Alfa Romeo Bulletin Board & Forums - Reply to Topic
Thread: GTA-style half shafts Reply to Thread
Post Icons
You may choose an icon for your message from the following list:

Register Now

In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


  Additional Options
Miscellaneous Options

  Topic Review (Newest First)
09-08-2017 01:13 AM
Originally Posted by Steve105 View Post
Is any one making reproduction course 15 spline axles? for GTAs

09-07-2017 08:52 PM
Steve105 Is any one making reproduction course 15 spline axles? for GTAs
07-15-2015 08:28 AM
bearbvd Precisely. And the ID of the inner race of the carrier bearings for the 2 liter axles is also much larger than it is in the earlier axles. hence my comment. Boring the carrier from an early axle to accept the late axle shafts would tend to leave the bearing seats on the carrier on the thin side.
07-15-2015 05:47 AM

The 2 liter axles are much larger OD than those in the 105 series cars.
07-14-2015 09:40 PM
bearbvd Sure doesn't seem like that would leave a lot of meat in between the ID of the carrier bearings and the OD of the axle splines---

07-14-2015 06:58 PM

Have a 2 liter axle resplined to the smaller 105 spline size.

Simple as well, convert to a 2 liter LSD Diff.

I build 105 sized LSD units by machining 2 liter LSD carriers to match bearing & ring gear positions of the 105 smaller unit. Then welding up the splined ends of the 105 axles and re-splining to fit the larger 2 liter drive splines which fit the LSDs units.
07-14-2015 02:32 PM
markjz Hello,

as my axle shaft decide to broke on track last week, I’m looking for a modern reproduction set of strong, solid 15 count spline GTA halfshafts (no original used or NOS parts - thanks!)

Anybody could help or knows a source?

11-22-2007 03:41 PM
bearbvd For new axles, talk to Moser Engineering (in Illinois) or Mark Williams (in Colorado. They happily do customs.

The stock axles are most certainly NOT cast, they are forged.

4140 is not a bad alloy selection for axle shafts, but is NOT necessarily the best.

Induction hardened shafts are likely the best way to go.

The REAL solution, especially for racing, would be to convert the rear wheel bearings to a 3/4 floating design--peek at an MGA rear for an example of this design. It removes the full alternating stress (due to vehicle weight, cornering loads, etc.) from the outer end of the shaft (EXACTLY where yours broke) and thus solves the problem.

The 3/4 floating design is a lot lighter and simpler than the classic full floating design, and almost entirely as reliable. And, just as with a full floater, the wheel bearing(s) run in gear oil, NOT grease. Another good thing about it.

Any tech inspector/racing organization that objects to such a conversion in any way deserves nothing more or less than a summons and complaint !!

Your break is a classic fatigue failure, and endemic to semi floating axles, particularly in racing applications.

Glad you had an angel riding on your shoulder (TWICE!!!!). It's not at all uncommon for the rear wheel/tire to roll its way out of the wheel well and pitch pole the car over the opposite corner. Many racers have died this way !!

I wouldn't take a GIFT of a used axle for this application, particularly where there's a past history of failures !!

11-12-2007 11:27 AM
alfavirus The axle shafts on the pictures are from a Montreal and have a thread for a castellated ring nut to secure the bearing.
As far as I know, this is specific to Montreal axle shafts.
11-12-2007 12:55 AM
Philip Hehir Many thanks Frank. I'll keep them in mind. At this stage I'm thinking of having some billet ones made up out of 4140 which will be much stronger than the standard cast ones, so I'll let you know if I have no luck.

Just a question.... Are the pictures you posted of the Montreal ones? As my axles are threaded and have a castellated ring nut to secure the bearing onto the shaft, Ive not seen this on 105 ones so presumed this to be peculiar to the Montreal.

11-11-2007 12:58 AM
alfavirus Hello Phil,
if you need used axle shafts for a Montreal, please reply.
I have one pair for sale.
11-09-2007 12:06 PM
Philip Hehir
Snapped Axle...

I snapped an axle while racing yesterday in my Montreal. It happened on the fastest corner of the track at about 140km on corner exit.
At first I thought I had been hit from behind, and it was a scary ride for 150 meters in the gravel trap, as with the car raised in the front it sort of surfed the gravel trap instead of digging in and slowing down.

This is the second snapped axle, last time it was the right hand side and the damage to the car was real bad, this time it was the left with minor damage.

I've fitted a 105 shaft one at the track from another racers spare to get me "mobile" to allow me to get the car on and off the trailer. The 105 ones are an inch shorter than the Montreal ones and only just engage into the LSD about 5mm (So I run the risk of stripping the splines if I attempt to drive it)

My problem is that if I get another Montreal one (most likely only second hand) It will be 40 yrs old and I'll run the risk it breaking again, and this time perhaps I won't be so lucky, and a concrete wall might not be as forgiving as a gravel trap. So does anyone know of an axle shaft manufacturer who is currently making billet 105 ones so I can have some new ones made up to the slightly longer length that the Montreal requires?

08-17-2007 04:52 PM
Curtis I broke a couple of early type axle shafts when I was running fully locked
spider gears. Once I switched to an LSD and the axles pictured above, no problems. I have wondered if the limited slip gives the whole system a little give an protects the axle?
06-20-2007 09:44 PM
Biscione yes, these have the 15 count spline.
06-20-2007 05:34 AM
ProCoach SWEET! But those are for the unobtanium 1600 GTA ZF LSD rear, right?
This thread has more than 15 replies. Click here to review the whole thread.

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

For the best viewing experience please update your browser to Google Chrome