CARC strip for bearing replacement.

[pete roper]

Take it off, drain the oil out.



Remove the clips from the top boot.



This exposes the reaction arm.



Front boot is retained by plate and two self tapping screws.



Remove it.



Front boot is now *loose* in housing.



Undo and remove all the bolts that hold the two halves of the case together. Then using a big flat bladed screwriver between the obvious pry points, (NOT BETWEEN THE MATING SURFACES OF THE CASE YOU RETARD! on the case crack the sealing goo between the cases. Holding the drive side case and giving a good 'Thwack' to the centre of the crownwheel/ wheel mounting boss with a dead-blow hammer will assist here. You AREN'T trying to completely separate the cases, simply break the seal. No need to be brutal!



Once the seal is broken turn the CARC over and heat the centre with a heat gun. Give it a couple of minutes and you will simply be able to lift the RHS case off the CARC mechanism.



Voila!



Use a press, making sure that the crownwheel part of the CARC doesn't foul the blocks, to press out the wntire CARC from the LH side case.



Bearing is now exposed.



Expensive seal is unfortunately sacrificial. Pry it out, heat case with heat gun to drop out *big* Bearing, take new big bearing out of fridge and drop into hot case and press or knock home. Re-insert and press home CARC. Apply sealant to RH side case, (I'd try Threebond 1211.) sparingly. Heat LH case a bit and drop onto RH case. Press home as gently as possible. Use bolts to pull it all back together in a crosshatch pattern. Reassemble the rest using reverse of disassembley.

The clips for the top boot can be substituted with ones from any Auto shop for attatching the boots to CV joints of FWD cars.

As an addendum to above as I've had cause to go further into one now. Note that Guzzi say that the CARC is a 'Non Serviceable' component? Well, yes and no. There is no way to easily get the pinion out of the 'Bridge' but crownwheel bearings wouldn't be too hard.

Getting the seal holder off is a right frontbottom.



Getting the crownwheel out also requires knife edges, heat and a 30 tonne press but it's doable.



Bloody difficult to get the pinion out as you can't push it, (And its bearings.) out from the back.



Both of the Pivot bearings can be replaced.

Parts 4 and 5 below

and while it may be possible to replace the actual crownwheel bearings with a bit of dilligence they aren't listed as a separate part. Also because of the construction of the pinion assembley it is pretty much impossible to replace the pinion bearings or at least it would be very, very hard.

Go get-em!!!!

Pete

[Oz1200Guzzi]

Pete,

Very succinct methodology and great photos - makes the "service station" manuals look like apprentices!

[NeroGuzzi]

Pete,

I'm always grateful when you and others take the time to provide some of us neophytes with step-by-step instructions. Thanks again.

[Billd]

Thanks Pete, excellent break down on rear drive unit. In reading about the BMW GS final drives it seems they are replaced by the factory rather than rebuilt by the dealers and they have a relatively high incidence of failure. Nice to know that the Guzzi is relatively straight forward. Have you had to repair many of these?

[pete roper]

Thanks Pete, excellent break down on rear drive unit. In reading about the BMW GS final drives it seems they are replaced by the factory rather than rebuilt by the dealers and they have a relatively high incidence of failure. Nice to know that the Guzzi is relatively straight forward. Have you had to repair many of these?

The Guzzi unit too is only supplied as a unit. You can purchase the cases, boots, bearings for the crownwheel etc. but the actual 'Buisness' bit of the CARC only comes as part of a complete unit, no crownwheels, pinnions, shims or whatever available as spares.

After the initial run of bad bearings the component seems to have been generally very reliable. I've done a couple of failed bearings outside the recall range, one of them on my own 1100G, but it had a 'Bad' bearing even though it was quite a way out of the recall run. The ones I have seen fail are usually on bikes whose owners have either through ignorance or choice got the compression damping and springing set up really hard on the back. I've also had to replace a couple of pinion seals. Something I haven't shown in this photo-essay as the seal is sacrificial and the one in this unit was fine.

The strory behind this one is that it is one I rebuilt before but it was leaking, hard to tell exactly where from, but I tore it down again to re gloop the cases. Tht's why I haven't removed the seal or 'Big' bearing as they have already been done.

Pete

[JAS]

I didn't realise pre load / rebound damping could possibly reduce the life of the bearing. I have wound the preload up a bit (4 clicks from soft) but have set the rebound at 10 clicks (8 clicks maximum), I wound up the rebound to stop the rear end bouncing around when the suspension was hot, going though sweeping corners with a rough surface. This change seemed to stop this behaviour, now I am a little worried that it may damage the bearing. Wondering whether I should wind it back to 6 clicks.

I have the bike on a stand at the moment, to free up / lubricate the front disc buttons. I have checked the rear wheel for play, I can feel a very slight amount of play (my father tested it and reckons there is none), which I don't think was there before. I am going to check and see if it has changed in another 1000km, if so then I guess there is a problem. The seal is fine, no leak. I checked the prices, BMW (Sydney) wants $50 for the seal and $180 for the bearing. The bearing shop down the road quoted $120 for the bearing (FAG), 1 day for delivery.

Bike is a 1200 Sport with 14 000km on the clock.

Pete, thanks for your efforts in explaining the procedure here, really appreciated.

Jason

[GuzziMoto]

If you have the suspension mis-adjusted so that the suspension was not absorbing the bumps in the road surface properly then it could reduce bearing life as the bearing is taking a beating. If you adjusted the suspension and it improved the ride quality then it will have no negative impact on bearing life. It is when you have too much rebound dampening and the suspension packs down resulting in frequent bottoming that rebound could have a negative impact on bearing life. The same is true for compression and preload, if you have it mis-adjusted so that the rear end is not absorbing the bumps in the road but instead either bottoming frequently or not compressing to begin with then bearing life may be shortened.
Improving the action of the suspension will not decrease bearing life.

[GrahamNZ]

Pete

Great post. Could be a few mechanics will benefit from it if they get to see it.

One aspect concerns me a bit. If the innards are pressed out from the left side, isn't there the risk that the large bearing will be pressed out of the cold case and the bearing housing damaged? Or is the interference between the inner race and the axleshaft modest enough for that not to be a problem?

When my CARC was stripped for bearing replacement, both case halves were heated and lifted off the bearing outer races and then a bearing puller was used to remove the bearings from the axleshaft. The new bearings were heated and then pressed onto the axleshaft with a tubular drift used on the inner races to ensure the bearings were fully seated. Cases then heated and pushed over the bearing outer races.

[pete roper]

Six of one and half a dozen of the other Graham.

I have found the resistance of the cold case on the bearing is greater than the resistance of the *axle* to the innner race, but at the end of the day it makes no odds really, especially if the bearing is a deader!

Pete

[RJVB]

Impressive, and illustrates nicely your remark that the thing is built like something out of a tank turret!

This is in relation to what you found on Rob's CARC?

(and, erm, I take it you still have stuff to service before you attempt reassembly? )