RTS slips at 10psi
Turbo Mini Forums

Only done 1700 miles, RTS AP type made from a 1275 spring and a turbo spring, AP rally plate 180mm. MED steel flywheel. Full weight car on a 2.9 final drive. Now slipping in 3rd and fourth at 10 psi
Seems to be contamination on the clutch plate though i have no idea where its coming from as the primary gear oil seal looks clean.

Also the marks on the flywheel and backplate suggest an uneven contact patch. I have just checked another 80000 mile flywheel and backplate and the wear marks are identical though
Thoughts please. Cheers

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Are the springs almost flat when all bolted up?
I had that same combination of springs and plate, no chance of it slipping with full boost on the gt20
It bent a solid top steady and 2 lower rear gearbox steadys launching at pod

Andy and johns 'tro van had 2x 998 springs

Yes i moved to the darkside

Instagram @jdm_brett

Springs are almost flat. However maybe they could be flatter to increase the clamping force a little? How can i do this?

Also my clutch bite point is 1 inch off the floor, everyone elses seem to be near the top. I can only think this is because the spring is not flat enough?

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My RTS has a low biting point but it's quite progressive.

If something is worth doing, it's worth doing half of.

that dosent look that flat to me,

I have seen a number of different pressure plates with the pillars that contact the springs at different hights, really we could do with somone making a billet setup so they are all the same.

Looks like that's hardly clamped up at all.

The spring/fingers should almost be flat when it's all clamped up

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Should look like this

Isn't it the length of the spacers that is crucial in making it clamp down flat?

nope, spacers are determined by the thickness of the springs

Ive been staring at this for two days now.
Please correct me anywhere i am wrong here because i am probably making assumptions....

Is it true that to make the spring sit flatter i either need a thicker clutch plate or would need to mill a little metal off my flywheel pedastals?

I have been playing around with a drill press and a dial gauge. With my clutch setup as it is, dial gauge on the outer part of the spring, and pressing down the centre with the drill press to release the clutch, as soon as i apply pressure to the centre i get a corresponding upwards deflection at the outer edge of the spring, meaning it is beginning to release.
What i cant understand is how can making the spring flatter can increase the clamping force, please could someone explain how this works cos i dont get it.
Cheers

Also after reading roberts clutch thoughts thread, page 4 says after the clutch wears slightly the clamping force increases a bit. The pictures on page 4 are not there any more so im having difficulty understanding this point too if anyone can enlighten me cheers

But what happens if they are too big?

I read it 20 times now and i think it has to do with the springs beeing pulled against the pressure plate with the bolts. So it clamped harder. That moment you don't puch the springs down against the cranck so it has no difference in to that If they are to big the springs sit to loose i think. But by far a specialist.. aqtualy Try to figure it out by myself but to luch time on my hands and toughts to forget not to answer this.

you can do anything if you set your mind to it...
i rather blow it up winning than keep it together losing.

finish date set for project 1... march 2018

Take it appart and take pictures as you do, as i think its not been assembled correctly. There is far too much discrepancy for it to be anything else

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

As it came apart:

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Final pic

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Cheers that clears that up. I have just proved what you said with an individual spring on my drill press

The spacers are probably too long.

Just checked the spacers, they are cock on. Spacers are 435thou which is the thickness of my two rings and two springs added together

It should be the thickness of the original spacer from the clutch plus the thickness of whatever spring you add in.

Whether that's different or not to adding them all up I'm not sure.

Now assumining it was all built correctly....... Let me know if it wasnt.

I have just bolted it back together using an old clutch plate and the springs are much flatter and i can feel just by the effort of bolting it to the flywheel that i have much more tension on the clutch plate now

The reason for this i think is because this old clutch plate is 35 thou thicker than my old AP rally plate i have been using. ( i have a new AP rally plate and that is thinner too)
Soooo. If i am going to use my Ap plate is it correct that I should mill 35 thou off the pedastals on my flywheel which the clutch bolts to? This should make the flywheel and AP clutch bolt up nice and tight with the spring flat

The problem will be with your spacers.

Whether some measurements say they are right doesnt mean in reality they are right.

It's quite clear the spacers need to be shorter to achieve correct clamp with your setup.

If anything your thicker friction disc ( if it really is thicker ) will actually help your cause.

A thinner plate would see even less clamp.

Either you're spacers need shortened, or the posts on the flywheel need shortened....whichever is easiest.

IMO shorten the posts by say a couple of mm ( or more ) and then you could get washers to allow adjustment.

Edited by stevieturbo on 2nd Apr, 2016.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Right.... spacers....

they need to be the length of the old ones pluss the added spring as already mentioned, so it sounds like they are the right length. the ketch below should help to clarify this.

I supose it would be possible to use a smaller diameter lower wire support and shorter spacers to increase the clamping but i wouldnt expect you to gain much. I think your best option is to mill the backplate lugs, maybe add some big washers in between the clutch plate and flywheel clamp it up to see where it sits, measure the washer stack and mill that amount off.

a furthur thought, do you have a mix of bits from different flywheels ( apart fromt he extra spring) I'm wondering if somthing from another clutch is causing the issue, also can you check the back plate lug heights against a std back plate?

I tried a different backplate and the lugs are identical in height. I will mill the flywheel pillars i think.
Thanks for all the good advice