1999 XC's wonderful Drive line

[tranmkp]

I am almost convinced, regardless of the experts that the main issues with the cars (I am talking abiut used ones not ones that were purchased new) that the Achilles heel is the VC. VC's have a life span in theses cars - Old VC's will have hard silicone in them - and they awill fail and that will lead to a cascade of failures. For example. A bad VC will eventually kill the driveshaft (undersized yolks to begin with) and that is what people will usually hear first. On mine I replaced the shaft only to be presented with another lower thumping sound while on tight turns. Observed that the torque tube (holds the VC) having good mounts would load up and hit the topo of the tunnel. - replaced with a Erie Tork tube and VC did exactly the same thing. I know Erie guarantees it but its still a old/used tube. UNless I can get a low mile TT, I am just going to bite the bullet and get a new one. Angle gear is just fine. It would be the last thing to break. This set is pretty primitive (soviet model it seems) there is no sensor array or data stream like BMW and Audi, the data is main't and using your ear. (i am not taking into account idiots and such that have different tire sizes and the like) I do have to admit I do not know the function of how the TRACS system plays into this - I would appreciate an explanation if possible.

I do wonder how related the forward and reverse are on these transmissions - while all my forward gears (not the trans that needs special fluid) are fine going into revers is sort of surge -y sort of flairs with a soft clung (could be the TT) any thoughts?

Car throws no codes.

[nortons]

Big problem with transmission on these cars is that there is no serviceable transmission filter and so most folks just never service the trans until it fails. Sludge builds up inside and causes sticky solenoids and clutch pack wear. I bought my eternal headache 2000 V70XC knowing it had a bad trans which was replaced with a used one with a warranty. I added an inline remote oil filter spliced into the lines to the cooler, (for easy access), mounted to existing threaded holes in body below air box and ahead of L/F wheel. This had been in my tool box for decades- finally found a use for it!
I use a Purolator "Pure One" filter which has the best (finest) filter medium and this also gives me access to do a periodic trans flush. When used trans was installed it was bench flushed and filter was changed about every 200-300 miles for first few months then at engine oil changes. Now well over 20k miles, runs/shifts perfectly. Fluid at changes is clean, red, not smelly. Use a WOLF'S HEAD synthetic fluid, about $6qt, locally available .

[tranmkp]

Updated : 99 XC 125k - Driveline noise - dropped AG - it was jello pudding inside - gears ok. Cleaned and seals replaced. New splined shaft. Put in new driveshaft and center mount - Road tested - dull clunking sound from rear when making tight turns. Replaced VC THREE TIMES (from Erie Volvo) last unit had only 60k - NOT the VC -

Now only culprit is the rear diff - Everyone tells me that they dont fail - well, how the hell to you blow the rear diff in these cars? Run them dry? I can run all day in a straight line but a sharp turn produces that thumping noise

[tranmkp]

Updated : 99 XC 125k - Driveline noise - dropped AG - it was jello pudding inside - gears ok. Cleaned and seals replaced. New splined shaft. Put in new driveshaft and center mount - Road tested - dull clunking sound from rear when making tight turns. Replaced VC THREE TIMES (from Erie Volvo) last unit had only 60k - NOT the VC -

Now only culprit is the rear diff - Everyone tells me that they dont fail - well, how the hell to you blow the rear diff in these cars? Run them dry? I can run all day in a straight line but a sharp turn produces that thumping noise

Update

Dropped rear end - Opened diff - nothing - fluid was old but no metal nothing - did notice big left and right mounts were broken. So:

BG looks fine, new spline'd coupler - new colorado DS, third VC, and rear diff is fine - bind bind bind on sharp corners left and right -

any ideas guys? This is ridiculous...

[cattlecar]

Jack up one rear wheel with all others on ground. Chock wheels securely. Use 32mm (or is it 30 or even 36mm) socket and a breaker bar on the nut on the lifted wheels axle nut in center of wheel. Turn the wheel. It should move heavily damped at 75 ft-lbs or so. If it takes a lot more torque and when it moves it jumps instead of moving smoothly then it is the VC.
The oil wicks out of the VC leaving the silicone gel as silica dust. Then the VC is bound up and doesn't allow the slight wheel speed differences that turns require to occur. You build torque and then VC incrementally turns a few degrees.

[tranmkp]

Update, this is where we stand - new VC, new DS, New shaft spline. Spider gears are fine, AG is fine. Car drives perfect. Tight lock to lock turns will produce (but not repeatably) some binding. From what I know now and from all the data I have looked at, this is something that I am going to have to live with...

http://www.2wd-goes-syncro.de/ the insides of a VC

http://www.vanagon.com/syncros/techn...view/index.htm

watch the latter part of the vid to see how the rear driveline is affected

http://www.youtube.com/watch?v=nc7msK2--x8

Just an interesting article http://www.thesamba.com/vw/forum/vie....php?p=6916420

[tranmkp]

ok - update

I really need to get some feedback from others- the 99xc runs prefect - new nivomats, new VC, new driveshaft, new shaft coupler, bevel gear looked ok when opened, cleaned and resealed)

YET,

On tight turns, slow or fast, left or right esp from a stop with torque will produce a bump bump at the VC (not the bushing on the VC)

Can any of you who feels their system is working correctly do some of the tight torqued turns and let me know if you experience the same thing?

This is getting real old.

[tranmkp]

It appears I can make this come and go based on entry angle and throttle. Slow gradually tightening turns will produce nothing. Abrupt, tight and heavy throttle will mape the binding sounds..

[tranmkp]

second update

in addition to the awd issues. The original 130k trans was slipping badly in reverse - tcu had no codes - ordered a rebuilt from volvo - installed it and EXACT same behavior - major slipping in reverse - NO tcu codes - no codes at all - codes read at dealer -

unreal - man, everyone must be out of town - not a word about any of this - even JRL is quiet...

[tranmkp]

Update - put some friction modifier in the dif. Drove for a while and now the binding is all but gone - not totally gone, I have to do doughnuts in the parking lot to produce the binding.

Lastly, was there something about drive shaft alignment that produced a noise? or was it only vibrations at speed?