80 series Centre Diff Lock erratic operation

Submitted: Thursday, Dec 26, 2013 at 09:12

ThreadID: 105589 Views:5084 Replies:2 FollowUps:3

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rb30e

Hi all,

I've done a bit of a search and spent some time understanding not only how the CDL works but the mechanism that operates it.

I read through virtually all the posts on this 10 page thread on IH8mud about a bloke with CDL problems. Although there was no resolution in the end.

http://forum.ih8mud.com/80-series-tech/536038-80-series-auto-diff-lock-always-wtf-10.html

Firstly I'll explain the set up in my vehicle before going over the symptoms as its probably not your ordinary rig.

It's actually a '94 75 series fitted with an 80 series auto transmission. (I'm paraplegic and can't drive manual anymore.). It's the earlier model auto with kick down cable. I've also fitted a Detroit 'no slip' locker to the rear and a Detroit 'trutrak' LSD to the front.

I bought it with the auto trannie in it but did the diffs myself. I've also had the transmission fully rebuilt. The previous owner hooked up a toggle type switch to activate the CDL and an LED to indicate that it is engaged.

I've virtually rebuilt this vehicle from the ground up as we plan to travel the world with it in the not to distant future. If your interested in our built and travel plans here's a link to our blog. Http://lostabound.wordpress.com

Ok so on the weekend we took it out for our first bit of 4wding and camping after 9 months of building it. We took it up a very steep, loose and long hill climb.
On a few occasions when we had all four wheels spinning in 4L we began to hear a grinding type noise and also noticed the CDL light flickering.
The vehicle also seemed to struggle more for traction as this noise was occurring.

From what I understand the CDL actuator operates a set of gears that engage a shift fork which locks the centre diff out. When the shift fork is in position it activates the limiting switch illuminating the CDL light. This is what I gathered from flicking some tech publication about the CDL.

Can't get the pic up but here's a link to what I read.

http://forum.ih8mud.com/attachment.php?attachmentid=391707&stc=1&d=1264812570

So if the CDL actuator is intermittently operating while the vehicle is in drive and the wheels spinning I'm imagining that the shift fork will be slipping back and forth trying to engage/disengage the CDL causing the grinding noise as the gears clash and the further loss of traction.

I'm hoping its an electrical problem maybe in the relays or wiring between the switch, relay or CDL actuator.

As I said before this has been converted from an 80 series so who knows how the previous owner had wired it all up.

I haven't had a chance yet to look at anything being Christmas and all but hoping to follow the wiring diagrams and check all the electrics first.

I'm also a little worried because it will be hard to reproduce as it only occurred under heavy load with all four wheels struggling for traction.

Any suggestions would be much appreciated.

Thanks.

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Reply By: Life Member TourBoy, Bundaberg - Thursday, Dec 26, 2013 at 13:28

Thursday, Dec 26, 2013 at 13:28

Hi Mate,
The pic attached shows the recess for the CDL motor however the 79 series is manually operated and you can see the levers. Why don't you make yours manually activated?

1st pic shows the manually operated levers and the CDL recess.

Cheers,
Dave
2010 Isuzu FTS800 Expedition camper
2015 Fortuner
Had 72 cruisers in my time

Lifetime Member
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AnswerID: 523528

Follow Up By: rb30e - Friday, Dec 27, 2013 at 08:03

Friday, Dec 27, 2013 at 08:03

How do you go bout this? Does that require a full replacement of the transfer case to a 79 series unit?

FollowupID: 805036

Follow Up By: Life Member TourBoy, Bundaberg - Friday, Dec 27, 2013 at 20:37

Friday, Dec 27, 2013 at 20:37

Hi mate, looking at that pic it is simply levers to activate the 4wd instead of the CDL motor (which are usually dearer than the transfer case itself) It looks like a 80 / 105 transfer in the pic but the later 79's look the same also. Check yours to see if there is a shaft sticking out where the lever in the pic is. I just checked my spare 105 series TC in the shed and next to where the CDL motor was mounted is the shaft sitting up about an inch just like in the pic. Yours is probably the same and maybe as simple as fitting the levers and blanking off the CDL motor hole.
Worth a look and way.

Cheers,
Dave
2010 Isuzu FTS800 Expedition camper
2015 Fortuner
Had 72 cruisers in my time

Lifetime Member
My Profile My Blog My Position Send Message

FollowupID: 805066

Reply By: Ross M - Thursday, Dec 26, 2013 at 16:12

Thursday, Dec 26, 2013 at 16:12

rb30e
Firstly I would drain a bit of oil out of the transfer to see if the gnashing and grinding is causing damage to the internals. If anything substantial, ie, chips and bits, it won't get better and may require a closer look inside for long term reliability.
Metallic particles in the oil or bits on the magnet of the drain plug may mean it has to be opened.
After that continue with finding the causes.

AnswerID: 523534

Follow Up By: rb30e - Friday, Dec 27, 2013 at 08:11

Friday, Dec 27, 2013 at 08:11

That's a good point, I actually had the tf-case out and apart recently when I had the auto rebuilt. We took the case apart because it was leaking from the sandwich plates and needed resealing. There were no signs of metal particles in the oil.

Perhaps the previous owner never worked it so hard in 4L.
It's fine 90% of the time, I only experienced the problem on a very steep and loose hill when both front and rear wheels were fighting for traction.

Guess ill start with the basics and go over the external electrical circuit before going into more in depth. Hopefully this is the cause as I've seen some real dodgy wiring in this car. The standard head light relay under the steering column was going to another relay he'd fitted in the engine bay and extension cords for the wiring from there to power both headlights on a single circuit.

FollowupID: 805038