I am in the process of building a 2.0 Zetec with Piper 285 cams, flowed head, and GSXR750 throttle bodies.

I am hoping for 180bhp?

I am using a lightened 1.8 Zetec fly wheel mated to a type 9 box, and my question is;
Can anybody recommend a clutch to handle that sort of power, or will a standard clutch be up to it?

Thank you in advance

I think it depends more on the torque than it depends on power. Will you have more torque than standard ?

Yes, I would hope so.

Not sure of what sort of figures to achieve though.

be interesting to compare figures we get im doing simular but with Newman 270 cams and Emerald ECU, as for clutches what clutch set up are you currently using? i would thing a basic standard clutch would be pushing it on your potential upgrade, in front wheel drive zetec porer i went through to cheep clutches befor a £300 Helix one as got fed up with laying on gravel drive changing them. hopefully someone can advise specifically fot RWD application

I was surprised at how much abuse standard clutches will take - I'm running a very cheap (£10 ebay job) standard 1800 Mondeo clutch behind my Zetec turbo and so far it is holding up OK, including some fairly abusive trackday driving. I think that the light weight of the car goes a long way to giving the clutch a much easier life that it has in a lardy tintop.

I'm running approx 230bhp, so I don't expect it to last all that long, but the fact that is working at the moment is probably cause for hope!

Different clutches seem to vary a bit as well, I know some others running standard clutches have had slipping problems at similar power, maybe this cheapo ebay one is actually not too bad after all.

My advice would be to try it out with a cheapo one and upgrade if it doesn't work!

Tom

I think you will be fine with a standard clutch. I have 167bhp in a 1.8 with the same cams, headwork and 45DCOE's. Being a 16v, that revs', the Zetec will always have torque that is less than the BHP figure.

Its always the torque that kills the clutch and the heavier the car, the stronger the clutch needs to be.

I have a standard 1.8 Mondeo clutch, which is more than fine.

If you think about it in terms of 'friction' and 'deadweight' it will make sense.

Being so light, you can run a lot higher torque in a Seven, than in a tin top.

Thank you to all who have responded to my post.

I forgot to add that I am currently running a 1.8 Zetec with Piper 285 cams, Griffin single throttle body plenum and Omex ECU which showed 160 bhp on Motoscope`s rolling road.
The clutch that is currently in the car has only done 11000 x miles. From what has been said, I may as well try that clutch 1st to see how it goes???

Thanks again

I'm putting 175bhp through the 115bhp mondeo clutch. I did wonder about it but it seems to be holding up fine.

I was thinking recently about standard clutches and gearboxes for uprated power and Im not sure the standard answer of "its a lighter car" its completely true.

Yes if you plan on accelerating at the same rate in your kit as you would do in the tin top (ie nice sedate driving generally) then the comment does stand true. But with the same power and half the weight we would want to accelerate much faster. So therefore the load on the working transmition parts would be roughly the same... I think my thinking is correct....

F=MA???

Youll find most clutches will be designed with a safety factor involved (probably around 2) so most will work just as well with higher powers anyway.

Weight is IMO irrelevant, especially in higher gears.

If your engine produces 200lbft of torque at 3000rpm it doenst matter what the weight of the car is it has to transmit that torque to the wheels assuming no wheel spin.

OK in a light car you arent going to be able to use all the available torque in 1st gear as the wheels are more likely to spin.

But once in 2nd or 3rd the wheels wont spin and you will need to transmit that much torque through the flywheel.

David

Yes weight is irrelevant...

An engine wont product less torque just because it is in a lighter car. The car will just accelerate faster. So the transmission has to take the same forces.

Thanks again for the replies/advice.

I think I am going to use my 11000 x mile clutch for now, ya know, a kind of, "suck it & see"

no doubt I'll get shot down for this but weight is relevant.


torque only exists if there is something resisting the turning force.

simple example is to take a torque wrench. that is capable of applying 100 lf/ft or more and that only happen with you have a bolt that is resisting the turning.

see where I'm heading?

in a car the resistance will come from the drive train, mainly the fritction between tyres and road surface. friction is related to weight.

therefore weight will affect torque and it will affect the clutch.

just look at the problems BECs have - the need uprated clutch springs - same torque yet this is not needed when engine is in a bike - what is the difference? - 2 driven wheels and more weight.

another example is rolling road - how do they measrue power and torque? by loading up the rolling road to increase its resistance.

if the rear wheels spin, then the engine is not producing its max torque, and that is likley in a kit car.

now waits to be told I'm wrong .....

[Edited on 14/12/09 by 02GF74]

quote:

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Originally posted by Findlay234
Yes weight is irrelevant...

An engine wont product less torque just because it is in a lighter car. The car will just accelerate faster. So the transmission has to take the same forces.

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quote:

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Originally posted by 02GF74
no doubt I'll get shot down for this but weight is relevant.

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Yes weight is irrelevant...

An engine wont product less torque just because it is in a lighter car. The car will just accelerate faster. So the transmission has to take the same forces. ---------------------------------------------

Try telling that to the BEC guys that break clutches and transmissions on a regular basis...



Agreed.
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I have a view that weight would play a part, but seeing as everybody has been most helpful, and I am wide open to opinion/advice, I wouldn`t want to get drawn into an argument over it.

I cannot thank the forum members enough for help with this and previous posts.

weight is the key to this and imo the lighter weight of a kit which is at least half the weight for example of a mondeo the standard clutch would have been designed to cope with the weight of the mondeo
now transfer this into a lightweight kit car and the standard stuff will be more than upto the job provided its decent stuff to start with.

to answer the original question stick with the standard one i don't think you will have any problems

Could it be that the difference between cars and bikes is that with a bike you are not actually able to get all the torque down when accelerating hard (this comes from a perspective of having never riden a bike as either rider or passenger so may not be accurate). Very small contact patch on a rear bike wheel and therefore very easy to spin the driven wheel. Whereas a bike engine in a kit car with two larger contact patches allows you to actually use more torque in a non-slip situation.

Torque for torque, in a non-slip situation the lighter vehicle should just accelerate faster but the total strain on the clutch should be the same.

I think the equation F=MA should the correct (again i say i think ) for two cars of different weight but the same acceleration then the forces involved will be less for the lighter one. but, because we lightweight car drivers drive the lightweight cars to get the maximum acceleration possible we would accelerate the lightweight car faster.

Torque is a moment of force (Newton meter) so will be proportional to the forces involved in the transmission.

taking my engine from an Ae86 (say 1000kg) and putting it in a kit car(say 600kg) and assuming non-slip conditions in both (more likely than assuming non-slip for a bike rear wheel) then if i accelerate my car 66% faster(in meters per second squared) which should be possible, the force required will be exactly the same therefore the clutch under the same stress.

Reiterate.... assumes non-slip between the tyres and road surface. which lets be honest wouldnt be the same for kit car to tin top. kit car with its low CofG and grippy tyres will probably spin at higher torque levels.

Cheers
Fin

[Edited on 14/12/09 by Findlay234]

I think if you took a bike and directly connected the rear tyre to the road without slip you would find your bikes accelerating A LOT faster.... therefore upping the forces through the clutch..... and therefore upping the need for possible repairs...

take a bike engine in a bike and in a kit. take it up to 2/3rds power and drop the clutch. which is more likely to overcome friction at the wheels.... the bike... therefore theclutch torque requirements for the kit are greater.

Now take a tin top and kit with the same engine... take it to 2/3rds power and drop the clutch... which is more likely to overcome the fricton limits at the tyre? the tin top with its front wheel drive and standard tyres...... therefore the clutch torque requirements are greater in the kit car......

But again. the designed in safety factor for the clutch should allow at least double the torque levels (depending on the SF values used)

Cheers
Fin

[Edited on 14/12/09 by Findlay234]

I still dont see why an engine will transmit less torque through the clutch just because weight is lower.

If the wheels arent slipping on the road and your engine is at its peak torque RPM then surely thats how much torque it is producing? That is if, and only if, all that torque is being used to create acceleration. Which in, say 3rd gear, it will be.

First gear is a bit different as you have a lot of momentum to overcome, i.e a lot more resistance for the car to move to start with. The dynamic load is much greater on the clutch, although the toque is the same, hence it will slip. The clutch in my Leon slips in first gear if you floor it (and the traction control kills the power) but not once its in second.

Its sudden changes in torque levels (such as dumping the clutch from a standing start) that will make it slip, even if the torque figure is the same as at the peak torque RPM once rolling when it doesnt slip.

And this is also where weight plays its part. In a lighter car you have less dynamic load at any one time under acceleration, and although the torque is the same there is less momentum resisting the torque being applied hence you can get away with a lighter duty clutch on a lighter car.

Not sure if you follow me, as I am finding it hard to put into words

All about overcoming inertia, the less the weight the trans has to move the less abuse the clutch is getting.

Standard 1.8 Mondeo clutch in mine (£20 off the bay) holding strong.

The tyres pin due to the lack of weight making them the bit that slips...

In a non-slip situation (i.e. clutch engaged) weight does not play a role as per Flak monkey's post.

However, when pulling away, weight does come into the equation, as less weight has to be accellerated. (in a CEC vs. the donor car)

In general therefore, the clutch should have a bit easier life in a CEC then in the donor car (and the other way round for a BEC vs. the donor bike...).

BUT: we (well, I, actually ;-)) seem to, ahem, abuse these cars a bit more then the average tintop which can be very hard on the clutch, seriously decreasing its service life.

Yes the clutch will have an easier life if you drive the kit like a mondeo. But yes you wont, youll drive it hard. Youll try and get best acceleration out of it most of the time you drive, is that not why we build these things... at full acceleration of a light car like this the lighter weight is counter acted by the higher possible rate of acceleration for the same force.... the same force results in the same load on the working parts.... This is simple physics.

Flakmonkey, the dynamic load will be less under acceleration as long as the rate of acceleration is the same as what you would do in a tintop.... but as you will most likely be accelerating at a higher rate the dynamic load on the system will probably be the same... F=MA

Cheers
Fin

quote:

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Originally posted by flak monkey
I still don't see why an engine will transmit less torque through the clutch just because weight is lower if the wheels arent slipping on the road

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Quantum use a stock Mondeo clutch on their Duratec demo car (or did) that was kicking out 190bhp as i asked before i bought it (and then found out it was just a stock Mondeo clutch..).