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Love it! Nice write up @Billj747
Crazy timing.... I just finished my Ronin 8.8 swap with Grande hubs/axles.
It should be able to take pretty much anything I throw at now.
Mine starts about page 14 in my build thread...
Thanks for the feedback! Awesome car and build! That thing is going to be incredible.
It's pretty cool to see various people on FB also post their setups:
Steve/estevan62274 (FL)
20B, DCT, 4.10 Ford 8.8 with a Detroit Truetrac LSD
Edward Steward (FL)
20B, CD009/A, 3.55 Ford 8.8 with a Wavetrac LSD
Stephen Crandall Jr (FL)
DCT, 4.10 Ford 8.8 with a Detroit Truetrac LSD
(GS7D36SG trans from 2015 F80 M3/M4 with a 0.671:1 top gear ratio)
Originally Posted by mr2peak
What is the weight difference going to 8.8?
Stay tuned for the next installment where we go over those exact numbers, but to answer your question: The complete aluminum Ford Explorer 8.8" diff weighs less than the cast iron OEM FD RX-7 diff, and the mounting X-brace and bolts weigh less than the OEM PPF.
The stock FD RX-7 differential is a little heavier than that if you include the bolt-on mounting bracket and rear diff bushings.
Updating:
Stephen Crandall Jr (FL)
13B, EFR8374, DCT, 4.10 Ford Explorer 8.8 with a Detroit Truetrac LSD
(GS7D36SG trans from 2015 F80 M3/M4 with a 0.671:1 top gear ratio)
Mike/whitexdevil_777 (CA)
20B, GTX4294R (TiAL 1.00), DCT, 4.10 Ford Cobra "Terminator" 8.8 with a Detroit Wavetrac LSD
(GS7D36SG trans from 2015 F80 M3/M4 with a 0.671:1 top gear ratio)
Edward Steward (FL)
20B, EFR9280 (TiAL 1.45), CD009/A, 3.55 Ford Explorer 8.8 with a Wavetrac LSD
(0.794 top gear ratio)
Project FD RX7 Restomod: Part 15 – Building the Ford 8.8 Differential with a Detroit Truetrac LSD and WPC
We take a junkyard Ford Explorer 8.8” differential and transform it by installing one of our favorite LSDs, the Eaton Detroit Truetrac, then we hand deburr the ring and pinion gears, WPC treat the gears and bearings, and modify the aluminum housing to fit the high-power goals, handling and drivability requirements of our FD RX-7.
The aluminum Ford Explorer 8.8" diff is actually lighter than the factory cast iron housing, and the Ronin mounting kit is also lighter than the factory PPF.
Are there any downsides to eliminating the PPF?
Friend says it has some sort of negative effect on the chassis, but I can't see why it would...
This is all heuristics as I have no quantifiable proof - and the cars I've driven have also been V8 swapped so there are going to be other factors at play such as the front subframe - but I've noticed something that I can attribute as a bit more torsional 'flex and creakiness' when going over a few of the odd low speed bumps on my 'shakedown' route on cars with no PPF and no extra bracing such as a half-cage. I did not notice the creakiness on a well done V8 swap WITH (I think it was a Rogue Fab) a half-cage.
Are there any downsides to eliminating the PPF?
Friend says it has some sort of negative effect on the chassis, but I can't see why it would...
There are far more downsides to keeping the PPF if you're making over 400whp.
Consider what the PPF does. It connects the transmission to the differential so the entire drivetrain hangs off the 2 motor mounts and the 2 diff mounts. All torsional force is exerted through these 4 bushings that load the front and rear subframes.
I removed the PPF and installed a Sikky front diff support brace and a Banzai racing transmission mount. This converts the Mazda PPF into a traditional drivetrain layout where 2 more bushings are added to support the transmission and diff. Torsional load now goes into the chassis at 2 more points with the Sikky/Banzai setup, but this is not bad for the chassis and I don't think there's ever been a tear in the chassis or an issue from this type of bracing.
The Ronin kit mounts the diff to a welded-in brace on the subframe, so all of the torsional load stays in the subframe like stock. There is a transmission brace but there are no 'negative effects on the chassis' from this.
Originally Posted by dguy
This is all heuristics as I have no quantifiable proof - and the cars I've driven have also been V8 swapped so there are going to be other factors at play such as the front subframe - but I've noticed something that I can attribute as a bit more torsional 'flex and creakiness' when going over a few of the odd low speed bumps on my 'shakedown' route on cars with no PPF and no extra bracing such as a half-cage. I did not notice the creakiness on a well done V8 swap WITH (I think it was a Rogue Fab) a half-cage.
IMO, a difference in swaybars will have far more to do with torsional stress on the chassis when going over low speed bumps or up driveways at an angle than adding transmission and diff mounts. A completely different subframe is also a very big factor vs a Ford 8.8" diff mount in this regard as well.
Project FD RX7 Restomod: Part 16 – Installing the Ronin Ford 8.8 IRS Mount Kit using DSS axles
We busted out the TIG welder and installed the Ronin Speedworks Ford 8.8” IRS Mounting Kit. Then we shipped off the subframe to get powder coated before installing the show car quality rear end into our FD with the new DriveShaft Shop “Direct-Fit” Axles.
Installing the Ronin Speedworks Ford 8.8 IRS Mount Kit might seem intimidating, but it was actually a lot easier than I originally thought. If you have a MIG welder, angle grinder, and know how to use a level; or know someone who can TIG weld and has more grinding tools, the installation process was very straight-forward with easy-to-follow directions. This further reinforces the argument that I made in PART 14:
“As soon as you need to replace the OEM limited slip differential with an expensive aftermarket clutch-type LSD, the Ford Explorer 8.8” swap becomes the better solution”
“As soon as you need to replace the OEM limited slip differential with an expensive aftermarket clutch-type LSD, the Ford Explorer 8.8” swap becomes the better solution”
My car has an OS Giken 1.5 way LSD in the stock housing with DriveShaftShop axles. It dyno'd at 427HP to the wheels. Should I have went with this swap to run my diff?
My car has an OS Giken 1.5 way LSD in the stock housing with DriveShaftShop axles. It dyno'd at 427HP to the wheels. Should I have went with this swap to run my diff?
I was looking for something that would fit in the stock diff housing, and this might be it. With stock housing I can keep the PPF in place which is an important component in my opinion.
Lot of guys in Australia with OS G or similar diff centre, OSG/Albins/PPG gearset, solid diff pinion spacer, solid poly or nylon diff bushes, diff brace that bolts to floor pan and additional gearbox brace to floor pan running decent power.
I think if you are going to a tremec gearbox to support alcohol race fuel torque levels it's sensible to swap a diff but for a street car running road tyres or circuit style semislicks in similar size to factory a full driveline swap is a lot of effort.
My car has an OS Giken 1.5 way LSD in the stock housing with DriveShaftShop axles. It dyno'd at 427HP to the wheels. Should I have went with this swap to run my diff?
No, it's plenty strong the OS Giken diff is a very good diff. You only need a 8.8 if you're making 3 rotor or V8 torque, want a wave track, or need to run gearing the stock case won't support. 8.8 is overkill for most people, but sometimes being overbuilt pays off.
My car has an OS Giken 1.5 way LSD in the stock housing with DriveShaftShop axles. It dyno'd at 427HP to the wheels. Should I have went with this swap to run my diff?
There's a lot of information and your question would be answered in Part 14 above. Give it a read.
Originally Posted by mr2peak
No, it's plenty strong the OS Giken diff is a very good diff. You only need a 8.8 if you're making 3 rotor or V8 torque, want a wave track, or need to run gearing the stock case won't support. 8.8 is overkill for most people, but sometimes being overbuilt pays off.
That's far from true. The OSG LSD is strong, but not the stock cast iron housing. Give Part 14 a read.
You can slap on a diff cradle. It's way less work than a full 8.8 swap, and a whole lot cheaper. Yes the 8.8 is stronger, but very few people get past needing anything other than a cradle. If you're dropping the clutch on a drag strip, that's a different story. Plenty of 500hp+ FDs road racing on stock diff or stock diff case with a small cooler.
Not saying you made the wrong choice for your car. But someone who already has an OSG should probably break the case before thinking of upgrading.
You can slap on a diff cradle. It's way less work than a full 8.8 swap, and a whole lot cheaper. Yes the 8.8 is stronger, but very few people get past needing anything other than a cradle. If you're dropping the clutch on a drag strip, that's a different story. Plenty of 500hp+ FDs road racing on stock diff or stock diff case with a small cooler.
Not saying you made the wrong choice for your car. But someone who already has an OSG should probably break the case before thinking of upgrading.
It depends on how he uses the car. At his power level of 450whp it is borderline for the OEM iron housing when driving the car hard. If he drag races on radials, he will eventually break the housing even with 75-100hp less.
The most cost effective option for him is to get a diff cradle and brace, but together that will be nearly $1,000. If he just gets the cradle, he might break the PPF.
If he just runs on the street and does an occasional track day, a cradle will likely give him a decent buffer. But if he wants to run more power, it becomes a ticking time bomb again.
I don't agree with your recommendation of breaking the diff first, which is throwing away $500-750 that could have been sold to offset the price of the 8.8 swap.
The point of the article is when you're in the 450whp range, it is a no brainer to go to the 8.8 swap BEFORE buying an upgraded LSD (since the all in cost is about the same once you sell all the OEM parts). Since he's already down the path of buying the OSG and expensive axles, if he plans on making more power in the future or be more aggressive with the car, it might make more sense to convert the axles to 8.8 inner stubs, sell the diff before breaking it, sell and possibly get back half to 3/4 the value of the OSG, and be in a far better position than spending even more money to brace the diff, only to break it in the future and be in an even deeper financial hole.
IIt's important to think and plan ahead based on your goals.
The 8.8 conversion probably works a lot better in North America, I doubt I could go anywhere near close to covering the cost of 8.8, subframe, axles and wavetrac with what I have spent on Cusco centre, brace and Green brothers girdle. I'd be lucky just to buy the Wavetrac for that.
At least if I do break something I can actually source spares too.
Watching an otherwise interesting conversation on drivetrain strength using horsepower numbers as a metric is painful beyond belief :|
While knowing the torque and rpm would be more accurate, almost all documented failures reference horsepower figures. Since most builds are fairly similar in powerband and torque curves, referencing HP figures is still relevant for most situations.
But even knowing and referencing torque figures of a failure is a challenge since the shock from wheel hop can be a force multiplier by 3X. This means failures can happen at a much lower torque output than a car that does not have wheel hop.
The difficulty of referencing power or tq limits of any component is mentioned in Part 14.
While knowing the torque and rpm would be more accurate, almost all documented failures reference horsepower figures. Since most builds are fairly similar in powerband and torque curves, referencing HP figures is still relevant for most situations.
But even knowing and referencing torque figures of a failure is a challenge since the shock from wheel hop can be a force multiplier by 3X. This means failures can happen at a much lower torque output than a car that does not have wheel hop.
The difficulty of referencing power or tq limits of any component is mentioned in Part 14.
Yeah, I disagree completely. Use the proper metric that has the most impact on failures in a part, not the fact that one build may be similar to another.
Yeah, I disagree completely. Use the proper metric that has the most impact on failures in a part, not the fact that one build may be similar to another.
It's still somewhat pointless because there are too many variables like usage, tires, bushings, wheel hop, what gear and rpm the failure happened at, the AGE of components, etc... that makes even discussing the right metrics.
Stating that the diff housing has broken at 407lb-ft of torque at 4800rpm in 2nd gear (and calculating the torque multiplication of the gearbox) is pointless if 300lb ft or torque breaks the diff when there's wheelhop with a 3X force multiplier.
Not to mention, the stock components are now 30 years old. Heat cycles and fatigue of components will make them weaker than they were 10-20 years ago. A new component may have been able to handle 407lb ft of torque, but now 30 years later it can't.
These are generalities for a reason and there are farore variables with bigger effects than just discussing a torque figure.
It's still somewhat pointless because there are too many variables like usage, tires, bushings, wheel hop, what gear and rpm the failure happened at, the AGE of components, etc... that makes even discussing the right metrics.
Stating that the diff housing has broken at 407lb-ft of torque at 4800rpm in 2nd gear (and calculating the torque multiplication of the gearbox) is pointless if 300lb ft or torque breaks the diff when there's wheelhop with a 3X force multiplier.
Not to mention, the stock components are now 30 years old. Heat cycles and fatigue of components will make them weaker than they were 10-20 years ago. A new component may have been able to handle 407lb ft of torque, but now 30 years later it can't.
These are generalities for a reason and there are farore variables with bigger effects than just discussing a torque figure.
Again, no. Torque is a measurement of rotational force with no reference to time and can be directly attributed to the things you're describing whereas horsepower is power over time. The other things you're describing plug directly in to the use of torque (take it as ft/lbs or NM) as your unit of measurement, whereas they do not with regards to horsepower.
Horsepower is a dumb metric for drivetrain component longevity. Period.
Dropping the clutch at 700hp is worse than dropping the clutch at 200hp, even if the torque is equal. It's a relevant measurement for a non-moving part, the diff case doesn't care how fast the diff is spinning, it's only seeing HP. Gears do care how many teeth are taking that load per second, so torque is a better measurement for transmission strength.
Originally Posted by Slides
The 8.8 conversion probably works a lot better in North America, I doubt I could go anywhere near close to covering the cost of 8.8, subframe, axles and wavetrac with what I have spent on Cusco centre, brace and Green brothers girdle. I'd be lucky just to buy the Wavetrac for that.
At least if I do break something I can actually source spares too.
yup, same for me. 8.8 is hard to source and expensive, wouldn't make sense to import a kit. A few people have moved on to Skyline diffs, but most just run a stock case with an aftermarket LSD. I've seen a quick change in a 4 rotor car, but that requires cutting out the center of the subframe and moving the gas tank. The fastest road raced FDs here are running stock cases, but with a cooler. Apparently the cooler is a very important part of making the stock diff last, spider gears generate a ton of heat.
So yeah, if you want to drag race your FD get a Quick Change with a 4 link rear
A while ago I asked about billet FD diff housings, seems nobody has made one. Popular in other platforms.
03-11-24, 11:00 PM
@Billj747
