: RWD V8 Limited Slip Differential Traction



MortnCyn
10-21-06, 05:16 PM
Anyone with a V8 RWD with the GM Versa Trak limited slip differential that can advise how the traction is on ice/snow winter driving.

ewill3rd
10-28-06, 07:42 AM
Mortn,

Even though I drive Cadillacs every day... all kind of them too, I haven't had a chance to do much with an SRX in the snow.
I would clarify that "versa-trak" is not used in SRX. It's actually probably a good thing. VT is a pretty complicated little system that actually has special fluid and an internal electrical pump in the rear end. I think Chevy uses it on some of their small SUV type vehicles, like Equinox.

The diff in the SRX is pretty close to the same unit they use in STS and CTS-V. It's a Getrag limited slip differential with clutches that transfer power to the wheel with more traction, sort of like the old GM Posi-traction rear ends.

As I said, I haven't had much opportunity to see how they drive in the snow, it's still a fairly new vehicle for Cadi and even though we get a few in we have like 30 techs, I get a few but on snowy days I haven't ended up with one. With AWD and a limited slip rear it should do great in the snow.
I wouldn't drive like a summer's day, but I wouldn't be scared to go out either.

Just out of curiosity have you ever looked at the RPO label to see if you have G80? If you have or if you do, let me know.

c5 rv
10-28-06, 08:34 AM
I had the posi on my CTS. With a good set of snow tires, I had no traction problems at all. The key was disabling traction control, especially when turning onto a paved road from an unpaved road or snow-covered side street. As soon as TC detects wheel slippage, it takes over the throttle and you're stuck there mashing the go pedal, having TC apply tiny bits of power to avoid any wheel slip, and having a big truck headed your way.

MortnCyn
10-28-06, 04:08 PM
c5rv, The CTS is a FWD which would generally do much better than a RWD.
Does your SRX V6 RWD have the LSD and have you driven it on the snow?

MortnCyn
10-28-06, 04:21 PM
ewill3rd, I will profess ignorance re what RPO is. Assume you are asking about my tranny/differential. I am in an '05 AWD V6.

c5 rv
10-28-06, 05:34 PM
c5rv, The CTS is a FWD which would generally do much better than a RWD.
Does your SRX V6 RWD have the LSD and have you driven it on the snow?

No, the CTS is most definitely RWD.

I leased my SRX in May without posi and have not driven it in the snow. I doubt it will see much snow since I still have an AWD truck.

MortnCyn
10-29-06, 05:00 AM
No, the CTS is most definitely RWD.

I leased my SRX in May without posi and have not driven it in the snow. I doubt it will see much snow since I still have an AWD truck.
Guess I had not paid any attention to the CTS. Possibly should read the CTS Forum posts. Thanks for the response.

ewill3rd
10-30-06, 08:08 AM
Mortn,

Under the cover in the rear there is a sticker that has a bunch of 3 digit alpha-numeric codes on it, they are in alpabetical order.
This sticker identifies production options on the car.
If you can't find it PM me the last 8 of the VIN, I'd like to see if it's listed.
The sticker is called a "service parts identification" label or "SPID".

And yes, the CTS is a RWD car, GM seems to be going back to RWD on a lot of cars lately.
Currently the only FWD Cadi is the DTS actually.

robhersch
10-30-06, 10:25 AM
To ewill3rd: two questions please: my 2005 SRX is a V8, RWD, 6ED26 with only the trailering option, ( selected after a full day of comparative road & off-road test driving MLs, BMWs, LEX, Lincolns, Dodges, Nissan, Escalades, etc ) ordered 11/4/04, assy ~ 12/15/04, del 1/21/05 -
1- I did not order the limited slip differential for normal/ typical Sou Cal driving(what benefit is the L-S-D with traction ctl?)
2- Is either the L-S-D or the non-L-S-D heavier, more rugged gears, less maintenance issues??
Thanks in advance; we just love the SRX & despite the nay-sayers herein, we have had NO PROBLEMS except for the CD changer replacement and the rear suspension check (although I refused to let my dealer re-flash my performance computer - no formal notice from GM, just noted in the dealer system)

ewill3rd
10-30-06, 11:11 AM
ROB

The real difference in the LS diff is just a mechanical one that has to do with the slip control parts themselves. The rears are pretty much the same, no real additional durability but on a 2WD vehicle it's always nice to have.

Typically the LSD would be identified by an RPO G80, but on some cars that have it I have seen that RPO absent.
I don't have any idea as to whether or not it shows up reliably on the SRX, but I would imagine that it should. Actually the LSD should mean more maintenance. At least on the trucks, it calls for a flush and refill after a seemingly short period. I haven't looked it up for SRX in the maintenance guide so be sure to verify what I say with the manual.

I know there might be some problem cars out there but I haven't seen any that we couldn't fix and SRX seems to be pretty good for such a young model car. Yes I see some radio issues, but not much more than that.

The limited slip rear might have come with the V8 package, not sure.
Look at the label in the back and tell me if you see the G80 code on the sticker.

robhersch
10-31-06, 12:34 AM
ewill: I recall from the 60s, my 64 PontiacBonneville 389 w/o PosTrac - had 248k when donated in 1995, made into show car by HS autoteacher - is still going strong; but some friends w/PosTrac on 389 GTOs had more than few diff maint probs.
No G80 on my SRX sticker; do have LH2(N*V8), M22(5-Spd-Auto), GU5(Axel 3.23); also have many RPOs on my sticker not ID on my web-downloaded SRX RPO code ID list: C4R, DL5, D7E, IL2, JE5, JJA, KG4, MX0, NU4, R7K, SLM, VG6, V08, V12, V4V, V55, V73, YB6, YD5, YD6, 1SB, 1SZ, 191, 192, 25U, 6NB, 7NB, 8MC, 9MC, HRHV3C, BC/CC, U-722J;
Listed on Window Sticker w/o RPO code: Disc Brks W/ABS & Trac Cont, Stabilitrak/Speed Sens Strg, Tire Pres Monitor, Ultrasonic Rear Park Assist;
Q1-Doesn't the Trac Control achieve nearly the same result as the LSD (for typical road/ street driving??) on RWD vehicles.
Q2-Does the Trac Control effectively replace the LSD for AWD vehicles??, ie, how does the auto-computer effect the % shift in AWD w/o Trac Control braking??
Thanks again for your response.

ewill3rd
10-31-06, 05:58 AM
I know a lot of guys used to switch to the Ford 9 inch for lots of reasons.
The biggest was because the gears, ring and pinion could be removed as an assembly. You could have setups that only required swapping the front half of the case to get different gear ratios.
The GM ones, you shim and set up in the housing making gear swaps a lot harder.

Traction control does effectively do what LSDs are designed to do, it applies the brakes as needed to limit wheel slip. The computer depends on a difference in wheel speed to identify slippage. I wouldn't know if it's an effective "replacement" as I don't know of any study that would indicate that.

If the slipping is bad enough the EBCM sends a signal to the ECM and TCM to control gear selection and torque output from the engine to help reduce wheel slip. I'd have to confess that I haven't studied it in great detail.
I know it uses spark advance or retard, plus the new ones have fly by wire throttles so it can actually reduce the throttle opening and upshift to reduce rpms and load up the engine a little.
It all depends on how the engineers program it though, I'd go far as saying it's probably slightly different depending on the car, the engine and the transmission.

MortnCyn
10-31-06, 08:16 AM
Mortn,

Under the cover in the rear there is a sticker that has a bunch of 3 digit alpha-numeric codes on it, they are in alpabetical order.
This sticker identifies production options on the car.
If you can't find it PM me the last 8 of the VIN, I'd like to see if it's listed.
The sticker is called a "service parts identification" label or "SPID".

And yes, the CTS is a RWD car, GM seems to be going back to RWD on a lot of cars lately.
Currently the only FWD Cadi is the DTS actually.
Image of the RPO or SPID sticker attached. Do not see any G80

ewill3rd
10-31-06, 05:35 PM
Yeah, I am not sure if that's an open diff or an LSD.
With AWD I am not sure they'd put one on it, especially with traction, abs, and stabilitrak.
I have never checked to see if they put limited slip units in an SRX.
Next time I have one in the air I'll take a look.



AH8 - 8-WAY POWER PASSENGER SEAT AL2 - POWER ADJUSTABLE LUMBAR
AM0 - THIRD ROW POWER SEAT (REPLACES RECONFIGURABLE STORAGE) AQ9 - LUXURY FRONT BUCKET SEATS
AY0 - INFLATABLE RESTRAINT DRI & PASS A45 - MULTI-DRIVER MEMORY SETTINGS
B19 - BURLED WALNUT WOOD TRIM CF5 - ULTRAVIEW
CJ2 - DUAL ZONE CLIMATE CONTROL C4R - GVW RATING 6, 008 LBS
C57 - REAR AIR CONDITIONING DD7 - ELECTROCHROMIC ISRV MIRROR
DL5 - DECAL - ROADSIDE SERVICE INFO DR2 - ELECTROCHROMIC OSRV DRIVER MIRROR
FE1 - 4-WHEEL INDEPENDENT SUSPENSION FE9 - 50-STATE EMISSIONS
GW1 - AXLE REAR 3.91 RATIO IL2 - TRIM INTERIOR DESIGN
JE5 - POWER ANTILOCK BRAKE SYSTEM JF4 - ADJUSTABLE PEDALS
JJA - PT DRESS SUBASSEMBLY INSTALLED KA1 - HEATED SEATS
KG4 - 150 AMP GENERATOR LY7 - 3.6L V6 VVT ENGINE
MX5 - ALL WHEEL DRIVE MX7 - ALL WHEEL DRIVE
NT7 - EMISSION - FEDERAL N30 - STEERING WHEEL DELUXE
N93 - WHEEL 17 X 7.5, ALUMINUM PCQ - LUXURY COMFORT PACKAGE *HEATED SEATS *ADJUSTABLE PEDALS *XM SATELLITE RADIO - OVER 130 CHNLS OF DIGITAL ENTERTAINMENT SERVICE FEE EXTRA.1ST 3MOS.INC
PDL - LUXURY UTILITY PACKAGE *THIRD ROW POWER SEAT (REPLACES RECONFIGURABLE STORAGE) *TIRE PRESSURE MONITOR *8 SPEAKER BOSE AUDIO SYSTEM Q15 - P235/65R17 FRT & P255/60R17 RR ALL-SEASON, BLACKWALL TIRES
R7K - HURRICANE EXPEDITING SLM - STOCK ORDERS
UA6 - THEFT DETERRENT SYSTEM UE1 - 1-YR ONSTAR DIRECT/CONN SVC
UG1 - HOMELINK GARAGE DOOR OPENER UJ6 - TIRE PRESSURE MONITOR
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U30 - CLUSTER INST, TACH, CLOCK U57 - 8 SPEAKER BOSE AUDIO SYSTEM
VM3 - LABEL INFORMATION CONSUMER, CONTAINS BPR IMP STANDARD FOR FRT 5MPH & RR 5MPH V73 - VEHICLE STATEMENT
YB6 - AXLE(BASE EQUIP) PROCESSING OPT YD5 - SPRING FRT BASE EQUIP, PROC OPT
YD6 - SPRING RR, BASE EQUIP, PROC OPT 1SB - LUXURY PACKAGE *BURLED WALNUT WOOD TRIM *AM/FM/6 CD CHANGER W/7 SPKRS (REPLACES STD/OPT RADIO) *REAR AIR CONDITIONING *RECONFIGURABLE STORAGE *MULTI-DRIVER MEMORY SETTINGS *8-WAY POWER PASSENGER SEAT *ELECTROCHROMIC OSRV DRIVER MIRROR *HOMELINK GARAGE DOOR OPENER
1SZ - PREFERRED EQUIPMENT SAVINGS 19I - INTERIOR TRIM EBONY
192 - EBONY 41U - BLACK RAVEN
6NB - COMPONENT FRT LH COMP SEL SUSP 7NB - COMPONENT FRT RH COMP SEL SUSP
8MA - COMPONENT RR LH COMP SEL SUSP 9MA - COMPONENT RR RH COMP SEL SUSP