Done the two clutch mods

A

api330

Member
Hi there, I have not owned my Z4MC for long and i do love it already its a great car, The one thing i did not like how ever was the notchey gear change and difficult clutch operation, but i have now done the cdv mod (removed the whole thing) and done the rework for the clutch stop poisition, What a differance the gear selection seems 75% easier and my gear changes and in town driving are so much smoother, I know most have been modded but if you have not done yours yet get it done i am sure you will be impressed, Cheers Tim. :thumbsup:
 
What's the "rework for the clutch stop poisition"? I heard of the cdv fix, but never of this one...
My Z is still bone stock except for the CSL wheels and soon the H&R springs, but the gear changes are very notchy indeed...
Thx
 
Iv read much on the forum about ' dodgy' gear changes and the cdv fix, as far as Im aware my car is 'stock' . Rarely I get caught out from 1st to 2nd , however not enough to look upon it as problematic , it may be Im needing a drive in a car with the cdv removed in order to compare .
 
Technically all it is doing is stopping you from fully depressing the clutch pedal, and at worst it will meal you're slipping the clutch every time you change gear as you've not fully isolated the gearbox, which will just increase clutch wear, which IMHO makes it a product for the gullible - after all the clutch is not simply an on/off switch and there's a range through which the clutch is neither fully engaged nor fully disengaged and this is where wear from slippage will occur.

All this product will do is teach the gullible to mash their clutch pedal without concern for the car, and I for one would not buy a car where I knew this or similar 'snake oil' mods had been installed.

Although we'll probably have someone from UUC coming on here to defend themselves.
 
Dont intend to have a :poke: at anyone. Is all this talk about clutch/gear changing problems aimed at the American market ?
When I was younger used to drive a old van , clutch ? what clutch , used to change gear without a clutch , slightly more difficult moving down the gears , TBH wouldnt try it in the zed . Yes , I am baffled about all this gear change clutch stuff with the Zed , mines fine , :D
 
Gerry said:
Dont intend to have a :poke: at anyone. Is all this talk about clutch/gear changing problems aimed at the American market ?
When I was younger used to drive a old van , clutch ? what clutch , used to change gear without a clutch , slightly more difficult moving down the gears , TBH wouldnt try it in the zed . Yes , I am baffled about all this gear change clutch stuff with the Zed , mines fine , :D
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:P You haven't got an ///M, so you don't count :D

I think it's just the combination of an on/off electronic throttle with the clutch engagement, which means the method everyone was taught to move off smoothly has to be relearnt to take both of the delay devices into account.

It took me a few weeks to get used to it (although never had the 1st to 2nd gear problem), and I've come from a background of ///Ms.
 
I'm slowly learning to drive around the CDV. Will consider having it removed when service comes up.
 
Gerry said:
:thumbsup: read the heading 'M Specific ' Ill scuttle away back into my corner :oops:
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Only kidding, as I think the CDV mod applies to all models, and not just Z4s either.
 
I’ve driven a range of Z4s and many many other performance cars but the Z4M is very very different to any other production car I’ve experienced with regards to clutch and gearbox operation.

Yes the CDV has an influence but removing the CDV on an M doesn’t help as much as other models. I believe there is another factor to be considered.

I’ve been in many other cars where the driver hasn’t been very skilled at matching throttle to clutch and their gear changes tend to be less than smooth. When that driver gets into a Z4M, they don’t notice any difference as they don’t have a feel for what is right and what is wrong.

I’ve also driven cars with high performance clutches and I’d liken the Z4M experience to this. Now on a race track, a slightly rough gearchange is less noticeable and if you are driving a Z4M hard, the same is true but it’s when you are trying to drive smoothly and slowly that the Z4M change is a bit of a challenge.

There is also a significant amount of end float in the Z4M countershaft in the gearbox. This again is typical of a gearbox designed to run at high temperatures but the effect of this is a lot of force is required to change gear which gives the “notchy” feel that we talk about.

I suspect that the clutch could be improved by using a driven plate with a softer material but then it will not be as long lasting if the car is driven hard.

As with most engineering applications – a compromise has to be reached somewhere!!

It has taken me months to learn how to drive a Z4M smoothly at low speeds. Once you’ve mastered it, it is rewarding to get it right.

Difficult gearchanges were characteristics of supercars of the 60s and 70s and to me this is just one of the “features” of a Z4M and driving the car smoothly is one of the rewards from familiarity of the M.
 
Wondermike said:
tomwac said:
What's the "rework for the clutch stop poisition"? I heard of the cdv fix, but never of this one...
My Z is still bone stock except for the CSL wheels and soon the H&R springs, but the gear changes are very notchy indeed...
Thx
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Some info here about what it does, TBH I've never been convinced about them.

http://www.uucmotorwerks.com/html_product/clutch_stop/index.htm
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Yeah I don't really understand it to be honest, don't see how it speeds up anything except wear.

Once the CDV is out the change is perfectly acceptable.
 
The valve is fitted in the clutch hydrulic pipe its there to help you smooth out clutch operation you notice it most when changing gear when driving hard you can feel and here clutch slip a bit on each change, (not good for your clutch) The fact you remove it stops this happening and also allows the cluch to move free'er as there is no one way valve in the line, if you do the stop mod you can set it so when you let your foot of clutch bite point can be just one inch from stop instead of the three inches they normally are this also helps with smooth clutch operation, I know you get used to it but why not make things better especially when both mods are free, The only reason I put this post on m section was because i did not know if all Z's had same system, Cheers Tim.
 
I have a clutch stop too and i'm perfectly happy with it. I've set it to be about an inch before the start of the biting point. I have also removed the CDV completely but as i said in other threads there wasnt much of a difference. I've bought stiffer transmission mounts that i'm going to install soon and from what i read on other forums that helps a lot with the 1->2 gear grind and somewhat improves the feel of the gearbox.
 
ga41 said:
I have a clutch stop too and i'm perfectly happy with it. I've set it to be about an inch before the start of the biting point. I have also removed the CDV completely but as i said in other threads there wasnt much of a difference. I've bought stiffer transmission mounts that i'm going to install soon and from what i read on other forums that helps a lot with the 1->2 gear grind and somewhat improves the feel of the gearbox.
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Now that does sound like a worthwhile mod. I've always felt there has been too much slack to take up in the mounts.

Which mounts have you got, where from and how much are they.

:thumbsup:
 
I got the Rogue Engineering mounts from CA-Automotive.co.uk dont really remember how much they were as i had other stuff in the order as well. From Rogue Engineering's website they're about 55 dollars. UUC also make at least two different kinds, one stiffer than the stock one (similar or the same as the one from Rogue Engineering) and another almost solid one.
 
ga41 said:
I got the Rogue Engineering mounts from CA-Automotive.co.uk dont really remember how much they were as i had other stuff in the order as well. From Rogue Engineering's website they're about 55 dollars. UUC also make at least two different kinds, one stiffer than the stock one (similar or the same as the one from Rogue Engineering) and another almost solid one.
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£69 ($108) from CA-Automotive, but that saves you the hassle of paying postage, vat, duty, import agent charges, etc.
 
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