How are people liking 4.09 gears in the MT82?

[MRGTX]

So I brought my car in for the swap on 8/5, as has been scheduled for a month and I'm back to report: Nothing.

The storm that blew up the east coast this past week knocked out power to hundreds of thousands which included the dealership (and my house too). They said that I could leave the car and take the Fusion loaner but they had no idea when they would get to the job, or they could call me when they were ready. I said, no thanks to leaving my car unattended in a sea of door ding potential...and that I would come back when they were open again.

Strangely enough, I was just out for a morning walk and there was a Fusion loaner car parked in my neighbor's driveway from the same dealership. Something tells me that this was the car that I scheduled a month ago. Maybe or maybe not....but they're clearly up and running again and they haven't called me yet.

So just a heads up on this- nobody wants to do this job. This isn't "easy money" for any shop and you may be treated accordingly.

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[Mikepol2]

For sure. I called 3 dealers trying to get a price on it and all said they'd call back but never did, which kind of forced me to do it myself.

 

[K4fxd]

For example my RPM's in 6th gear would be at about 2600-2800 while cruising at 80mph.

I find that amusing. Back in the day stock factory cars turned 2500 rpm at 55 Mph.

My question is, do you need a diff cooler if you were to drive on the freeway for 600 plus miles at a time using the 4.09 gear?

 

[Superspirit]

I find that amusing. Back in the day stock factory cars turned 2500 rpm at 55 Mph.

My question is, do you need a diff cooler if you were to drive on the freeway for 600 plus miles at a time using the 4.09 gear?

My opinion would be no. On a 600 mile trip you won't be constantly accelerating and decelerating at high rpm to load and heat the gears like you would on a track.

 

[MRGTX]

I find that amusing. Back in the day stock factory cars turned 2500 rpm at 55 Mph. ...

So true!
My old Dodge isn’t representative of general stock equipped cars from its day but it could have been bought new with these ratios; with the Torqueflight 3spd and 4.10 final drive, I’m sitting right about 2,000 at 40MPH (on ~27” tires). Not great for engine longevity nor environmental concerns. Fortunately, it’s a fair weather/summer/weekends only car and it sure is fun.

 

[K4fxd]

I had several cars with 3.23 rear gears that turned 2500 at 55 mph.

The old rule of thumb for gearing was to keep it at 3000 at 60 Mph for a decent street strip setup

 

[ice445]

So I brought my car in for the swap on 8/5, as has been scheduled for a month and I'm back to report: Nothing.

The storm that blew up the east coast this past week knocked out power to hundreds of thousands which included the dealership (and my house too). They said that I could leave the car and take the Fusion loaner but they had no idea when they would get to the job, or they could call me when they were ready. I said, no thanks to leaving my car unattended in a sea of door ding potential...and that I would come back when they were open again.

Strangely enough, I was just out for a morning walk and there was a Fusion loaner car parked in my neighbor's driveway from the same dealership. Something tells me that this was the car that I scheduled a month ago. Maybe or maybe not....but they're clearly up and running again and they haven't called me yet.

So just a heads up on this- nobody wants to do this job. This isn't "easy money" for any shop and you may be treated accordingly.

Can't say I'm surprised, really. If you have a specialty Mustang/muscle car shop near you they will probably be fine with doing it, but dealers hate specialty jobs like this that requires an experienced tech to be sidelined. The irony being that if they had a tech who has installed gear sets before or at least knew how, I guarantee he wants to do that customer pay job over warranty BS.

Doesn't help its like 4 or 5 hours of labor to remove the rear diff, and you gotta do new fluid, new nuts, etc.

 

[MRGTX]

Can't say I'm surprised, really. If you have a specialty Mustang/muscle car shop near you they will probably be fine with doing it, but dealers hate specialty jobs like this that requires an experienced tech to be sidelined. The irony being that if they had a tech who has installed gear sets before or at least knew how, I guarantee he wants to do that customer pay job over warranty BS.

Doesn't help its like 4 or 5 hours of labor to remove the rear diff, and you gotta do new fluid, new nuts, etc.

I’m sure you’re right about all of that...what’s annoying is that this is WHY they have specialty techs, right? The stuff that goes wrong and needs to be fixed on the general population of CUVs and pickups should be routine and not require their ace tech. People like us are the ones who are personally invested in their products, are ambassadors for their brand.

It’s just frustrating.

So I called them to reschedule and the receptionist said that the service department was trying to catch up and would call me back. 30 hours later, no return call. I called them again and held until I could talk to someone in the service department. They had no loaner cars until 8/24 so I’ll be waiting a big longer...they were sincerely apologetic for the delay and I believe them. They seem like they are doing their best even if they’re dropping the ball at the moment.

I’m getting some more miles on the 3.55s which will only make the 4.09s feel that much better!

BTW, what 0-60 times have you guys managed with your 6spd 3.55 cars?

Admittedly, I have only tried a few times but I have yet to crack into the 4s! The car feels faster than that but I guess it’s not.

My 2011 GT Brembo package car (just a tune and these exact same 285 tires, optional 3.55 axle ratio) was easily in the high 4s on most runs. The best I measured was 4.55 (GPS Gtech). It definitely felt quicker than the 2020.

 

[Mikepol2]

It’s just frustrating.

Agreed... I think in an earlier post I mentioned trying 3 different dealers to get a price to do the job and getting zero call backs. In the end I'm glad because it forced me to do the diff removal and install myself which probably saved around $800-ish.

 

[Angrey]

Just now reading this thread. I swapped gears in my GT350 (3.73 to 4.09) over a year ago. I had Lund tune it for 4.09s when I did my E85 tune. As discussed earlier, the speedo is now based on wheel speed (not trans/ds speed) so it won't mess with your speedo, as for torque values and such, I'll defer to others. I haven't had any ECU issues with the gear swap.

As far as the work goes, the Super 8.8 is a pain in the ass and not a lot of shops have experience or knowledge in how to do it. From my understanding it's much more involved than the old 8.8 swaps. For the few shops that I found that actually did the swap, I got a range of $800-$1300 to do the swap. Crazy (compared to an old 8.8 solid axle swap). The shop I used is top notch and actually sent me vids and photos of the backlash, etc.

I went with US gear (I did my swap before FRPP offered the lightning isotropic finish). I actually had to buy the FRPP 4.09 (US Gear makes them) and send it off to their partner facility to have the isotropic finish. FRPP is weird with their licensing lockups, so at the time that's the only way I could get a set of 4.09 with the full treatment from US Gear. I think FRPP now offers the upgraded finish.

I went with the 4.09 (as opposed to US Gear who can still sell the 4.11) because of the tooth count. Although US gear admitted both sets would be sufficiently strong, the higher tooth count means a little smoother running and also gets more incoming contact and outgoing contact from more teeth (as opposed to the 4.11 that has beefier teeth, but less of them so less contribution from the incoming and outgoing teeth). All brain damage aside, gears have been in and factory quiet since installation.

The TR3160 is even worse (paired with the GT350) than the new MT ratios. With the extra rpm, the 3.73 is just too tall (paired with the trans ratios). In discussions with US Gear, apparently, 4.09 is as large as FRPP can go without violating some sort of CARB restriction. I think that has something to do with why all the newer trans variants have really tall gearing compared to the older oem trans offerings.

The car is much livelier with 4.09s but at 500 rwhp on an N/A setup, it's about as much gear as I can stand on street/track radials. The car is on rollers skates on concrete or any unprepped surface. I can't run anything less than a 19" tire, so there's that. If I could run smaller wheels and some DR's it might be able to take more gear.

My new trans setup is about to go in and pairs perfectly with the 4.09s (a close ratio magnum XL). I now have the best of both worlds (lively lower gears and a .50 second overdrive for nice and calm/quiet long cruises, hopefully I'll be able to have a phone conversation without having to slow to 60 mph).

If you're planning on staying naturally aspirated, I highly recommend the cost and pain of the 4.09 swap. Aside from the E-85 tune, it's probably the most "felt" mod I've done. Car just feels livelier in all situations.

 

[MRGTX]

Great insights, @Angrey. It seems that the GT350 would benefit from the shorter final drive even more than Coyote cars. You’ve got a lot of variables in your combo to figure out how this relates to us poor GT slobs but it is good info just the same.

In particular, hearing that the IRS version of the 8.8 is uniquely difficult to work on, is enlightening and it explains why multiple shops did their best to convey that they didn’t want the gear swap job.


My GT has been in the Ford service shop since Monday...they’re predicting that it won’t be done until Friday. I’m skeptical they will even have it done by then. I’m enjoying the brand spanking new Ranger loaner vehicle...at the least, it’s nice to spend some time with an Ecoboost 4 banger and educate myself on what it’s like to live with one for more than a quick drive. The Ranger had 28 miles on it when they handed me the keys...since it’s not even close to being through the break in period (and it’s obviously not my property) so don’t expect any reports on max acceleration performance or videos of Smokey burnouts. Oh well.

BTW, my 2020 is a 100% stock base GT 6spd...only changes other than the gears and Torsen unit are irrelevant to the performance. I have added the PP bracing, catch can, the old RTR wheels/285s from my S197. So hopefully the changes that I observe will be a another good baseline for folks.

 

[K4fxd]

Having to beak in an engine went away with the Dodo bird. No longer necessary. Ford breaks them in at the assembly factory.

Hammer away

 

[MRGTX]

Having to beak in an engine went away with the Dodo bird. No longer necessary. Ford breaks them in at the assembly factory.

Hammer away

Please tell us that your owner’s manual isn't still wrapped in plastic.

You may be right, you may be wrong but it’s in the manual and as far as I can imagine, Ford has no reason to include this if it didn’t have some value.

The problem you’ll find is that Internet forums are full of people who argue that it “doesn’t matter“ because they didn’t follow the instructions for whatever reason and they are compelled to defend their choice...and like debating motor oil, it’s very difficult to discern cause and effect in the long term.

Personally I follow the guidelines, especially when it’s someone else’s $40k pickup truck. I’d want them to extend the same respect with my property.

 

[Angrey]

Please tell us that your owner’s manual isn't still wrapped in plastic.

You may be right, you may be wrong but it’s in the manual and as far as I can imagine, Ford has no reason to include this if it didn’t have some value.

The problem you’ll find is that Internet forums are full of people who argue that it “doesn’t matter“ because they didn’t follow the instructions for whatever reason and they are compelled to defend their choice...and like debating motor oil, it’s very difficult to discern cause and effect in the long term.

Personally I follow the guidelines, especially when it’s someone else’s $40k pickup truck. I’d want them to extend the same respect with my property.

The motor breaks in in the first few miles. The clutch and rear gears however, need longer. I wouldn't flog a brand new car for some time, not necessarily for the motor, but because the clutch needs proper bedding (to achieve maximum hold capacity and longevity) and the rear gears are supposed to be worked a bit before completely abused.

 

[K4fxd]

You are correct, the engine is broken in at the factory, the rest is not. But everything is worn in long before 4000 miles. Machining is one hell of a lot better than 30 years ago.

Actually the rear gears are run in also, that is why they give pinion depth and backlash settings. They do need to heat treat in service and that takes about 500 miles.

I'll guarantee you the kids or senior Union members who load the cars on the trains are not being easy with them. Same with the dealer mechanic who does the dealer check off. My name is on a bunch of GM cars sign off sheet.

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