LSD/Axles

[Alfar7]

Copying this as this group might find this helpful..

If you are working on a 105 type car the simple solution is to just swap out a 115 complete diff assembly, as all the mounting bolts & hardware are similar and in the same location on the axles.

BUT, for you few enquiring minds:
The 115 LSD unit can be modified to fit into all the other rear end configurations. The 750, 101, and 105 series. Using the original housungs ring gears (for the GTA hard to find ratios)
I won`t tell you how but there are pics at :Install of a 2 L Into The Giulietta Spider
It requires having the right machinist, metalurgist, and fabricator
As well the GTA splined axles can be built from the common 105 or later 115 large diameter axle.

[Max Banks]

true, but all pretty out of date now! Direct fitment competition type LSD units are available to fit both non LSD 105 axles and to upgrade from ZF unit in 2000 axles. Advantages are great weight savings over 2000 GTV unit retro fitment and far superior operation with variable ramp angles and better friction materials which are more durable etc.....

[Gordon Raymond]

Max,
Disadvantages for us yanks is (!!! ) cost of these components, and a non authentic appearance for our vintage racing. Guess if I wanted to I could put an entire aluminum axle from a dirt track outlaw car under there as well. Golly, I would have quick change gear sets, and any kind of adjustable LS, MUCH less weight, and an axle that would take 500 or 600 Hp, plus available parts! This would probably be somewhat costly as well. I LIKE RJ's solution, though I suppose if you work for Alfaholics, you might get these bits at less cost, with no shipping or import duty. I think it's all relative to what you need to do, and what you can AFFORD to spend. I'm sure you would agree. Just my opinion. Gordon Raymond

[Subtle]

While I have yet to do some aggressive driving with Rj's work on the diff in my Spider, it seems a reasonable set up for street use.

About 2.5 lbs of inertia was machined off the ring gear, and then there is the anachronism of a 1962 Giulietta that for some weird reason had 750 axles, having --carbon fiber--LSD discs.

[Alfar7]

Quote:

true, but all pretty out of date now! Direct fitment competition type LSD units are available to fit both non LSD 105 axles and to upgrade from ZF unit in 2000 axles. Advantages are great weight savings over 2000 GTV unit retro fitment and far superior operation with variable ramp angles and better friction materials which are more durable etc.....

[la_strega_nera]

Whats a FHI?

[genericwood]

Quote:

Originally Posted by Gordon Raymond Max, Disadvantages for us yanks is (!!! ) cost of these components, and a non authentic appearance for our vintage racing. Gordon Raymond

[Gordon Raymond]

Yes, I know Eric, and had one in my hand before I did the same as you, but grafted my 1600 tubes to the 2L center. I still have my GTA 5:13 on my shop shelf, but that one really is too hard and expensive to find and / or make parts for, and that's a fact! My point is in being able to use, as you and I and RJ suggest, easily available components that can be replaced quickly and economically as wear or failure dictates. I'm with you in that options are always better than economic dictates! Gordon Raymond

[genericwood]

Gordon, I'm curious how you grafted the 1600 tubes to the 2L center section. Did you just cut and weld the tubes?

Erik

[Gordon Raymond]

No Eric I cheated. I thought about this for a year, and how to get the tubes square to the flanges, Exactly the right length and so on. I contacted the best race car fabricator I know, and he said I need to build a jig, it would be costly for just one axle. Talked about it with a friend who told me Jack Beck had just such a jig. I called Jack, and found he had done a bunch for racing. Rather than cut all the stuff off the 105 tubes, and then weld back on all the Giulia spider stuff, he just cut the spider tubes, cut the 2L stuff off the flanges, put them in his jig and after tacking them around, laid in a penetrating bead. His job is 100 % perfect.
Actually, better than the factory axle. He came up with exactly 1/16 toe in per side, measured from the differential centerline with a laser alignment machine. He probably could have added a little negative camber if I had asked. This allows the use of the common 2L center section, with is many ratio's and any variation of the LS set up one may want for track or street. I carved the aluminum casting outside a bit, to resemble the earlier 1600 center, and to clear my Ausca rear sway bar. Looks right, works great, couldn't be happier. RJ's modification allows the use of the 1600 casting with 2L internals. Better still, but when I did mine 7 years ago, I wasn't aware Richard could do this work. He can even use the 2L LS in a 750 center!!! Very nice fabrication indeed. Subtle, here on the BB, has a tuned 2L in a Giulietta, with this 750 center and 2L, LS by Richard. He is one happy guy!
It's really great that machinists like Jack and Richard can do this stuff for us affordably.
If this sound like I am promoting Richard and Jack, well.... I am! The GTA axle in my Ausca spider was pretty limiting for anything other than pure race track work. The 2L LS makes the car street worthy and not just a garage queen. I have no fear of any type failure that requires speciality parts. Having owned my car from new, it's great not to have to worry about parts specific to the GTA unit. I strongly recommend this upgrade to anyone with concerns about their GTA unit, or just for street or track applications with the older rear axle's. Richard and Jack can do the job RIGHT! Gordon Raymond

[Alfar7]

With a proper set up LSD (115 type) axle breakage with smaller diameter axles are almost non existant particularly with low HP/Torque 1300/1600/1800 motors. (less than 170 lbft Tq)

The Keep it simple (no tube cutting) method requires tube flange mods to fit the larger case. As well the LSD unit must be machined to both fit the left tube`s smaller bearings and closer positioning to the RGC.

The axle mods are critical & require correct metalurgical skills. The splines are cut depending on application. All of course to fit the 115 drive recievers, but the taper and even percentage of contact is dependant on the camber and toe desired. Toe and camber should be gained by shrinking the tubes in the correct locations rather than cutting. Done correctly 1 degree negative camber and 1/8 overall toe is easy. With careful build and spline cutting 1.5 degrees is about as much as they seem to live with without frequent inspection.
Below is a 101 tube & axle with 115 center & modified 4 disk LSD Lightened ring gear with 1 degree negative camber and 1/16 toe per side.
On my website are pics of the axle in my Giulietta, which is modified similar to Gordon`s, so that the 115 axles can be used.
If using Drum brakes as on my Giulietta, the spacer between the axle seat and wheel bearing must be changed before pressing on the bearing, so that the drum matches the brake backing plate and centers the shoes correctly. As the 115 wheel/brake mounting flange is located differently.