Thread: Detroit Truetrac for 1st gen front diff with ADD. Personal experience wanted.

  1. #1
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    Default Detroit Truetrac for 1st gen front diff with ADD. Personal experience wanted.

    Hello everyone. I have a new to me 02 reg cab 4wd and am planning to regear and put truetracs in the front and rear.

    What I am looking for is personal experience in two areas. Did the ADD specific fitment issues get addressed for the Truetrac? There were some issues early on and it seems like they were resolved but there really are not that many responses to the issue. What part number did you use if you have ADD?

    What if any issues did you experience going from the open diff to the truetrac? It doesn't seem to me it would effect the front end much costing or under light load. But I'm wondering if the different axle speeds in a tight turn might be enough to bias the front diff and make the steering heavy.

    Some ground rules please:
    This is about a Detroit Truetrac which is a helical gear LSD. It is not a locker and it is not a clutch or cone type diff. If you don't know what this sentence means this thread is not for you.

    If you comment on the thread with "I had a LSD in the front and it felt like x or y" can you be doubly sure you are talking about a gear type front diff and not a locker or clutch type diff? I would appreciate it. I think all the front end push and heavy steering is from non-gear type of diffs but no one ever specifies exactly what they are using.

    This one is a big one and sorry I have a chip on my shoulder but there must be a 100 horrible threads on the interwebs with the following: PLEASE DON'T COMMENT ON THE MERITS OF TRUETRAC VS LOCKERS. I AM 100% FAMILIAR WITH HELICAL LSD'S (I have them on two vehicles) AND I KNOW WHAT I WANT AND WHAT SUITS MY USE CASE AND PREFERENCE. THESE COMMENTS ARE ALMOST ALWAYS WRONG ON SOME LEVEL AND NOT THE POINT OF THIS THREAD ANYWAYS

    OK after all my annoying prerequisites are out of the way what are people's experience?
    Last edited by roving1; 12-15-2017 at 05:47 PM.

  2. #2
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    From what I've read, a LSD/automatic locker isn't always a wise decision in the front axle, because the torque of engagement could yank the steering wheel out of your hands. I have no direct experience with it, myself, so I could very well be wrong.

    Regardless, the TrueTrac is a great choice; a gear-based LSD seems to cause less control and handling issues than clutch-type LSDs. It's not a bad idea overall.
    I'm a backpacker with a wheeling problem. Or a wheeler with a backpacking problem, I can't really decide.

  3. #3
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    Quote Originally Posted by Doc_ View Post
    From what I've read, a LSD/automatic locker isn't always a wise decision in the front axle, because the torque of engagement could yank the steering wheel out of your hands. I have no direct experience with it, myself, so I could very well be wrong.
    I'm going to go with - steering wheel ripped out of hands is not gonna happen. I've owned 10+ vehicles w front lockers (arb, Detroit, 'lunchbox' lockers) and that has NEVER happened.

    I'd hesitate to put a TT in an ADD, though... since one shaft will always be turning, it means the TT will always have internal motion... could *potentially* result in increased wear on the TT. If you can throw manual hubs at it, then it would be a great choice for the front. I just don't know about ADD issue.

    Before you buy one, make sure that they have switched back to fine thread bolts for the case. I had bolts back out of a TT in a 96 4Runner. They were coarse thread... they destroyed the carrier, gears, etc. Look up "jack factory" on ih8mud 4runner section for pictures. If they are still coarse thread, I'd consider a different option.

  4. #4
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    This doesn't directly pertain to your rig, but I have a Tru Trac in the front or my 04 ram 2500. It doesn't have selectable hubs, the front driveline and axle shafts are always turning. It's completely seamless, you would never know it's there. I plow alot of snow with the truck and it works great and have had no problems 50k miles of hard use on 37" tires

  5. #5
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    Quote Originally Posted by bkg View Post
    I'm going to go with - steering wheel ripped out of hands is not gonna happen. I've owned 10+ vehicles w front lockers (arb, Detroit, 'lunchbox' lockers) and that has NEVER happened.

    I'd hesitate to put a TT in an ADD, though... since one shaft will always be turning, it means the TT will always have internal motion... could *potentially* result in increased wear on the TT. If you can throw manual hubs at it, then it would be a great choice for the front. I just don't know about ADD issue.
    This is exactly what I was worried about. I am also worried about something accidentally biasing (triggering) and then it trying to spin up the front driveline at freeway speeds. I'm not against manual hubs but it looks to be a bit of a pain in the *** and I don't really want to source used parts for it. There's none in the rust belt anyways. I'm, saving money for the diffs and a re-gear so the hubs are a no go at least at first.

    I've driven Lockers on the front and they make the steering really tight in 4-LO and tight turns which would suck all the time but i don't *think* that will be an issue with the TT.


    Quote Originally Posted by bkg View Post
    Before you buy one, make sure that they have switched back to fine thread bolts for the case. I had bolts back out of a TT in a 96 4Runner. They were coarse thread... they destroyed the carrier, gears, etc. Look up "jack factory" on ih8mud 4runner section for pictures. If they are still coarse thread, I'd consider a different option.
    I don't member when exactly but I am 95% sure this issue has been resolved. I have a 7.5 TT on a 5 lug 2WD Taco and it has been used as my commuter, tow rig, rallycross racing vehicle, and general thrashmobile for 60K and many years. The TT in that has worked flawlessly and suited my needs perfectly which is why I hate when people who might go rock crawling once every 2 years dismiss these LSD's as useless.

  6. #6
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    Quote Originally Posted by leelikesbikes View Post
    This doesn't directly pertain to your rig, but I have a Tru Trac in the front or my 04 ram 2500. It doesn't have selectable hubs, the front driveline and axle shafts are always turning. It's completely seamless, you would never know it's there. I plow alot of snow with the truck and it works great and have had no problems 50k miles of hard use on 37" tires
    Thanks. I'm thinking of maybe just rigging the ADD selector to stay locked all the time if I have issues and turning it into how your truck works. I don't really want the front end turning all the time but I know lots of vehicles do it and it would be way easier and cheaper than manual hubs.

  7. #7
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    I had a TrueTrac in the front of a 1994 4wd Xcab pickup with ADD for several years in the Lake Erie snowbelt. Onroad in 2wd, obviously there was no impact whatsoever. There were no mechanical issues - the Xcab IFS front behaved exactly the same as prior to the TT, no problems, no wear issues, nothing. The times I put it in 4wd onroad in heavy snow, it worked well; same offroad. The torque biasing in 4wd was a bit odd at first, but after a few times it became 2nd nature. I ended up going with manual hubs and permanently locking the ADD collar into engaged mode, again no issues at all. (The truck also had a Detroit-locked rear end.) I was a big fan of the TT and would definitely do it again with no hesitation...
    ------------------
    Joe
    2007 GX470 - Radflo suspension, Hankook AT's, OPOR sliders

  8. #8
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    Thanks for the response!

  9. #9
    I have a TT in the front of my '97 4Runner. It has been installed since 2005ish. I have owned the rig since 2003. The TT functions just like Detroit says it does.
    The steering is heavier when in 4WD and you can feel the wheel wanting to return to center but it is not abrupt or irritating. I don't know if it has actually freed the vehicle from being stuck but it has certainly prevented me from becoming stuck...does that make sense?
    Overall I would not hesitate to run one again. It has over 100k miles on it and has been flawless.

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