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Traction Control


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21 replies to this topic

#1 WoodsWagon

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Posted 22 March 2007 - 08:51 PM

"Subaru's two-wheel drive 1995 Legacy Sedan, 1995 Legacy Station Wagon and 1996 Legacy Sedan may be equipped with the Subaru Traction Control System (TCS) as an option. Prior to dyno testing, the TCS switch on the dash must be placed in the "off" position after starting the engine."

Would there be any way to put TCS on a 98 Outback with an auto and ABS? It seems like it should just be a piggyback controller on the ABS system.

#2 crazyhorse001

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Posted 23 March 2007 - 09:04 PM

TCS isn't necessary with awd, in fact it'd be redundant. I also can't comment on wether it might actually damage the awd system or not.
That said, however, what you'd end up with is the fancy schmancy AWD most SUV's pass off as "Command Trac" ETC using TCS to make up for REAL 4wd.
If you've seen the video of the OB beating up on the Volvo offroad, you can see what TCS does to an otherwise decent AWD system.
I like Subie's system because it's SIMPLE.

#3 WoodsWagon

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Posted 23 March 2007 - 09:16 PM

TCS can make a huge difference to a 4wd car. Take a quick search on "dual handbrake" in the offroad section. That's the most basic form of traction control. What I need is a computer that hooks into the ABS to kick the brakes on on the two spinning wheels to try and break loose the non-spinning wheels. The 2wd legacy's used it, so there must be a system that was make to interface with the subaru ABS system.

My mom has a penchant for getting her outback stuck, then coming home after digging it out and complaining that the AWD sucks. I had to point out to her that her taurus would have been buried way before the outback gets sunk, but I'd like to make it even harder to get the car stuck.

#4 86BRATMAN

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Posted 23 March 2007 - 09:24 PM

My wife had problems with my dad's 92 L wagon awd. She had the thinking that awd meant she needed to give it more gas when it started spinning. Ending her up in the ditch more than once.

#5 nipper

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Posted 23 March 2007 - 09:45 PM

I hate traction control. Its just an excuse to hide poor driving skills.
I rented a top-of-the-line Volvo with AWD and traction control. There was this tiny idiot light telling me when it was active ( I had to look up what the light actually meant). I was driving across PA in a snow storm and decided to shut off the traction control. I discoverd to my dismay i was over driving the car for the weather conditions. The traction control was hiding this from me, by adjusting for individual wheel slips.

Traction control works by several methods. In the older system it cuts power to the engine. Thats the same thing you should be doing with your right foot in bad weather.
Newer systems cut engine power, may play with the gear selection in an automatic transmission, and also applies the brakes.

nipper

#6 WoodsWagon

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Posted 23 March 2007 - 10:04 PM

How does the TCS in the 95 and 96 2wd legacy's work? I'm assuming it uses the abs, not a fuel cut.

My mom isn't an idiot driver, she's been driving new england weather for more than 40 years. When she gets the car stuck is when she takes it off the road to get to trailheads and water sampling sites. The AWD does all it can, but it ends up with one front wheel and one rear wheel spinning, just like EVERY 4wd with open diffs does. It sucks, and an ABS based TCS system would make it a lot harder to get the car stuck.

#7 nipper

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Posted 23 March 2007 - 10:09 PM

Ok i did some research. I cant find a thing on the 1996 traction control. Maybe it did operate the brakes. That would be very unusual for this price range in that year. I know it did cut the fuel injectors to reduce power. I found one refernce to a differnt part number for an ABS unit for TC, but i only found it once.
Aparently this was a short lived option. In googling it i did find awd cars in that year with traction control, but lets face it, people dont even know how many cylinders they have under the hood most the time.

nipper

#8 BruceyWV

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Posted 24 March 2007 - 09:29 AM

Do what I did and make your own traction control:

Posted Image

Not that hard thanks to Subaru's goofy ebrake method. Actually made things easier.


Echo'ing Nipper, it would be odd for Subaru to have traction control in '95. My Mark VIII didn't get traction control until '97, and Lincoln is ford's
"top o the line" getting all those expensive near useless toys first.

#9 frag

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Posted 24 March 2007 - 10:23 AM

Do what I did and make your own traction control:

Posted Image

Not that hard thanks to Subaru's goofy ebrake method. Actually made things easier.


Echo'ing Nipper, it would be odd for Subaru to have traction control in '95. My Mark VIII didn't get traction control until '97, and Lincoln is ford's
"top o the line" getting all those expensive near useless toys first.


Excuse my ignorance but what is that we are seeing? Two e brake levers each one being connected to only one rear wheel? Could you elaborate on the nature of the system and what you had to do to install?
Thanks in advance.

#10 nipper

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Posted 24 March 2007 - 10:54 AM

yes do share .....


nipper

#11 BruceyWV

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Posted 24 March 2007 - 04:37 PM

Check out the off road forum, thats where I got the idea from, but I went and grabbed another e brake handle from the scrap yard, grinded it down some and welded it to my stock one, widened the hole some (I might re do it, I dont like having the metal exposed) and linked the rear e brake cables.

Each wheel has a single cable coming to pull the e brake, two two meet at the handle and are joined into one, I just removed the joining piece and now each handle independently pulls the brake cable.

#12 dmanaenk

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Posted 24 March 2007 - 07:10 PM

Judging by 1995 wiring diagram that could be easily located via this forum - TCS in 95 cars uses ABS.
I think it was only an option on FWD L trim, which did not sell a lot of cars.
I'd just get a rear vLSD.

#13 WoodsWagon

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Posted 24 March 2007 - 10:40 PM

Judging by 1995 wiring diagram that could be easily located via this forum - TCS in 95 cars uses ABS.
I think it was only an option on FWD L trim, which did not sell a lot of cars.
I'd just get a rear vLSD.


could you throw us a link to this diagram? It doesn't appear in the 1998 outback FSM I have, so i'd love to see it.

Dual E-brakes is awesome, but I'd rather use the existing ABS systems which has the ability to brake each wheel individualy, not just the backs, and do it with split second reaction times.

#14 nipper

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Posted 24 March 2007 - 11:02 PM

could you throw us a link to this diagram? It doesn't appear in the 1998 outback FSM I have, so i'd love to see it.

Dual E-brakes is awesome, but I'd rather use the existing ABS systems which has the ability to brake each wheel individualy, not just the backs, and do it with split second reaction times.


The ABS unit for traction control has that ability. The standard ABS unit does not.

nipper

#15 hankosolder2

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Posted 24 March 2007 - 11:07 PM

could you throw us a link to this diagram? It doesn't appear in the 1998 outback FSM I have, so i'd love to see it.

Dual E-brakes is awesome, but I'd rather use the existing ABS systems which has the ability to brake each wheel individualy, not just the backs, and do it with split second reaction times.


I don't mean to be discouraging, but it's unlikely you'll be able to make this work. The traction control system for the FWD Legacy is only going to modulate the front two channels of the ABS. Not much good in an AWD car. Also, it's quite probable that there are differences in the ABS hydraulic block.

Nathan

#16 Manarius

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Posted 24 March 2007 - 11:19 PM

I can't imagine that the front diff would really like the two wheels changing speeds at random intervals. I also can't imagine that the clutch packs would like that much either. I would think that's why Subaru doesn't use TCS on AWD vehicles ;-)

#17 WoodsWagon

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Posted 24 March 2007 - 11:26 PM

The ABS system has all the mechanical parts necesarry for a TCS system.

When the ABS is doing it's thing, it shuts off pressure from the master cyl, dumps the pressure, and then reaplies pressure to the wheel from it's own accumulator and pump. That's all you need for TCS, a way for the brakes to be applied individually without you pushing the brake pedal.

The only part that's needed is a secondary computer to run the ABS as a TCS and a switch to turn it off when you're not wheeling.

#18 dmanaenk

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Posted 24 March 2007 - 11:33 PM

It's here

#19 WoodsWagon

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Posted 25 March 2007 - 12:32 AM

Page 93 and 94 of the "1995_legacy_wiring_diagrams" for those into instant gratification.

#20 hankosolder2

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Posted 25 March 2007 - 08:40 PM

[quote name='91Loyale']The ABS system has all the mechanical parts necesarry for a TCS system.

I'm afraid it doesn't. Don't believe me? Go to 1stsubaruparts.com , look up 1995 Legacy "anti lock brakes" then go to "modulator valve."

Modulator valve W tcs $920
Modulator vave W/o TCS $ 702.19

If the modulators are identical, why the price discrepancy?

Once again, the FWD TCS computer is only going to be looking at the speed sensor inputs from the front two wheels- how exactly do you expect to modulate the ABS on the back wheels to achieve AWD traction control?

Futhermore, if it was just a matter of a different ABS/TCS control computer to add AWD traction control to these cars why on earth would Subaru have NOT included it as an option on these cars?

Nathan

#21 86BRATMAN

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Posted 25 March 2007 - 08:51 PM

[quote name='hankosolder2'][quote name='91Loyale']The ABS system has all the mechanical parts necesarry for a TCS system.

I'm afraid it doesn't. Don't believe me? Go to 1stsubaruparts.com , look up 1995 Legacy "anti lock brakes" then go to "modulator valve."

Modulator valve W tcs $920
Modulator vave W/o TCS $ 702.19

If the modulators are identical, why the price discrepancy?

Once again, the FWD TCS computer is only going to be looking at the speed sensor inputs from the front two wheels- how exactly do you expect to modulate the ABS on the back wheels to achieve AWD traction control?

Futhermore, if it was just a matter of a different ABS/TCS control computer to add AWD traction control to these cars why on earth would Subaru have NOT included it as an option on these cars?

Nathan[/quote]

In theory, you could run two tcs computers, one front one rear. But thats a lot of crap to go through imho.

#22 WoodsWagon

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Posted 25 March 2007 - 09:33 PM

Or you could make your own.

I'm not saying the factory TCS vs ABS valve block is the same. The factory TCS probably had some way of making the on-off switch of the brake aplication smoother, so that the system would be streetable.

Nonetheless, the ABS system can turn the brakes on and off independently without input from the brake pedal. A system for off-road use only could be pretty basic and unrefined, but it would get the job done.




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