ABS differences and opinoins

[carfreak85]

OK Im looking for a turbo sedan and Ive been trying to decide what year to get. Nothing I have come across so far has been a deal breaker either way. The killer in this deal is the ABS. While Subaru may have updated to the 3 selinoid system for simplicity, if the two systems are both sound and dont have problems a 4 selinoid is always better than 3. This seems to be the tie breaker between the two cars for me. The only question I have is other than simplicity, why did Subaru go from a 4 channel to a 3 channel ABS system? Of the people who have driven both systems, which is better?

[vrg3]

It's not a 3-solenoid system in later cars. There are four solenoids, and the computer has the ability to independently control each wheel. The hardware is no simpler.

The difference (if there really is any -- I haven't seen any official documentation) appears to be one in the programming of the computer. According to the service manual, setups intentionally modulate the rear wheels together in order to minimize the effect they have on yaw. Apparently many cars do this today.

I dunno, though... The difference may not be so well-defined. The listed part numbers for ABS computers don't seem to support the idea that 91 had a different system from all others:

90-94 4WD 5MT: 26725AA000
90-92 4WD 4EAT: 26275AA010
93-94 4WD 4EAT: 26720AA210
91-92 FWD: 26720AA010
93-94 FWD 5MT: 26720AA010
93-94 FWD 4EAT: 26720AA200

It's possible that in 91 they originally had different computers but they superceded the part numbers; I don't know.

I've heavily driven a 91 and two 93s with 4WD and ABS through all kinds of weather and didn't feel that they performed significantly differently. The 91 was not a turbo (the 93s were); I don't know if that matters but I doubt it.

[carfreak85]

what about this? http://legacycentral.org/library/93_packet_absawd.htm Sounds like 3 solenoid system to me! I think this means that unless there were large problems with the old system that warrented a redesign (the new 3 channel) then the 4 solenoid is the better of the two!

[ciper]

I dont see how any of them could be 3 solenoid.

Remember how he brake systems act as backup, so if on fails you have one front wheel and one rear? Isnt that impossible with a 3 "curcuit" setup?

[vrg3]

In 1993 they introduced the 2E system, yes, and it uses a single solenoid valve to operate both rear channels. The independent circuits are maintained because the solenoid basically acts through a sandwich that can act on both circuits.

But even before 1993 they used the select low logic to operate the rear wheels. The 1992 4-solenoid system is functionally the same as the 1993 3-solenoid system.

Worth noting, also, is that 2E is only used on 93-94 4EATs.

Someone with a 90-91 manual can confirm or refute this, but I will throw this supposition out there: I believe that all the ABS systems used on BC/BF Legacies modulate the rear wheels together, whether by programming or by physical limitation.

[scottzg]

i dont think it particularly matters. There are reasons for both. But what would you choose; the $2k 91 with 190k, or the $2k 94 with 90k. Ya know what i mean? It's not like theres enough of them on the market to afford you a choice of such a minor difference.

[carfreak85]

if i can find a 91 for cheap with few miles, ill take it over a leter car for the same price or year.

[rallysam]

Scott has a good point. Most people spend season after season trying to find even a single turbo legacy for sale in their region (for a reasonable price). Do you really have so many to choose from that you're choice hinges on some nuances of the ABS system?

[carfreak85]

Well there is a sport sedan and two touring wagons within 25 miles of where I live, all autos though. I see them running around all the time, and for sale even more often than that. Im not to worried about finding one. I have relitives in cali too so if i fond someone with a good T-sedan down there, Ill pay them a visit and pick up a new car too! Like I said, Im not too worried at all! By the way, will the tail lights off of a 92 go onto a 91? they have the same front ends so I assume it was just a touch-up and will swap. I know the later (93-94) wont.

[vrg3]

92s and 91s do not have the same front end. 92s have the same body style 93-94s.

You understand, right, that all 5-speed turbo Legacies appear to have identical ABS systems? That the whole "3-solenoid" issue (if there even is one) appears to only apply to 93-94 automatics?

[rallysam]

Well there is a sport sedan and two touring wagons within 25 miles of where I live, all autos though. I see them running around all the time, and for sale even more often than that.

Ok. Lucky guy!

[carfreak85]

I dont think the 3 solenoid is just for automatics. I beleive it was just conicidence that the auto update and the ABS update were in the same bullitin. Why would they have two different systems for the same car?

[vrg3]

Uh, the AT and MT ABS systems are different. All years. The MT setup uses a G-sensor underhood to sense vehicle deceleration, for one thing.

Subaru also used two different ABS systems many years -- one made by Bosch and one made by Nippon. They just sourced the systems from two companies.

I have a 93 5MT turbo which had the exact same underhood hydraulic unit as earlier years. In fact, I swapped one in from a 91 Legacy LSi and they appear identical in all respects.

Given that the same computer is specified for all years of 5MT but 93-94 autos have a different computer, it would follow that the 2E system was only used on autos.

[carfreak85]

OK, I stand corrected!