968 differential bearing replacement
11-12-2002, 04:16 AM
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968 differential bearing replacement
I need to replace the drivers side differential bearing and drive shaft oil seal on my 968. Trouble is, the factory manual says that the ring gear should be re-shimmed if the bearings are replaced. Re-shimming requires removal of the pinion for part of the process, so that would require not only removal of the transaxle from the car and virtual complete stripdown, but loads of special tools and a large assortment of shims.
So, my question is, since this bearing is on the ring side of the differential, I think that when I refit the diff. back into the housing, the engagement with the pinion will not change, since that is controlled by the shims on the bearing on the other side of the differential. I don't plan to touch that other bearing or shims. All I think I need to worry about is whether the new bearing will affect the preload on both diff bearings. So, I propose to bolt it back up with one of the shims removed from the ring side bearing and measure the end float, which should only be in a direction away from the pinion, thereby removing the need for the pinion to be removed for this check. Once I have measured the end float, I can determine the correct size shim required to set the preload. Right????
Anyone done this? I have found a couple of threads here and on 968.net that suggest that there shouldn't be a need to shim at all just for a bearing change. Any first-hand experience of working with the differential and bearings would be much appreciated.
cheers
Derek
So, my question is, since this bearing is on the ring side of the differential, I think that when I refit the diff. back into the housing, the engagement with the pinion will not change, since that is controlled by the shims on the bearing on the other side of the differential. I don't plan to touch that other bearing or shims. All I think I need to worry about is whether the new bearing will affect the preload on both diff bearings. So, I propose to bolt it back up with one of the shims removed from the ring side bearing and measure the end float, which should only be in a direction away from the pinion, thereby removing the need for the pinion to be removed for this check. Once I have measured the end float, I can determine the correct size shim required to set the preload. Right????
Anyone done this? I have found a couple of threads here and on 968.net that suggest that there shouldn't be a need to shim at all just for a bearing change. Any first-hand experience of working with the differential and bearings would be much appreciated.
cheers
Derek
11-13-2002, 10:48 AM
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I have never done this, But I would measure the contact surface of the bearing to the shim, compared to the new bearing. Inside to the outside, see if there is a difference. Compare it to the end float. see where you are at. I Think end float alone will give you a no preload condition.. Sorry not what you asked for.
11-14-2002, 08:00 AM
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Thanks for the input, Dwight.
I guess not many people have actually worked on the differential on these cars, since I also got very limited first hand experiences on 968.net.
Anyhow, an update: I pulled the differential last night, and the bearing on the ring side is totally shot. Both of the races, and all the rollers are very badly worn and pitted. I am just surprised that there was no real indication of this until I got the oil leak. The inboard bearing is in a much better condition but I will change that as it's not perfect.
cheers
Derek
I guess not many people have actually worked on the differential on these cars, since I also got very limited first hand experiences on 968.net.
Anyhow, an update: I pulled the differential last night, and the bearing on the ring side is totally shot. Both of the races, and all the rollers are very badly worn and pitted. I am just surprised that there was no real indication of this until I got the oil leak. The inboard bearing is in a much better condition but I will change that as it's not perfect.
cheers
Derek
