clutch slipping at Drag Strip, dec 2015 query? new clutch time! OS Giken!!!

[jimGTS]

bit spur of the moment, but popped along to the evening RWYB session at santa pod on saturday.

but i encountered, as i did last year, yet more clutch slip coming on boost in 2nd/3rd/4th.
dam annoying.
it meant i couldn't put any sort of load on the engine off the line to get a good 60ft time.
only times it didn't slip was an easy off the line launch, most of the time, which of course, doesnt bode well for quick 1/4mile times.

clutch is a oruga single plate, apparently good for 400lb!


the clutch doesn't slip on the road at all, so I'm either doing something wrong at the drag strip? or the clutch just doesn't like any load on it at the biting point, which is why i don't see it on the road.

no wheel spin issues.

last year i done a 13.973 at 102.57mph, 60ft of 2.331.
again, poor launch as couldn't put any load off the line as it would slip all the way down the track.

this time, after a few tweaks over the past year, i beat my time and gained 4mph terminal speed, so i think I'm running a tad more power than back then.
i done a 13.406 at 106.54mph, with a 60ft of 2.209.

I'm certain there is at least a 12.8+ in the car with a good launch.

here are some vids


my best run
https://www.youtube.com/watch?v=DxdaPCokcZc

example of the slip i encountered, what are peoples thoughts?
https://www.youtube.com/watch?v=s9e8QCVuW3g

[Ryan S]

how many miles has the clutch done?? sounds ruined man, that MUST slip when you're on the road

[jimGTS]

no clue

no slip what so ever on the 3 hour drive home.
thats with obvious 5th gear pulls on the motorway.

[Ryan S]

no clue

no slip what so ever on the 3 hour drive home.
thats with obvious 5th gear pulls on the motorway.

could be the slave/master cylinder? you checked for air etc?

I'd be tempted to pull the clutch out and inspect it, provided you don't find any leaks or air in the hydraulic system

[Driftlimits Performance]

Not still holding the handbrake off the line are you?

[jimGTS]

no, definitely no resistance when i launch, so is for sure down once i move.

[2mad]

Just watched your video, its ether your clutch is not disengaging properly and your riding it (check bgb how to set up pedal and push rod) .. or.. your clutch has failed mate, mine does the same thing (intermittently) if I boot it my clutch is toast

[jimGTS]

strange thing is i have no slipping issues on the road.
none what so ever in the past year since the first drag attempt with this car when it first happened.

i did adjust the biting point a while back on the pedal so it was a little higher, as was quite close to the floor. so either where it was or bit higher has meant the same result on the strip, on the road, no problems with either.

i did the disengaging test a while back, clutch on floor, in 1st, rev the car high, and it doesn't bite/move, so id say its disengaging.

though i think the quick 1st-2nd gear changes are whats causing it to slip.
it'll then slip in higher gears too.

id guess I'm potentially riding it for a split second on the 1st-2nd change.

as said, was fine on the 3hour drive back.

[2mad]

id guess I'm potentially riding it for a split second on the 1st-2nd change.

What I ment was your coming off the clutch pedal and because your clutch pedal is not adjusted right (stab in the dark) its causing slippage .

My mr2 did this I had to adjust the pedal height to its pretty much max height setting to not to slip and ingauge properly (no idea what clutch was fitted)

My gt4 slips intermittently if I boot it, pretty sure clutch has failed

Also if I turn boost up it slips like bu**ery, on low boost is ok ish.

[jimGTS]

Thing is I have already adjusted it. I can try out a few more positions I guess.
Problem is testing it out. I'm going to have to find my own drag strip to replicate it, lol, because as I've already metioned, I don't get any slip at any point in B road quick driving.
I'd expect slippage in a high boosted 5th gear pull, or 4th from down low wih a busted clutch, but I've never had any issues with this at all so struggling to point it directly to clutch life at least.
I didn't have these issues driving the same style in my old car at santa pod, that was a os gikon twin plate.


Gearbox and selection is good, no problems selecting gears or crunching of any kind. Syncros I think are in great condition.
so pedal push rod length must be a decent length.

[Driftlimits Performance]

Explain your launch procedure

[jimGTS]

Handbrake on.
I'd bring it up to about 3-4k, release handbrake and when it's virtually down bring up clutch to biting point till I'd started moving a few foot, fully off clutch now then foot to the floor.
That's as best as I can describe, least that's what it feels like I'm doing.
Could be a possibility I'm putting some more throttle down while it's still in the biting area. Hard to tell.

I certainly don't feel like I'm riding clutch much.

Had no issues with that method in my old car. I got down to 1.9 60ft in that which isn't too bad. And I rode the clutch a bit more to get those times as brought boost in quicker.

[ashley]

Off topic- but are you pre-loading the transmission?

[jimGTS]

No, it seems like a quicker way to burn out the clutch.
I only us handbrake as sometimes it'll roll back slightly.
Last thing I wanted to do when getting the odd random slip was leaning on the handbrake.

It wasn't getting worse if that makes sense. Sometimes would slip, sometimes not throughout the afternoon.

[ashley]

Gotcha...I was just thinking about your gearbox and cv joints

[synXero]

What a bizarre set of circumstances.

Suppose you can make a change, and test on the road with a simulated drag start? Somewhere safe obviously.

[jimGTS]

so anything i can check out this weekend peeps?

i guess i need to replicate the slip on a quiet road and see where im at with clutch adjustment, other than that, what else?

cheers

[bobhatton]

bring up clutch to biting point till I'd started moving a few foot, fully off clutch now then foot to the floor.

So you are slipping the clutch for 2, 3 feet? If so that will not help at all

[jimGTS]

slip/biting point = same thing, when pulling off the line is all i meant.

how else can you pull away, the clutch has to engage to get you moving.

[bobhatton]

slip/biting point = same thing, when pulling off the line is all i meant.

how else can you pull away, the clutch has to engage to get you moving.

On the sprints and hill climbs we just rev the engine and drop the clutch, no slipping at all then control the wheel spin with the throttle