Frequently Asked Questions

Billet pressure plate / hat torque spec

All Direct Clutch billet 7.25″, 8″ and 9″ pressures run 6x M8x1.25 bolts or studs . The recommended torque setting is 25nm. A small amount of blue loctite can be used on the threads.

We always recommend crank bolts to be torqued to factory specifications..

Should they not available, this below chart can be used as a guide.

ARP Bolt Torque Guide

SizeTORQUE*
(Ft. / Lbs)
TORQUE*
(NM)
1/4″1418
5/16″2838
3/8″5068
7/16″80108
1/2″125170
9/16″180240
5/8″240325
6mm1317
8mm2838
10mm5575
11mm72100
12mm85120
14mm165220
16mm225310
Grease supplied in ARP sets is to be used under the bolt heads only.
Some mild thread locker is recommended for threads.
Always fasten bolts in diagonal sequence.
Always fasten in 3-4 stages to the recommended torque.

What HP is a billlet Direct Clutch rated to?

We get asked this question multiple times per day….The answer to the million dollar question depends immensely on the application and or what type of use the car or clutch will see in a worst case scenario….

Aside from HP and NM or torque, a clutch has to be built to cater for varying windows of heat, relative to the type of use that it will see , worst case.

For example 600hp in a drift car, is a completely different clutch to that of a 600hp circuit race car in terms of clutch material and weight, despite having the same HP/KW /NM.

Generally speaking the Direct Clutch billet range of clutch can cater from 200 to 2000hp.

That said we don’t have a 1 clutch fits all. We aim to build each and every billet unit to the customers supplied information of the type of use his or her vehicle will see.

Does the billet range of clutch utilize sprung hubs?

All Direct Clutch 8″ billet Single , Twin and Triple plate units utilize solid / un-sprung clutch hubs. This is done for 2 reasons. The un-sprung disc is lighter allowing for faster shifts. The second is the sprung hub is usually a weak link in the system.

In back to back comparisons, a sprung hub only offers dampening to sound and offers very little difference in feel. A reduction in engine / gearbox feedback / noise only can be expected, which is contrary to many opinions.

I run a cut and shut welded bell housing, is the billet clutch suited to this?

Due to the solid discs, the Direct Clutch billet unit , is NOT suited to any conversion that has had a “cut and shut welded” bell housing. This is due to the missalignment we have commonly seen in these conversion methods. The solid disc offering zero tolerance to this missalignment. A unit with a sprung hub will “tolerate” this missalignment for a longer period, compared to that of the solid disc .

What bearing do I need to run?

Generally speaking, the billet range of clutch, likes a rolled face bearing with a 52mm contact face.

In Exedy world this bearing is a BRG2149. This bearing has a 40mm ID which suits many Japanese carriers. the most suited bearing with a 45mm ID is a BRG2133. Either of the bearings will be supplied with any new Direct Clutch billet unit

How do I adjust my billet clutch?

This is done in 2 ways:

1/Under dash by shortening the threaded rod from the pedal to the master cylinder.

  • Shortening this rod lowers the clutch take up point
  • Lengthening the rod raises the clutch take up point.
  • We advise customers to aim to have the take up point of the clutch as 40mm off the floor.
  • This ensures there is sufficient free travel at the top of the pedal

2A/Internally inside the bell housing on set ups running an internal slave cylinder

  • In general we like to see 8mm of gap from the clutch fingers to the bearing face, with the bearing fully compressed or pushed to the gearbox.
  • This allows for the clutch diaphragm fingers to “grow” toward the gearbox as the clutch wears
  • By completing our custom spec sheet, we are able to assist u with this

2B/ Externally we need to ensure the clutch fork and push rod can be compressed into the slave cylinder 20mm from its resting position .

  • In the case of a cable , lengthening the out of the cable raises the take up / engagement point of the clutch
  • Shortening the outer we see the lowering of the engagement point
  • We again advise customers to aim to have the engagement point at 40mm off the floor.

If running a Sintered iron billet unit, refer to our Billet 8inch + 9 inch Sintered Adjustment PDF in the footer below. It has additional information to the above.

Do I need to bed my clutch in? and how?

All clutches require a run in / bed in period. Failing to see a run in / bed in period, may see the clutch flair / slip / overheat / damage your the clutch and dramatically shorten the clutch life.

In most cases we ask there to be 1000km of normal stop start driving, prior to any full power / high load type use.

We appreciate that this isn’t always possible, especially in the case of a competition only or non registered vehicles. So in these cases we suggest, light forward and reverse take offs (just off engine idle rpm) in a car park area or similar for 3 x 5 minute sessions, while allowing the clutch to cool between sessions for 15mins as we do not want to overheat the new clutch!.

Any run in is better than none at all, but be mindful all clutches that are not completely bed in, WILL NOT usually be able to cope to their rated HP / NM, until completely run in.

After run in, be mindful of clutch flares (engine may over power the not fully bed in clutch and see RPM flares). This can overheat and rapidly damage the clutch

Always re- adjust the free play of the clutch pedal after run in period.

Always aim to have the take up / engagement point of the clutch at less than 40mm off the floor. This ensures there is always free travel at the top of pedal and the throw out bearing is not pre loading the clutch diaphragm fingers.

Contact us anytime for any further information or clarification of the above.