Detailed discussion of Toyotas awd system, specifically for the st205 Options

[enderswift]

hey everyone,

here's what I 'think' I know. The awd system fitted into the st205 is pretty ancient compared to today's cars, but was decent when it first came out and was organized out like this:

1. There was an open differential in the transversely mounted transmission that had a transfer case coming out of the rear.
2. No center differential but a center bearing instead. So it always had a 50/50 front/rear torque split
3. rear differential came with a torsen limited slip

lets compare this to other awd systems. Past and present. Subaru is really big on the fact that they have a symmetrical awd system. Do you guys think the fact that an st205s unequal front axles hurts the car?

and, could it be possible to fit the limited slip from an mr2 and have torsens front and rear? I think that would be interesting since apparently one of the biggest handling problems with the st205 is that the the inside front wheels spin on really sharp turns.

heres an interesting video comparing modern awd system:

http://www.youtube.com/watch?v=ooQRxlChvMw

[playr158]

You can get CUSCO differentials for the ST205

[delusionz]

The GT4 should have no problem getting up that ramp, it's 4WD system works very well.

[delusionz]

I think that would be interesting since apparently one of the biggest handling problems with the st205 is that the the inside front wheels spin on really sharp turns.

Whoever said that I presume is describing the GT4's tendency to understeer-drift, which I can tell you only happens if its wet and the corner is negative camber.

I don't see this as a problem since in order to experience this, your entry speed into the corner would have to be too high for any car really, at which stage you would be using the hand brake.


And yes, really sharp turns we're talking about

[3WayStunna]

Firstly i want to know who said GT4's have unequal axels. I did a comparison of mine a while back, and as best i can remember, both fronts were the same length...



Corrected they are...sorry but these were the only pics i could find

[presure2]

yea, the '4's front axles are equal legnth.

[klue]

Just to add my comments. Yes the gt4s all share equal length axles, the rear are the same lengths and the fronts aswell. The st205 axles you have pictured are 1 piece design, but the older versions (st185,165) are 2 piece design allowing the to be hybridized nicely.

There is a center differential in the transmission, its located inside the transfer case. It is not fully open in the sense that if one wheel is free all the power goes there. It has a split between the front and rear, so if one wheel is free at the front, power goes to the back. You can further this by adding the LSD rear end which came optional in the st185, came factory on st185 CS/RC, and also st205 chassis.

I think personally the all wheel drive system is great. The tranny is very strong holding holding all the power I have thrown at it, and also I have never had issues with torque steer sometimes experiences on FWD bias AWD cars. Even at power levels just shy of 500AWHP.

On thing to remember is that this car is not AWD, it is 4WD.

Love that gt4

[enderswift]

awesome this cleared up some misconceptions. I assumed the axles were unequal length because its a transversely mounted engine, and most of those have different lengths.

There is a center differential in the transmission, its located inside the transfer case. It is not fully open in the sense that if one wheel is free all the power goes there. It has a split between the front and rear, so if one wheel is free at the front, power goes to the back. You can further this by adding the LSD rear end which came optional in the st185, came factory on st185 CS/RC, and also st205 chassis.

I knew there had to be something like that. Its good to hear that if the fronts slip then the rear still gets power.

how do you guys think this system stacks up compared to modern cars with torque vectoring and the like? Personally I hate systems that use computers to take over. I prefer mechanical enhancements like lsd's that offer the driver more control as opposed to doing things for the driver.

[bccentaur3]

Given the fact that the Sti's and evos have a button for the drivetrain to react to the different surfaces the gt-four's drivetrain is no match when it comes to technology. If you're talking about strength probably the same.

[3WayStunna]

True, when compared to AWD/4WD systems of today, there really isnt any comparison. Most companies like subaru have an added 15+ years of "getting it right" compared to the GT4, Toyota exiv, and caldina...

For example the GC8 of the same year suffered greatly from poorly designed transmissions, and the EVO's of that same time dealt with "some" tourqe steer. Now not saying the 205 was the best thing since buttered bread, but when comapred to vehichles of the same year, ( and after driving both evo's GC8's as well) i would give it up to the 205...after 99 though, i would speak differntly...

[ST205WRC]

3WayStunna i think you hit the nail on the head. its hard to compare 2 things that are from completely diff. times as far as technology is concerned. its like comparing a model T to a BMW. in its time it was great but now not so great but it gets the job done and we still love it. the gt4 did what no other could do in its day. it took down lancia in the WRC which is what every japanese manufacture was trying to do and didnt really have great success at it and had been trying a lot longer.

so better then a 2011 evoX no, sexier yes, easier to work on yes, and its a toyota so you cant go wrong!!!!

[enderswift]

On thing to remember is that this car is not AWD, it is 4WD.

Love that gt4

love those gt4s too. But I dont think we can call it 4wd. observe:

http://www.rubicon-trail.com/4WD101/4WD-AWD-autoAWD.html

The whole naming thing is a crapshoot. Still, I think its fair to call the gt4 an awd


So from what I have read online, and from what you guys have said, the gt4 is a pretty decent system. The front and rear axles both get 50% of torque all the time because of the differential in the transfer case. I wonder what the celi would be like if it had a driver controlled center diff . The differential up front is open so any loss of traction up front puts all the responsibilities on the rear. So in the worst case scenario the st205 can be one wheel drive if the fronts and one of the rears lost traction. I'm amazed that the torsen was only standard on the 205, it just seems like such a vital thing to have...

Someone said you could put a Cusco torsen up front, what about the lsd from an mr2? I think that would be a lot cheaper and really bring out the capabilities of awd system.

This post has been edited by enderswift: Jan 17, 2011 - 11:33 AM

[jeffrosie]

Read some where that the last of the 1st Rav4 with the 3SFE engines came with a driver controlled transfer box. Think they were the facelift post 98 ones.

[Hanyo]

awesome this cleared up some misconceptions. I assumed the axles were unequal length because its a transversely mounted engine, and most of those have different lengths.

There is a center differential in the transmission, its located inside the transfer case. It is not fully open in the sense that if one wheel is free all the power goes there. It has a split between the front and rear, so if one wheel is free at the front, power goes to the back. You can further this by adding the LSD rear end which came optional in the st185, came factory on st185 CS/RC, and also st205 chassis.

I knew there had to be something like that. Its good to hear that if the fronts slip then the rear still gets power.

how do you guys think this system stacks up compared to modern cars with torque vectoring and the like? Personally I hate systems that use computers to take over. I prefer mechanical enhancements like lsd's that offer the driver more control as opposed to doing things for the driver.

each of those systems have their strengths.

Mechanical awd systems are great for strength and power. When you add more power beyond what the computer is programed for the car will react the same. However awd system without computer control is a thing of the past.

In the real world there are too many road surfaces to deal with that one single system to work for all of them. Another reason why computer controlled awd systems are superior is the computers ability to control the way the car drives. Two good examples of smart awd systems are the Mitsubishi evo and the Nissan gtr. Both the cars rely heavily for the computer to each wheel.

[enderswift]

could someone post pictures of the underside of an st205? I mean complete front to back pictures of a celi on a lift? I'd really like to see how everything is placed and how the drivetrain sits. I think it would be helpful to those of us who want to research doing awd conversions

[Neon90424]

That first video is a subaru fanboy drooling over their acronym filled awd system.

All I care about 4wd awd everywheeldrive is that it makes me slide in a vector when stomping on the gas pedal as opposed to turning the steering wheel and slide forwards.

Example.

http://www.youtube.com/watch?v=3Ber5KFsXyw...feature=related

This post has been edited by Neon90424: Jan 22, 2011 - 1:58 PM

[bccentaur3]

could someone post pictures of the underside of an st205? I mean complete front to back pictures of a celi on a lift? I'd really like to see how everything is placed and how the drivetrain sits. I think it would be helpful to those of us who want to research doing awd conversions

Just look at Jmeyers build. Its really that simple. Its the matter of you having the right parts ad tools. Simply look under the the alltracs. They all look the same. 2 spots for the carrier brackets to bolt onto under the tunnel for the prop shaft. And 4 spots to mount the rear cradle onto. What I plan to do with the build is essentially show a step by step on how everything is done come Summer of 2011. What you want to do is have the engine in place with the transaxle connected of course, and go from there. You'll what lines up where.

[delusionz]

That first video is a subaru fanboy drooling over their acronym filled awd system.

All I care about 4wd awd everywheeldrive is that it makes me slide in a vector when stomping on the gas pedal as opposed to turning the steering wheel and slide forwards.

Example.

http://www.youtube.com/watch?v=3Ber5KFsXyw...feature=related

doesn't handle like that on tarmac. just snow, gravel, dirt and grass.

if u wanna go sideways like that on the road u need a rwd biased 4wd such as a GT-R Skyline. or otherwise just pull up the handbrake and hope for the best.

[3WayStunna]

Not too true delusionz...try a stiffer rear end, a GT4 making around 280-320 horses, and a bit of clutch kicking with the right tires, and you can get it to do that...oh and might i add some extreme guts...

I dont have video proof so you would have to take my word, But i have initiated a 3rd and 2nd gear drift before...not the safest thing i have done because i was hauling ass at to do it, but still can be done on tarmac/road surfaces. If you want, i had help with a stiffer rear ARB, and my front dampner settings set softer than the rears....

On gravel and grass it meant i had no control of the a$$ end whatsoever...could barely drive the car right lol...
Anywho, there are some videos on youtube of a GT4 drifting with an 180 and an MR2 up on a track here in mainland japan...cant find it though.

EDIT: think this is it.. http://www.youtube.com/watch?v=yqKgyRRtVa0...feature=related

Also i hear from the UK guys that a 2 way or 1.5 way center diff would help out dramatically..although i dont think i want to do that to my car.....might go with a 1.5 way if i ever did though...

This post has been edited by 3WayStunna: Jan 24, 2011 - 8:25 PM

[delusionz]

on factory suspension my st205 understeer drifts on tarmac,

on coilovers the required speed needed to enter a drift is so high it scares me so ive never done it since the change. car drives like its on rails

[nammer]

could someone post pictures of the underside of an st205? I mean complete front to back pictures of a celi on a lift? I'd really like to see how everything is placed and how the drivetrain sits. I think it would be helpful to those of us who want to research doing awd conversions

best ones I have..

taken from the back of the car:



taken from the front of the car:

[delusionz]

that bolt on exhaust system from japan has a really bad bend in it how it gets close to the drive shaft. mine came from japan with a similar bolt on system but that bend was alot straighter.

[enderswift]

What I plan to do with the build is essentially show a step by step on how everything is done come Summer of 2011.

That would be beyond awesome.

On gravel and grass it meant i had no control of the a$$ end whatsoever...could barely drive the car right lol...
Anywho, there are some videos on youtube of a GT4 drifting with an 180 and an MR2 up on a track here in mainland japan...cant find it though.

EDIT: think this is it.. http://www.youtube.com/watch?v=yqKgyRRtVa0...feature=related

The gt4 just looks good doing anything doesn't it?

Thanks for posting those nammer, they are exactly what i was thinking of. Wow it looks like theres actually two spots for the center bearings, I always thought there was just one... I cant tell from the pictures but does the awd system use any u-joints in the driveshaft? Or is it all just splined together?

If its splined together, the best way to go about welding up the brackets for the drivetrain is to have the awd transmission installed in the car and mock up each component separately to get the right spacing correct?

How would you know if you have to factor in a little bit of extra space to allow for play? I'd imagine its a bad idea to have everything tightly pressed together and that a 1-2 mm horizontal breathing room would be good.

Also, what about the angle of the driveshaft? Does an st205 have the shaft level with the bottom of the car or is it a bit angled?


This post has been edited by enderswift: Jan 27, 2011 - 11:45 AM

[3WayStunna]

Why not install the rear diff and support etc. etc., along with the tranny...that way you could find out yourself?!?!?! I mean would that work out for you as well in trying to determine what you are looking for?

[enderswift]

Why not install the rear diff and support etc. etc., along with the tranny...that way you could find out yourself?!?!?! I mean would that work out for you as well in trying to determine what you are looking for?

I have another 2 semesters left before i graduate so funds are tight till then. The earliest I could buy a clip would be this fall if my internship comes through. So in the mean time I'd like to get some information before diving into a project that needs a pretty large amount of preparation. Furthermore I would like the info in this thread to be a good consolidation of all the scattered drivetrain info