Thread: no go in the front of my 89RRC

Diff cross-shafts are a common 'weak link' and you may not necessarily get any offensive noises from the diff when they are busted. Has happened to me.

Having recently acquired the same model RR (FA), and having replaced my vcu last week, make sure that the front end is ok before you look at the vcu. Ten spline diffs can break clean and not give any indication of grinding.
Since you don't mention having to be towed home, then the VCU isn't the problem. If it had totally failed, then you'd have no drive at all.

yep just got it all out and it was the left axle, snapped off in the diff center, ive pulled both the cv's out and the axles, also the front prop shaft, everything is back in place so should be getting me to work tomorrow morning :S

Originally Posted by sped 86

yep just got it all out and it was the left axle, snapped off in the diff center, ive pulled both the cv's out and the axles, also the front prop shaft, everything is back in place so should be getting me to work tomorrow morning :S

If it's got the BorgWarner Viscous transfer case .... Don't drive it with "no drive to the front wheels" ... as you will fry & seize up the viscous, real quick




You will have to test that the viscous works properly, before you put the front propshaft back on.


If you drive it seized (viscous) ... then you will only snap a axle again

Mike

oops, bugger, well looks like im riding to work tomorrow.

how do i test that? and is there anyway i can drive it with a broken axle?? i am getting a new one tomorrow (with luck)

so the viscous transfer case has to have resistance on both sides (front and rear wheels) to operate normally?

To test the Viscous Unit jack one wheel off the ground. Using your wheel wrench try to tighten one of the wheel bolts. If you use the same force as you would normally use to do up a wheel nut and keep that same force you will be able to rotate the wheel slowly without the rest of the vehicle moving of course. In your case the front axles is broken so you won't be able to test it this way. You will need a large set of multi grips to grab hold off the front drive flange of the front diff or the drive flange on the front of the transfer case and try and rotate it in the same fashion. If you can't rotate the drive flange slowly then the Viscous unit is stuffed, and take out your front drive shaft and run around on the rear until you can afford to fit a real transfer case like an LT230.


Don't worry about overheating the Viscous unit, when driving on the highway.

The second time I broke my rear Diff I drove it for an hour on the open road on the front diff only.
That was many years ago and my Transfer Case is only just being pulled out today. The Actual viscous unit is still fine. The Centre Diff Gears and Chain are totally ****ed thou!

Once a Viscous is locked the friction from the heated silicon fluid is NOT used to hold the friction plates together. In other words as long as you don't keep going on and off the throttle then the Viscous fluid won't get worked up. Around town driving will give it more of a hurry up than driving on the highway. Think of it like this...if you had a locking dog type diff lock. IE Maxi Drive engaged and you started driving a gentle turn and maintained that same turning direction and choose to unlock the locking dog type diff, it simple wouldn't do it. It would stay locked until you took the load off the splines by turning the other direction.

What does kill them is having 2 half worn tyres on the back and 2 new tyres on the front or visa versa. A small mismatch in front and rear diameter works the viscous unit all the time.

The other way to test it is

Put the Auto in neutral ... Handbrake on

On the TC ... the front output flange has 4 bolts for the propshaft

Put 4 oversize nuts on it and then put on the nylon nuts and nip them up

Grab a bar and place between 2 of the bolts and apply a down force to try to turn the flange ... Apply a constant force and the viscous will turn with resistance ... there is a specified torque force & time, to figure whether it is in spec... but I don't have that info at hand ... (my memory says @ 20nm = 1/4 turn = 20 seconds)

A brand new replacement viscous unit is worth about the 800 smackers region

Mike

its a 5 speed manual not an auto so what difference dose that make??