OFFROADSUBARUS.COM

Go Back   OFFROADSUBARUS.COM > Technical Forums > Transmission and Driveline

Notices

Reply
Thread Tools Display Modes
  #21  
Unread 7th August 2013, 10:45 PM
havachat's Avatar
havachat havachat is offline
Forum Member
 
Join Date: Jan 2013
Location: near Healesville Victoria Australia
Year: 2002
Model: Forester SG
Transmission: 1.447 low range 4.44 diffs
Posts: 902
havachat is on a distinguished road
Default

PigSti,
I have both a manual and auto Forester and there is no doubt the manual is more sure footed in slippery conditions.
I spend a lot of time at Mt Buller in the snow season and this year I am using the auto instead of the manual. I have a 4wd access permit so I can park in the village. Using the hold function as you say locks out first gear and therefore reduces the chance of wheel spin. I am not convinced that when hold is activated that the torque is distributed 50/50. The auto has what I would describe as a happy tail compared to the manual.
With the power function I suspect most of the torque is going to the front. I have noticed that the wheel wear on the manual is even between the front and rear whilst on the auto the front tyres wear quicker.
That's my two bobs worth.
__________________
Foz 2002 1.447 LR, 4.44 Diffs, 2004 XS & 2011 XS
Reply With Quote
  #22  
Unread 8th August 2013, 12:14 PM
PigSti PigSti is offline
on sabbatical
 
Join Date: Jul 2013
Location: never never land
Posts: 504
PigSti is on a distinguished road
Default

You're right about the tyre wear, the fronts disappear at twice the rate of the rears.
It would be great if there could be a way to tap into the OBDII and get a 0-50% digital read out of what the torque split is happening between the front and the rears real time! Could there be a module read out for this in OBDII?
Reply With Quote
  #23  
Unread 16th March 2014, 03:25 PM
jf1sf5's Avatar
jf1sf5 jf1sf5 is offline
Forum Member
 
Join Date: Aug 2012
Location: Geneva, Switzerland
Posts: 1,594
jf1sf5 is on a distinguished road
Default torque split

We drive 4wheel drive cars, but how much torque does each wheel get ?

Well, it depends what differentials we have and the surface we drive on.

In a straight line with open diffs, each wheel will get 25% of torque…

Now lets imagine a Subaru with welded center and rear differentials and lifting the rear left wheel, how much torque will the rear right wheel get…25% or 50%

I think its 50% but am waiting your thoughts and answers
__________________
Subversive...
Reply With Quote
  #24  
Unread 16th March 2014, 04:58 PM
MiddleAgeSubie MiddleAgeSubie is offline
Forum Member
 
Join Date: Dec 2013
Location: AZ
Year: 2013 / 2008
Model: H6 5EAT OB with SubieLiftOZ kit / Tribeca
Transmission: 5EAT
Posts: 844
MiddleAgeSubie is on a distinguished road
Default

Of course, the 90:10 is not bogus. It comes straight from Subaru. But it refers to the earlier 4EAT OBs and Foresters. Others claim that it is really 80:20 in testing. Others again think that 90:10 may have been the case early on (like my 95 Legacy), 80:20 subsequently. But whatever the details, the 60:40 split on 4 EATs is a relatively recent development.

PAY ATTENTION TO CHANGE OVER TIME
__________________
18 4R TRDOP, 08 Tribeca
(13H6OB 2" SLOz, 06 B9)
Reply With Quote
  #25  
Unread 16th March 2014, 05:07 PM
MiddleAgeSubie MiddleAgeSubie is offline
Forum Member
 
Join Date: Dec 2013
Location: AZ
Year: 2013 / 2008
Model: H6 5EAT OB with SubieLiftOZ kit / Tribeca
Transmission: 5EAT
Posts: 844
MiddleAgeSubie is on a distinguished road
Default

As for the person who asked about torque distribution above:

No, you won't get what you want. I am unsure as to the maximum transfer my VTD can provide to either axle, but assuming 60% rear and one rear wheel in the air, I do not get 30% on the other one: the wheel braking function is not equivalent to full lock. In addition, the Subaru systems transfer torque all over the place in the blink of an eye, there is no such thing as fixed ratios on a slippery off-road terrain, I think. As for the limited slip: I would rather have the wheel braking, thanks. Thus the tears shed on forums after the LSrD was dropped were a result of misunderstanding. What matters, at the end, is that with the VTD I have never experienced traction problems, be that in mud or slippery desert terrain.

My angles and my clearance stop me well before I need a full lock.

The old AWD system on the 1995 Legacy made that vehicle feel much closer to an ordinary FWD than to my 2013 OB. Neither is made for the off-road, but the latter's traction is so awesome that one gets really irritated by the lack of adjustable height suspension.
__________________
18 4R TRDOP, 08 Tribeca
(13H6OB 2" SLOz, 06 B9)

Last edited by Kevin; 17th March 2014 at 02:58 AM.
Reply With Quote
  #26  
Unread 16th March 2014, 05:11 PM
MiddleAgeSubie MiddleAgeSubie is offline
Forum Member
 
Join Date: Dec 2013
Location: AZ
Year: 2013 / 2008
Model: H6 5EAT OB with SubieLiftOZ kit / Tribeca
Transmission: 5EAT
Posts: 844
MiddleAgeSubie is on a distinguished road
Default

Quote:
Originally Posted by jf1sf5 View Post
Sorry for the new thread but my question was not only about Subaru AWD specs but more general.
I know nothing about the others except that I do not see them where I go: unless we talk approach dirt roads, in which case they do not enjoy the sight of me for long.

I think what marks Subaru's systems is the continuous transfer of torque as the system "hunts" for traction. That is why it is important, when traction is lost, to keep one's foot on the gas: not too much, so one does not "burn" tires, but no taking the foot off either, so that the system can do its job.
__________________
18 4R TRDOP, 08 Tribeca
(13H6OB 2" SLOz, 06 B9)
Reply With Quote
  #27  
Unread 16th March 2014, 05:36 PM
jf1sf5's Avatar
jf1sf5 jf1sf5 is offline
Forum Member
 
Join Date: Aug 2012
Location: Geneva, Switzerland
Posts: 1,594
jf1sf5 is on a distinguished road
Default

I am ok about what you say, my question was just more mathematics/physics, I could compare it to a bicycle/tricycle (no rear diff on the tricycle !)

When accelerating with your bicycle, 100% torque goes on the rear wheel... on the tricycle, 50% torque goes on each rear wheel…

Now if you lift one rear wheel of the tricycle, what will be the torque split ratio ?
__________________
Subversive...

Last edited by jf1sf5; 16th March 2014 at 05:49 PM.
Reply With Quote
  #28  
Unread 16th March 2014, 06:51 PM
Ratbag's Avatar
Ratbag Ratbag is offline
Administrator
 
Join Date: Jan 2012
Location: Bayside, Melbourne, Vic
Year: MY06, MY10
Model: Forester SG & SH
Transmission: 5MT/DR & 4EAT Sports
Posts: 6,219
Ratbag is on a distinguished road
Default

100% less wind resistance, etc of the lifted wheel.

From my Batphone
Reply With Quote
  #29  
Unread 16th March 2014, 10:28 PM
NachaLuva's Avatar
NachaLuva NachaLuva is offline
Senior Member / Product Developer
Contributing Member
 
Join Date: Oct 2011
Location: SE Melbourne
Posts: 5,513
NachaLuva is on a distinguished road
Default

Quote:
Originally Posted by MiddleAgeSubie View Post
As for the limited slip: I would rather have the wheel braking, thanks. Thus the tears shed on forums after the LSrD was dropped were a result of misunderstanding. What matters, at the end, is that with the VTD I have never experienced traction problems, be that in mud or slippery desert terrain.
I would prefer both! IMO dropping the rLSD was merely to save money, rather than it not being needed. With the VTD/VDC, a rLSD isnt as critical, but having both would certainly increase rear grip, it would also reduce power loss due to less braking being applied on the lifted wheel
__________________
SUBIELIFTOZ, QUALITY LIFT KITS FOR SUBARUS
1" & 2" lift kits; custom lift kits; all models
Reply With Quote
  #30  
Unread 16th March 2014, 11:11 PM
MiddleAgeSubie MiddleAgeSubie is offline
Forum Member
 
Join Date: Dec 2013
Location: AZ
Year: 2013 / 2008
Model: H6 5EAT OB with SubieLiftOZ kit / Tribeca
Transmission: 5EAT
Posts: 844
MiddleAgeSubie is on a distinguished road
Default

Quote:
Originally Posted by NachaLuva View Post
I would prefer both! IMO dropping the rLSD was merely to save money, rather than it not being needed. With the VTD/VDC, a rLSD isnt as critical, but having both would certainly increase rear grip, it would also reduce power loss due to less braking being applied on the lifted wheel
Lol, sure. But it is not needed: Subarus are built for the bad weather and the off-pavement, not for the off-road, after all, even if we take them there. If the company cared one little bit about off-road we would be getting an adjustable height suspension or a slight factory lift option (1"), a proper tire option with a full size spare, and a factory skid plate option. Oh, and angles would have been a bit better. It is true that Australia gets better vehicles than the US, or at least it used to be true with low range and full size spare, but are Subarus really marketed as off-road there?
__________________
18 4R TRDOP, 08 Tribeca
(13H6OB 2" SLOz, 06 B9)
Reply With Quote
Reply

Tags
4-at, 5-mt, 6-mt, auto, awd, f:r, torque split

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -3. The time now is 12:37 AM.


Powered by vBulletin®
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.