Delayed clutch release

[old-git]

Sort of transmission related.

I am looking for a 2-way valve to fit into the hydraulic clutch pipe. It needs to allow full flow into the slave cylinder and have the facility to be able to restrict the flow back to the master cylinder (and be adjustable).

This is to allow a controlled engagement of the clutch after the pedal is sidestepped.

Any ideas?

 

[HDi fun]

Try not sidestepping the clutch perhaps? :-D

 

[stamford]

Have you asked the question to any supplier of said hydraulic parts? Pretty sure it is an off-the-shelf valve, similar to in-line flow restrictors used in pneumatics.

 

[old-git]

Try not sidestepping the clutch perhaps? :-D

It's a delicate balance, quickly engaging the clutch slowly is how my guru put it. In order to get maximum traction and acceleration you need to engage the cluch immediately, but smoothly. By slowing the fluid returning to the master cylinder by a few milliseconds you can take out the shock impact on the drivetrain allowing the tyres to hook up better.

If you try to slip the clutch yourself (me especially) there is a fine line between getting it right and not. By having it done mechanically it is both adjustable and repeatable.

 

[old-git]

Have you asked the question to any supplier of said hydraulic parts? Pretty sure it is an off-the-shelf valve, similar to in-line flow restrictors used in pneumatics.

Yes, I have a few feelers out at the moment but thought it was worth asking on here in case someone had already done it.

 

[claymore]

Keep us updated on this. I'm watching with interest.

 

[old-git]

Will do.

 

[hicusdicus]

CLUTCH? Is that something related to your left shoe or back seat shenanigans with your main squeeze? My first pickup was 46 ford, 4 on the floor, ton and a half that had to be double clutched if you wanted to get where you were headed. The good old days are a myth.

 

[old-git]

These days, any back seat action would be with a reserve squeeze

 

[Yugguy]

I have to say I'm an automatic loving old fart now. I can't even be bothered with semi auto altho it was sweet seeing it kickdown from 5th to 2nd the other day.

 

[old-git]

I have to say I'm an automatic loving old fart now. I can't even be bothered with semi auto altho it was sweet seeing it kickdown from 5th to 2nd the other day.

For pootling about town as a daily driver I agree, but this isn't going to be a daily driver

 

[old-git]

Whilst walking the dog in the woods opposite our house this morning I thought of an analogy to better explain what we are trying to do.

Take two light switches, one a normal on/off type and the other a dimmer switch.

The on/off switch is like side stepping the clutch, the power to the bulb goes from 0 to 230v (in the UK) in an instant which is what happens to the force exerted on the tyres when you side step the cluth pedal.

A dimmer switch, on the other hand, allows the power to be fed in gradually and smoothly. Even if you turn the switch from off to full power as fast as you can the power is still fed in over a period as opposed to instantly.

This is the effect we are trying to achieve with the clutch engagement, very fast but smoothly so the shock to the tyres is reduced giving them a better chance of hooking up. It will also reduce the shock loads experienced by the rest of the drive train which will be no bad thing.

Does this make sense?

 

[T9 man]

Well that makes perfect sense to me OG, I just hope you are able to achieve it.

 

[SLEEPER]

Im not sure what the ecu situation is with yours but just wondered if it would be possible to acheive the same result by mapping the engine instead to give the power the wheels can cope with which might the same results. Some ecus can definately do this type of thing .
Im pretty sure I read that T9 had to have this done kind of thing done untill the traction issue is sorted by an awd systam

 

[old-git]

Yes, we have already worked out a base line max BHP for each gear. However, this won't eliminate the sudden shock of sidestepping the clutch pedal.

We are talking milliseconds here and fine judgement with regard to getting the clutch to slip VERY slightly on take off. This requires a lot of experience and practice (especially with a cintered clutch which is almost an on/off switch anyway), both of which I lack. If we are able to devise a system that does it automatically and is adjustable then we can wring the maximum traction out of the tyres by taking the variable that is nut behind the wheel out of the equation.

 

[stamford]

Are we trying to replicate a 'powershift' type system? As per a motorbike upshift where you just flick up through the gears with no clutch action but maintain max power with minimal power/rev drop? Without reading back through the pages what gearbox are you running again? Wouldn't it be a better route to use a different gearbox that allows a sequential shift? I'm thinking aloud here so I may be way of track from where you currently are so please forgive me.

 

[old-git]

Elite IL300 6 speed sequential with full throttle up and down shift. However, this doesn't help on launch. We need to engage the clutch as quickly as possible and that is achieved by simply sidestepping it.

However, this imposes large shock forces to the system and can cause the ttyres to break traction.

So the normal solution is to slip the clutch. Getting this right every time using a standard organic clutch is difficult enough but with a twin plate cintered it is almost impossible for mere mortals like me

 

[pgarner]

had thought about something like a airline restrictor to slow the clutch fluid on the way back up could be used however it would slip in every gear then

 

[old-git]

It needs to cope with brake fluid. I think I have found something that will do the job. I will post a photo when I get home.

The slip is minimal and will be utilised on all gear changes.

 

[hicusdicus]

When tires get hot enough to begin to melt the molecules blend with the asphalt and give maximum traction. The problem is the tires won't last very long and the shock to your drive line can pop a U joint or whatever. 0 to 60 jackrabbit starts are for the folks with money to burn. 25 mph to 100 mph is a lot easier on your car and requires more knowledge on how to set the power curve of your engine.

 

[old-git]

When tires get hot enough to begin to melt the molecules blend with the asphalt and give maximum traction. The problem is the tires won't last very long and the shock to your drive line can pop a U joint or whatever. 0 to 60 jackrabbit starts are for the folks with money to burn. 25 mph to 100 mph is a lot easier on your car and requires more knowledge on how to set the power curve of your engine.

Yes, but not a lot of use on the drag strip

 

[hicusdicus]

Yes, but not a lot of use on the drag strip

Drag strips are for the rich. But then again they might be cheaper than traffic tickets, bail bond fee's and astronomical insurance rates. I must also include vehicular manslaughter which really sucks. Maybe just staying at home and chit chatting on the internet is the way to go.

 

[old-git]

Why are drag strips for the rich?

 

[claymore]

Drag strips are for the rich. But then again they might be cheaper than traffic tickets, bail bond fee's and astronomical insurance rates. I must also include vehicular manslaughter which really sucks. Maybe just staying at home and chit chatting on the internet is the way to go.

I take it that you are aware that this whole thread is about building a super fast drag car, or have you simply read the last page or two?

EDIT: My apologys, as OG has just pointed out to me, this is a separate thread to his build thread, so it's all Old Gits fault

 

[old-git]

Unfortunately, I started a new thread for this so he won't have seen the project this relates to.

I have therefore continured this thread in the project threasd where I should have started it

If interested, it can be found in General Car Chat under "At Last!. I have started on my car PART 2"

 

[hicusdicus]

Why are drag strips for the rich?

If you want to win you better have a fat pocket book. The one with the most money takes home the trophy. I like fast cars but with me handling comes first engines comes second. When I was younger the girl magnet factor was also very important.:blink:

 

[old-git]

I take it that you are aware that this whole thread is about building a super fast drag car, or have you simply read the last page or two?

EDIT: My apologys, as OG has just pointed out to me, this is a separate thread to his build thread, so it's all Old Gits fault

Gosh, just like at home

 

[old-git]

If you want to win you better have a fat pocket book. The one with the most money takes home the trophy. I like fast cars but with me handling comes first engines comes second. When I was younger the girl magnet factor was also very important.:blink:

But, surely, that is a fact in all forms of racing?

Actually, thinking about it, it isn't. All forms of racing have 'newbie' classes that run pretty standard cars. Drag racing is no different in that you can run in the 'bracket' classes. These are classes where you have to run below a max ET, so the skill is in the start and knowing your car. You can run stock cars in this class of competition so costs are kept to a minimum.

However, I am just trying to build the fastest Lotus Elan in the world

 

[hicusdicus]

Spending money on cars is very much like spending money on women. Expectations are high but you never quite reach your goals and they keep soaking up the green till your tires and head are completely bald. But God ain't it fun.

 

[old-git]

I can tick both of those boxes