JohnVallo
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- Joined
- Feb 9, 2015
- Threads
- 49
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- Location
- Venice, FL
- Website
- racersreunion.com
- First Name
- John
- Vehicle(s)
- '16 GT350, Shadow Black, Whipple Supercharged
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- #1
Wanted to share my experience for others interested in working with the newer 'Super 8.8', as well as information on how the project went.
Been driving my 16’ GT350 around Florida for 2 years now, 8000 + miles on it. About a year in I started wondering about the Final Gear Ratio in the GT350. I am mainly interested in Street Performance now, as a personal preference.
(I raced Stock Cars on oval tracks up North for 40 years before retiring so I’m done with the track stuff and I just prefer Street Performance at this point.)
Just so we’re on the same ‘Terminology Page’, here is a chart I made on the different terminology for Most-Common descriptions that people use to describe Rear Gear Ratios.
3.15 : 1 (Gear Ratio)
Lower Number
Higher Gear
Longer, Taller Gear
Shallower Gear
Less Gear
4.11 : 1 (Gear Ratio)
Higher Number
Lower Gear
Shorter Gear
Steeper Gear
More Gear
Personally, I think because of my Stock Car Racing, I prefer the ‘Less Gear, More Gear’ Jargon.
Anyway, the more I drove the 3.73 GT350 the more I thought, “This car needs a little more Gear”
How much more? This is where I began my project. (I was thinking, 4.11 or maybe 4.30)
SEMA SHOW 2016 -US GEAR- announcement Link:
Well, the 4.11 or 4.30 question got answered quickly, as I wrote to AxleTech/US Gear and acknowledged that they were indeed making 3.73, 3.91, and 4.11 gears for the 2015-Up Mustang “Super 8.8” IRS rear end, but did they have plans for a 4.30 ratio? The answer was: “NO Plans”. This happened just at the time Ford Racing had advertised a 4.09 gear-set, but suddenly it was not available, so at that time Ford had nothing to offer for the Lower gear choice.
Well the Ford 4.09 (Ford Performance) dilemma may have had something to do with suppliers, as we then had the 2017 SEMA announcement.
SEMA SHOW 2017 -US GEAR- announcement Link:
So, 4.09 (Thru Ford Performance) or 4.11, (US Gear now makes them both), what’s the difference? Well the short answer is: “Tooth Count”, 11 tooth pinion, 45 tooth ring-gear for the 4.09, and 9 tooth pinion, 37 tooth ring-gear for the 4.11. The long answers to my questions, (I never received). My questions were: Which one was stronger? Which one was quieter? Which one was better? Which one would you choose? US Gear did not answer these questions, other than to say: “If your car is still under warranty, you may want to go ‘Ford Performance 4.09’ for warranty concerns.”
Well I went with: US-GEAR 07-888411-15, Picked one up for $255.00 (including shipping.)
Also bought: Ford Racing M-4210-B3 (Install Kit) $110.00, as well as: TA-29 (Motorcraft Silicone sealer) $6.00, and 2 quarts of (Motorcraft 75W85 Fully synthetic gear lube) $44.00. Also 2 cans silver high-heat spray paint, $20.00.
I decided the best thing for me to do was to try and find another rear end from a GT350, rebuild it, so as to keep my original rear end intact. I did luckily find a 2016 Low-Mileage GT350 take-out rear end, purchased it for $750.00 + $150.00 shipping.
The rear-end build went relatively well
14 years as a Ford Registered Technician, and many years racing with the Ford 9” rears sure helped, but I had sold or let a lot of my shop tools get away. Without a shop press & bearing splitter, I had to get creative.
Harbor Freight has a Bearing Separator Set that works well with a slight modification. (Item 62593)
I used my 25% off coupon and it was a little over $42.00.
This tool will pull the Yoke off the pinion, as well as pull the inner pinion bearing from the pinion.
The modification needed on the splitter tool is to grind a little more metal from the clamshell splitter, with a (Dumore/Dremel, I used a Craftsman Pro rotary grinder) and grinding bit. The splitter needs to clamp under the pinion bearing, when tightened, without hitting/bending the pinion bearing cage. You have to grind a little from the sides of the splitter for clearance. I wanted to save my old pinion bearing without ruining it so I could later hone it out a little, so as to make a slip-fit setup pinion bearing. This is needed to be able to quickly change shims under the bearing when doing set-up (Pinion Depth).
Honing out the inner (Large) pinion bearing to make a setup bearing is easy, here’s how:
Use a round “Sanding”, -NOT Grinding, bit in the end of your die grinding tool.
It takes about 5 minutes to evenly hone a couple of thousands out of the bearing to get it to: “Slip Fit on the new Pinion”. Believe me, this will save you time later.
Another tool needed is a tool to hold the pinion flange from turning while removing, or torqueing the new pinion nut & crush sleeve. I easily made this tool, Here’s how:
I used a handle I had from a conduit bender. Flatten about 3” on one end with anvil & big hammer, drill two 13/32” holes, 1 + 13/16” apart in the flat end to match hole spacing on pinion yoke, that’s it.
If you don’t feel like making one, you can buy a Pinion flange holder at speedwaymotors.com for $21.99, or JEGS.com for $39.99
The other problem I overcame was how to hold the diff: (Torsen) & ring gear ASSY to replace and torque the new ring gear bolts. I had used a hydraulic press in the past, as well as a heavy duty big vice, but now I had neither.
You really do not want to clamp the Torsen in a big vise, as the barrell on the Torsen is quite thin.
I went to Home Depot and for $3.50 I bought the wood needed to build this holding fixture (Pictured), that I designed. It worked like a champ. I also had some deck screws, and 3” C-Clamps that I used.
View attachment 152605
Another method you can use to work with the ring gear bolt (100 lbs) torque is to use a long prybar as shown below.
On disassembly I noticed the factory had marked the diff carrier caps with yellow paint stripes on each side. I always mark them myself with number stamps anyway, but may not be necessary.
After all parts were cleaned with solvent/blow dried I began the assembly/set-up. What pinion shim to start with was my concern. I have used many pinion depth tools in the past, but I ALWAYS relied on gear-marking compound, and rolling a pattern for my final settings. If I would have had a professional Pinion Depth checking tool today, I could have set it at the (2.259 marking on the end of my new pinion.) I called my Master Mechanic friend at the Ford garage to ask if he had done any newer IRS Mustang rear ends and what pinion shim he ended up with. I also contacted US Gear Tech, as well as Strange Engineering Technical. No-one could give me an answer, other than start with what came in it. So that’s what I did.
Started with (Original): .027 Pinion shim, .273 Left Side Carrier Shim, and .279 Right Side Carrier Shim.
I have set up hundreds of rear ends, and I knew right away this was WAY-OFF. Only had about .003 backlash and the pattern looked like crap. (Way low on drive side, and Way high on coast side)
Here is a link to a very good discussion of Ring and Pinion Setup and other topics:
https://www.cartechbooks.com/techtips/ring-and-pinion-gear-selection-for-optimal-performance/
I must admit I am somewhat of a perfectionist, so I ended up changing the pinion shim and Carrier shims 8 or 9 times to get the pattern I wanted. Ended up with .037 Pinion Shim, .261 Left Side Carrier Shim, .291 Right Side Carrier Shim, and .008-.009 backlash. Pattern was near-perfect.
TIP: To save time when changing shims, and checking patterns I did make a 2 + 1/8” long spacer, out of 1 1/4” PVC, then grind a little from the inside on one end. This eliminated me having to draw the Pinion Yoke on every time, as the yoke is a press fit, and the spacer was a loose-fit. The outer pinion bearing on this rear end is already a slip-fit so everything was fast/easy to change. Do not use crush sleeve for this step.
For the final assembly of the Pinion, (I did replace both press-in cups in the housing) They are easy to replace, you can use a long drift punch, working evenly, side to side)
TIP: On the inner pinion bearing final assembly. For those who don't have access to a press, here are two options that will work on getting the inner pinion bearing pressed on the pinion shaft: (1) (Put the pinion gear in the freezer over-night (or at least 8 hours) before assembly, and then 15-20 minutes before assembly, heat-up the inner pinion bearing in the oven to 375 degrees. The frozen pinion, and the heated bearing make it very easy to tap the bearing down on the pinion, it just about falls on. (Don’t forget to wear gloves, and put pinion shim on first). (2) Buy a 2" threaded black pipe, 8" long, and a 2" pipe cap, at Lowes or hardware store. This will make a perfect bearing driver to install the pinion bearing. Always use new outer bearing, seal, crush sleeve and pinion nut for final assembly.
One other thing about the Pinion Flange, while it is off, paint the dang thing. (I don’t know why Ford doesn’t paint them). I had to use Naval Jelly to remove rust, and wire brush to prep for painting. I masked off seal area, and splines, and used silver header (High Heat) spray paint.
UPDATE: Here is Fords 'Super 8.8' newer Pinion Flange... "It's Painted" !
Did they take that suggestion from me?... Probably NOT
Now for the Swap:
Ford has a great guide for the swapping, and bolt torque specs. I actually found it in the Ford Performance GT350 Diff Cooler install instructions. Most of the steps are the same. But what was important, none of the rear-end remove/install video’s I examined were specifically for the GT350 (Only regular Mustangs). The GT350 is slightly different, especially in the emergency brake area.
Ford Instructions link:
https://performanceparts.ford.com/download/instructionsheets/FordInstShtM-4000-M8SGT350.pdf
I put my car fairly high-up on 4 jack stands, using an 18” 2x4, or the fixture I made (below) you can then lower/remove the exhaust by yourself quite easily with a floor jack. (Put the 2x4/Fixture under the exhaust just in front of where the middle bracketry is welded on the exhaust.)
While it was off, I cleaned and painted the entire exhaust system with silver (High Heat) spray paint (masking off the two-stage muffler electrical cutouts). I also used a 12” 2 x 4 and floor jack also to remove and install the rear end housing back in the car. (Don’t try to handle it by hand, it weighs about 120 Lbs.)
TIP: Removing Half Shafts. The pry-bar method does Not always work so well. I pried and pried on mine with 2 long pry bars, NO Luck, they would not budge. Also prying on them next to the seal area may damage the seal. The trick to popping them out of the diff is to use a sudden blunt force. I still had a “Tire Bead Breaker” slide hammer tool that I ended up using to EASILY pop out axles. If you can’t get this type of slide hammer tool, consider using Long ½” extension and big hammer. (Place end of extension on big round metal half-shaft housing, (Right where it comes out the side of the diff). You will have to hit it a slight angle, as you can’t hit it straight on. It should pop out easier than prying on it.
Gear Oil and Cooling concerns: I filled the rebuilt housing thru one axle hole with a small funnel, before installing. This rear end spec says 1.5L -Without cooler, (I do not have cooler). That is about 51 oz. + the friction modifier. I wish Ford had designed this rear end to hold a little more fluid, as the Older 8.8 Mustang rears held 2.7 quarts. Anyway, I ended up using 60 oz. (I didn't add any Friction Modifier). The fluid level was right at the bottom of check plug hole when I checked it after installing. Keep it level when installing, and no fluid will leak from Axle openings.
If you want to see a pretty cool thread on my rear-end cooling solution see the following link: https://www.mustang6g.com/forums/threads/additional-cooling-and-fluid-capacity-solution-for-the-mustang-‘super-8-8’-rear-end.117720/
Now for the Comparison/Evaluation:
This is not a huge change, it is a minor change.
If your cruising in 5th gear at 70 or 80, and punch it you definitely feel faster acceleration.
I was somewhat surprised to learn that the Speedometer/RPM was not off after swap, (It remained accurate)
I still plan to use Forscan software, and a OBDLink Tool (426101) to change my BCM Data at: 726-12-01, From: 0175 -3.73 Axle Ratio, To: 019A -4.11 Axle Ratio.
I understand that this setting has absolutely No affect on Mustangs with Manual transmissions.
It does affect Mustangs with Automatic transmissions (It affects the shift points)
Here is a chart of the comparison of both gears, speeds, and approx. RPMs.
3.73 Rear Gear
Trans Gear : Speed (MPH) : Engine RPM
5th : 50 : 2250
5th : 60 : 2750
5th : 70 : 3150
5th : 80 : 3650
6th : 50 : 1400
6th : 60 : 1700
6th : 70 : 2000
6th : 80 : 2250
4.11 Rear Gear
Trans Gear : Speed (MPH) : Engine RPM
5th : 50 : 2500
5th : 60 : 3000
5th : 70 : 3500
5th : 80 : 4000
6th : 50 : 1600
6th : 60 : 1900
6th : 70 : 2200
6th : 80 : 2550
Overall this was a Great, Challenging and Fun project.
Having driven with the new setup some 400 miles now, the Gas mileage remains at 18-21 MPG on the highway, 15-17 in town.
Am I glad I did it, and happy with it? Absolutely!
My next Venture?
a 4.56
To read about my Gear Change from 4.11 to 4.56
SEE: https://www.mustang6g.com/forums/th...gear-to-4-56-in-my-gt350.104766/#post-2263820
For some more detailed info on the "Super 8.8" rear... SEE LINK:
Inside the "Super 8.8" Rear End | 2015+ S550 Mustang Forum (GT, EcoBoost, GT350, GT500, Bullitt, Mach 1) - Mustang6G.com
Been driving my 16’ GT350 around Florida for 2 years now, 8000 + miles on it. About a year in I started wondering about the Final Gear Ratio in the GT350. I am mainly interested in Street Performance now, as a personal preference.
(I raced Stock Cars on oval tracks up North for 40 years before retiring so I’m done with the track stuff and I just prefer Street Performance at this point.)
Just so we’re on the same ‘Terminology Page’, here is a chart I made on the different terminology for Most-Common descriptions that people use to describe Rear Gear Ratios.
3.15 : 1 (Gear Ratio)
Lower Number
Higher Gear
Longer, Taller Gear
Shallower Gear
Less Gear
4.11 : 1 (Gear Ratio)
Higher Number
Lower Gear
Shorter Gear
Steeper Gear
More Gear
Personally, I think because of my Stock Car Racing, I prefer the ‘Less Gear, More Gear’ Jargon.
Anyway, the more I drove the 3.73 GT350 the more I thought, “This car needs a little more Gear”
How much more? This is where I began my project. (I was thinking, 4.11 or maybe 4.30)
SEMA SHOW 2016 -US GEAR- announcement Link:
Well, the 4.11 or 4.30 question got answered quickly, as I wrote to AxleTech/US Gear and acknowledged that they were indeed making 3.73, 3.91, and 4.11 gears for the 2015-Up Mustang “Super 8.8” IRS rear end, but did they have plans for a 4.30 ratio? The answer was: “NO Plans”. This happened just at the time Ford Racing had advertised a 4.09 gear-set, but suddenly it was not available, so at that time Ford had nothing to offer for the Lower gear choice.
Well the Ford 4.09 (Ford Performance) dilemma may have had something to do with suppliers, as we then had the 2017 SEMA announcement.
SEMA SHOW 2017 -US GEAR- announcement Link:
So, 4.09 (Thru Ford Performance) or 4.11, (US Gear now makes them both), what’s the difference? Well the short answer is: “Tooth Count”, 11 tooth pinion, 45 tooth ring-gear for the 4.09, and 9 tooth pinion, 37 tooth ring-gear for the 4.11. The long answers to my questions, (I never received). My questions were: Which one was stronger? Which one was quieter? Which one was better? Which one would you choose? US Gear did not answer these questions, other than to say: “If your car is still under warranty, you may want to go ‘Ford Performance 4.09’ for warranty concerns.”
Well I went with: US-GEAR 07-888411-15, Picked one up for $255.00 (including shipping.)
Also bought: Ford Racing M-4210-B3 (Install Kit) $110.00, as well as: TA-29 (Motorcraft Silicone sealer) $6.00, and 2 quarts of (Motorcraft 75W85 Fully synthetic gear lube) $44.00. Also 2 cans silver high-heat spray paint, $20.00.
I decided the best thing for me to do was to try and find another rear end from a GT350, rebuild it, so as to keep my original rear end intact. I did luckily find a 2016 Low-Mileage GT350 take-out rear end, purchased it for $750.00 + $150.00 shipping.
The rear-end build went relatively well
14 years as a Ford Registered Technician, and many years racing with the Ford 9” rears sure helped, but I had sold or let a lot of my shop tools get away. Without a shop press & bearing splitter, I had to get creative.
Harbor Freight has a Bearing Separator Set that works well with a slight modification. (Item 62593)
I used my 25% off coupon and it was a little over $42.00.
This tool will pull the Yoke off the pinion, as well as pull the inner pinion bearing from the pinion.
The modification needed on the splitter tool is to grind a little more metal from the clamshell splitter, with a (Dumore/Dremel, I used a Craftsman Pro rotary grinder) and grinding bit. The splitter needs to clamp under the pinion bearing, when tightened, without hitting/bending the pinion bearing cage. You have to grind a little from the sides of the splitter for clearance. I wanted to save my old pinion bearing without ruining it so I could later hone it out a little, so as to make a slip-fit setup pinion bearing. This is needed to be able to quickly change shims under the bearing when doing set-up (Pinion Depth).
Honing out the inner (Large) pinion bearing to make a setup bearing is easy, here’s how:
Use a round “Sanding”, -NOT Grinding, bit in the end of your die grinding tool.
It takes about 5 minutes to evenly hone a couple of thousands out of the bearing to get it to: “Slip Fit on the new Pinion”. Believe me, this will save you time later.
Another tool needed is a tool to hold the pinion flange from turning while removing, or torqueing the new pinion nut & crush sleeve. I easily made this tool, Here’s how:
I used a handle I had from a conduit bender. Flatten about 3” on one end with anvil & big hammer, drill two 13/32” holes, 1 + 13/16” apart in the flat end to match hole spacing on pinion yoke, that’s it.
If you don’t feel like making one, you can buy a Pinion flange holder at speedwaymotors.com for $21.99, or JEGS.com for $39.99
The other problem I overcame was how to hold the diff: (Torsen) & ring gear ASSY to replace and torque the new ring gear bolts. I had used a hydraulic press in the past, as well as a heavy duty big vice, but now I had neither.
You really do not want to clamp the Torsen in a big vise, as the barrell on the Torsen is quite thin.
I went to Home Depot and for $3.50 I bought the wood needed to build this holding fixture (Pictured), that I designed. It worked like a champ. I also had some deck screws, and 3” C-Clamps that I used.
View attachment 152605
Another method you can use to work with the ring gear bolt (100 lbs) torque is to use a long prybar as shown below.
On disassembly I noticed the factory had marked the diff carrier caps with yellow paint stripes on each side. I always mark them myself with number stamps anyway, but may not be necessary.
After all parts were cleaned with solvent/blow dried I began the assembly/set-up. What pinion shim to start with was my concern. I have used many pinion depth tools in the past, but I ALWAYS relied on gear-marking compound, and rolling a pattern for my final settings. If I would have had a professional Pinion Depth checking tool today, I could have set it at the (2.259 marking on the end of my new pinion.) I called my Master Mechanic friend at the Ford garage to ask if he had done any newer IRS Mustang rear ends and what pinion shim he ended up with. I also contacted US Gear Tech, as well as Strange Engineering Technical. No-one could give me an answer, other than start with what came in it. So that’s what I did.
Started with (Original): .027 Pinion shim, .273 Left Side Carrier Shim, and .279 Right Side Carrier Shim.
I have set up hundreds of rear ends, and I knew right away this was WAY-OFF. Only had about .003 backlash and the pattern looked like crap. (Way low on drive side, and Way high on coast side)
Here is a link to a very good discussion of Ring and Pinion Setup and other topics:
https://www.cartechbooks.com/techtips/ring-and-pinion-gear-selection-for-optimal-performance/
I must admit I am somewhat of a perfectionist, so I ended up changing the pinion shim and Carrier shims 8 or 9 times to get the pattern I wanted. Ended up with .037 Pinion Shim, .261 Left Side Carrier Shim, .291 Right Side Carrier Shim, and .008-.009 backlash. Pattern was near-perfect.
TIP: To save time when changing shims, and checking patterns I did make a 2 + 1/8” long spacer, out of 1 1/4” PVC, then grind a little from the inside on one end. This eliminated me having to draw the Pinion Yoke on every time, as the yoke is a press fit, and the spacer was a loose-fit. The outer pinion bearing on this rear end is already a slip-fit so everything was fast/easy to change. Do not use crush sleeve for this step.
For the final assembly of the Pinion, (I did replace both press-in cups in the housing) They are easy to replace, you can use a long drift punch, working evenly, side to side)
TIP: On the inner pinion bearing final assembly. For those who don't have access to a press, here are two options that will work on getting the inner pinion bearing pressed on the pinion shaft: (1) (Put the pinion gear in the freezer over-night (or at least 8 hours) before assembly, and then 15-20 minutes before assembly, heat-up the inner pinion bearing in the oven to 375 degrees. The frozen pinion, and the heated bearing make it very easy to tap the bearing down on the pinion, it just about falls on. (Don’t forget to wear gloves, and put pinion shim on first). (2) Buy a 2" threaded black pipe, 8" long, and a 2" pipe cap, at Lowes or hardware store. This will make a perfect bearing driver to install the pinion bearing. Always use new outer bearing, seal, crush sleeve and pinion nut for final assembly.
One other thing about the Pinion Flange, while it is off, paint the dang thing. (I don’t know why Ford doesn’t paint them). I had to use Naval Jelly to remove rust, and wire brush to prep for painting. I masked off seal area, and splines, and used silver header (High Heat) spray paint.
UPDATE: Here is Fords 'Super 8.8' newer Pinion Flange... "It's Painted" !
Did they take that suggestion from me?... Probably NOT
Now for the Swap:
Ford has a great guide for the swapping, and bolt torque specs. I actually found it in the Ford Performance GT350 Diff Cooler install instructions. Most of the steps are the same. But what was important, none of the rear-end remove/install video’s I examined were specifically for the GT350 (Only regular Mustangs). The GT350 is slightly different, especially in the emergency brake area.
Ford Instructions link:
https://performanceparts.ford.com/download/instructionsheets/FordInstShtM-4000-M8SGT350.pdf
I put my car fairly high-up on 4 jack stands, using an 18” 2x4, or the fixture I made (below) you can then lower/remove the exhaust by yourself quite easily with a floor jack. (Put the 2x4/Fixture under the exhaust just in front of where the middle bracketry is welded on the exhaust.)
While it was off, I cleaned and painted the entire exhaust system with silver (High Heat) spray paint (masking off the two-stage muffler electrical cutouts). I also used a 12” 2 x 4 and floor jack also to remove and install the rear end housing back in the car. (Don’t try to handle it by hand, it weighs about 120 Lbs.)
TIP: Removing Half Shafts. The pry-bar method does Not always work so well. I pried and pried on mine with 2 long pry bars, NO Luck, they would not budge. Also prying on them next to the seal area may damage the seal. The trick to popping them out of the diff is to use a sudden blunt force. I still had a “Tire Bead Breaker” slide hammer tool that I ended up using to EASILY pop out axles. If you can’t get this type of slide hammer tool, consider using Long ½” extension and big hammer. (Place end of extension on big round metal half-shaft housing, (Right where it comes out the side of the diff). You will have to hit it a slight angle, as you can’t hit it straight on. It should pop out easier than prying on it.
Gear Oil and Cooling concerns: I filled the rebuilt housing thru one axle hole with a small funnel, before installing. This rear end spec says 1.5L -Without cooler, (I do not have cooler). That is about 51 oz. + the friction modifier. I wish Ford had designed this rear end to hold a little more fluid, as the Older 8.8 Mustang rears held 2.7 quarts. Anyway, I ended up using 60 oz. (I didn't add any Friction Modifier). The fluid level was right at the bottom of check plug hole when I checked it after installing. Keep it level when installing, and no fluid will leak from Axle openings.
If you want to see a pretty cool thread on my rear-end cooling solution see the following link: https://www.mustang6g.com/forums/threads/additional-cooling-and-fluid-capacity-solution-for-the-mustang-‘super-8-8’-rear-end.117720/
Now for the Comparison/Evaluation:
This is not a huge change, it is a minor change.
If your cruising in 5th gear at 70 or 80, and punch it you definitely feel faster acceleration.
I was somewhat surprised to learn that the Speedometer/RPM was not off after swap, (It remained accurate)
I still plan to use Forscan software, and a OBDLink Tool (426101) to change my BCM Data at: 726-12-01, From: 0175 -3.73 Axle Ratio, To: 019A -4.11 Axle Ratio.
I understand that this setting has absolutely No affect on Mustangs with Manual transmissions.
It does affect Mustangs with Automatic transmissions (It affects the shift points)
Here is a chart of the comparison of both gears, speeds, and approx. RPMs.
3.73 Rear Gear
Trans Gear : Speed (MPH) : Engine RPM
5th : 50 : 2250
5th : 60 : 2750
5th : 70 : 3150
5th : 80 : 3650
6th : 50 : 1400
6th : 60 : 1700
6th : 70 : 2000
6th : 80 : 2250
4.11 Rear Gear
Trans Gear : Speed (MPH) : Engine RPM
5th : 50 : 2500
5th : 60 : 3000
5th : 70 : 3500
5th : 80 : 4000
6th : 50 : 1600
6th : 60 : 1900
6th : 70 : 2200
6th : 80 : 2550
Overall this was a Great, Challenging and Fun project.
Having driven with the new setup some 400 miles now, the Gas mileage remains at 18-21 MPG on the highway, 15-17 in town.
Am I glad I did it, and happy with it? Absolutely!
My next Venture?
a 4.56
To read about my Gear Change from 4.11 to 4.56
SEE: https://www.mustang6g.com/forums/th...gear-to-4-56-in-my-gt350.104766/#post-2263820
For some more detailed info on the "Super 8.8" rear... SEE LINK:
Inside the "Super 8.8" Rear End | 2015+ S550 Mustang Forum (GT, EcoBoost, GT350, GT500, Bullitt, Mach 1) - Mustang6G.com
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