gear changing/clutchless

[AlpineRaven]

Hey all, I've gotten into a habit lately with my Liberty with 3rd/4th & 5th as I change gears without pushing the clutch.... I don't allow to crunch or grind as I change the gears spot-on revs to match.... is that bad for the gearbox?
Cheers
AP

[dibs]

LOLROF holding belly

only if ya miss n grind.n when i do i just say to brooksy ya gota clean em

dibs
bit of a joke in our cars but i can do that even with the clutch hehehe

[brumbyrunner]

Short answer is yes.
It may not damage the gears themselves but it wont do the syncros any favors. If you don't use them I guess you wont miss them.
Certainly not something I'd do.

[AndrewT]

agreed with the above.
but you must have some kind of a reason to do it?

[El_Freddo]

A lazy left leg due to injury? I started doing the same cos I'd smashed my left shin on a stone, the muscle damage came later - to use the clutch became painful.

I've really gotta change my clutch cable - my clutch is the stiffest one I've had on vehicle of mine so far...

Cheers

Bennie

[AlpineRaven]

A lazy left leg due to injury? I started doing the same cos I'd smashed my left shin on a stone, the muscle damage came later - to use the clutch became painful.

I've really gotta change my clutch cable - my clutch is the stiffest one I've had on vehicle of mine so far...

Cheers

Bennie

You've hit the nail mate... Yes it is which is part of the reason - its an bike injury that i had few years ago and never been right... Today I've been driving the truck and it was fine and same with my car so today is fine.
Cheers
AP

[discopotato03]

Truck gearboxes are a different situation , diseasel engines run over a shorter narrower rev range than most petrol so the gearboxes turn slower as well .
Truck gearboxes have much larger heavier (innertia wise gears) so that can hinder at times and help others .

Some trucks , light to medium ones are pretty much mostly syncromesh type nowdays , have whats called constant mesh dog boxes and are pretty much like a synco box only there are no baulk rings or cones on the sides of the mainshaft gears . They have a series of dove tails on the sides of the gears and similar but longer ones on the sides of the coupling sleeves . When the dove tails or "dogs" if you like are engaged there is a fair bit of backlash present and this is because the dovetails are shorter on the gears than the sleetves . Also the larger gaps give you a better chance of getting the thing into gear if the shaft speeds are not as close as they'd like to be .

Syncromesh gearboxes differ in that the dogs are smaller and greater in number and don't have the larger gaps - or the backlash .
They really don't like clutchless changing because the coupling sleve moves sideways and over the dogs on the outside of the baulk (syncro) rings which then pushes against the cones on the sides of the gears . If the gear/sleve speed was exactly equal it wouldn't be a problem but when it's not you can't feel it and you are pushing two conical surfaces together at different speeds . These cone clutches are only designed to slow down or speed up part of the inertial load of the gearbox - not the mass of the flywheel crankshaft etc so the engine can easily overpower this small cone clutch .

Baulk rings are often made of materials softer than the cone on the side of the gear because they are a wearing part and cheaper than their mating gears to buy .

Another gospell to take to the grave . A gear that cruches doesn't necessarily have a worn out baulk ring , if the cone on the side of the gear becomes highly polished - or some dick polishes them at rebuild time - the best baulk ring in the world is gonna have a hard time trying to apply friction to it . Result ? GRRRRRRRUNNNNNCCHHHH .
Really switched on people glass bead blast the cones on their gears (not the teeth or the internal surfaces) and many say they never need to change baulk rings because they work fine on a surface they can grip on .

I tend to think syncro boxes driven clutchless work their baulk rings harder and spend more time trying to polish the gears cones than would be the case if the load was taken off the box (clutch) and the ratios changed quickly and easily .

I drive a lump with an 18 spd Fuller Eaton RR box from time to time and while it's possible to drive them clutchless I don't spend enough time in that truck to do it . People who live in trucks can do it but they spend thousands of hours in the cab and know the thing inside out .

I can't see a reason to drive a road car like that particularly when it's box is not designed to cope with that sort of use .
I know for a fact that the rally people don't do it with syncro boxes so I'm not going to either . Also gearboxes are a major PITA to R and R in an L series and I don't want to do it again if at all avoidable .

My 2c , cheers A .

[Outback bloke]

I disagree completely. When did dis-engaging a clutch become a gearbox brake? The gearbox is continually turning while you are driving. The use of the clutch is to remove one of the 2 driving forces in to the gearbox. You have two inputs towards the forces on the gearsets. One is from the motor, the other is from the wheels/tails/driveshafts.

Think about it, if you towed a car along with out an engine in it would you be able to change gears with there being no clutch? The answer is yes if the input and output of the gear you want is matched. No different to being able to do it with the engine in front of it.

The gears are always meshed. It is the syncromesh system that is locking the chosen gearset. If you can change with out feeling/hearing a fault then there is going to be no damage done.

I tend to think syncro boxes driven clutchless work their baulk rings harder and spend more time trying to polish the gears cones than would be the case if the load was taken off the box (clutch) and the ratios changed quickly and easily .

Do you have a picture of these "cones"? I have had plenty of EJ boxes apart (got one apart and the moment fixing first gear syncro) and don't know which part you are talking about.

[Matatak]

i could be getting my parts and names mixed up. but i believe the 'cone' is the slightly tapered shinier section off the side of the gear here, whihc the Baulk Ring is getting put on

[Xtreme_RX]

i could be getting my parts and names mixed up. but i believe the 'cone' is the slightly tapered shinier section off the side of the gear here, whihc the Baulk Ring is getting put on

Yep that's it.....

[Outback bloke]

That's what I thought he was talking about but I have never known it as a cone.

[tex]

A picture says a thousand words and its stands to reason that they last longer when they only have to make up the difference between the input shaft and the gearbox rather than the whole engine and the box.
I have driven crash boxes for a few years now and am currently driving an 18 speed to do this you change gears according to your ear and no matter how good you are you wont get this perfect you may not hear anything but something somehere must make up for it thats why we don't run staight cut gears etc. I personally beleive that they designers of these vehicles put clutches in for a reason otherwise they would have something else by now, But in saying that I beleive they have jacobs, exaust, dynatard brakes for a reason too but the do gooders say otherwise!

[discopotato03]

Actually it's quite comical watching someone drive those RR dog boxes in a modern truck with the windows up . When they think they're doing pretty well we get them to open the window so they can hear the gearbox going click clank bang runch ...

Yes you will get turning forces into both ends of a gearbox but it's the engine side that has the ability to make rapid accelerations/decelerations with the clutch engaged .

Like I said syncro boxes have many more dogs if you like and no gaps - have a look at that pic of the first motion shafts gear . See the high number of "dogs" just inboard of the shiny "cone" , these are designed to allow the mating dogs of the coupling sleve to slide into mesh once everything is revolving at the same speed . If you're using "the force" instead of the clutch the engine will easily over power that cone clutch so that when the dogs try to meet if the speeds are not exactly the same they bounce over each other making that grating noise .

My rally specialist told me ages ago about Datsun gearboxes that had the no frills close ratio job done on them and the smallest 5th gear syncro hub/baulkring/cone became 1st . At times going 10 10ths on the dirt you get situations where you MUST get 1st or your going to die - cliff/rock face/major tree etc . Probably going too fast for an easy change so 1st gets literally forced to the point where the coupling sleve is gutsed at the gears dog teeth so hard that the dogs are all burred over and no power on earth will get it into first - until the box is gutted and the burs ground away .

You may not find pics of a constant mesh dog box from a truck but Rex dog boxes are essentially the same thing but on a smaller scale . Look closely at the much larger dogs involved and the gaps between them that allow them to snick into mesh if the speeds of the sleeve and gear are not perfect . This system can be driven clutchless but it does knock the points of the dogs around more than is necessary and for what ?

You get given a clutch so if at all possible use it . 95% of its wear and tear is by standing starts or slipping them .

Gear form , helical will always be stronger than straight cut because there is always three pairs of teeth in mesh instead of one pair .
True - you get end float loads from them but if the gearbox is designed properly the bearings handle it .
Subaru gearboxes do it tough because they are a split case aluminium type and they twist and warp under high torque loadings . The cases aren't really rigid enough nor the shafts far enough apart to allow larger diameter gears to fit . Thats why even dog conversions aren't enough to save them in serious tarmack and dirt competition use .

A .