Budget IRS options?
Budget IRS options? I know that Heidts does a full drop in kit for 4th gens, and some people have done C4 swaps, but has anyone tried to retrofit 5th/6th gen rear suspensions into their 4th gen? It's pretty easy to come across a donor, so it could feasibly save a good bit of money on an engine and trans, too.
I know that Heidts does a full drop in kit for 4th gens, and some people have done C4 swaps, but has anyone tried to retrofit 5th/6th gen rear suspensions into their 4th gen? It's pretty easy to come across a donor, so it could feasibly save a good bit of money on an engine and trans, too.
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The reason you need to narrow the cradle is that the c5/c6 cradles are too wide and will have the wheels sticking far outside the wheel wells (rear width on the 4th gen is 64.75, the c5 is two inches wider). Once you narrow the cradle, the mount points for it, and the control arms fall inside the existing hard points (the unibody where the spring pockets are).
You will need to build a frame that support the cradle and merges back in to the existing unibody, either by tying it back in to the existing hard points, or by back halving the car with an entirely new frame. Either way you have impinged on the fuel tank area, so you'll need a custom fuel tank that will fit in the reduced area, or relocate the tank to the trunk.
The least intrusive differential options are the gen V camaro diff or a viper diff with custom cv drive axles. You can get the c5 cradle and arms cheap, as you've seen, but it becomes an adventure quick
- Cradle narrowing
- Reworking the frame
- custom fuel tank
- Drive axles
- Differential
- New drive shaft
- Exhaust
I have a complete gto rear cradle and a rear diff and cv axles/rotors and calipers sitting in my back yard. well the axles and diff are inside my shop. My opinion vs try to undertake this....sell the f body and get a vette or gto.
I think the most "budget friendly" option to get an IRS would be to buy a C5 vette >>
On a more serious note, IRS conversion and the word "budget" don't go together, as lees alluded to. You either spend a bunch of money on a pre-made kit, or you spend a bunch of money having a guy with a welder engineer one to work in your car. Both would end up putting you over the cost of a medium-mileage C5 (or maybe even a high mileage C6)
On a more serious note, IRS conversion and the word "budget" don't go together, as lees alluded to. You either spend a bunch of money on a pre-made kit, or you spend a bunch of money having a guy with a welder engineer one to work in your car. Both would end up putting you over the cost of a medium-mileage C5 (or maybe even a high mileage C6)
I think the most "budget friendly" option to get an IRS would be to buy a C5 vette >>
On a more serious note, IRS conversion and the word "budget" don't go together, as lees alluded to. You either spend a bunch of money on a pre-made kit, or you spend a bunch of money having a guy with a welder engineer one to work in your car. Both would end up putting you over the cost of a medium-mileage C5 (or maybe even a high mileage C6)
On a more serious note, IRS conversion and the word "budget" don't go together, as lees alluded to. You either spend a bunch of money on a pre-made kit, or you spend a bunch of money having a guy with a welder engineer one to work in your car. Both would end up putting you over the cost of a medium-mileage C5 (or maybe even a high mileage C6)
For most people, who, having passing love - for the car of the moment - doing these types of upgrades ($10k engines, and suspension improvements) is a diminishing return on investment. Just save for the car you really want.
I am currently in the process of C6 swapping the rear of my trans am. I have some info for anybody stumbling onto this thread
This is all based off of swapping the corvette suspension
Right now I've spent a little over 3500 excluding tools to do this. I have yet to buy the axles, driveshaft, and coil overs. I am expecting to spend around 7000 at the end but the tools needed easily push that number to 10000. You will not save money by doing it yourself and you really won't gain much either.
IMO buying the setup from Heidts is a safer bet for people who really want to have an IRS f-body although there is still cutting and welding required.
This is all based off of swapping the corvette suspension
- The width differences between the vette and f-body is massive. on paper it does not seem like much but it is huge
- You will have to end up notching your frame. The upper control arm mounts end up inside the frame just behind where the spring pocket was
- The only good diff options that I found were 9" irs, Ford super 8.8 (from a mustang s550), and the 5th gen camaro zl1 diff. Nothing else seemed reliable enough for the power I wanted
- The stock gas tank will not fit with the vette suspension, I will end up cutting out my trunk to fit it and keep some storage space
Right now I've spent a little over 3500 excluding tools to do this. I have yet to buy the axles, driveshaft, and coil overs. I am expecting to spend around 7000 at the end but the tools needed easily push that number to 10000. You will not save money by doing it yourself and you really won't gain much either.
IMO buying the setup from Heidts is a safer bet for people who really want to have an IRS f-body although there is still cutting and welding required.
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Just thinking out loud, What I find comical is gears with solid rear axles want independent rear axles and guys with independent rear axles want solid rears. I have independent and I'd rather a solid rear axle. With irs you have to deal with: axle hop,cv shafts breaking, inner stubs breaking and outer stubs breaking. I dont even know why you'd want to give yourself those headaches.
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Verdad Gallardo Just thinking out loud, What I find comical is gears with solid rear axles want independent rear axles and guys with independent rear axles want solid rears. I have independent and I'd rather a solid rear axle. With irs you have to deal with: axle hop,cv shafts breaking, inner stubs breaking and outer stubs breaking. I dont even know why you'd want to give yourself those headaches.
I am currently in the process of C6 swapping the rear of my trans am. I have some info for anybody stumbling onto this thread
This is all based off of swapping the corvette suspension
Right now I've spent a little over 3500 excluding tools to do this. I have yet to buy the axles, driveshaft, and coil overs. I am expecting to spend around 7000 at the end but the tools needed easily push that number to 10000. You will not save money by doing it yourself and you really won't gain much either.
IMO buying the setup from Heidts is a safer bet for people who really want to have an IRS f-body although there is still cutting and welding required.
This is all based off of swapping the corvette suspension
- The width differences between the vette and f-body is massive. on paper it does not seem like much but it is huge
- You will have to end up notching your frame. The upper control arm mounts end up inside the frame just behind where the spring pocket was
- The only good diff options that I found were 9" irs, Ford super 8.8 (from a mustang s550), and the 5th gen camaro zl1 diff. Nothing else seemed reliable enough for the power I wanted
- The stock gas tank will not fit with the vette suspension, I will end up cutting out my trunk to fit it and keep some storage space
Right now I've spent a little over 3500 excluding tools to do this. I have yet to buy the axles, driveshaft, and coil overs. I am expecting to spend around 7000 at the end but the tools needed easily push that number to 10000. You will not save money by doing it yourself and you really won't gain much either.
IMO buying the setup from Heidts is a safer bet for people who really want to have an IRS f-body although there is still cutting and welding required.
I bought c5 frame rails to make my jig, and built a sub frame that replaced the cradle and frame rails. I am finishing the frame modifications today and start the mounts for the sub frame next weekend. I'll do a full wright up once the sub frame is mounted and I find out the pinion angle.
Last edited by Jeringo; May 25, 2020 at 06:18 PM.
Just thinking out loud, What I find comical is gears with solid rear axles want independent rear axles and guys with independent rear axles want solid rears. I have independent and I'd rather a solid rear axle. With irs you have to deal with: axle hop,cv shafts breaking, inner stubs breaking and outer stubs breaking. I dont even know why you'd want to give yourself those headaches.
Not to say you can't be successful drag racing a vette or road racing an fbody, just that it takes more effort to make one as good as the other.