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Clutch Comparison AASCO/Tilton Twin v. Clutchmasters 725 Twin v. CM 350/400 v. Spec3+
Hi AZ.
I've been waiting to upgrade my clutch trying to make sure I get the right combination for my street-ability and torque holding needs. I live in a very hilly area and my drive to work likewise has multiple stoplight/intense hill situations that need to be managed in rush hour traffic, yet need to hold the designed power of my build to avoid needing to upgrade the clutch system again. My targeted HP/TQ range is 440-550, although working with custom rods and pistons I may want something able to go a bit higher if I can push these heads, as long as I can get street-ability out of the system where I'm not stalling or having to give the next car 3s lead off a light to avoid jumping into their bumper trying to feather and modulate on a hill. Durability of the system is also a concern, as higher power can burn through clutches quickly sometimes a bit of overkill is a good thing for longevity as long as it doesn’t impact street-ability too much. This build is meant to be done with a LWFW so for all possible builds assume that unless otherwise specified a sprung clutch will be used with the corresponding manufacturer’s LWFW.
So far the options within the single disc option are ClutchMasters FX350, which gives "110% holding capacity over stock"(525ft/lb?) using segmented kevlar and "New Formula Button" Discs that appear to be 8 puck discs that would allow plenty of street-ability, but the barely more than double holding capacity concerns me for the longevity of this clutch as my build will be near it's holding capacity and could cause high wear. For slightly more holding capacity at 170% over stock (687 ft/lb?) the FX400 uses ceramic 6 puck 4 wing "Ceramic Button" discs, however the listing for this item warns of high chatter and quick engagement due to the ceramic. This makes me concerned for the featherability of the system without jumping the car drastically with higher hp.
Some members I know on this board have the Spec Stage 3+ system installed currently and are loving the 679ft/lb holding capacity of the plate without having to go to a puck design. However I have read a ton on quality control issues and general quality issues with this system and would like to avoid it unless absolutely necessary. This disc does feature “carbon semi-metallic full faced material” which could provide great surface area for durability, given a high build quality. The appearance of the plate leads me to believe they are a ceramic metallic mix, and could still be jumpy discs. Given that these are the popular single disc options and the latter ones that should hold my target hp well are not the most durable or street-able options, I looked into twin discs.
ClutchMasters FX 400 with "Ceramic Button" 4-wing 6 puck design
ClutchMasters FX 350 with "New Formula Button" Disc
Spec Mini Twin R-Spec Weight Reduced LWFW System
The conversation switches to single disc vs. twin disc at this point, Spec has both a single and twin disc option, although their highest rated street system is rated at 679 ft/lb vs 800 on the twin disc. Their stage 5 710 ft/lb holding clutch is terrible for modulation as it's a full race build, would a twin disc allow for reasonable street-ability at a high holding tq.? The flywheel for the Spec twin disc appears to have weight reduction holes cut from it, which both makes me concerned for it's durability and too light a flywheel.
My top pick for this clutch system was originally the 725 Clutchmasters kit, which features 2x 7.25" clutch discs for surface area but low rotating mass for better response (similar to Spec's "Ralley" classification vs their "Drag" twin). I'm thinking CM did the original tooling for a twin on this vehicle, and Spec got ahold of some tooling and made a similar one. CM claims "The cover assembly is machined from billet aluminum with 25% more tensile strength than the competition’s cast unit." and Spec loudly states on its Stage 1-5 clutches that they've redesigned the pressure plate with a billet pressure plate, on it's twin listing no such literature is found. This makes me suspect Spec is using cast covers to allow their own tooling, which would explain their 3 puck option in the absence of CM having a 3 disc unit. The unit states in it's description that the CM twins "... are designed to hold high hp/tq while retaining a very smooth operation" leading me to believe the 725 genuinely will be a smooth engage with two smaller clutches and a minor increase in clamping force, where the 850 would be the model oriented for track/drag/intense usage.
Typically twin discs are on/off switches, at least that's the impression i've been lead to believe, however CM offers what they call a "Race/Street TD7S" twin disc kit which HeelToe calls "Street" which through research on their BMW Twin FX725 system I found has one "fiber tuff" rigid disc, and one ceramic rigid disc in the "Race/Street TD7S" system and two ceramic discs in the "Race TD7R" package which HeelToe calls "Street/Race". This rewording by a company that's been around the model for a while makes me believe CM genuinely did get the FX725 system streetable if HeelToe has rewritten the classes of those clutches one step down each.
ClutchMasters FX725 7.25" Twin Disc System
Stumbled across a custom AASCO/Tilton listing on heeltoe that i've got to assume is something they must have set up independently, as even on the site it allows input for "Power Holding Needs" and "Engine/Trans Application" and a "completely custom billet flywheel"(like AASCO or otherwise per application? Unknown). The twin system uses 4 puck cerametallic discs, and later in the listing mentions "Suitable for most racing application where limited clutch slippage/modulation is desired" leading me to believe this would be worse street-ability wise in comparison with the CM systems either 725 or 850. If anyone has further information on this combination, I know Tilton makes great clutches and has for a long time, would love to know if there are more modulatable options for the discs and if the weight of the flywheel can be custom or what that aspect of the listing meant.
AASCO/Tilton Twin 4 Puck "CeraMetallic" System
The choice between Spec's twin disc and ClutchMasters's seems easy where the CM even claims by description to have higher build quality and part strength. Hard to do that in 2019 and be wrong, worth the extra $300 for durability and a description that claims smooth driving. Unless i'm missing something about the intricacies of twin discs, a 4 puck with ceramic in the mix is going to cause a jumpy response with the Tilton option. That same trait may be great for a true rally/drift car that could use the quick engagement and wants fast response on the pedal with high TQ requirements, but here I need the slippiest twin setup possible to retain streetability. CM's twin kits do not have sprung clutches, so any driveline harshness will be felt in full, which makes me wary of the modulatability of these twins but would that also not make it easier to feather with improved feel on what's going on at the discs?
I've put this up as an open discussion for the viability of each of these high power holding designs, and to open a discussion on the benefits and drawbacks of each system. If anyone has a twin disc system or has had one on their AZ car, please give us your input from experience as nothing beats pedal feel for knowing how well a clutch works for a car in a certain situation. Price point of the system is not to be a discussion point, as this is meant to be an even comparison of features of each system unmotivated by finance. Likewise I would like to hear thoughts from those of you with experience with these systems for my application, I can feel the end of this clutch coming up and I would like to get this next system decided on soon and value y'all's input.
I take it this is a turbo build or is it a supercharger? How did you come up with 450-550 TQ - is this wheel or flywheel?
The clutch disc materials you have described (Metallic/Ceramic/Kevlar) are not what I would consider a DD type clutch material, they will all be grabby and take a bit to get used to.
I take it this is a turbo build or is it a supercharger? How did you come up with 450-550 TQ - is this wheel or flywheel?
The clutch disc materials you have described (Metallic/Ceramic/Kevlar) are not what I would consider a DD type clutch material, they will all be grabby and take a bit to get used to.
Yup, that's to be expected however. In no way do I expect to be able to hold twice the HP of stock without SOME increase in pedal feel/difficulty in shifting. I'm simply looking for the smoothest option out of the high HP holding capacity options. The dual wheel materials (one fiber one ceramic) on the CM twin leads me to think the fiber disc will smooth out some of the grabbiness of the ceramic disc. I'm still expecting to need to modulate 2-3 times per second to get a smooth start, i'm just looking to not be in a rocking chair while i'm doing it like an old puck on/off design.
As to the build design, yes the intent is a "Twincharger", with a supercharger and a runner injected W/M system to start and a turbo up the line/down the timeline. All accompanying mods will be done as well, already ATLP V2-R pipe, custom 2.5" single exhaust 1 free flow res 1 free flowing muffler (may be redone after 400 into 2.5 duals if need be), PnP runners, PnP magnesium manifold, bored TB (no 3.7 IM/TB until Hondata, no rev hang for me, then i'll polish that one up as well), TL-S Springs in the head, MDX hollow cams, will be porting this 32A3 head in the following weeks to get ready for the build possibly with new valve 3angle/radius cuts done like the last head, solid LCA bushings to prevent wheel hop, stiff springs as well, extra urethane on any remaining steering busings, oh and turning it into an oversquare stroker 3.5 with forged 3.5 rods and an RL cam. Stroker and the head port are in the works, Hondata and the clutch to hold power and use the power are the priority right now, then I can show off the build and it's progression.
Alright i'm experiencing more slippage on my clutch than i'm comfortable with. I'll be picking up the 750 twin if nobody has a compelling argument for any others or against the twins and use this as a documentation thread.
Was going uphill today and lost speed in 6th, going to try and limp this car along a few more days until I get the alt car running for DD. Was going to pull the trigger on Twin Disc, but 4th of July is coming up and there's no way I can miss a sale on that day on a $1500 purchase. Worth the wait.
On a side note, has everyone gone and bought the clutch replacement "finger compressor" tool or has someone figured out an alternative solution? Not looking to spend $400 on a tool and $1500 on a clutch unless I need to.
Was going uphill today and lost speed in 6th, going to try and limp this car along a few more days until I get the alt car running for DD. Was going to pull the trigger on Twin Disc, but 4th of July is coming up and there's no way I can miss a sale on that day on a $1500 purchase. Worth the wait.
On a side note, has everyone gone and bought the clutch replacement "finger compressor" tool or has someone figured out an alternative solution? Not looking to spend $400 on a tool and $1500 on a clutch unless I need to.
Read from @zeta that the finger depressors were for oem installs only.
I didn’t need one on my recent aftermarket clutch install.
On a side note, has everyone gone and bought the clutch replacement "finger compressor" tool or has someone figured out an alternative solution? Not looking to spend $400 on a tool and $1500 on a clutch unless I need to.
I'm pretty sure the OEM type "finger compressor" clutch tool is only needed for an OEM type self-adjusting pressure plate. Since you are, most likely, going with an aftermarket non self adjusting pressure plate, like Saving4aTL, you would have to do any future clutch adjusting at the clutch pedal. The only one I know who has actually admitted to purchasing the OEM "finger compressor' tool recently is @horseshoez when he did his 'refresh' on his 3G TL6. Although, I'm not sure if he still has it.
Thanks for the info on that, was wondering the same thing on the drive in to work; if the clutch isn't self adjusting it should be relaxed upon install and only see pressure once the pedal's actuating.
Just have to bide my time until a good sale pops up, I may try and grab Hondata at the same time as the next step for this build is an M112.
Back from the dead! Torque capacity has zero relation to durability/reliability. Race type clutches would make your car more race car, in terms of how often you need to replace things. Had the tilton twin, loved it even in traffic conditions. The skill it took to drive it, the chatter and the acceleration was awesome. Awesome until I had to change it out in less than a year. Replaced it with clutchmasters fw-040-al and fx250 in 2017 and I just dropped her off today to get worked on again. If this doesn't help you change your mind, I got that tilton twin collecting dust in the garage. You would have to buy new discs and shims and possibly a friction plate. Fits 07-08 Type S
I have run both and am much happier with the spec 3+. Twin disc clutches provide more holding power that the transmission will handle. Quite a few guys have snapped gears with 300 whp using quick engaging clutches. I am running 600 + whp with the spec 3 + and it’s night and day difference from the Tilton twin. I hated the twin disc, engagement was way too abrupt and violent. Combined with the LW flywheel it would stall very easily. My advice is to run the most mild clutch you can for your power level. I ran the stock disc up to 350 whp.
06-11-2019, 12:25 AM
Clutch Comparison AASCO/Tilton Twin v. Clutchmasters 725 Twin v. CM 350/400 v. Spec3+
