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diff lock


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27 replies to this topic

#1 Jack in Norfolk

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Posted 02 October 2003 - 06:25 PM

I have only seen this once in real life (on a sube anyways).
Which diff is it that locks? What are the advantages? Why arent you guys swapping this into your hopped up brats and hatches?
Just curious.
Also, could you get diff lock with the DR?
-Jack

#2 GeneralDisorder

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Posted 02 October 2003 - 06:32 PM

The RX had a 5 speed D/R with locking diff option. Although not all RX's had them - some were Auto's. People do swap these in, but I think the main reason you don't see it often is because they are not easy to come by. 5 speed D/R tranny's can be found pretty cheap at the drop of a hat, but not the special diff locking ones.

GD

#3 RallyKeith

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Posted 02 October 2003 - 06:42 PM

The diff lock locks the center diff. Other wise the center diff is a normal open diff. The cars that came with diff lock came with mechanical LSDs in the rear, so locking the center diff means you can basically get out of (or into :D ) anything.

Keith

#4 Jack in Norfolk

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Posted 02 October 2003 - 06:51 PM

ok,
let me get this straight,
the diff locking mechanism is in the tranny?
So if you have a car that came with a locking diff but not dual range, you cant just swap in any dr tranny and keep the original locker?
I'm am just rying to make sure I follow you. This sounds alot different from lockers on Jeeps and other trucks.

#5 Subafly

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Posted 02 October 2003 - 07:05 PM

just weld the crap out of it. lots cheaper:D

#6 TheSubaruJunkie

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Posted 02 October 2003 - 07:14 PM

It is alot different than any Jeep locker. The diff lock is built into the tranny. it only locks the center diff. Your front and rear diff are still open (or rear might be LSD, depending on model). You cannot remove the locking center diff and install it into a Tranny. Diff Locks only come on Full Time 4WD 5 speed Transmissions. If the car is not Full Time, than it doesn't even have a Center Diff to Lock.

Hopped up Brats, Hatch's Wagons... Any 4speed or 5 speed 4WD tranny have no center diff's, they use a different type of mechanism to create the 4WD when engaged, and that mechanism act's like a locked diff at all times (when 4WD is activated).

You cannot take a Single Range 5spd with diff lock and convert it to Dual Range. 1987+ Subaru RX's are the only model that came with Dual Range Full Time 4WD Transmissions with a Center Diff lock.
Honestly, I wouldnt want to do any heavy off-road use with a Full Time 4WD tranny because it still has an open center diff, and if the diff lock malfunctions, your going to be set back using an open center diff.

-Brian

#7 Qman

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Posted 02 October 2003 - 07:20 PM

The purpose behind the center locking diff is to make the power split 50/50. When in the unlocked position I believe it is like a 70/30 split front to rear.

#8 TheSubaruJunkie

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Posted 02 October 2003 - 07:25 PM

So, with the diff lock off... its still powering both rear and front? I thought since it was an open diff... it would transfer power to whichever axle had the least amount of friction.

Something i've been pondering, because if I get this GL10 TurboWagon sold, i'll probably have to drive it to deliver it. I was thinking of removing both rear CV's in order to drive it. Since it has miss-matching tires, i dont want to blow the tranny with the FT4WD.

-Brian

#9 Skip

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Posted 02 October 2003 - 07:25 PM

Excuse me Brian but your statement
"Diff Locks only come on Full Time 4WD 5 speed Transmissions"

I belive the automatic (4EAT) FT4wd also had diff lock switches

Please correct me if I am all wet.

#10 TheSubaruJunkie

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Posted 02 October 2003 - 07:27 PM

I could be wrong. In actuallity... ive never even seen a full time 4WD Auto. So im not sure if they have locking centers or not. But ive seen plenty of 5spd's :)

-Brian

#11 shanonsf

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Posted 02 October 2003 - 08:08 PM

OK, what if ya got both......

I have a 4 spd, D/R works flawslessly......(82 GLW)
If i need SUPER traction I throw the luv lever..50/50 split right?..schwing!!

the puzzle....
I also have a 5spd, full time 4wd w/ ctr locker (from 87+ RX) and it's 3.7 LSD..........sitting on the shelf (along w/ all the custom bits to make it fit my wagon = drive line and axles..)

why would I want to put the conversion in.........

I need convincing that it's actually better (relaible?)
trying to learn here too before I go thru the transplant hassle only to wish I didn't

thx
shanonsf
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#12 Jack in Norfolk

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Posted 02 October 2003 - 08:19 PM

??????
you mean weld the gears together so they wont slip?

#13 Skip

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Posted 02 October 2003 - 08:23 PM

Shanon, your wagon with the lever in one of the 4wd positions is only two(2) wheel drive, the front and rear open diffs only give power to the wheel with the LEAST traction.

With the LSD and the center diff locked you will have three (3) wheel drive.
Plus in some nasty situations where the car may get out of hand before you can grab and shift the lever the FT4wd may keep you out of trouble.

Plus who wouldn't want a ten (10) speed in their car (The RX tranny can be shifted hi/lo/hi at any time, your wagon can not go into low at any appreciable speed.)
Note the low range is not as low as yours (numerically).

Please email me if your decide to sell the set up rather than instal it.

Jack, Sfly is no doubt talking about welding the spider gears in the rear diff, turning it into a permantly locked diff - not a good choice if you want to drive it on dry paved roads, in my op.

#14 TheSubaruJunkie

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Posted 02 October 2003 - 08:45 PM

Shannon. With what you want to do with your Wagon, your best bet is to use the 4spd dual range that came with your car, convert the LSD to a 3.9 and just run with that. I have no idea how that center lock is supposed to be wired, and it might be a huge headache like the EA81T was.

-Brian

#15 shanonsf

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Posted 02 October 2003 - 09:19 PM

oh what to do

I'll keep ya'll posted,
contemplating what to do with a stash of parts :eh:

after putting on the suspension, seats, and brakes...WOW!
craving power et al.......:headbang:

shanonsf
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#16 TheSubaruJunkie

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Posted 02 October 2003 - 09:25 PM

Did you get the brakes and everything done? Bravo! I wanna see it. I just upgraded the ignition on my brat and WOW! We need to race. Do you got your weber on there yet?

-Brian

#17 shanonsf

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Posted 02 October 2003 - 09:32 PM

Snow White's crazy for corners......still have to install rear arms for its sway bar....bad bearing, RXs bearings not cheap......

but oh my, what a difference w/ the KYBs............and real seats.

shanonsf

#18 TheSubaruJunkie

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Posted 02 October 2003 - 09:34 PM

DREWL!!

When are we going to race? We can meet up at that track in Fairfield. I need tires, but thats about it... oh, and a rear sway bar and a webbah.

-Brian

#19 calebz

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Posted 02 October 2003 - 09:39 PM

Having that rear sway bar makes a big difference doesn't it? My last wagon didn't have it.. This one does.. even though its a little higher off the ground than the last one, it still handles better.

#20 baccaruda

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Posted 02 October 2003 - 11:49 PM

shannon, one more thing about the RX trans is that the low range is not as low as in the common dual range trannys, so it won't be as slow as the normal dual ranges are. It's not as useful for offroading. I swapped that transmission into my turbowagon and LOVE IT because that low range is very nice for street driving.

As far as the locking feature goes.. you wouldn't have to enable it at all as long as you wouldn't mind not being able to lock it up.. i still haven't matched up the wiring harnesses yet in my car; all it means is that i can't enable the locking center differential. it also means i don't have reverse lights so i have to be extra careful :P

If you want to enable the locking center differential, it would be simple. Go find a single range push button 4wd car at the JY and grab the vacuum actuator deal in the corner by the driver's strut tower. It has green plastic parts on it. Get the vacuum lines it sends to that transmission (they'll hook to your RX transmission in a similar fashion) and get at least both sides of its wiring connection(s). If you have the switch for the locking diff for your RX transmission you can use that once you get the wiring installed, or you can use the switch in the shifter for the same car you get the vacuum actuator from.
The RX uses the same type of vacuum actuator as the single range push button 4wd cars, the difference in the switch is that there's a power and a ground for a light in the RX's diff switch.
Most of what you'd be looking at besides the transmission interchange ( i think your car is an EA81?) is the wiring-in-the-vacuum-actuator issue.. shouldn't be too hard.

#21 shanonsf

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Posted 03 October 2003 - 10:57 AM

hey all-

I do have the vacuum unit (working?!)from the doner project and an RX ctr Dif switch (very neato, I'll be just like the new STIs) and the schematic diagram.........just have to learn to read the bugger.

it's sounding simpler all the time. seems like I'll be giving up a Lil' Low Range 4wd capabilitiy but w/ the ctr dif lock it seems to even out.......?!

just might have to complete this science project a bit sooner :drunk:

I'll keep ya posted

shanonsf
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#22 MilesFox

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Posted 03 October 2003 - 06:48 PM

junkie: the rx tranny when open diff, allows for it to be in 4wd without axle bind. when locked electrically, it is just like a normal 5spd 4wd, when its in 4wd its locked all the time.

with a locked diff, you have power to one ot the other wheel in front, and one or the other wheel in back, and both must turn at the same rate. when oppen, you have power to one or the other in front, and one or the other in back, baut are allowed to turn at different rates.
the lsd will make it one wheel up front and both in back.

Jack:you woul;d have to take apart both trannies to swap the electric lock into a 5spd from an rx, but i dont know squat about taking a tranny apart!

#23 TheSubaruJunkie

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Posted 03 October 2003 - 07:31 PM

I want to remove both rear CV's to eliminate binding cause the tires do not match. Front tires are smaller than the rear tires right now. The car isnt moving, so its not a problem, but if I do have to drive it to deliver it, or drive it to test it, i was thinking of removing the rear cv's to eliminate bind since the car is FT4WD. What I dont want to do is ruin the tranny by running it in FWD or have it transfer ALL the power to the rear diff since there will be no friction back there.

-Brian

#24 MilesFox

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Posted 04 October 2003 - 11:56 AM

you should have that fuse that disables the 4wd, its under the hod on the passenger firewall.
put a fuse in therer for front wheel driv.

check that out first!

#25 NoahDL88

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Posted 04 October 2003 - 01:21 PM

Shanonsf: the dual range is always locked when its in 4wd 50/50 if your getting rid of the low range to get a locking center you're doing it for the wrong reasons. with the diff lock on, the FT4wd acts like a single range part time 4wd. all of the manual shift 4wd cars are 50/50 if they're part time.




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