm guessing we'll be putting 40-50k per year on it once we start full timing next year.

 

My release fork is with the mechanical engineer right now, not sure which version I have. From a quick Google search I can't tell if it's the Eaton A7786 (new style) or A7414 (old style). I bet I have the old version and those seals on the pivot have failed, I recall being able to see pretty deep into that pivot bearing. I'm going to go pick it up tonight, I'll post an update once I know.

2004 Volvo 630, Cummins ISX, Eaton 10 speed (air assist clutch), 3.71 3.07 rear locker, ET jr, 200" WB, GearMaster

2017 Forest River Sierra 372LOK

Full time June 2017

DW, 2 kids, and 2 dogs

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Jeff

Would you be up to building me one. I also have an Eaton 10 speed.

 

Roger

 

Absolutely! I consider this a must have. If I find a combo of OEM parts that work, I'll be sure to share. If no stock parts get this done, my ME will design and FAB a custom solution. If we go that route, I already asked him to save the plans so that we could make a few extras for other interested parties. :-)

2004 Volvo 630, Cummins ISX, Eaton 10 speed (air assist clutch), 3.71 3.07 rear locker, ET jr, 200" WB, GearMaster

2017 Forest River Sierra 372LOK

Full time June 2017

DW, 2 kids, and 2 dogs

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Picked up the release fork. Part number says "A7413" on it. Having trouble finding info on this one online

post-8344-0-02093600-1475643054_thumb.jpg

2004 Volvo 630, Cummins ISX, Eaton 10 speed (air assist clutch), 3.71 3.07 rear locker, ET jr, 200" WB, GearMaster

2017 Forest River Sierra 372LOK

Full time June 2017

DW, 2 kids, and 2 dogs

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I really like what Sibernut did with his clutch assist. I would have tried to go that route if I had the "right" transmission and knew about the parts when I made up my air assist. Unfortunately, it did not appear that the parts being used on his transmission would work on my Meritor 10 speed to do a retro assist project. Just for info there is another approach to an air assist if it can't be done at the transmission. The system I built that attaches to the firewall and activates the clutch with a roller chain and a button on the gear shift lever has worked flawlessly for five years. No problems and probably has kept me from knee replacement. If you cant make the transmission parts work go back and look at what I came up with.

300.JPG.c2a50e50210ede7534c4c440c7f9aa80.JPG

Randy, Nancy and Oscar

"The Great White" - 2004 Volvo VNL670, D12, 10-speed, converted to single axle pulling a Keystone Cambridge 5th wheel, 40', 4 slides and about 19,000# with empty tanks.

ARS - WB4BZX, Electrical Engineer, Master Electrician, D.Ed., Professor Emeritus - Happily Retired!

 

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Absolutely! I consider this a must have. If I find a combo of OEM parts that work, I'll be sure to share. If no stock parts get this done, my ME will design and FAB a custom solution. If we go that route, I already asked him to save the plans so that we could make a few extras for other interested parties. :-)

I'll be on your list as well. Rockwell / Eaton 10sp same as Rogers.

Jim's Adventures

Old Spacecraft.... Who knows whats next

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A7413 is just the fork inside the assy. The Roadranger stuff doesn't list it or show it too well but the ebay fork assy from the same guy shows the 7413 fork inside. http://www.ebay.com/itm/Fuller-Clutch-Release-Fork-A7414-For-Heavy-Duty-Truck-Applications-/111888315910?hash=item1a0d103606:g:re4AAOSwxCxT73Jc&vxp=mtr So at least that confirms the A7414 assy works for you.

 

Wish I knew Volvo & Wabco stuff better as getting it to fit is only 1/3 of the battle. Somehow you have to get the hydraulic lines to fit each other and I guess I'm going off the assumption that the Wabco slave and the Wabco servo ought to be the same type or at least get-able to the same time (either threads or clip type) :huh: . On top of that I'm betting the air inlet threads are some sort of BSPP thread that won't be fun. That servo is used on the newest ProStar's so a trip to an International dealer might dig up a fitting as well.

 

Release bearings are all pretty sloppy on the shaft so that isn't a worry. Use hi-temp grease only on the release bearing. Doing a new-to-you adjustment and setting up new hydraulics at the same time is going to drive you batty!

 

I wouldn't even know where to start on a hydraulic release for Meritor/Rockwell trans. That's like pure Volvo. But I would guess that if you have the same slave as pictured in Jeff's box above then the servo ought to go on just the same.

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Randy I can't find a link to your system

I can't find it on the forum anymore. Guess it got lost. Anyway, here are links to the Photobucket pics that may or may not make sense. There are some other project pics mixed in with the pneumatic clutch project that have no relationship. In a nutshell it is a double acting 8" pneumatic cylinder mounted on the firewall using a roller chain to pull the clutch pedal in. A microswitch on the gear shift activates the cylinder air control valves.

 

http://s21.photobucket.com/user/professor95/slideshow/HDT%20-%20Pneumatic%20Clutch%20Assist%20Project

 

http://s21.photobucket.com/user/professor95/slideshow/HDT%20-%20Pneumatic%20Clutch%20Assist%20Project%20II

300.JPG.c2a50e50210ede7534c4c440c7f9aa80.JPG

Randy, Nancy and Oscar

"The Great White" - 2004 Volvo VNL670, D12, 10-speed, converted to single axle pulling a Keystone Cambridge 5th wheel, 40', 4 slides and about 19,000# with empty tanks.

ARS - WB4BZX, Electrical Engineer, Master Electrician, D.Ed., Professor Emeritus - Happily Retired!

 

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As a sidebar to this thread...a few months ago I bought one of the clutch servos on Ebay as I was leaning towards getting a truck with an Autoshift or a manual. It is brand new and made in the USA. Well, I got a truck with a Freedomline. If anyone is interested in the servo send me a private message.

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