3.73 to 4.88 Gear Swap Problems in 2020 Bullitt

[gismo4]

There definitely is a noticeable drivetrain rumble/low whine. It bothered me at first, but honestly now I don't even notice it. I'm so incredibly happy with the new ratio that I'd trade some minor noise for the better ratio all day, every day.

No changes. Extremely happy with the 4.88s. I'd strongly consider them instead of 4.56s. The torque is just insane.

At first I was going to supercharge it, but even that was just an $8k bandage to the real problem; too high (or long) of gears. Once swapping to 4.88s, I am so happy with the feel I changed my mind and probably won't SC anytime soon. The problem on these cars is gearing, not a lack of power.

I've said it before but it's like reading my own feedback about the car. I was considering supercharging as well for the same reasons. Let me bother you again about the track apps or even the drag strip now that the weather is slowly getting better. Post some times when you can!

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[GreenS550]

Thanks a lot for getting back with me. I absolutely believe what you say makes the most sense. When I took my Whipple charged Bullitt to the drag strip, I had a REV that sucker to 5,000 RPM and with my Mickey Thompson on, pulled the front wheels off the ground but it still didn't fix the gearing issue and I shifted at over 100 miles an hour into third and the clutch would slip. Totally dissatisfying pain in the butt. And even then it was only running mid 11s on a car that should easily do high tens. My naturally aspirated 2018 with the automatic transmission does low to mid 12s all day long on street tires.

The best I did with my Bullitt stock was low 13s on the PS4s that came with it. It was a bear to launch and you either spun the tires or you slip the clutch in an unsatisfying way.

 

[L0566Bullitt]

I've said it before but it's like reading my own feedback about the car. I was considering supercharging as well for the same reasons. Let me bother you again about the track apps or even the drag strip now that the weather is slowly getting better. Post some times when you can!

I'm out of town for work quite a bit but I will if I ever get the chance.

 

[L0566Bullitt]

Thanks a lot for getting back with me. I absolutely believe what you say makes the most sense. When I took my Whipple charged Bullitt to the drag strip, I had a REV that sucker to 5,000 RPM and with my Mickey Thompson on, pulled the front wheels off the ground but it still didn't fix the gearing issue and I shifted at over 100 miles an hour into third and the clutch would slip. Totally dissatisfying pain in the butt. And even then it was only running mid 11s on a car that should easily do high tens. My naturally aspirated 2018 with the automatic transmission does low to mid 12s all day long on street tires.

The best I did with my Bullitt stock was low 13s on the PS4s that came with it. It was a bear to launch and you either spun the tires or you slip the clutch in an unsatisfying way.

Sounds about right. Although it will be harder to get traction in first and second with lower gears...

 

[GreenS550]

Sounds about right. Although it will be harder to get traction in first and second with lower gears...

Ah, drag radials and slicks my friend!

 

[Elp_jc]

1st is nearly identical. That is the real issue, the rest are more closely spaced as the Tremec has 5th 1:1 and the MT82D4 has 4th 1:1.

Man, that's weird. It has worse gearing than the MT82-D4 then. The good news is that with 4.56/4.88s, you'd have really nicely spaced gearing all around. I don't like the huge jump from 5th to 6th with a 1:1 5th; that's why I like the D4 a lot. I use the car a lot to travel, and not having a useful 5th is a deal-breaker for me, since 6th is quite tall for anything other than flat. And with such a small fuel tank, the car would have a lousy range with anything shorter than the current 6th. Current highway range on my car is barely acceptable now. I'm probably in the minority, but for me, Ford nailed the gearing on the Bullitt, since it's mostly a GT car, not a sports one. But for those who want to use it as a track or drag car, I see how inadequate the gearing is. Ford should have used closer gearing on the PP2 cars IMO, but it's perfect for PP1s. But now that there are no more PP2s, and the Mach1 is more of a PP2+ (which I'd never consider buying), with all the coolers and stuff, it should have shorter gearing indeed. Or at least shorter (like 4.56) gears.

Final question: Why does changing gears add noise, if they're also beveled? Just curious about that. Thx.

 

[NGOT8R]

I believe that most of the gear whine comes from inadequate backlash settings. I’ve never done it, but if I did want gears installed, I’d do it myself, because to do it right might require a few tries with different shims to achieve the correct backlash. I just don’t think most installers are willing to invest that time (taking apart two or more times to try different thickness shims), in gear installs and it’s just easier to tell the customer: “Oh, that’s normal.They all whine.” To that I say: “Yeah right.” And yes, I have paid for a gear install before 3:73 in an 89 GT and it howled like a werewolf. The installer gave me that same BS line of crap about it being normal.

 

[GreenS550]

My next door neighbor owns a ring and pinion shop. If I take the diff out he will do the gears for $150. That is all he does is differentials...

 

[NGOT8R]

My next door neighbor owns a ring and pinion shop. If I take the diff out he will do the gears for $150. That is all he does is differentials...

That sounds like the way to go. If that’s all he does, I’m sure he will get you set up right. Are you going to outfit the subframe and control arms with all the necessary goodies while you’re at it?

 

[L0566Bullitt]

I believe that most of the gear whine comes from inadequate backlash settings. I’ve never done it, but if I did want gears installed, I’d do it myself, because to do it right might require a few tries with different shims to achieve the correct backlash. I just don’t think most installers are willing to invest that time (taking apart two or more times to try different thickness shims), in gear installs and it’s just easier to tell the customer: “Oh, that’s normal.They all whine.” To that I say: “Yeah right.” And yes, I have paid for a gear install before 3:73 in an 89 GT and it howled like a werewolf. The installer gave me that same BS line of crap about it being normal.

Interesting...these guys are supposedly the best on the east coast. But who knows

 

[GreenS550]

I believe the whine almost always comes from incorrect install.

 

[GreenS550]

That sounds like the way to go. If that’s all he does, I’m sure he will get you set up right. Are you going to outfit the subframe and control arms with all the necessary goodies while you’re at it?

Not necessary in my opinion.

 

[NGOT8R]

Not necessary in my opinio

Not necessary in my opinion.

I gotcha. No wheel hop on the Mach1’s?

 

[GreenS550]

I'm supercharged three S550 so far and I don't have a problem with will hop. The only mods that I've used are BMR cbo-05. But I just never really seem to have a problem with it.

 

[Elp_jc]

I gotcha. No wheel hop on the Mach1’s?

Nothing changed in the suspension from other high-trim Mustangs AFAIK, so it must still be prone to it.

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