Xtreme_Ford

Hey, i own an '88 XF fairmont Ghia 4 speed manual and around a month ago the car seemed to be having trouble delivering power to the wheels. So i looked at the driveline to check for any obvious damage and noticed that the rear uni joint has some loose play where it connects to the diff. I'm pretty sure that the uni joint should be firmly attached to the diff? Anyway, that was the only damage i noticed, so i still drove it around. My main problem now is that while driving the car, there's a banging noise coming from the rear of the car when i give it power and also when i slow down with the clutch depressed. Also just recently, when i don't drive the car for a while (say near a week) and i decide to take it for a spin, i think the diff is locking up cause i can't get it to move until something from the rear makes a huge bang and the car starts to move. The diff has LSD and i'm really scared to drive it incase i do serious damage to it. I never do any burnouts in the car, so that couldn't have caused the damage. Any suggestions on how i can fix the problem and what may have caused it will be greatly appreciated! I really want to drive the car again and have reasonable power delivery!
Does anyone know of a good mechanic to recommend for this sort of problem?

TruBlu351

Try and tighten up the bolts holding your rear uni in place. There shouldn't be any movement there. You may have damaged the uni joint if accelerating hard whilst it was loose.

Yes, this would create all sorts of wacko noises if loose!

See how it goes.........if it still makes noises, just undo the attaching bolts/nuts and the rear end of the driveshaft will then fall down. The front end of the driveshaft (with the yoke) just slides out of the gearbox. Put a small container uner the gearbox to catch any oil that may drip out.

Inspect the uni joint for any damage (Cracks in the bearing caps, pull the caps off and look for broken needle roller bearings etc).

If its broken, replace it.

If its good, the problem may be inside the diff.

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XE Falcon
393 Tremec TKO 9"

Xtreme_Ford

Thanks TruBlu351. I'll check the bolts to see if they need tightening. I'll also check the uni joint for any obvious damage. If the uni joint does need replacing, will i have to realign the driveshaft once fitting a new uni joint? I've also had several opinions on how to replace a rear uni joint properly, but all sound risky. Do you know an appropriate method to safely and effectively replace one?

TruBlu351

The rear uni is mounted to a flange which then bolts up to the diff pinion with 4 bolts (these may be loose). If so, should be an easy fix.

You may also have the design where the rear uni fits into a saddle on the diff pinion and is held in place by 2 U-bolts this is a 9" design, not sure if some stock late model Falcons have this too).

If you have to take the driveshaft out you should see 2 alignment paint marks on the rear uni setup. One on each of the 2 flanges that hold the uni. If you can't find it, either scribe or paint your own before removal. This is done for balance purposes. Just make sure you refit the flange to the driveshaft with the same orientation when removed and not 180* out.

Removing and refitting uni's takes a little practice, but is dead easy once you get the hang of it

1. Remove driveshaft (be prepared to plug the rear of gearbox to prevent excessive oil spill). If you jack the car way up from the diff (with axle stands), this sends most of the oil forward in the box.

2. Remove the 2 bearing cap snap rings on inside of flange (they tap out with a hammer and screwdriver). Some have circlips on the ouside. Get some circlip removal pliers.

3. Balance the driveshaft flange over some open vice jaws with one of the flange uni caps pointing up. Then get a socket (slighly smaller diameter than bearing cap) and hit the top cap, this will force the bottom one out and thru the vice jaws. You may need to get some grips to pull the cap out if it doesn't fall out.

***The caps are full of small needle roller bearings and could go everywhere if not careful. The grease inside should hold them in place.

Flip the driveshaft over and tap the protruding uni joint shaft (don't damage it) back down to pop the remaining cap out the other side. You should then be able to jiggle it out!

Inspect for cracks in the caps and broken needle roller bearings. If they're OK, fully clean them. Carefully replace all the bearings inside the cap, held in place with some grease. Refill with grease once refitted to car. You may just want to fit a new one anyway..........about $30.

Refitting..........

1. Take caps off uni spider and slide spider into flange.

2. Get 2 caps at opposite ends and push them into the cap holes (opposite from removal), they'll only hand push in a little way. Then put the whole lot between some vice jaws and slowly compress the whole lot together, until the clip grooves are visible on the inside. Hardest part is not letting the uni spider dislodge the bearings as you compress the caps together. Helps if 2 people available. Make sure the uni has a smooth free movement. Don't over compress the caps.

3. Refit clips.

4. If the clips are on the outside of cap, then gently tap the cap in with socket until groove appears.

IF the caps don't compress at the very end by about 1-2mm, then there's a needle roller thats come loose! Remove and try again. The caps are stiff to fit, but avoid the sledgehammer

If have access to a "dial gauge" you could check the runout (alignment) of the driveshaft once its all back together. The rear driveshaft max allowable runout is 0.6mm. It should be OK though?? Unless there's vibration shouldn't need to worry.

Good luck!

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XE Falcon
393 Tremec TKO 9"

Xtreme_Ford

Thanks Heaps. I'll keep you posted on how it goes.

ebv888

when you have the caps off the spider smear some more grease in there.it will help the rollers stay put and ensure lube if they are the type without nipples.if you have nipples and you change the front one as well install them 180degrees out of phase.