How to determin condition of central diff in an 80 seris constant 4WD

Submitted: Sunday, Feb 08, 2009 at 12:55
ThreadID: 65801 Views:2092 Replies:3 FollowUps:3
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Hi all
Is there some way of determining the condition of the central diff in a constant 4WD?
My mate has an early one which has heaps of free play when you back off / accelerate and i expected it would of gone bang by now as he give it a hard time and lots of km as well but uts still hanging in.
How much backlash should they have and is there any simple checks to determin if they are in good condition?

Kind regards
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Reply By: Falco80 - Sunday, Feb 08, 2009 at 13:44

Sunday, Feb 08, 2009 at 13:44
Hi GN,

From my experience the early 80's seem to have more backlash than the later ones. When i had my 92 80 series, the backlash was quite noticable. You had to really "ease" the clutch out in every gear. It took a while to perfect the shifting technique, but it did get tiresome after a while. Installing the part-time kiit solved all those problems.

In my 97, there is basically no backlash. There is of course a bit, being all wheel drive, but compared to my 92 it is a dream to shift through the gears. I think Toyota slightly upgraded the front driveline in 95, when the dash changed. Longer CV's or something...

As far as i can tell they are strong units and people have found(myself included) that you start to strip teeth off the front crownwheel before damaging the centre diff. Especially if your rough in reverse.

The simplest free mod you can do to the fulltime 80's is unplug the connection at the 1:00 o'clock position on the rear of the transfer case. What this does is stops the CDL locking when you shift into 4L. It gives you full manual control of the centre diff lock so you can lock it only when you want too. It allows you to use 4L with the CDL unlocked. Perfect for reversing up steep driveways, or pulling a boat up a ramp without winding your driveline up.

You'll soon see how bad it is if you take it for a test drive. Just remember to ease that clutch out.

AnswerID: 348151

Follow Up By: Member - G N (VIC) - Sunday, Feb 08, 2009 at 14:57

Sunday, Feb 08, 2009 at 14:57
Thanks again Falco 80

Sonds good as i would not be happy to buy if its like my mates early 80.
Will see how it goes.

FollowupID: 616371

Reply By: Member - Rob S (NSW) - Sunday, Feb 08, 2009 at 18:00

Sunday, Feb 08, 2009 at 18:00
Hi G N
You will find the centre diff will probably be ok.
The backlash comes wear in the front axle splines and axle flange
in the early models.
Later models have longer splines.
You can check this by removing the grease caps and rock the wheel back and forward.
You will need to replace the front cv and axle flange.
There are plenty of kits available to do this.
You can also check them out on ebay. look at the link heaps more info.
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AnswerID: 348187

Follow Up By: Member - G N (VIC) - Sunday, Feb 08, 2009 at 21:41

Sunday, Feb 08, 2009 at 21:41
Thanks Rob S

My knoledge of the center diff stuff is limited.

Many thanks GN
FollowupID: 616460

Reply By: Member - DOZER- Sunday, Feb 08, 2009 at 20:53

Sunday, Feb 08, 2009 at 20:53
The slop is in the front c/v;s and the drive plates, early cruisers wear the splines....take the dust cap off the drives up front, and rock the car in gear, if you see movement between shaft and drive, thats the source of the clunk, it is heard in the centre diff as it works to get power to the front and rear shafts, when they turn with different amounts of backlash, the centre diff has to take it up.
AnswerID: 348223

Follow Up By: Member - G N (VIC) - Sunday, Feb 08, 2009 at 21:40

Sunday, Feb 08, 2009 at 21:40
Hi Dozer
Thanks for that info.
Its all new to me with the center diff stuff.
FollowupID: 616457

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