sluggish in lower gears

[tcman54]

When I am on the expressway and stepping on it (4th,5th,6th gears) the car feels very spirited and just wants more.

When I then get off the expressway and just drive around town at residential speeds (1st,2nd,3rd gears) the car seems sluggish, have experienced a few lesser cars get the better of me, it is getting really annoying.

Anyone else experience this, is this just the way the gear is geared or what?

TC :shrug:

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[jtmat]

I'm back on the stock tune... mine is opposite... it is not so quick on the highway, but very quick in the lower gears.

When I had unleashed tune on it, it was quick hwy and city driving... fast all the way around.

Can't wait to get another tune on this thing...

 

[Witj85]

I'm with tcman54 mine is better in 3rd and above most of the time. I've noticed that boost doesn't build into upper teens til after 4k. Maybe it's the way it's tuned from the factory but boost seems very limited down low.

 

[jbailer]

Maybe it's the gears in your cars? I have the Performance Package with the 3.55 gears and the low end is VERY peppy!

 

[tcman54]

Maybe it's the gears in your cars? I have the Performance Package with the 3.55 gears and the low end is VERY peppy!

I got 3.15

If I upgrade to this http://www.americanmuscle.com/frpp-355-gears-2015.html would I have to change the differential?

The change appears to be a little more complicated then I thought after reading this, http://www.americanmuscle.com/mustang-rear-differential-gears.html


TC :shrug:

 

[Terminator2]

I got 3.15

If I upgrade to this http://www.americanmuscle.com/frpp-355-gears-2015.html would I have to change the differential?

The change appears to be a little more complicated then I thought after reading this, http://www.americanmuscle.com/mustang-rear-differential-gears.html


TC :shrug:

I thought about swapping my GT from 3.31s to 3.73s but after seeing you have to drop the whole rear cradle out. Yeah no thanks until I actually need to rebuild to replace something in the rear end.

 

[TheLion]

I got 3.15

If I upgrade to this http://www.americanmuscle.com/frpp-355-gears-2015.html would I have to change the differential?

The change appears to be a little more complicated then I thought after reading this, http://www.americanmuscle.com/mustang-rear-differential-gears.html


TC :shrug:

I still need to post my DIY rear end swap, completely forgot about that (several people were asking) but I did a rear end swap in my garage with no special tools. I bought a used GT PP diff assembly from a generous GT driver (hint hint) on E-bay for $650 with the Torsen LSD, that assembly costs $1900 new on CJ Pony or AM. It was worth it for the Torsen alone.

Dropping the IRS isn't as daunting as it sounds if your a competent home mechanic. If you can coil springs on struts, control arm replacements or other suspension work, you can do a rear end swap.

I simply made a wood cradle holder from some scrap 2x10's I had left over from building a deck, put the jack under it and lowered it all down. Once its down with some muscle you an maneuver it around, roll it away etc.

HOWEVER, I did NOT do a gear swap, I did the entire diff assembly swap. There are several reasons:
1. you need a case spread to remove the diff and ring gear, which is a specialized tool I could not find anywhere. You could fabricate one if you can weld (I can't nor do I have the equipment).
2. you need a proprietary socket for the diff housing bolts (looks like a torque socket of sorts).
3. I also wanted to upgrade to a torsen because my goals were more in line with Stang TV's 5 Liter Eater project car, I wanted to built a track / street car, not just a drag car and the torsen is a must for auto cross or track to actually put power down out of corners (also it's nice to have to winter if you live in a 4 season state because it acts like posi on slippery roads which is better than 1 wheel drive!).
4. You need to shim the pinion properly to get the mesh correct, while this isn't a super complex process, it can be tedious as you have to keep pulling the diff in and out of the housing and make adjustments.

If you buy a used non pp S550 diff or just the housing, you could have the diff built at a shop which would have the case spreader etc. then swap out the assembly yourself. OR you could buy a used GT PP rear end in 3.73 and get the Torsen LSD with it for about $900 on e-bay or a scrap yard. S550s are new, most of the diffs out there have around 10k to 20k miles or less.

If your not going big turbo / nitrous or other power adders, I would recommend the 3.73 over the 3.55 (unless you have an auto, if you have an auto go 3.55, you can buy an AUTO GT PP diff used that has the torsen in 3.55). It really helps the car get off the line FAST. It also is much easier to control launch with the low gearing if your not running DR's (which most of us don't).

Here's a few example photos:

 

[neodark]

Nice, that looks a bit daunting for me. I have 3.31s, and auto. Thought about 3.55s but I think the difference wouldn't be enough to make it worth it.

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