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Operable locking diff for 7.5" GM

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Operable locking diff for 7.5" GM

Post by photo_van » Wed Jul 02, 2014 2:10 am

So I haven't been overly impressed with the TruTrac I put in the rearend. When I need the axle locked, I need just that. The TruTrac works good when all wheels are in contact with the ground but not at all if one is in the air.

I have recently come across threads that talk about Hummer H3, Chevy Colorado, and GMC Canyon having 7.5 frontends. There are air and electric lockers available for these differentials. So my question is; are the carriers the same? I haven't been able to find a definitive answer. This site http://www.drivetrainshop.com/ARB_Air_L ... -rd148.htm says the ARB RD 148 will fit Astros, but it is the only reference I've found (Astros aren't listed on the ARB site (go figure!).

So, anyone know??
1998 AWD/4WD
4" lift, 31x10.50's, NP 242j/c hybrid, 4.10 gears, S10 front disconnect, rack & pinion steering, trans cooler, rock sliders, ARB fridge, house battery and 100w solar, swing out rear rack with foldout camp table, bed and passenger swivel chair
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Re: Operable locking diff for 7.5" GM

Post by Stroverlander » Wed Jul 02, 2014 4:56 am

That's funny, you've reminded me that I sent ARB USA an email with this same query over a year ago and never received a reply (had to double check my email, nope no reply).

In comparing parts between the two differentials on http://www.ringpinion.com/DiffWizard.aspx they appear to use most of the same parts with carrier cases and spider gears being different. One carrier case and spider gear set fits our 7.5 and 7.625 rear with the other fitting the Hummer 7.6 IFS diff while the ring and pinion gears and individual bearings are the same between both. Being 28 spline and same bearings, you'd think it would fit.

Now looking at the link you provided, it shows it fitting our 7.5 / 7.625 rear ends so even better...
ARB Model: RD148 Application: GM 7.5" / 7.625" Axle Shafts: 28 Spline Gear Ratios: All / 3.23 +

This ARB Air Locker fits GM 7.5" and GM 7.625" axles with 28 spline axle shafts.
(Fits Hummer H3, Chevy Colorado, and GMC Canyon front axles with 3.23 and higher gears.)
It's completely overkill for my current needs but I'd still like to see someone do this! Perhaps you'll have better luck if contacting ARB USA? :cheers:
2004 Astro LT AWD Stroverlander

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Re: Operable locking diff for 7.5" GM

Post by Captn. Crunch » Wed Jul 02, 2014 11:55 am

I know that the Torsen diff I put in the rear of my 99 operates on the same principle as the diffs in military hummers. According to the military guys The trick when a wheel is off the ground is a little brake pedal
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Re: Operable locking diff for 7.5" GM

Post by photo_van » Wed Jul 02, 2014 1:33 pm

I tried to contact ARB via email too, maybe a phone call is order. Not that I'm looking to take the rearend all apart again!

I didn't realize that Hummers had Torstens in back. The H3s have an E-locker in front, which BTW is also a 7.5" and may work in an Astro rearend. I know of the "braking" trick, it hasn't worked for me....
1998 AWD/4WD
4" lift, 31x10.50's, NP 242j/c hybrid, 4.10 gears, S10 front disconnect, rack & pinion steering, trans cooler, rock sliders, ARB fridge, house battery and 100w solar, swing out rear rack with foldout camp table, bed and passenger swivel chair
dirt bag camping rig
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Re: Operable locking diff for 7.5" GM

Post by Captn. Crunch » Wed Jul 02, 2014 2:39 pm

I don't know about the H-2 or H-3's but the military versions were/are equipped with Torsens front and rear if memory serves. Guess we are gonna have to spend some time in those offroading forums and pick up some tricks of the trade
Captn. Crunch
"I don't beat my rig-I use it to it's maximum potential"
1994 Safari conversion (sold) and miss'n it!
1999 Safari SLE AWD junked
2003 GMC Safari AWD SLT
cast iron Torsen equipped front diff
S-10 leafs-G80 rear w/3.73’s
2” body lift w/Falken Wildpeak AT’s

photo_van
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Re: Operable locking diff for 7.5" GM

Post by photo_van » Wed Jul 02, 2014 3:40 pm

This just in from ARB; oh well...

Hello,

The RD148 only fits the front AAM760 ifs. It does not fit the 7.5” rear.

Cheers!


Bill

ARB-USA
720 SW 34TH STREET
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Tel: 425-264-1391
Fax: 425-264-1392
1998 AWD/4WD
4" lift, 31x10.50's, NP 242j/c hybrid, 4.10 gears, S10 front disconnect, rack & pinion steering, trans cooler, rock sliders, ARB fridge, house battery and 100w solar, swing out rear rack with foldout camp table, bed and passenger swivel chair
dirt bag camping rig
1981 Toyota 4x4 pu
1974 John Deere 710
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Re: Operable locking diff for 7.5" GM

Post by LiftedAWDAstro » Wed Jul 02, 2014 5:21 pm

I would imagine the front IFS in the H3, Colorado etc is reverse rotation where the 7.625" rear in the A/S vans is a low pinion.

You are right about the Truetrac slipping with one wheel in the air. An option is to swap in the open carrier and install a Power Trax no-slip locker. It's not selectable but it works every time! Does ARB make a locker for the S-10 rear diffs?
Current rides:
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2008 Dodge Nitro 4x4
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Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy

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Re: Operable locking diff for 7.5" GM

Post by Herbie » Wed Jul 02, 2014 6:09 pm

LiftedAWDAstro wrote:Does ARB make a locker for the S-10 rear diffs?
Sadly, no.
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Re: Operable locking diff for 7.5" GM

Post by photo_van » Wed Jul 02, 2014 8:11 pm

I opted not to use a non-selectable locker as I was of the understanding they weren't so great for winter hwy driving. What has been your experience with that Dean?
1998 AWD/4WD
4" lift, 31x10.50's, NP 242j/c hybrid, 4.10 gears, S10 front disconnect, rack & pinion steering, trans cooler, rock sliders, ARB fridge, house battery and 100w solar, swing out rear rack with foldout camp table, bed and passenger swivel chair
dirt bag camping rig
1981 Toyota 4x4 pu
1974 John Deere 710
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Re: Operable locking diff for 7.5" GM

Post by LiftedAWDAstro » Thu Jul 03, 2014 5:35 pm

The problem with a non-selectable locker like a Detroit or a PowerTrax no-slip is that as soon as you torque them they lock. So going around corners in snow will cause a drift if you are not careful. Astrozam ran one in his 95 RWD and liked it in winter as he had great traction. He just drove carefully so as to not be surprised when it kicked out. It really wouldn't be all that different than the Truetrac or an Auburn clutched posi in the snow. On dry pavement, they will chirp the tires going around corners if you are on the gas. The real issue with the lockers is if you ran one in the front...steering in snow in 4x4 is tricky.
Current rides:
2013 Toyota Tundra DC 4x4
2008 Dodge Nitro 4x4
2005 Nissan Sentra 1.8S Special Edition

Mileage spreadsheet

Vans owned:
1986 Safari 2.5L 4 speed manual - scrapped
1995 Astro 2WD conversion 4.11 posi, shift kit, DHC rock rails - sold to Skippy
1998 Astro 4x4 D44, D60, NP231, full hydraulic system with 9k# Milemarker winch and snow plow - sold to Lockdoc
2003 Astro AWD all stock - traded for a 3/4 ton truck
2005 AWD, 4.10's - sold to skippy

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Re: Operable locking diff for 7.5" GM

Post by Herbie » Thu Jul 03, 2014 6:22 pm

LiftedAWDAstro wrote:The problem with a non-selectable locker like a Detroit or a PowerTrax no-slip is that as soon as you torque them they lock. So going around corners in snow will cause a drift if you are not careful. Astrozam ran one in his 95 RWD and liked it in winter as he had great traction. He just drove carefully so as to not be surprised when it kicked out. It really wouldn't be all that different than the Truetrac or an Auburn clutched posi in the snow. On dry pavement, they will chirp the tires going around corners if you are on the gas. The real issue with the lockers is if you ran one in the front...steering in snow in 4x4 is tricky.
Is the "driftiness" mitigated at all with those who re-gear so the front is a tad shorter? Like the 4.10/4.11 re-gear anecdotally seems to make the locker behave a bit better since the front is "pulling" more...
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Re: Operable locking diff for 7.5" GM

Post by Herbie » Tue Jan 06, 2015 9:44 pm

Herbie wrote:
LiftedAWDAstro wrote:The problem with a non-selectable locker like a Detroit or a PowerTrax no-slip is that as soon as you torque them they lock. So going around corners in snow will cause a drift if you are not careful. Astrozam ran one in his 95 RWD and liked it in winter as he had great traction. He just drove carefully so as to not be surprised when it kicked out. It really wouldn't be all that different than the Truetrac or an Auburn clutched posi in the snow. On dry pavement, they will chirp the tires going around corners if you are on the gas. The real issue with the lockers is if you ran one in the front...steering in snow in 4x4 is tricky.
Is the "driftiness" mitigated at all with those who re-gear so the front is a tad shorter? Like the 4.10/4.11 re-gear anecdotally seems to make the locker behave a bit better since the front is "pulling" more...

I wanted to revisit this and see if anyone has any more info before I pull the trigger on my re-gear/locker purchase. It sounds like I probably want the Detroit Locker* (not to be confused with what Eaton is now calling the "Detroit TrueTrac", which is the helical LS). Given that I will occasionally (but only occasionally) use this in snowy conditions, it sounds like I want to do the 4.10/4.11 thing, but I've yet to see any definitive answer on that.

Anyone have any preferred vendors to order parts from? Anything I need to be sure to order other than the R&P sets and the locker? Doing the setup is well beyond my abilities, so I'll be farming this one out, but I always prefer to line up my parts for this van, since it always seems to surprise people...

*EDIT: After reviewing the G80 video in another thread, now I'm thinking that's a better compromise for me. Maybe just eBay a reman'd G80?!?!?
"My minivan is cooler than your bro-truck"
2003 Astro AWD Astrolander/ZMB - GTRV Top Transplant, 4" OLV Lift, NP233 T-case, evolving interior
1995 Safari GTRV Organ donor - gutted and gone.
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Re: Operable locking diff for 7.5" GM

Post by photo_van » Tue Jan 06, 2015 10:47 pm

I purchased used OEM 4:10's on ebay. Personally I wouldn't recommend the G80 for any semi serious off road use. It's lightweight engaging mechanism IMO, is not designed for high speed wheel spin differential (ie one wheel in the air). The first time mine was exposed to that, it blew up.....
1998 AWD/4WD
4" lift, 31x10.50's, NP 242j/c hybrid, 4.10 gears, S10 front disconnect, rack & pinion steering, trans cooler, rock sliders, ARB fridge, house battery and 100w solar, swing out rear rack with foldout camp table, bed and passenger swivel chair
dirt bag camping rig
1981 Toyota 4x4 pu
1974 John Deere 710
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Re: Operable locking diff for 7.5" GM

Post by doyoulikeithere » Wed Jan 07, 2015 2:10 am

photo_van wrote:Personally I wouldn't recommend the G80 for any semi serious off road use. It's lightweight engaging mechanism IMO, is not designed for high speed wheel spin differential (ie one wheel in the air). The first time mine was exposed to that, it blew up.....
Mine too ! not up in the air though, but on a snowy/icy street, in a 2wd van.
The nickname Grenade 80 was "Earned".
And my 4wd G80 van drifts like crazy when in only 2wd, on a wet street, trying to turn at an intersection with even a tiny amount of power applied, it just slides out like crazy.
I have to be very carefull, and my kids are not allowed to drive that one.. !
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Re: Operable locking diff for 7.5" GM

Post by photo_van » Wed Jan 07, 2015 2:55 am

Also I absolutely enjoy the 4.10s in the big hill country I live in. I don't know that I personally would use them if I were to run any tire under 31" tho. My current set up of 31's and 4.10s runs 10% higher rpm than stock (ie speedo reads 10% fast)
1998 AWD/4WD
4" lift, 31x10.50's, NP 242j/c hybrid, 4.10 gears, S10 front disconnect, rack & pinion steering, trans cooler, rock sliders, ARB fridge, house battery and 100w solar, swing out rear rack with foldout camp table, bed and passenger swivel chair
dirt bag camping rig
1981 Toyota 4x4 pu
1974 John Deere 710
Image

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