BGTV8 needs a new clutch
 

I spent yesterday at Sandown Raceway in Melbourne and put around 240km on the car at competition pace.

Got down to PB times (high 1:26's) but noticed that the clutch was starting to slip on 4th to 5th change, and if I slowed the change so that the revs matched, the slip was not so noticeable, but in the end, it eventually saw me fold for the day.

It recovered enough for the drive home having let the car cool for 45 minutes.

So now I need a flywheel and clutch.

I can see JWT offer a package, but I am interested in alternatives, especially as the car will get a big weight diet, HR head conversion and sequential shift gear box in the medium term, but for the time being, will be DD, so a sprung centre is mandatory.

What is the range of alternatives - I'm keen to have any feedback.

I've already PM'd Valkyrie MotorSports and the Doran Racing guys, but I suspect they will use a solid centre race clutch which won't suit my immediate requirements.

Thought that Doran Racing was using a Southbend set-up. And that Valkyie was using a Tilton set-up.

SpecialtyZ 6 puck lightweight flywheel/csc and it to comes with a Tilton setup!

:eek: Awesome!!!!!!

Try this:

http://www.the370z.com/parts-sale-pr...nce-parts.html

Thanks but freight from US to AU for this weight is not going to be cheap .. is a really good option though.

May have found an AU-based option which looks "promising"

im guessing your clutch is fine. its just the clutch fluid boiling since the cable passes directly over the cats. flush with RBF600 or castrol SRF and add a stainless steel line. you'll be set

Nope, clutch is slipping. Boiled fluid means you cannot pressurise the clutch circuit and properly disengage the clutch to support shifting as the air-bubbles compress rather than the CSC pushing on the pressure plate fingers and disengaging the drive.

The dead-giveaway was the stink of the clutch which indicated that the flywheel was rotating faster than the clutch driven plate - engine speed was higher than it should be for the road speed.

I have experienced slipping clutches before and this is a classic case and the smell of burnt clutch driven plate facing material is a dead give-away.

Either the pressure plate fingers have lost tension (unlikely as they usually collapse entirely) or the facing material has worn which is the most likely.

Given that this was my first session at Sandown which has an (up-hill back straight) with the 4.08:1 final drive gears - which means I am pulling higher RPM for a given road speed/gear combination, I am actually putting a bit more torque thru the clutch at a given road-speed which may have contributed (remembering that the function of gearbox and diff is to
"multiply torque").

The other factor is that the car has covered ~ 120,000 kms and done a heap of track days - well over 50, many of which involve standing starts (our club-sprints are paired standing starts with the field gridded in practise time order and each pair starting 6-8 seconds apart for a 6-lap "dash").

These "super-sprints" do not qualify as a "race" because it is not a massed start with everyone stepping off the clutch when the lights go green, but the I still still launch the car in race mode, and the fact that the OEM clutch has survived the brutality is in its favour.

We have installed many different clutch kits here, we have had our hands on even more clutch kits, everything from OE to the super high end twin and triple disk clutch kits. for a competition car there are only two clutch kits i can reccomend that will gurantee solid performance and relibaility.

Specialty Z's 6 or 5 puck clutch kit, and the OS Giken line with a Tilton CSC.

All other clutch kits are hit or miss when it comes to track cars, they hold up okay on street and recreational abuse but when put through 20+ minute sessions at the speed way the SZ and OSGiken are the only ones i would recommend. so whenever you are ready let me know!

-Juan

Australian Clutch Services (who own the Xtreme brand) have agreed to make me a 1350kg billet cover plate with 5-puck sprung centre for AU$1450 (about US$1160 at current exchange rates). USD/AUD exchange rates have moved significantly in the past month or so which effectively makes US-based purchases 15% more expensive, on top of freight which is always more expensive coming from the US to AU - one of the realities of life unfortunately.

Race Brakes in Yarraville, Melbourne will install it in 10 days.

Thanks for all the feedback and suggestions.

RB

Xtreme clutch and lightweight ACS flywheel fitted for $520 - so I am a happy camper.

Driveline is a bit noisy between 1400-1900 rpm (which the OEM dual-mass flywheel damps out) and the clutch "bite" is abrupt, but easy enough to cope with after the first day.

The 2015 objective for the car is a pair of new manufacture HR heads, the JWT C11/RZ1 cam and valve kit and then the Valkyrie path with VQ40 crank and JWT rod/piston combo.