Gear change 'clunky'

UK forum for general and technical discussion about the Z3 roadster
Post Reply
Dr. Wilson
Joined: Tue 30 Sep, 2008 20:25
Posts: 117

  Z4 M roadster
Location: London

Gear change 'clunky'

Post by Dr. Wilson »

Can anyone help? I've been looking at the various forums re: this issue and have read about how its actually quite normal and how changing over to a braided clutch pipe can solve this particular problem.

But does anyone else have any further advice? My 2.8 is very clunky during gear changes. Slower changes help this a little but its still feels quite harsh. Any ideas on how I can get a smoother gear change?

Thanks
Dr Wilson :rtm:
User avatar
Robin
Joined: Sun 14 Dec, 2003 18:35
Posts: 2691

  M roadster S50
Location: Southampton
Contact:

Post by Robin »

I found braided hose improved shift.:- http://www.zroadster.net/forum/viewtopi ... ht=braided
Image
'High G' motoring enthusiast
User avatar
aceman
Joined: Sun 01 Jun, 2008 11:16
Posts: 1479

  M roadster S50
Location: Wakefield

Post by aceman »

Mine is the same until the gearbox warms up, it is a trait of the gearbox from what I have read although apparently a gearbox oil swap does improve things somewhat so that is on my list of "todo's".
Aceman

Arctic Silver '98 Z3M

Previously;
Bright RED '99 Z3 2.8

Rocking seats ? You need seat bushes click HERE
Dr. Wilson
Joined: Tue 30 Sep, 2008 20:25
Posts: 117

  Z4 M roadster
Location: London

Post by Dr. Wilson »

Much obliged. I just emailed the hose company, and will also look into changing out the gear oil - see if that works.
User avatar
Justin Time
Joined: Thu 22 Jun, 2006 20:34
Posts: 2183

  Z3 roadster 2.0
Location: Kent

Post by Justin Time »

Fitting a Storm Motorwerks V1 helped with my clunky gear shifting due to it's significant weight increase over the normal gear knobs.
BMW Z3 2.0L Velvet Blue Individual Edition
Dr. Wilson
Joined: Tue 30 Sep, 2008 20:25
Posts: 117

  Z4 M roadster
Location: London

Post by Dr. Wilson »

That looks great too JT. Over half a kilo of engineered steel. Will look into it.
Guest

  

Hose

Post by Guest »

I don't believe that a larger-bore hose will make any real difference - if the clutch pedal goes down to the floor without hesitation, then that is it. The standard hose does not impose a flow restriction like a clutch delay valve does, and as it works under very low pressure, it is not going to 'baloon' even when the engine is hot.

Perhaps those who extol the virtue of a braided clutch hose should first have tried removing the slave cylinder, and fully bleeding it, to see the effect before fitting the new hose.

By fitting a new hose, the over-age fluid is of course changed, and I bet this is the real cause of the improvement.
BarneyBoko
Joined: Wed 18 Jun, 2008 15:37
Posts: 158

  Z3 roadster 2.2i
Location: Inchture

Post by BarneyBoko »

Justin Time wrote:Fitting a Storm Motorwerks V1 helped with my clunky gear shifting due to it's significant weight increase over the normal gear knobs.
I had much the same experience with the gear change when my Zed was new to me. I was one day away from ripping out the clutch, when I came on here looking for advice.

The advice that I got from the more experienced Zed community on here, was change to the Storm knob and then just get used to it. I was highly sceptical that it would make any difference, however after fitting it, I can only say that it made a significant difference for the better. The getting used to it advice also turned to be good as I now really like the gear change and find it quite normal.

Buy the big ball.

Barney
User avatar
Robin
Joined: Sun 14 Dec, 2003 18:35
Posts: 2691

  M roadster S50
Location: Southampton
Contact:

Re: Hose

Post by Robin »

Mike Fishwick wrote:I don't believe that a larger-bore hose will make any real difference - if the clutch pedal goes down to the floor without hesitation, then that is it. The standard hose does not impose a flow restriction like a clutch delay valve does, and as it works under very low pressure, it is not going to 'baloon' even when the engine is hot.

Perhaps those who extol the virtue of a braided clutch hose should first have tried removing the slave cylinder, and fully bleeding it, to see the effect before fitting the new hose.

By fitting a new hose, the over-age fluid is of course changed, and I bet this is the real cause of the improvement.
Mike I don't the follow logic behind your dismissive comment.
Why are you going for the least likely explanation first :puzzle:
Surely the most likely explanation as to why steel braided hoses give fuller declutching between gear shifts & more positive braking when fitted on brakes for that matter, is that the steel braided hose is less compliant so less spongy. With steel braided you aren't wasting leg energy inflating a piece of rubber hose. More of pedal movement is going towards creating oil flow to separate the clutch plates properly.
If you are so confident in the inelasticity of rubber then perhaps you ought to consider fitting a rubber front strutt to stiffen up your front end :lol:
Image
'High G' motoring enthusiast
Guest

  

Rubber

Post by Guest »

You may not realise it Robin, but I did not suggest that rubber was as strong as steel!

What I did say was that as the clutch system does not experience the pressures involved in braking systems, I found it hard to imagine the clutch hose - even when the engine is hot - swelling enough to cause clutch drag.

You can fit as large a bore braided hose as you like, but the flow restriction in the clutch system is imposed by the bore of the steel pipes to and from the master cylinder, and that of the outlet port in the master cylinder.

What I suggested was that if people flushed and bled the slave cylinder properly before fitting a braided hose, they may well find that the new hose made no difference - except that it looks nice, which I am all in favour of!

It's hard to find anyone who has tackled the problem that way - they all rush out to fit a braided hose, and then give it all the credit for any improvement, even though their clutch has never been bled since the car was built. The same comment applies to fitting braided brake hoses.

On the subject of braided brake hoses, the ABS system will not operate properly on them, as it is designed to use the natural elasticity of the rubber hoses to absorb shock waves in the hydraulic fluid.
User avatar
Robin
Joined: Sun 14 Dec, 2003 18:35
Posts: 2691

  M roadster S50
Location: Southampton
Contact:

Re: Rubber

Post by Robin »

Mike Fishwick wrote:You may not realise it Robin, but I did not suggest that rubber was as strong as steel!

What I did say was that as the clutch system does not experience the pressures involved in braking systems, I found it hard to imagine the clutch hose - even when the engine is hot - swelling enough to cause clutch drag.

You can fit as large a bore braided hose as you like, but the flow restriction in the clutch system is imposed by the bore of the steel pipes to and from the master cylinder, and that of the outlet port in the master cylinder.

What I suggested was that if people flushed and bled the slave cylinder properly before fitting a braided hose, they may well find that the new hose made no difference - except that it looks nice, which I am all in favour of!

It's hard to find anyone who has tackled the problem that way - they all rush out to fit a braided hose, and then give it all the credit for any improvement, even though their clutch has never been bled since the car was built. The same comment applies to fitting braided brake hoses.

On the subject of braided brake hoses, the ABS system will not operate properly on them, as it is designed to use the natural elasticity of the rubber hoses to absorb shock waves in the hydraulic fluid.
Mike I can only say from my experience of having steel braided clutch hoses fitted that:
1) It improves the gearshift which is hardly surprising since steel is less compliant than rubber.
2) Your theory that it's always due to draining the fluid & thus bleeding the system, is not the most likely explanation as to why fitting braided hoses gives a more positive gearshifting due to better declutching.
In fact it's merely conjecture on your part.
3) It's a recognised improvement because I had mine changed on both my ///M's under BMW warranty. If the notchy gearshift due to inadequate declutching was was always due to air in the clutch hydraulic system or old fluid then they surely wouldn't bother with steel braided hoses.
4) As regards ABS & steel braided hoses. I have no experience of steel braided brake hoses on my cars.
5) Whilst the clutch fluid pressure is not as high as brake fluid pressure, the clutch on these cars does require considerable effort & I doubt the standard rubber clutch hose is as thick walled as a standard rubber brake hose. So the change to steel braided on the clutch is a significant step.
Image
'High G' motoring enthusiast
Guest

  

Conjecture

Post by Guest »

Robin - my comments are not conjecture, but are backed up by my own experience of pre-and post clutch bleeding.

Your comments are conjecture, as you do not know if your clutch would have been improved by bleeding.

As for braided clutch hose being a 'recognised' improvent - it is not recognised by BMW, as otherwise they would have a part number for it. It is recognised by those who sell it, and those who fit it without ever having bled their clutches!

Much as I like stainless fittings and braided hoses, I don't credit them with anything but being the 'right' way to do things - ABS operation apart.

I have heard lots of motorcyclists praise the improvement made to their brakes by fitting braided hoses, yet never found this after fitting them on my three bikes - probably because I am a brake bleeding junkie, doing it every year.

I'll fit a braided clutch hose this winter, just to see what I think, and will be let you know if it makes any change.
User avatar
Robin
Joined: Sun 14 Dec, 2003 18:35
Posts: 2691

  M roadster S50
Location: Southampton
Contact:

Post by Robin »

Mike it will be interesting to know if braided clutch hose makes a difference in your case, since I imagine with you being an enthusiastic maintainer of your cars, your clutch fluid is unlikeley to be old & your system is likely to be have been regularly bled. I wish I'd known about the braided clutch hose option when I owned a 2.8 becuase the shift from 1st to 2nd in particular was dreadful at times, especially when the engine was hot on a hot day in slow traffic & thus dare I say it... the rubber hose was even more soft & stretchy !
Image
'High G' motoring enthusiast
User avatar
c_w
Joined: Thu 19 Aug, 2004 16:50
Posts: 4032

  M roadster S50

Post by c_w »

Well I fitted a stainless clutch hose over the week (but also changed the gearbox oil too) and the shift is nicer (it was never bad before though) but it's hard to attribute it to either as I did both at the sametime. HOWEVER, I have noticed more NVH through the clutch pedal as the braided hose is very stiff so I wonder if the OE rubber hose also acts as a vibration damper between the engine/gearbox and body. I realise the hose is mounted in a rubber grommet but the stiff pipe is still connected rigidly up to the metal clutch pipe and this can transmit the vibration through to the pedal, however slight.

The rubber clutch hose has the same appearance as a brake hose, so if that is the case it IS overspecified, as Mike said the brake system sees pressures many many times more than the clutch system. I will swap it back at some point to see if gearchange remains the same and the NVH at the pedal goes away.
Last edited by c_w on Tue 14 Oct, 2008 16:02, edited 1 time in total.
User avatar
SpunkyM
Joined: Mon 08 Mar, 2004 18:26
Posts: 1142

  M roadster S54
Location: Harrogate

Post by SpunkyM »

I'll fit a braided clutch hose this winter, just to see what I think, and will be let you know if it makes any change.
..it didn't make any appreciable difference on my car I have to say. Maybe that's because with it being an 02 year the rubber has not 'perished' as much as others or maybe it's cause the fluid is still relatively clean and new!

I think you can make arguments for both cases, but it wouldn't at all surprise me to find that a good bleed and fresh fluid made some improvement. I agree the rubber hose is over-specified considering the pressures involved
Image
Sapphire Black 02 S54 M Roadster
Guest

  

Air

Post by Guest »

I've heard that many people find problems in the 1st to 2nd gear change when the engine is really hot, but this could easily be due to air in the system. When the airlfow from the engine is really hot, and the slave cylinder is heated up, any air inside it will expand, and therefore require additional fluid to compress it before fully disengaging the clutch.

As the fluid available is limited to the amount the master cylider can transfer, it would be very possible that a small amount of air could promote clutch drag and gearchange problems in these conditions.

I sometimes find a small problem with engagement of first gear while at rest, which is obviously a symptom of clutch drag, but it seems more a symptom of the friction plate swelling after a week or two without use, particularly iwhen it rains. After a few hundred miles it is virtually gone.

It will be interesting to see if a braided hose has any effect - we'll see.
User avatar
SpunkyM
Joined: Mon 08 Mar, 2004 18:26
Posts: 1142

  M roadster S54
Location: Harrogate

Post by SpunkyM »

I can say for a fact that even the smallest amount of air in the slave cylinder makes the clutch virtually impossible to operate - that is why (as I found out) you have to be so particular when bleeding it. By the same token, I guess you could say the same about even a small amount of 'stretch' in the rubber hose.

You have to consider though that the fluid is hydroscopic and (despite being the same reservoir as the brakes) the changing of the fluid in the clutch circuit is never replaced as part of any of the inspections - it makes sense to flush it through every 40K or so (or 5 years).
Image
Sapphire Black 02 S54 M Roadster
User avatar
c_w
Joined: Thu 19 Aug, 2004 16:50
Posts: 4032

  M roadster S50

Post by c_w »

SpunkyM wrote:I can say for a fact that even the smallest amount of air in the slave cylinder makes the clutch virtually impossible to operate - that is why (as I found out) you have to be so particular when bleeding it. By the same token, I guess you could say the same about even a small amount of 'stretch' in the rubber hose.

You have to consider though that the fluid is hydroscopic and (despite being the same reservoir as the brakes) the changing of the fluid in the clutch circuit is never replaced as part of any of the inspections - it makes sense to flush it through every 40K or so (or 5 years).
Yes, but suppose in the same token the with the lower pressures and temperatures involved I don't think it would affect things as I doubt it would ever boil as it would in a brake circuit.
User avatar
aceman
Joined: Sun 01 Jun, 2008 11:16
Posts: 1479

  M roadster S50
Location: Wakefield

Post by aceman »

Just found this hose on ebay it looks the same but not sure if it would fit the Z3 varients, opinions anybody.

http://cgi.ebay.co.uk/New-BMW-E36-M3-Ev ... m153.l1262
Aceman

Arctic Silver '98 Z3M

Previously;
Bright RED '99 Z3 2.8

Rocking seats ? You need seat bushes click HERE
User avatar
SpunkyM
Joined: Mon 08 Mar, 2004 18:26
Posts: 1142

  M roadster S54
Location: Harrogate

Post by SpunkyM »

Well it looks very similar but it's more expensive than the ones from Hampshire Hoses and we know for a fact that one fits. Safest bet is to order from Hampshire Hoses (or the other supplier that was listed on the thread at the time).
Image
Sapphire Black 02 S54 M Roadster
User avatar
c_w
Joined: Thu 19 Aug, 2004 16:50
Posts: 4032

  M roadster S50

Post by c_w »

I got mine from Earls at Silverstone, think it was around £15 plus carriage.
Dr. Wilson
Joined: Tue 30 Sep, 2008 20:25
Posts: 117

  Z4 M roadster
Location: London

Post by Dr. Wilson »

Wow - I know a lot more about hoses now, thats for sure. :lol:

Thanks all. Going to try the heavier Storm Werks knob, incrementally followed by a clutch bleed if needed.
Bracey
Joined: Sun 28 Sep, 2008 21:06
Posts: 82

  Z3 roadster 3.0i
Location: ormskirk

Post by Bracey »

What's the verdict, Dr Wilson?

I have the same symptons (I wouldn't call it a problem, but it is noticable). Did you try the braided hose and/or the heavier gear knob?
User avatar
Gazza
Joined: Tue 04 Oct, 2005 20:58
Posts: 9521

  M roadster S54
Location: Romford Essex

Post by Gazza »

I've had the heavy Storm Knob for about 2 years and it made the gearchange much smoother for me. I also have the Braided hose now and that improved it further,maybe because the system was bled ? :shrug
Gazza

"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"

Z3 S54 M roadster Image, BMW Z1, BMW M3 CSL, Z4M Coupe
ImageImage
ajones13
Joined: Sat 16 Jun, 2007 11:43
Posts: 230

  Z3 roadster 2.0
Location: Belfast

Re: Rubber

Post by ajones13 »

Mike Fishwick wrote:
On the subject of braided brake hoses, the ABS system will not operate properly on them, as it is designed to use the natural elasticity of the rubber hoses to absorb shock waves in the hydraulic fluid.
Gosh, and there was me thinking that the ABS system worked by using an ABS speed sensor in the wheel hub to detect sudden decreases in the speed at which the hub turns i.e. a wheel locking up.

Well you learn something new every day lol :shock:
User avatar
SpunkyM
Joined: Mon 08 Mar, 2004 18:26
Posts: 1142

  M roadster S54
Location: Harrogate

Post by SpunkyM »

To say it won't work properly is a bit strong. I think the issue is that when the ABS 'pulses' the brakes on and of many times a second during a lockup, a resonance is set up between the pump, hoses, pistons etc. The resonant frequency can be calculated and the ABS system is designed to cope with it.

If you change the hoses you alter the resonant frequency and the amplitude of the reflected waves and that could alter the effectiveness of the ABS system depending on what frequency you end up with. In practice, the chances are it will still work just fine though.
Last edited by SpunkyM on Sat 22 Nov, 2008 23:57, edited 1 time in total.
Image
Sapphire Black 02 S54 M Roadster
phb10186
Joined: Sun 16 Sep, 2007 07:18
Posts: 383

  Z3 roadster 2.8
Location: London and Bournemouth

Re: Rubber

Post by phb10186 »

Mike Fishwick wrote:You may not realise it Robin, but I did not suggest that rubber was as strong as steel!

What I did say was that as the clutch system does not experience the pressures involved in braking systems, I found it hard to imagine the clutch hose - even when the engine is hot - swelling enough to cause clutch drag.

You can fit as large a bore braided hose as you like, but the flow restriction in the clutch system is imposed by the bore of the steel pipes to and from the master cylinder, and that of the outlet port in the master cylinder.

What I suggested was that if people flushed and bled the slave cylinder properly before fitting a braided hose, they may well find that the new hose made no difference - except that it looks nice, which I am all in favour of!

It's hard to find anyone who has tackled the problem that way - they all rush out to fit a braided hose, and then give it all the credit for any improvement, even though their clutch has never been bled since the car was built. The same comment applies to fitting braided brake hoses.

On the subject of braided brake hoses, the ABS system will not operate properly on them, as it is designed to use the natural elasticity of the rubber hoses to absorb shock waves in the hydraulic fluid.
I agree with Mike.....

I have bled the hell out of my clutch, and the slave cylinder is absolutely fine. The fundamental reason why the gearbox is clunky is due to the gearbox design.

I can't see how fitting braided hoses will make any difference other than in your head. A well serviced and bled system disenagaes that cllutch very easily, it'd not as if the clutch is not fully disengaging at all, even with a rubber hose or a bit of air.... so I say the whole reasoning behind fitting braided clutch hoses is flawed - and ive taken it to bits 3 times!

As far as fitting a really heavy gear-lever goes, that's a pretty low-teck way of increasing the inertia on the gear change, but it could actually provide some imporvement theoretically..... I would go with that over the braided hose... But I would also say that you are throwing good money at nothing, as you will not get that box to change like a modern small car, it just isn;t designed that way.

Pretty much, all big engined manual cars have the issue, as you are moving a lot of gearing and changind a lot of torque and power there.

The best thing you can spend on is a good oil change. Also about 50% of ZF gearboxes leak from the seal of the shift lever input.... although the leak itself is not too much to worry about, the gearbox oil may be low as a result, and that could potentially lead to poor changes if the box is not full, not to mention vast premature wear on the box itself.
Image
1998 2.8 M52TU, pre-facelift, hard top, montreal blue, tan interior, 91K
User avatar
Gazza
Joined: Tue 04 Oct, 2005 20:58
Posts: 9521

  M roadster S54
Location: Romford Essex

Post by Gazza »

Don't knock it 'til you've tried it :wink:

Your comments are theory, mine are factual :wink:
Gazza

"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"

Z3 S54 M roadster Image, BMW Z1, BMW M3 CSL, Z4M Coupe
ImageImage
phb10186
Joined: Sun 16 Sep, 2007 07:18
Posts: 383

  Z3 roadster 2.8
Location: London and Bournemouth

Post by phb10186 »

garythefish wrote:Don't knock it 'til you've tried it :wink:

Your comments are theory, mine are factual :wink:
True, I'll put up with the gearchange for less agro though, and maintain that oil is the best first step, that at least is factual :P

Besides, I have now got a 30,000 mile fresh gearbox in my 92K-er, and you know what difference that made?..... almost none. The only difference is that 5th doesn't stick so much any more. Those gearboxes are pretty much bomb-proof if you want my opinion, I had a look inside the old one (out of curiocity) and it's like a 1950's aeroplane factory in there.
Image
1998 2.8 M52TU, pre-facelift, hard top, montreal blue, tan interior, 91K
User avatar
Gazza
Joined: Tue 04 Oct, 2005 20:58
Posts: 9521

  M roadster S54
Location: Romford Essex

Post by Gazza »

phb10186 wrote:
True, I'll put up with the gearchange for less agro though, and maintain that oil is the best first step, that at least is factual :P
And cheaper option :)

Your comment on the 5th gear reminded me of years ago (1988) when I had a new Escort RS Turbo that had problems with 5th, I had to more or less tug it out of gear, out of warranty by 3 months :bawl:
Gazza

"Understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear of the car. Horsepower is how fast you hit the wall and torque is how far you take the wall with you"

Z3 S54 M roadster Image, BMW Z1, BMW M3 CSL, Z4M Coupe
ImageImage
phb10186
Joined: Sun 16 Sep, 2007 07:18
Posts: 383

  Z3 roadster 2.8
Location: London and Bournemouth

Post by phb10186 »

At least it had a 5th gear!

At that time my Mk 2 Cavalier had 4 gears..... saying that my Mk 2 Golf auto only had 3!
Image
1998 2.8 M52TU, pre-facelift, hard top, montreal blue, tan interior, 91K
Post Reply