4.10's in GT PP

[pinero61]

Okay, so I'm gearing up to do a Tremec t56 swap...

To achieve the setup I want, the 2.66 ratio w/ 4.10's out back would be perfect. Unfortunately, I can't find anything besides the stock ratios from FRPP. Does anyone know where I can find these?

Maybe the 2.97 w/ 3.73 will be a better setup.

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[Grimace427]

I've driven a PD blown 2011 with the 2.97 Tremec and 3.73 gears. IMO and also the owner's opinion the gear spacing was not very good, especially the 3-4 shift. I would go with the 2.66 option and at minimum 4.10 gears. If you are N/A having 4.30 gears would be even better. With boost go with 3.73 and the 2.66.

If you go with 4.10 or 4.30 you might want to consider upgrading your driveshaft because you will be increasing DS RPM's due to the shorter final drive gears.

 

[pinero61]

Yeah, that was the plan, but I can't find the gears I need. I'm going with the DSS aluminum shaft and a mcleod RST.

Car is NA w/ CJ, Headers, and soon to have cams.

 

[Grimace427]

Check with Kelly at BMR as he's got a lot of experience swapping the rear gears on the S550. For the CJ intake definitely go with 4.30's if they are available.

What is your tire diameter? This is the gear ratio calculator I use. http://www.f-body.org/gears/


Assuming 4.10 gears, 27" tires and 7,800rpm redline:

1. 2.66...57mph
2. 1.78...86mph
3. 1.30...118mph
4. 1.00...153mph
5. 0.80...191mph
6. 0.63...1,900rpm @60mph

With 4.30 gears:

1. 55
2. 82
3. 112
4. 146
5. 182
6. 2,000rpm @60mph

 

[pinero61]

Here's one specific to the MT82 and T56:

https://drive.google.com/file/d/0B2y...ew?usp=sharing

 

[pinero61]

I love how easy it is to drop the chunk for a gear swap in these cars.

 

[Grimace427]

Here's one specific to the MT82 and T56:

https://drive.google.com/file/d/0B2y...ew?usp=sharing

That file didn't work for me.

What is your tire size and redline?

 

[pinero61]

27.4, 7,500

 

[Grimace427]

27.4, 7,500

With 27.4" tires, 7,500rpm redline, and 4.10 gears:

1. 54
2. 80
3. 110
4. 143
5. 178
6. 2,000rpm @60mph

With this setup if you're trapping 120mph in the 1/4 you'd have to shift into 4th gear and cross the stripe at 6,300rpm which is definitely not ideal. If you dropped down to a 26" rear tire(just for drag racing) you'd still cross the finish around 6,700rpm assuming about 120mph trap.

If drag racing is your thing you'd either have to finish in 3rd gear or go crazy with 4.56 or 4.88 rear gears to finish in 4th gear.

 

[mustang_guy]

See if yukon has any gears out for this new super 8.8. They might. https://www.yukongear.com/ i dont believe strange has any options yet.

 

[pinero61]

With 27.4" tires, 7,500rpm redline, and 4.10 gears:

1. 54
2. 80
3. 110
4. 143
5. 178
6. 2,000rpm @60mph

With this setup if you're trapping 120mph in the 1/4 you'd have to shift into 4th gear and cross the stripe at 6,300rpm which is definitely not ideal. If you dropped down to a 26" rear tire(just for drag racing) you'd still cross the finish around 6,700rpm assuming about 120mph trap.

If drag racing is your thing you'd either have to finish in 3rd gear or go crazy with 4.56 or 4.88 rear gears to finish in 4th gear.

Not really a drag racer. I run sometimes, but the build is more geared toward carving corners.

Final Drive Ratio (T56 2.66)
3.73 3.55 4.1 4.3
1 9.92 9.44 10.91 11.44
2 6.64 6.32 7.30 7.65
3 4.85 4.62 5.33 5.59
4 3.73 3.55 4.10 4.30
5 2.76 2.63 3.03 3.18
6 1.87 1.78 2.05 2.15


Transmission Gear Ratios
MT82 Mag XL 1 Mag XL 2
1 3.66 2.66 2.97
2 2.43 1.78 2.10
3 1.69 1.30 1.46
4 1.32 1.00 1.00
5 1.00 0.74 0.80
6 0.65 0.50 0.63

Engine Speed @ 70
3.73 3.55 4.1 4.3
6 1602 1524 1760 1846

 

[Grimace427]

Not really a drag racer. I run sometimes, but the build is more geared toward carving corners.

This is good to know. Get the 2.66 gears since they are more closely spaced. Drive it a while with your 3.55 gears and decide which rear gears you want. You will almost feel like you are starting in 2nd gear with the MT-82.

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