Is there a different brand/manufacturer differential that will fit where a Eclipse 2G rear differential lives?
Subject, 1997 Eclipse FWD that I would like to make RWD. The GSX RWD parts were never meant to be the only way power was transmitted to the ground. Does any other differential physically fit into the confines of the stock rear GSX cross member? Miata? 350/370Z? Or may it be easier to transplant FRS/BRZ rear drive parts into the car. Just a mind exorcize at this point. Unless someone knows of something that will bolt itself into place.
I know very little about Mitsubishis, but maybe the rear bits from a 3000GT? Supposedly they had a lot in common, but a lot more torque, so maybe they got a stronger rear diff?
I am about to do some experimenting with a first generation Avenger. Basically a bigger Eclipse. We melted down the 2.5 v6 that was in it and a guy gave me a 5.7 Hemi. Yes I know it's crazy and can't be done, but I have to prove that to myself, or to everyone else it can.
Driven5
UltraDork
9/14/20 10:51 p.m.
noddaz said:
Does any other differential physically fit into the confines of the stock rear GSX cross member?
Just about anything can fit if you own a welder.
ShawnG said:
Vajingo said:
Awd 9sec eclipses exist.
Not for long.
I used to think this, but there are a couple places who can make the drivetrain pretty bulletproof if you're willing to spend the $$$.
In reply to noddaz :
I don't think you're going to find a bolt-I'm solution to this, but I believe the 2G is like the 1G - the rear floor pan stamping a on the AWD cars are completely different than the FWD ones. So if you're going to have to cut up the rear floor anyway, figure out your projected power output, find a diff that will hold up to the anticipated abuse, and modify the rear subframe/axles/hubs/uprights as needed to make it all work.
The rear will be trivial compared to the front, where you will need to essentially remove and replace the whole front suspension, firewall, and floor. The engine and transmission are going to want to be where the rack and pinion and half the floor are.
It's nothing not doable, but the rear is simple by comparison.
NickD
UltimaDork
9/15/20 5:52 a.m.
There was an LS-swapped RWD Eclipse I saw locally once, but I really do not know what he was using for a rear diff. It had inboard disc brakes on it, whatever it was (Jaguar?)
NOHOME
MegaDork
9/15/20 7:23 a.m.
ShawnG said:
Vajingo said:
Awd 9sec eclipses exist.
Not for long.
That why they are called 9 second Eclipses.
A friend of mine has a jig to build 3000GT diff adapters for 2G GSX rear subframes. He had a customer killing stock GSX diffs and since the swap no longer.
In reply to buzzboy :
Sounds like he needs to start selling them. My thought is cut the rear floor and drop in a 350z subframe diff and all. I think I'm turning into a Nissan/Infiniti fan boy.
drock25too said:
I am about to do some experimenting with a first generation Avenger. Basically a bigger Eclipse. We melted down the 2.5 v6 that was in it and a guy gave me a 5.7 Hemi. Yes I know it's crazy and can't be done, but I have to prove that to myself, or to everyone else it can.
RWD Avengers used to be a fairly popular drag build. I think Mopar Performance had made some sort of kit for a while. I'm not sure how much rear suspension / floor pan was shared with the AWD Eclipse, but it is a fairly close relative.
Some inspiration:
Pete Gossett (Forum Supporter) said:
In reply to noddaz :
I don't think you're going to find a bolt-I'm solution to this, but I believe the 2G is like the 1G - the rear floor pan stamping a on the AWD cars are completely different than the FWD ones. So if you're going to have to cut up the rear floor anyway, figure out your projected power output, find a diff that will hold up to the anticipated abuse, and modify the rear subframe/axles/hubs/uprights as needed to make it all work.
I'll echo what Pete said, there is certainly not any bolt-on solution for a 2G FWD to convert to RWD, even a 2G AWD to RWD. The floor and subframe are completely different on the 2G FWD, and if you want a better starting point for a true RWD swap the 2G AWD would be easier (not easy...but easier). As mentioned a 3000GT VR4 differential can be made to fit, some more serious drag racers have fit explorer differentials in the rear however that requires a tubular subframe and custom driveshaft, so not "bolt on". This swap would be exponentially difficult compared to other platforms, and for what gain? The 2G chassis is quite flexible from the factory and you would have to completely re-engineer the front and rear subframe, suspension, and unibody to make it all work. The 2G FWD is quite good, faster than the 2G AWD from the factory, and has the same excellent front suspension.
Then, what transmission will you use to send power to the rear differential? Another tricky proposition, as an off the shelf RWD transmission for a 4G63 does not exist. You could find a narrow block 4G63 (Very rare) that would bolt up to a handful of older Mitsu transmissions, or buy a custom bellhousing to fit the standard wide block 4G63 to a number of transmissions. Again, lots of stuff that is not "bolt on".
If you want to know more about 4G63 RWD swaps, there is a bounty of information on ProjectZeroG. However that is mostly aimed at platforms that are already RWD, like the Starion, MightyMax etc. If you want 4G63 RWD fun, a Starion/Conquest is more up your alley. If you want something different, it's still probably better off to start with an existing RWD chassis. It's been done before so there are resources, I hate to sound pessimistic but in this case it might be better not to reinvent the wheel.
https://projectzerog.com/
In reply to MadScientistMatt :
Yeah, the first Avengers I saw were the 1994 IROC cars and I was hooked. Too bad production cars were fwd. I know Mopar made kits for the Daytonas but have not found anything for the Avenger. I have two 98 Avengers and just got an 02 Eclipse GT convertible. Rear suspension looks real close. Is that your car?
In reply to Stampie (FS) :
He does. I can't find a photo of them, only of the car the diff went in.
drock25too said:
In reply to MadScientistMatt :
Yeah, the first Avengers I saw were the 1994 IROC cars and I was hooked. Too bad production cars were fwd. I know Mopar made kits for the Daytonas but have not found anything for the Avenger. I have two 98 Avengers and just got an 02 Eclipse GT convertible. Rear suspension looks real close. Is that your car?
Not mine, just the first good picture of such a conversion that I turned up. The cars were run in Pro Stock for a while, and there were a lot of these campaigned at lower levels of drag racing. I doubt the hardware used is in production now, but the volume of these campaigned in the '90s makes me suspect that there was some sort of mass produced conversion kit. Not sure if it was a four link or a ladder bar, but it was definitely not the same approach as using the Eclipse IRS with a larger diff.
