760gle 1988 Carrier Shaft Bearing

DeRail · Post by **DeRail** » 26 Sep 2009, 12:01

When I first got the car, a mechanic replaced the center carrier shaft bearing on the driveshaft because according to him it needed replacing.

My problem has been happening for awhile now, but I haven't really paid much attention because it's a very slight rumble on acceleration. And it happens at speeds between 1-10mp/h. Since the center driveshaft bearing has been replaced already, I'm leaning more toward transmission mounts, as my shifter does move when in gear. Let me know what you guys and gals think!

Thank you
Darrell

Post by **billofdurham** » 26 Sep 2009, 12:26

The shift lever is designed to move with drive train movements preventing the need for occasional linkage adjustments. If it moves a lot it could be engine or transmission mounts. Some movement is normal.

If the movement appears to be too much there are bushings in the ends of the shift linkage rod. If these are shot then the shift lever will appear to have a life of its own.

Bill.

DeRail · Post by **DeRail** » 26 Sep 2009, 14:17

Thanks for the quick reply Bill,

shifter rumbles a bit in place, have never had it fall out of gear or anything, it stays stationary except for the slight rumble... is it safe to assume it's normal movement? Just figured I'd throw that bit in because I wasn't sure if it was linked to the rumble you feel upon acceleration from a stop.

I'm willing to bet that the mounts could do with being replaced, I'm not sure the last time, or if it was ever done. When at a stop, you occasionally feel the cabin shaking around from the engine, but once that baby is up past the 10mph speed, it is a smooth ride!

Thanks
Darrell

Post by **billofdurham** » 26 Sep 2009, 15:26

Things like engine and transmission mounts are rarely checked on routine servicing because they just sit there and do their job. However, they do deteriorate and yours could be 21 years old and could be the cause of the rumble.

Bill.

DeRail · Post by **DeRail** » 12 Oct 2009, 21:56

Sorry haven't been able to report back, been a hectic week...

I was digging and found this Service Bulletin on the VolvoClub FAQ

Driveline Take-Off Vibration: Shimming May Be Required.

From Volvo Technical Service Bulletin 45/102 Jan '91. [Symptom:] Take-off vibrations at low speed, especially with high acceleration and/or heavy load, can occur in some cases.

[Solution:] Before you conclude this is the problem, make sure your engine and transmission mounts are in good shape. The level of driveshaft vibration can be reduced by changing the vertical position of the center support bearing. The support bearing is bolted to a bracket, which in turn is bolted to the underside of the car body. Adding shims or washers between the car body floor and bracket will shift the bearing down. Adding shims inside the bracket between the bracket and support bearing will shift the bearing up. Best results differ from car to car. Start with a change of 6mm (1/4") upwards. If results are not acceptable, try positions from 5mm (3/16") downwards to 12mm (1/2") upwards from the original position. Note that clearance between drive shaft and fuel lines must be at least 20mm, and between drive shaft and the fuel tank at least 16mm. Shimming upwards should not exceed 12mm (1/2") and after re-positioning the center support bearing housing should not contact the floor pan.

You ever hear of anything like this and is it worth messing around with shimming the bearing?

Thanks
Darrell

Post by **billofdurham** » 13 Oct 2009, 11:50

I hadn't heard of this but I do have the TSB - complete with bonny pictures.

700 take off vibration.pdf: (164.4 KiB) Downloaded 117 times

However, yours has already been replaced so I don't think that will be the problem. The engine and transmission mounts are the most likely culprits if they are original or have been replaced a long time ago.

Bill.

DeRail · Post by **DeRail** » 13 Oct 2009, 19:30

Bill, thanks for the insight

Need to get a few parts online anyway, how much of a bear is it to do the tranny mounts on the AW71 and on the B280F without an engine hoist?

I'm also thinking my tie rod ends are in need of replacement, the steering has been wandering and seems less responsive at times. Will do a visual inspection and grab the tire at 3 and 9 oclock when I change the oil this weekend. I also noticed that my right wheel grinds when making a left turn, does it sound like the bearing may need to be repacked? Last time I did a visual inspection everything was tight and had no play (including a bearing check by holding the wheel at 12 and 6). An alignment was also done about 6 months ago.

This weekend is my planned winterization extravaganza, hopefully the weather will permit.

Thanks,
Darrell

Post by **billofdurham** » 14 Oct 2009, 12:47

The transmission mount is easy as you only need to support the box on a trolley jack, remove the gearbox crossmember and replace the mount. Be aware the gearbox mount for the B280F/AW71 is not the same as the mount for the B230FT/AW71.

The engine mounts are harder to do and you should have some sort of hoist, although it can be done by, very carefully, raising the engine with a trolley jack.

Take a look at Swedishbricks Engine mounts and Engine support.

Bill.

DeRail · Post by **DeRail** » 14 Oct 2009, 19:57

Hi Bill, thanks for the tips. I think I might go with the trans mount for now and see if there's any improvement with that. I figure, it will have to be replaced at some point anyway.

Looking further into my steering looseness, I checked the PS reservoir, the easiest place to look first, I would think. I looked down with a flashlight, it did seem as though the fluid was low (I couldn't see any) and the dipstick was low. I added some Dex3 tonight and as I was adding it, I could see the new stuff mixing with the brown murky old fluid and it looked like there were some flakes floating around. I "burped" the system (locked the wheel both ways a couple of times) and capped it up as I just wanted to get some fluid in it rather than letting it run near dry. I've read that some suggest throwing a rare earth magnet into the reservoir and have it secured to the bottom and then swap the fluid, but then again is it even worth it if the rack is toast?

Thanks for following thru my ramblings

Darrell

Post by **billofdurham** » 15 Oct 2009, 12:20

I agree with changing only the transmission mount as a starter because it is more likely to affect the powertrain than the engine mounts. Have a good look at the engine mounts and see if there is any obvious weakness.

If you are going to replace the rack it is a good time to replace the fluid.

Bill.