Helical LSDs

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fordem
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Does anyone know how to verify if an iO has a limited slip differential without pulling the axle apart?

Five door iOs are supposed to have limited slip differentials in the rear axle, I assumed mine did not because with one wheel off the ground I can rotate the other - but - I'm now starting to think that it may have one.  The test I originally used, as described above, is apparently not valid for a helical limited slip diff, which is the type that would be fitted, if there was one.

 

NZIO
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LSD

I don't know about helical diffs specifically, but not all diffs can be identified with your original test as they may need to be loaded up before the limited slip functionality kicks in. Try jacking up one wheel slightly off the ground, apply the handbrake and attempt to drive off the stand. If you can do it, you've got an LSD.

fordem
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This is kind of why I asked...

I was hoping some one might know of a code on the axle, or in the ID tag - I believe with a helical LSD you can perform that test and not be able to drive off the jack.

What I've noticed is that the back of the iO can be somewhat "twitchy" in tight corners if the road is wet, it's predictable, but somewhat more sensitive than your average rear wheel drive vehicle, and then yesterday I managed to get it, one rear wheel in a muddy rut left by a garbage truck and the other on the asphalt, and in that situation even though the inner wheel had very little traction, the vehicle continued to move forward, which is one of the traits of an LSD, and I'm now wondering if the sensitivity of the rear end in the wet is in any way related to the differential attempting to drive both wheels at the same rate, which I believe is another.

Claude io
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rear diff

I am not sure but as Nzio said for them to engage , I have read somewhere (one Greece forum?)  that on the Io the diff engage after around, as high as, 7 full turn of one of the wheel (over the other side), and they explained that the slow action could be, on some occasion, a problem (the same type of diff, different model, can engage quicker). Based on that, what Nzio said could work, but I would do it this way.... using a floor jack, lift the rear driver side, get in first gear, spin that rear wheel (slowly!) after a few turn the diff should engage and maybe move the car a bit, at the very least the wheel in the air should be harder to spin by hand (in neutral). An extra pair of hand may be handy to check if the wheel get hard to turn, just after the wheel spin. I never done that, and I could be completely wrong...again:). One sure thing, if you haven't got that type of diff, nothing will happen:)

Happy io.

NZIO
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what's the worse that can happen?

If  I was you I'd try a few test scenarios - as long as you're sensible about where and how you do it I don't think driving off a stack of wood blocks or whatever you want to use to hold up one wheel is likely to cause any damage.

fordem
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In case you missed it in my earlier post

I don't think that's a valid test for a helical LSD.

NZIO
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Excuse me

I thought you wanted to know if you had a functional LSD or not. I hope someone smarter than me can help you out.

fordem
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I've though long & hard before replying to you

NZIO wrote:
I thought you wanted to know if you had a functional LSD or not. I hope someone smarter than me can help you out.

You're too bloody touchy - how does performing a test that is not valid prove that the vehicle is or is NOT fitted with a limited slip differential?

So I jack it up and block one wheel off the ground, and it doesn't drive off the block, what does that tell me?  How do I know if it's

a) an open differential?

b) a helical limited slip differential?

Your suggested test will tell me that it's not a locker, or a clutch style limited slip differential - both of which I know already - it gives me no more data than I currently have, and still leaves me in the dark as to what's in the rear axle.

Claude io
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Diff

Fordem, like you, Nzio is trying to help and nothing else. Don't forget that it is very hard to express something properly using a forum.

I have done some research....I think that Nzio is right and I was wrong...again....don't tell my wife she is keeping count...lol

I think  that what Nzio advised you to do is for me valid,  what you said is also true "So I jack it up and block one wheel off the ground, and it doesn't drive off the block, what does that tell me? " because my understanding is that type of diff is useless if you have one wheel with no traction at all as it can only transfer and multiply the resistance from the lower traction to the other wheel, so zero traction/resistance even multiplied is still zero!!!

Ok, BUT! you forgot one main important point to what Nzio said: "the hand brake" the fact of applying the hand brake will create a resistance to the wheel of the ground and it will transfer and multiply it  to the wheel on the ground...then your car should move!! a proper floor jack might still be safer!!

Find below some info that was given to me.

Please, if I am wrong...don't tell my wife...and don't forget...like all....I am just trying to help....!!!

Happy io

 

  The Quaife ATB Helical LSD differential is a "different beast" so to speak. It uses all gear design for ultimately smooth transfer of torque to the proper places. This is not to say it does not use friction, just no fixed torque clutch or brake plates.

The essence of this design is high angle helical gears. When both wheels have equal traction the differential works in normal fashion. This is a torque sensing differential rather than speed sensing. As such it does not try to make the inside wheel turn same speed as the outside wheel. As long as both wheels have traction it transmits equal torque to both wheels regardless of relative wheel speed, very similar to an open differential. One nice feature here is very little affect on understeer or over steer with throttle changes.

When one wheel starts to slip the helical gears slide endwise with a force proportional to the torque on the wheels (not fixed torque and not proportional to speed). This applies a load on a sidewall friction plate to generate resistance to bias the output torque accordingly. This is in effect applying a braking force to the wheel that has less traction, but the reaction force is transferred to drive the other side rather than energy being lost as friction heat. Changing angle of the helical teeth changes the limit of torque bias. These can be designed with torque bias of 3:1 or up to 5:1. So if one wheel begins to lose traction the other wheel can receive up to 5 times as much torque as the one that is slipping. It also has the advantage of being able to transmit nearly all of the propshaft input torque to the wheels, proportioning torque appropriately up to the point where both wheels might spin at the same time.

Unfortunately five times zero is still zero, so when one wheel hits a patch of wet ice it will still spin, and the other wheel will be limited to five times the torque as the one on ice. This works well as long as the low torque wheel still has some grip and some available torque, but if you lift a wheel in a fast turn it will immediately revert to zero torque all around like an open differential. As such, this works best with well tuned suspension that can keep the drive wheels planted on the pavement. If you happen to be aware of the total loss of traction when it happens, and you understand how these things work, you can step gently on the brakes to stop spinning of the unloaded wheel. This will then apply up to five times as much torque as the light braking effect to the wheel that is not spinning, which will in turn overcome the light braking force and push the vehicle. Competition drivers may soon develop the technique of "left foot braking" while they keep the right foot on the throttle. (Incidentally this torque sensing differential works quite well in conjunction with a modern antilock braking system).

Another significant advantage of the Quaife design is that the all gear unit will have very little wear, so it is maintenance free and comes with a lifetime warrantee. They are relatively expensive to purchase, but value may come with the results. You can buy these off the shelf for installation in your MGA or early MGB banjo style rear axle. Just specify the number of splines required in the sun gears to match the splines on your half shafts.
.

 

fordem
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Claude

Under those circumstances, pulling the handbrake up with an open diff will cause the car to attempt to drive off the block - so I would still be at square one ...

a) do I have an open differential?

b) do I have a helical limited slip differential?

That question remains unanswered.

NZIO
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your question

....Self-moderated in the interests of maintaining the globabl brotherhood of io-dom...

Claude io
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Handbrake

Ok, I understand what you mean,

I have just try on my car, open diff, with the handbrake fully on, one wheel in the air, releasing the clutch makes the engine stall. Same thing with the handbrake 3/4, the engine have enough power to make the wheel in the air turn and the car isn't moving (I used the floor jack) increasing the handbrake made the engine stall but not moving the car.

I think that doing the same with the LSD diff would make the car move once the handbrake gets around 3/4 on as it should be enough resistance for the diff to kick in.

I never tried this and there is lots of factors that could make this ...unrealiable

Happy io.

 

fordem
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For those who may be interested

My 5 door iO has an open differential - one of the Mitsubishi parts websites allows you to enter your chassis number and will filter the replacement part listings to ensure you get the correct parts for the vehicle - if you're curious about yours PM me the chassis number, and I'll look it up for you.

Claude - I'm guessing you didn't have enough throttle on - if you try it with the car on a trolley jack sitting fore/aft, it should move the car, but you need to remember the rear brakes are impeding both wheels evenly - when you have some time, google "fiddle brakes" - it's a traction control technique that's been in use on farm tractors probably before you & I were born.

Claude io
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All fixed then!

All fixed then!! but it doesn't solve your question!! Can anyone that have a 5 doors with that diff (should be all Australian 5 doors) could give it a try? It would be great and interesting to know if it does work or not. I thought that an open diff would send all power to the least resistance side, with or without handbrake (properly adjusted ) wouldn't it?

For the open diff, I am trying to understand how the wheel on the ground would make the car move with the handbrake on, I thought that if it doesn't make the wheel in the air turn, how can the one on the ground move as the wheel in the air do have the least resistance, no matter how the handbrake is tight (again, properly adjusted) or no matter how much power you put in. I have tried on my car again applying a bit more power,  it just doesn't move!!  Am I missing something?

Happy io

 

fordem
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Testing, testing ...

Claude

If you brake only the wheel that is in the air, that will force torque to be sent through the differential (open or limited slip), to the wheel that is on the ground, which will then attempt to move the vehicle - if you brake both wheels, you MAY not get any movement because you will also be stopping the wheel that's on the ground from moving the car.  It typically works because the rear brakes are not "perfectly matched" side~side.

Now - only a locker will actually allow the car to drive off a block - I had suggested you try it with a trolley jack, in the hope that the wheels on the trolley jack would have allowed sufficient "freedom of movement" for the experiment to work - because limited slip differentials will always allow some degree of slip (how much will be determined by the design, and in some cases the "condition" (whether worn or not) of the LSD), they will be unable to redirect enough torque to overcome the friction of a block, but given a "slippery" situation, the LSD will provide more drive than an open differential.

 

NZIO
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LSD, or...

As I mentioned in another thread, I spent most of sunday playing around in sand. I took the opportunity to do a bit of testing of diff behaviour by crawling in 1st gear low ratio up a slope that got steeper as you went up it. I was doing this alongside an early model Pajero (not an io, not sure what model exactly) and we were seeing who could get the furtherest up before bogging down.

We tried several times in 4wd and 2wd modes. I won a couple, but most times he went further than me. He had a heavier car with a passenger (I didn't) so perhaps that's part of the reason, but I noticed when I broke traction, always at the rear not surprisingly, it was with just one wheel spinning - i.e no sign of limited slip behaviour. I figured this might just mean there wasn't enough force to engage the LSD, but when he lost traction at the rear his LSD was engaged as both wheels were spinning together. Again maybe it was because of his heavier weight that his engaged and mine didn't, but surely this is exactly the situation where it should work for me.

So I did another test this morning on a greasy bit of grass in 2wd - slipped the clutch from a standing start. It left just the one 5m long skid mark. No sign of limited slip function - perhaps this was again not enough force to engage, but if so you start to wonder under what circumstances it will actually do something.

So now I'm wondering if my 5 door has a limited slip diff - Fordem, what is the parts website you mentioned please? Or do I need to send you my VIN.

Cheers

 

 

 

 

singlecell
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.

I removed that diff from a 99/00 model 4 door io, and it definately was a LSD. My brother identified it as one of those torque style ones.

Thats not to say they all have one, but that one definately did.

fordem
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www.epc-data.com

Go to http://www.epc-data.com and select Mitsubishi and enter your chassis number, the site shold identify your car and give you details such as the date of manufacture, select rear axle & rear axle differential - look in the list for item #34062 - DIFFERENTIAL KIT, RR LIMITED SLIP - if it doesn't appear, you don't have one.

You can use this site in two ways - you can work your way through the menus, selecting the vehicle type etc., and it will give you part numbers broken out by year, so you can see, just for example, if the spark plug that was used on a 1998, was also used on a 2001 - or you can enter your chassis number and it will give you just the part numbers applicable to that particular vehicle.

We're using this last aspect to determine if there's an LSD fitted as standard - if you choose the vehicle type, it should show you all the part numbers, including the LSD, but if you enter the chassis number, it will "hide" the numbers that don't apply, so if you don't have an LSD standard, it won't list it.

If you run into trouble PM me with the chassis number and I'll take a look.

Question - is your vehicle imported into New Zealand new or as a used JDM (japanese domestic market) vehicle?

NZIO
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EPC-Data

Interesting site but unfortunately it doesn't recognise my frame number past the first 4 characters. my frame no (which I don't mind sharing here) is H76WLNUER8.

My io is NZ new - it may not be the same spec as Australian models.

Claude io
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Nice site

Mine didn't work too but once you have the "didn't found" message, you can then choose by make, then model...http://mitsubishi.epc-data.com/pajero_io/

I am not sure about the next step...!

Happy io

Edit, Mine start with H67W and it does show a rear LSD kit  while I wasn't sure if I had one or not "Bob" mentioned that the 2 doors doesn't have one in Australia, and a site called redbook.com.au say the same (no LSD on a 2 doors)...mine is no longer on the car anyway...

NZIO
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LSD

The local dealer who sold the car new has done some research for me and while they can't be 100% sure they are pretty confident it is not limited slip. Their rationale for this is that the specified gear oil for the NZ model is not the type they would expect to see specified for limited slip diffs, and in their experience (they are probably the longest standing mitsi dealer in the country) they would not expect this model to have been specified with one.

I asked about NZ vs Australia spec and they said it was common for us to have a different spec here - usually lower because there's not the same demand for off road touring capability.

So... not conclusive, but on the basis of all this info, and what I experienced in my weekend tests, I think mine is an open diff :(.

fordem
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Claude

If you don't specify a frame number, the site will show you all available parts for that model - and you have to select what's correct for the car - if you enter the frame number it removes the "incorrect" parts from the display - try it with H76W-0001477 (which is my frame number) - look specifically at spark plugs - it will only show one, and then back out and select, from the menu this time, an LRPC Sorrent 4FA/T and go look at the plugs again, this time it will show four and you get to choose which is correct.

I've used it to look up three maybe four iO's mine - and those of a couple of friends and this is the first time I've seen it not recognise the frame numbers.

If you look at the rear axle with & without my frame number, you'll see without it the LSD is shown and with the LSD is not - which I interpret as it's not fitted.

Daniel
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my frame no.

ok i havent been following this thread very closely, but i have been on this mentioned site before.
i guess ill chip in though...
anyone want to try my frame no.
H67W-MNUER8
if i have followed it correctly, i think i may have an LSD in mine... i only say this because i am able to select it after i put my frame no. in...
 

EDIT>> Claude what is your full frame no? just for a comparison. if you dont mind sharing of course...

CHECK OUT MY BUILD  VVV
http://www.pajerio.com/forum/daniels-io

singlecell
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.

It would be interesting to know what different diffs there are in the IO.  I know mine wasnt swapable with the 3door lsd. As my rear axles were thinner and had 25 splines insted of the 28 of the 4 door.  Which also means the kaisier auto lockers wouldnt fit my rear, and i suspect the ARB also wouldnt.

The fact that Claud was able to get a ARB locker would suggest to me that he had the same thicker axle type as the 4 door lsd diff I had.

Or I could be completely wrong.

fordem
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Daniel

It doesn't your frame number either - if it did, it wouldn't give you the choice of two different vehicles which is what is showing up when I try it.

Maybe it's a JDM only site sad

Daniel
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yeah i had two different

yeah i had two different vehicle choices also.
i just thought that just maybe, being a ZR it might. because from what i can see in this thread, i think i'm the only owner of a zr in this particular thread.
i dont know if claudes is a proper zr or just has some zr options. please excuse me if im wrong by all means claude...

EDIT>>> Sorry claude i just went to your introduction thread as i vaguely remembered talking about this. and i have realised that i myself told you it was a zr, pointed out by the passenger airbag. long story short. my bad lol

CHECK OUT MY BUILD  VVV
http://www.pajerio.com/forum/daniels-io

Claude io
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ZR

Lol... for a while I wasn't 100% sure too...after a bit more research, yes it is the ZR, I found that this model have a few more extra such as (at least for Australia!) ABS, passenger air bag, body colour fitting, remote/keyless, EBD, fog lamp front, roof rail and the spoiler and less not forget a couple of sticker!! (gone on mine)

Now that I have fitted a few more mod, I should call it the "ZZ"  or the ZClaude...lol...

Happy io.

koos990
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Hi all.Firstly I did not

Hi all.

Firstly I did not read all the replies in detail, thus if something was already mentioned - appologies.

As far as I know all the 5 doors were fitted with a Torsen rear differential (LSD). This is a fully mechanical diff thus I would imagine this does not reguire special oils as with clutch LSD's.

a Torsen is basically a Torque Sensing (TorSen) device. It muliplies Torque to the wheel with less toque/slip by a fixed ratio (worm gear angle in Torsen).

For this reason if one wheel is in the air and one wheel on ground and you start to drive the Torsen is non-working, becauce there is 0 torque in the air wheel wheel (only torque in this wheel is the friction of bearing loss), thus the Torsen does not work by multplying Torque because there is almost 0 torque to be transferred to the wheel on the ground. 

In short: a Torsen LSD is no help for us Off Road-ing. It is only OK for snow and gravel and sand in my opinion. And with these situations a 4x4 is more than capable anyway.

The later Torsen T-2R diff does however allow for wheel in air to be locked, but I dont think we have this later Torsen in the 5 doors.

From http://en.wikipedia.org/wiki/Torsen

"If one wheel were raised in the air, the regular Torsen units would act like an open differential, and no torque would be transferred to the other wheel. This is where the parking brake "trick" can help out. If the parking brake is applied, assuming that the parking brake applies even resistance to each side, then the drag to the airborne side is 'multiplied' through the differential, and TBR times the drag torque is applied to the other side. So, the ground side would see (TBR X drag torque) minus drag torque, and hopefully that can help restore progress either forward/backwards. In Hummer/HMMWV applications, there are both front and rear Torsen differentials, so the use of the main brakes will operate this "trick" on both axles simultaneously."

 

Thus best sollution for us with Torsens (and without) is to use handbrake (because the handbrake apply more friction on the wheel in air thus the torque increase thus you have more than 0 Torque to be transferred to the grounded wheel) and this needs to be practised.

Again this is just my thinking on the system. I have a 2002 2.0L 5 Door, I am sure I have the LSD as my diff seems quite large for a small vehicle.

fordem
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Another test ...

I don't know if this test is valid for Helical LSDs, I know it's valid for clutch style LSDs in good condition.

Whilst in Miami last November I picked up a book called the "Four Wheeler's Bible" and in one of the chapters it discusses differentials and gives the following test.

With both wheels off the ground, rotate one forwards and observe the other - if they both rotate in the same direction it's limited slip, if the rotate in opposite directions, it's an open diff.

As expected my wheels rotate in opposite directions.

Pinin on the rocks
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Guys, there is not any way u

Guys, there is not any way u can determine if a diff is LSD by rotating it's wheels... that way it behaves as open, u cannot stimulate driving conditions with the car jacked up... the ONLY way is either open it or see if it drifts...  smiley

fordem
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Drift is no evidence of an LSD either.

As a teenager I was drifting my mother's Morris Marina, and trust me, even the sport model (the Marina TC) did not have an LSD as an option. 

Also with a clutch type LSD in good condition if you have both wheels off the ground and the transmission in neutral, rotating either wheel will cause both wheels to turn in the same direction - a clutch LSD has spring loaded clutches between the side gears and the differential hemisphere, as long as these clutches are in good condition, turning one side gear drives the diff hemisphere (through the clutch) and that drives the second side gear (through the other clutch) and the entire unit rotates as one.

Glen
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iO LSD

Bummer, I didn't realize some 5doors came without LSD.

I knew mine was just from doing U turns on gravel, the inside wheel would grind like a race car with a welded diff :)

 

But I was worried i didnt have an LSD this night, http://pajerio.com/forum/weekend-urban-4x4-fun watch the video.

Some more discussion on the iO LSDs there too.

 

Ojak
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Hi there, On my rear axle its

Hi there,

On my rear axle its actually a little text sticker that says LSD. And second, the hand brake test should work, you just need to find a spot with no grip. This means that with or without an LSD only one of your rear wheels will be spinning. Then apply handbrake and see if you have two sliding wheels. I will try it here next time we get some ice, havent tried yet as i know i have an LSD.

On a side note the LSD can become really nasty in winter conditions. If its really really icy, the way it can become when its just around zero and tarmac gets a thin layer of watery ice on it, the LSD throws torque desperately between left and right as the car starts to slide. Coupled with an auto gearbox this works miracles to guide you in any random direction you didnt choose. Only escape is to quickly slam the selector to neutral or engage 4WD.

Best regards!

fordem
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.

Ojak wrote:

Hi there,

On my rear axle its actually a little text sticker that says LSD.

The problem with text stickers is that they can come off...

Quote:
And second, the hand brake test should work, you just need to find a spot with no grip. This means that with or without an LSD only one of your rear wheels will be spinning. Then apply handbrake and see if you have two sliding wheels. I will try it here next time we get some ice, havent tried yet as i know i have an LSD.

DO let me know what happens when you do try it ...

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