Author Topic: 8" trutrac in front Diff  (Read 655 times)

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8" trutrac in front Diff
« on: Jun 10, 2018, 07:50:53 PM »
Ok guys I am sure I can do this but I would just like to check the collective brains of the group.  I don't have problems finding 8" trutrac diff for the 8" rear in the wifes 4runner. The only Front diff ones I can find are for 7.5". Now I am sure I have heard and seen lots of guys on here put the 8" 30 Spline Rear TruTrac in the 8" IFS diff.  Have I got that right or did I just have a brain fart?

Wife knows how to drive a locked truck on the street, but First I don't want to use a clutch pack LSD( they wear out fast, and fail at the worst time), second an Automatic locker is too harsh for her in daily use.

« Last Edit: Jun 11, 2018, 03:01:47 AM by V-Man »


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Re: 8" trutrac in front Diff
« Reply #1 on: Jun 10, 2018, 09:03:20 PM »
Pretty sure the Trutracs are directional.
1989 4Runner: Dual Ultimate (Inchworm front & Marlin 4.70 rear), Marlin Twin Stick, 1200-lb clutch, 4.88 R&P, Aussie Front, Detroit rear, 30-spline Longs, Long hub gears, ARP hub and knuckle studs & 35x12.50 Cooper STT PRO tires.  Marlin rear bumper & sliders.  FROR front bumper.  SAS with Alcan springs & Rancho 9000XL shocks.  Budbuilt Bolt-on traction bar.  Custom Interior Cage by Those Guys Rod and Customs.

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Re: 8" trutrac in front Diff
« Reply #2 on: Jun 11, 2018, 12:25:40 AM »
There is a Different part number for the front and rear 8" Toyota Tru-trac diffs. Their Rep at the Pomona Expo showed me the info in their catalog, can't find the numbers.  They should be available on their website.
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V-Man [OP]

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Re: 8" trutrac in front Diff
« Reply #3 on: Jun 11, 2018, 03:13:51 AM »
I have been on the website and I have talked to a rep. They don't list anything on the website, and the person I spoke with basically said they really don't make anything for toyotas newer then 1989.


     An LSD with friction plates in a "clutch pack" would be have a directional bias. That is part of the design to make it disengage when you coast/easy off the throttle.

      A Torson LSD uses a combination of worm wheels and worm gears. It has no directional bias, and only locks if the wheels on either side of the diff exceed a set ratio. Here is how they work.

The trutrac is a torson style diff with a slightly different design, and looks to have a small amount of bias.

But having said that, you can select the directional bias in the gear set. By flipping the gears( changes the bias) you can set the truetrac to be used in the rear or in the front.

Now I can run the rear diff up front without flipping the gears, because it works just as well in reverse as it does going forward.

But it is kind of like running a ring and pinion backwards.  So since the gears can be reconfigured to make a front diff out of a rear diff, why not set it up correctly.
« Last Edit: Jun 11, 2018, 03:47:30 AM by V-Man »


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