Rear axle bearing modfication MarkII

[Colin Byrne]

A couple of pics of the latest mod.  I'm still chasing stability in the rear axle,  The double row bearing modification we came up with works very well, particularly on the track, unfortunately the rough surfaces encountered during tarmac rally's shorten the life of even the double row bearing considerable.  By the 4th day of Tasmania this year we had considerable free play on both sides, the 16" wheels I run make the situation worse.

So version 2 of the bearing upgrade involves installing a small needle roller bearing down further down the axle shaft to support it.  The 2 litre 105 axles are much bigger, and for some unknown reason have a machined section that runs nearly a foot down the axle for no apparent reason.  I managed to source a bearing that was very similar in ID to the machined section and get the axle cylindrically ground to match the size.

The hardest part will be installing  the bearing carrier inside the axle tube.  I've managed to carefully remove the cast end of the axle tube and have turned up the bearing carrier to suit the ID.  Today I'll press the carrier into the tube and plug weld it into position, then re-weld the cast end onto the tube.

[AikenDrum105]

Amazing - just thinking of the forces involved to deflect that shaft radially in the tube. 

Appreciate you posting all this work - it's fascinating !

Cheers,

[Colin Byrne]

Well, as with most jobs like this, it didn't go completely to plan.  I initially made the bearing carrier a reasonably serious press fit into the axle tube, and since the axle tubes are taller than my press I had to "tap" the carrier in with a  sledge hammer, all the time thinking how glad I was that I wouldn't have to ever take it out again.  On installing the axle to check everything was OK it was very obvious that nothing was lining up properly. 

On closer inspection of the axle tubes in appears that there was little care in the manufacturing process to ensure the actual tube was centralised to the machined ends. (or that even the two machined ends are centralised together  So I had to remove the bearing carrier (which I had plug welded by this stage) then re-machine the new carrier to allow it to be offset inside the tube.   

So after a lot of careful measuring with a dial gauge, welding, and measuring again I managed to get the axle centralised, then repeated this on the other tube.

So all the hard work is done now, I've just finished rebuilding the rear end and will chuck it back in the car on the weekend. Also managed to make a little tool to allow pulling out the new bearing from the wheel side so I don't have to pull the entire axle out to change it.

[Colin Byrne]

Well we gave the bearings a good thrashing at Targa High Country and the mod seems to be working fantastically well.  There is zero play in the rear wheels now, good enough to pass any scruitineering! and the added stability at high speed it's added to the vehicle is awesome.  It's certainly more involved than the phase 1 upgrade and us probably only useful for more serious track/race cars, but it's a huge improvement. and should also increase the life of the outer bearing significantly.

Also the clutch mod appears to be working well also, unfortunately I've got an engine removal in front of me so I'll be able to use the opportunity to give the clutch a full inspection

[Ads]

Thanks for the detail Colin, your work is always appreciated. Got to see the car at THC and it looked the goods when you had it up and running hard!

[Philby]

Hi Colin
I am a 105 tragic from the Gold Coast. I used to race my Guilia Sprint GT about 25 years ago.
I have been talked into getting the car back on the race track and have spent the last 18 months fixing pretty much everything on the car.

Brakes have been a problem for the last 6 months, and I read with interest your posts about modifying the rear wheel bearings to help prevent pad knock off. I found a couple of threads about the topic, but am wondering if you did a separate tab detailing what you did to get a 23mm wide double row bearing into a 17mm wide bearing space.
I am also wondering you reasoning behind not using the 4 point of contact single row bearing (qj207) which is 17mm wide.
Was it that this bearing has a split inner race, or were you looking for more support in the bearing to help prevent the impacts of axle flex?
Hope you get this message as i am new to this forum.
regards Phill O'Callaghan

[LaStregaNera]

Phil, I think Colin used a combination of machining 3mm from the retainer plate, and a 3mm spacer (which pushes the rear wheels out by 3mm per side). The idea behind the double row bearing is to attempt to provide a stiffer, better supported outer bearing to help control pad knockoff - the 105 LSD does a spectacularly poor job of supporting the inner end of the axle.