Clutch questions. Puck disks etc...

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Re: Clutch questions. Puck disks etc...

Postby vlad01 » Sat Nov 18, 2023 8:33 pm

I don't know what happened to my post, maybe the internet dropped while posting. I am sure I saw it there once I posted? That was a few days ago. Only noticed now that it was not there.


Anyway, Scott I think was the name? said that he recommends a good (proper) exedy organic disk (about $400 for the disk alone) and to mod a pressure plate (can't recall what make of plate but it wasn't exedy) to have about 1200kg of clamp.

He said he can make something good to drive pedal pressure wise and is the best for the driveline protection, the clutch should be the weakest point in a performance build which totally makes sense.


He agreed on all of my points and concerns I mentioned in the OP. The organic disk is lighter, lighter than ceramic cushioned by a fair bit but puck can be lighter depending on the config. This will help the shifts alone.

He said ceramic can perform badly and slip once they get hot from a lift off condition from the disk expanding unevenly, which causes the disk to distort into a cone or some other shape that reduces the contact to edge of the pucks. Similar to how pushbike disks get hot and buckle into a cone and stop working until they cool down.


He said exedy OEM are garbage and wasn't at all surprised that I had those issues. CI used to be good but are mediocre now but still better than exedy according to him. He said there isn't nay good options anymore in terms of OEM parts to start from when building a clutch.

His opinions on Xteme is they tend to chop and change so what you got 12 months ago is now different so the winning formula to build a certain combo no longer applies.

Explains why the Xtreme in the shitbox I installed last weekend looks a little different to the other few I have used over the years and feels a lot heavier too, more like 50% more clamp over stock than the claimed 25% on the specs. The older kits of this one I have were much closer to stock pedal and inline with the 25%

And I feel in terms of it's hold is way over kill at the sacrificed of pedal effort. It chips gears easily, 2nd, sometimes 3rd. The bite when driving hard is instant. Driving in traffic is good but does feel heavy.

NPC was considered good, especially their flywheels.

For the white car, the replacement daily. I will give him a bell once I am ready and he'll setup a clutch that is somewhere around the Xterme in performance but hopefully more like the factory effort.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Clutch questions. Puck disks etc...

Postby v6bucket » Sun Nov 19, 2023 5:46 am

Sounds like you got good advise.
"Definition of a Drag Racer: A person who spends money he doesn't have on parts he doesn't need to impress people he doesn't know." - Grumpy Jenkins----- Poverty---

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Re: Clutch questions. Puck disks etc...

Postby vlad01 » Sun Nov 19, 2023 9:54 am

He had a VN or something with 550hp with a organic single plate with a T5 before the T5 eventually failed and then upgraded to a different box, twin plate organic and more power.

He said for what I want, a single plate organic as mentioned built for 400hp will be ideal and that he'd go for a better box so I an always increase power.

I said no issues as I really want a PPG gear set for the straight cut gears, which are rated somewhere around that 500hp anyway and that being NA V6, I'll never exceed that 350-380hp rage and have no plans to go boosted ever. So we agree that this should be the best option.


I have shied away from hydraulic clutches due to reliability issues and feel, but starting to think with the high quality hydraulic bearings and under dash factory converted pedals these days, that I can perhaps work around the factory issues with getting quality cables these days and get away from the heat management issues associated with the clutch fork cover, the cable and exhaust clearance.

How have you found hydraulic in terms of effort and feel? I feel like effort as long as the cable is in good nick, don't improve much with hydraulic, often I felt worse due to the sloshy feel when I drove them but that's with older conversions.

Ultimately, the leverage and diaphragm pressure remains the same, but in theory the cable and fork friction is removed. You can I suppose alter the leverage at the cost of travel that might give better tunability for you preference.
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Re: Clutch questions. Puck disks etc...

Postby immortality » Sun Nov 19, 2023 10:10 am

What I did in the past was soak the cable in some kero and then work the inner to wash all the crap out of the cable, high pressure air to dry it all out and work some graphite dry lube into the cable. This seemed to work well to keep factory cables alive and working smoothly.

I've never driven a hydraulic clutch car that has the same feel as a cable clutch but don't have that option with the VT.

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Re: Clutch questions. Puck disks etc...

Postby VK_3800 » Mon Nov 20, 2023 4:05 am

None of this stuff is cheap but I feel like you could rob some decent OEM parts and get a similar result these days.

I'm a fan of hydraulic thrust bearings, fewer moving parts and no side loading without any fork mechanism does tend to keep the effort consistent over time. It's a TIlton screw-on type so it locates well on the input shaft with good adjustment, was originally to suit Muncie but adapted it to the TKO when I changed box.
Image

Master cylinder is a universal Tilton with a custom made pedal assembly under dash.
Image

Clutch itself is a McLeod twin disc full organic, pedal effort is similar to a heavy duty single. Had a single disc with organic flywheel side and ceramic button on the pressure plate side which worked fine but only lasted 18 months - apparently that's normal.
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Re: Clutch questions. Puck disks etc...

Postby vlad01 » Mon Nov 20, 2023 6:58 am

That's exactly along the lines what I was thinking too.

I found AP brakes list a heap of different OEM based concentric slaves with all kinds of options that they have added. I'd prefer that over the ACE/Malwood type which they call a hydraulic bearing. The bearing is fixed and the whole assembly moves, but I like that the OEM ones have dust boots and don't have to have a heap of movement/clearance to considered for the hoses, housing, locating pin etc... like the Malwood ones.

For the T5, I'd probably find some nice double ended studs, ARP or something similar. Use them to bolt the input retainer down as normal and then the protruding studs can be used for a machined up support plate for the slave.

The T5 retainer doesn't have anything to support a locating pin or alike, like I see on your TKO.

I am not surprised about your previous clutch wearing out. With ceramic, they should be operated on/off and slipping or riding them kills them quick smart. Having one side organic would move most of the biting load to the side that has most grip, the ceramic, making it work harder than it needs to and organic being a slipping type material would exacerbate the wear on the ceramic side if you know what I mean.

If it was all ceramic it likely would have lasted longer, but of course machining or replacing flywheels often gets expensive.

The twin plate should not be harder effort wise than a single and often enough are lighter if a similar power capacity is used. The clamp load experienced by each disk is the same regardless of the amount of disks involved. The idea is 2x or what ever multiple surface area.

This was an idea I was tossing around with Scott when I called him, same power capacity but much lighter pedal in exchange. But of course way more inertia on the gearbox side which is something I want to reduce due to pushing the rpm on the T5.

Those multi plate small diameter motorsport clutches would be great if they had a tiny organic disk option but don't seem to exist, they are all ceramic but do offer low inertia and option for a light pedal and high rpm/hp capacity.
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Re: Clutch questions. Puck disks etc...

Postby immortality » Mon Nov 20, 2023 7:07 am

Came across this on my searching.

https://howeracing.com/products/82876-gm-t5-hydraulic-throw-out-bearing-stock-clutch?_pos=2&_sid=fca5d5d3d&_ss=r

Seems to be some decent stuff for the circle track community.

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Re: Clutch questions. Puck disks etc...

Postby vlad01 » Mon Nov 20, 2023 8:00 am

That looks alright. Bearing would have to change to the rolled lip type, but the sizing is all correct for the Holden T5.

Only thing is , you'd have to add a spacer as the V6 T5 input is stupidly long and those pins would need to change or something else as they would need to more than double in length for the same reason. Then there might be excessive flex potentially.

Also, I am worried about the clutch load on the retainer and it effecting the box bearing preload, the Holden T5 has a rather flimsy alloy retainer and so placing the load on the outer 4 bolts would be better and hopefully have minimal effect on the bearings in the box.

All this stuff is relevant when talking about heavy performance clutches.

All food for thought.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.


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Re: Clutch questions. Puck disks etc...

Postby vlad01 » Mon Nov 20, 2023 6:49 pm

Yeah basically.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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