Strada axle shafts too long for 128SL

kco2949785

kco2949785

Daily Driver
I'm in the process of putting together the front suspension of the blue 1973 128SL that has a 1979 Strada 1500 engine (Euro head and cam) and 5 speed transmission. It appears the axle shafts with the CV's installed are 25 to 35 mm too long. Has anyone run into this? The Strada axle shafts have inner CV joints, not tripode joints like the 4 speed 128 or 5 speed Yugo transmissions. Has anyone out there who has installed a Strada 5 speed transmission in a 128? Did you narrow the axle shafts? Are there shorter axle shafts made by Fiat for other Fiat models?
Thanks in advance for any replies, Ken
 
I'm pretty sure the track of the Strada is wider than the Coupe, hence longer shafts. A pair of 1500 X1/9 shafts might be worth a try. I should add that many years ago I fitted a Strada 105TC engine and box in a 3P. That has a "stretched" bellhousing making the driveshaft issue even worse. I had custom shafts made.
 
The track is wider on a Strada (by 2 inches?). I thought about the 1500 X1/9 shafts but the outer CVs are different. The Strada outer CV is splined and is used to tighten the wheel bearing. If it is the right length it could be modified to fit a Strada outer CV by cutting a groove for the CV retainer clip. Do you know the length of the left side X1/9 shaft? The right side X1/9 shaft would not work as it's too long. The Strada has an intermediate shaft on the right the splits the length of the shaft although the right side outer shaft is longer by over 25 mm than the left side Strada shaft. Less torque steer that way and as a former owner of a Saab 99 Turbo, that's a good thing.
Do you remember who made the custom shafts for your 3P?
Thanks for the reply, Ken
 
Don't bother trying to figure or mix-match axles that sort of-kinda work. Take the springs out of the struts, get a pair of wood dowels (aka broom sticks), adjust the length of each broom stick as needed over the ENTIRE travel of the suspension and make sure there is over travel margin. This means pushing the axles in-out of the CV joints at both ends of FULL suspension travel.

This will set up the length of axle needed per side. find a know good axle that is a bit too long then contact the folks at Moser Engineering to have them cut to the required length and splined and snap ring groove added.

Contact Us | Moser Engineering

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www.moserengineering.com www.moserengineering.com

This is not expensive and will get this done properly..


Bernice
 
Hi Ken, I'm in the UK so not much help regarding driveshaft makers I'm afraid! Mine were bodged up using bird-mouthed sleeves to my spec by a skilled welder friend of mine, as I was young and reckless. There are specialists who can make custom shafts properly with snap ring grooves in the correct place for your chosen CVs, as Bernice has mentioned. The inner CV is a "plunge" joint that allows axial movement but is limited in angular movement. The outer CV as used for the FWD cars and the 4 speed X1/9 allows large angular movement for steering but allows minimal axial movement. Some Uno Turbo swaps into X1/9s use the Uno's intermediate shaft, and a second short X1/9 shaft has to be obtained to fit on the right side. This may work for you but you need to check for binding over the range of suspension movement and sort out the snap ring grooves as per Bernice's instructions!
 
Thanks for the replies. They are very helpful.
I checked the front track width on a Strada and it's 1400 mm. The 128SL track is 1325 mm wide. It looked like the Strada axles shafts were about 1 1/2 inches (38 mm) too long but tomorrow I will follow Bernice's advice and get an accurate measurement of what length is ideal.
Does anyone know what the length of the Uno axle shafts without the CVs attached? Maybe they could be used?
Regards, Ken
 
Ken, when you get this project completed please be sure to share what you did as others might want to do this in the future.
 
A 5 speed X1/9 short shaft should be pretty close and probably easier for you to obtain compared to an Uno.
 
An update on the axle shafts project
The original length of the Strada shafts are left side is 388 mm and the right side is 407 mm. On Monday I followed Bernice's set-up advice and used 1 inch wood dowel rod to make models for the lengths needed. The left shaft new length is 306 mm and the right shaft is 358 mm. Today the axle shafts were sent to the machine shop and hopefully will get them back in a few weeks.
I had looked at trying to find a list of Fiat axle shaft lengths and was not able to find one.
After I get the axle shafts back from the machine shop I'll update this thread with the results. Hope those measurements are correct.
Regards, Ken
 
Here's some photos of the shortened axle shafts.
I ended up going to a local machine shop (Apex in Bensonville IL) that has done a lot of Lotus Elan rear axle shafts that were replaced with shortened VW axles. The first photo shows the process of the initial inner weld that's covered by a welded two piece sleeve.
Hopefully I'll get this car driving be the end of October
 

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Welded axles have a high risk of failure due to differential hardness from the heating-cooling process of welding. Only way to resolve this is to anneal the axles to relax the stress from welding then heat treat the axles back to their designed strength (this process will likely completely alter the shape of these welded axles due to stress relaxation). In the real racing world weld axles are strictly prohibited due to risk of failure.

Might work, might fail. Previous, "worked ok" or "done this before many times" is not relevant.

Bernice
 
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