I have a rust free Fiat 124 spider shell at home, and with all this time on my hands with the pandemic, I have been putting pen to paper to dream up how to mod it to make it faster, handle and brake better, and be more reliable with those abilities. While the stock stick axle is not bad, things like better brakes and limited slips are non-existant.
In the rear is a stick axle with four trailing arms, two long below the axle and two short above, with a panhard rod. The shocks and springs bolt to the top of the axle itself. I am thinking of either going with a 5 bolt or 4 bolt Mustang unit just for the huge amount of aftermarket these cars have.
The question is: Can I keep the stock suspension with the Ford axle? Can a competent welding shop move all the mounts from the Fiat unit to the ford? While I would love an IRS unit (and have one from my old 318ti sitting around) that opens up way too many varibles for me to consider, so I am thinking of staying with the tried and true in a more robust version.
mad_machine (Forum Supporter) said:
I have a rust free Fiat 124 spider shell at home, and with all this time on my hands with the pandemic, I have been putting pen to paper to dream up how to mod it to make it faster, handle and brake better, and be more reliable with those abilities. While the stock stick axle is not bad, things like better brakes and limited slips are non-existant.
In the rear is a stick axle with four trailing arms, two long below the axle and two short above, with a panhard rod. The shocks and springs bolt to the top of the axle itself. I am thinking of either going with a 5 bolt or 4 bolt Mustang unit just for the huge amount of aftermarket these cars have.
The question is: Can I keep the stock suspension with the Ford axle? Can a competent welding shop move all the mounts from the Fiat unit to the ford? While I would love an IRS unit (and have one from my old 318ti sitting around) that opens up way too many varibles for me to consider, so I am thinking of staying with the tried and true in a more robust version.
Most of the dirt track guys around here are using ford 9" or 8.8's in the GM metric cars with "stock" trailing arms. A good machine shop can remove the mounts and re-weld onto the new axle or fabricate new ones. Can the 318 IRS complete assembly be transplanted? A Toyota rearend like they use in the dwarfs and legend cars may be an option also.
How much power are you hoping to make?
The 8.8" is heavy, but relatively easy to narrow and get new axles for.
You absolutely can keep your stock linkages. When I did something similar, I jigged off the stock axle, cut off the brackets, and welded them to a new beam.
It looks like all your link points are off the pumpkin, which is good. It can be problematic welding to the cast steel, or whatever the pumpkin is.
I have to ask, have you considered a miata subframe?
Note, after attatching to your unibody, all you'd have to fab is upper shock/spring mounts. Arguably less work than an 8.8 stick. Plenty of stronged junkyard diffs (with LSD) can be adapted cheaply if the miata diff isn't strong enough.
In reply to drock25too :
I think your idea of the Toyota rear is better than the ford especially if there's not going to be a swap to a much bigger engine as there will be less drag. Swapping the brackets should not be too difficult.
Unsprung weight is the enemy here. The Ford unit is too heavy. The stock Fiat rear is already at the upper limit of mass relative to the overall mass of the car. The original geometry is very good too. If the torque remains within 150% of stock I would try to source a limited slip and brake upgrade from Italy, I am sure something exists. Otherwise the Toyota unit is the easy button. Bracketry might need fabrication, but it is all doable.
Toyota it is then. I am looking to build a screamer of an engine. 16v head from europe bolted to the TC bottom end, balanced, ported, and ITBs to give me a good 8000rpm range. So torque is never going to be great, but I would want the ability to get a decent LSD under the car to keep it under control. I agree that Fiat did their homework with the 5 link rear, it's why I wanted to keep that suspension.
