LJ70 Build Thread!

[Jon Wildsmith]

i didnt use a torque wrench John, as i couldnt get a torque wrench on some of the bolts.

but i did do them all up very tight.

How tight very tight is depends on the length of the lever you're using IIRC an 80 is 130ft/lbs on the nut and bolt end and 180ft/lbs on the captive end (rear, can't remember front), easy to achieve with an 18" breaker bar and probably all but impossible with a 10" ratchet or standard length spanner ...

 

[Ben]

i can see where your coming from Chris, and now i feel even more confused about what could be causing the death wobble.

John, 10" ratchet.

 

[Ben]

i wonder if anyone happens to know how long 80 series panhard rods are?

i know there longer than 70 ones, just not sure how much longer. might be easier/better than cutting and shutting my ones.

 

[Jon Wildsmith]

A loose front panhard rod can easily cause a death wobble - the axle moves because the bush is loose, the wheels turn slightly because the axle moved and the drag link is fixed at the steering box end, the wheels want to return to centre because the castor is good, the axle shifts because the wheels moved, repeat ...

 

[Rob]

I would be tempted to tape a camera to the underside of the truck pointing at various suspect parts one after the other with a couple of shots of the axle, front and back. Clamp the camera down hard so you get a good image even when its vibrating. Then post the videos up on here with as much info per video as possible (speed etc). It's either this or wiring up a load of accelerometers and analysing the frequencies on a FFT plot and comparing it with theoretical frequencies of the every component of the drive system...

 

[Ben]

A loose front panhard rod can easily cause a death wobble - the axle moves because the bush is loose, the wheels turn slightly because the axle moved and the drag link is fixed at the steering box end, the wheels want to return to centre because the castor is good, the axle shifts because the wheels moved, repeat ...

i think your spot on with your diagnosis John.

i do think its this now damaged bush on the end of the panhard rod that is causing the death wobble.

the question is why has the panhard rod bush become damaged?

could the fact the panhard rod is too short, and so constantly putting side ways pulling pressure on the bush be enough to damage it?

or could it just be that the bolt wasnt done up tight enough?

I would be tempted to tape a camera to the underside of the truck pointing at various suspect parts one after the other with a couple of shots of the axle, front and back. Clamp the camera down hard so you get a good image even when its vibrating. Then post the videos up on here with as much info per video as possible (speed etc). It's either this or wiring up a load of accelerometers and analysing the frequencies on a FFT plot and comparing it with theoretical frequencies of the every component of the drive system...

ive thought this a few times Rob, but unfortunately i dont have the right equipment.

 

[Jon Wildsmith]

the question is why has the panhard rod bush become damaged?

The bolts weren't tight enough (no doubt about that in my mind with a 10" rachet, not even close ) so the bush was being hammered by the metal sleeve. A correct length panhard will improve the handling a touch if you're really pushing it, and your tyres might rub earlier on one side when articulating now but otherwise I wouldn't worry about the length. Rotating the end slightly would give a bit less bind in the bush but on your size lift I should think it's only a small amount.

 

[Roger Fairclough]

The chassis mounted Panhard rod bush on my motor has 150,000 miles under it's belt, and it's still going strong.

I have a similar set-up to Ben's, 2" lift, 16"x8" rims with 32 mm neg off-set and I don't get any vibration, and I didn't have any problems putting it all together.

I suggest Ben fits the new bush and tightens the bolt to 130 ft-lbs, with the wheels on the ground or on a set of ramps. The axle mounted bush needs to be 92 ft-lbs.

Roger

 

[Ben]

thanks guys.

will get the replacement bushes fitted tonight, and correctly torqued up. will torque the back ones aswell.

maybe then i can start fitting the switch and air line for the front locker.

 

[Ben]

decided to start fitting the front locker bits.

so the view of my dash.

so one spare switch space, ready and waiting for the front locker switch.

stereo and switch panel off, and i can start identifying the correct wires in the spaghetti of wires.

switch fitted.

checking they all illuminate with side light, and when the switches are switched on.

needed to fit the second solenoid and air hose to the compressor.

luckily i managed to find the compressor instructions.

had to remove the battery and then rotate the compressor forward to get the solenoid on.

all fitted and battery back in.

so the compressor is all ready for the second air hose to be connected.

so air hose all connected and clipped in place.

runs along the bulkhead with the other hose, but keeps going to behind the brake servo.

then drops down with all the brake hoses.
put some tape over the end to keep dirt out, and left quite a bit of slack on the hose for now, ready to connect up after the locker is fitted.

next i decided to sort the front panhard bushes out.

panhard rod off.

the bush on the axle end didnt look too healthy as it was indented from where the axle had been digging into it.

tapped the metal sleeves out.

then used a socket, and an off cut of box section and the vice to push the bushes out.

the bush from the chassis side (the one showing the movement in the video) was very badly damaged!

even the other side of it had started to split.

compared to a new one.

pressed the new ones in in the woodworking vice.

ready to bolt back in with the new bushes fitted.

decided to actually read and follow the FSM this time.

used a washer this time to prevent the new bush from getting damaged by the axle.

all done and torqued up properly. i tightened it the same as i did last time, so it felt tight, and then got the torque wrench on it, and it went about another turn.

no time to test drive it tonight, but im 99% certain this will have fixed it, will find out tomorrow on my way to work.

i just hope these bushes last a bit longer than the last ones.

 

[Rob]

While your at it I would torque up the hokey sticks as well according to the FSM, and any other suspension parts that you have removed

 

[Ben]

yes very good idea Rob, thanks.

thats tomorrows task then!

 

[wobbly]

On the last two photo's....are these bushes offset? It doesnt look like the bolt is going through the centre of the bush.

Pete

 

[Ben]

Pete if you mean the bushes in the radious arms where they mount to the axle, then yes your correct there off set.

there the castor correction bushes, which rotate the axle back a few degrees to compensate for the suspension lift and correct the geometry of the steering on the axle.

 

[wobbly]

Cool, not my eyesight then.

Did you fit a digital engine temp/coolant temp gauge?

I'm starting to forget whats been done.....

Pete

 

[Ben]

yes digital temp gauge can be seen on the previous page. its to the right of the stereo.

still need to finish wiring it up.

 

[wobbly]

1. was there a seperate thread on the temp gauge, cos I cant find it in this one?

2. Did the wobble start after you fitted the free wheeling hubs. Does it make any difference if you have the fwh locked or unlocked?

Pete

 

[Ben]

1. no is all in this thread some where. i fitted the temp gauge about 2-3months ago, so im guessing 20ish pages ago.

2. free wheel hubs are standard on all UK model LJ70's and KZJ70's.

no difference if the hubs are locked or unlocked.

the death wobble has gone now ive fitted the second new set of panhard rod bushes, just hope these ones last a bit longer.

 

[Jon Wildsmith]

No reason they shouldn't last now you've done the bolts up properly Ben

 

[Chris]

Ben, I know it's all coool now, but had you considered that damage might have started to occur when you pressed the bushes in? They are a tight fit and generally need greasing up like a little piggy to slip 'em in. Done dry as it looks in your pic, they might suffer a little.

Chris