Rear end gears for magnum XL trans and these tires?

So one thing I don't know crap about is figuring out the best gear ratios and tire sizes I should be sticking to. Thinking I'm going to be putting a magnum XL trans in here that has the option for 2.66 or 2.97. I currently have 3.55 gears in the rear end and 28.46 DIA tires.

Current Setup -

3.55 Rear End
28.46 DIA tires
Probably 20# boost from a supercharger setup (maybe going to go back to the ole TVS route)

So do I get the 2.66 or 2.97 first gear in the magnum?
Do I need different rear end gears?
I have a leaking seal in the rear end I have to fix and I plan on putting in a truetrack so doing gears isn't the worst thing in the world.

The focus would be on street drivability.

If you want to keep the 3.55's, I'd reccommend the 2.97 first gear.

I would say it depends on the amount of torque. I have the 2.66 first gear and 3.73 gears in the rear on my GT500, which is currently running around 24lbs of boost.

On the 27.4" R888 street tires the car is pretty unusable in 1st, 2nd, and sometimes 3rd. I'm dropping it to 3.31s in the back soon to compromise between street and 1/2 mile. My race wheels are a little taller, and a little softer, but still...

In my Bullitt with well over 600hp to the wheels I had 3.73 gears and the 2.97 first gear. It was too tall for me to run a 28" tire at the track, I'd bog first gear every time. I was ready to go to 4.10 gears just so I could run a normal size tire.

Avoid the 2.66 first gear unless you have some insane horsepower level or you want to run 4.30 or 4.56 gears.

I don't know shit about the transmission you guys are talking about lol, but I have a set of 373 and 410 gears if you end up being interested in them.

I have the 2.97 first gear with 3.73s and just a little 7lb. boost. LOL with the RST twin disk and drives very civilized. I also have Mickey Thompson Street Comp 285/35-19s and can fry 1st and 2nd on demand. So driving around town is good,

I have the 2.66 first gear XL and I just took out my 4.10s and put in 3.55s. I run a 29" ET street R drag radial at the strip and 295/35-20 MPSS on the street. Can't compare 60' times yet, but I did have a 3.73 in it before as well. With 4.10s I cut 1.46-1.53 60s and with 3.73 I was cutting 1.53-1.56. My car is about 650 rwhp with a twin screw Saleen supercharger running mid-10s. Traction has never really been an issue for me with the torque arm and MPSS tires. I can't floor in first on the street but it dead hooks in second shifting at 7000 rpm. At the track I hold about 5000 rpm, dump the clutch and it goes. So it really depends on what you are wanting to do with the car. The 2.97 gear is spaced more for drag racing and 2.66 is spaced more for road racing with closer ratios. The 2013-2014 gt500s come with the same gear ratios as the 2.66 XL and have a 3.31 gear ratio. I have found that my my car is easier to drive on the street with the 3.55 gear than I expected. Honestly I like it much better than the 4.10 at this point. I need to give it time though since I have only had it in for a week. Here's a video of me drag racing with 4.10s and the 2.66 first.

https://youtu.be/J51jp_rw6Tk

Like mentioned its going to be based on your setup. I find the 3.55s to be a tad too tall for my liking with the 6 speed at the track anyway(turbo setups), they are okay on the street. Just hard to get out of the hole at the track. With a 28+" tire and 7000 rpm rev limiter I was trapping in 3rd around 124-126psi at 12psi and never shifting to 4th. Cant seem to 60ft better than 1.8 either even with 6krpm launch in boost on the 2step. Also 6th gear is almost unusable for me, it bogs and drones from the low rpm at standard highway speeds so I only go to 6th if I'm going to be cruising above 70mph. I'm debating throwing 410s in.

I was talked into the 2.66 with 3.55 rear and 487whp / 482trq.. it was a DOG.

I swapped in 4.10s and it's ok, but the oem TR3650 and 3.55s were faster in the 1/4.

I'd go with the 2.97 if I could do it again.

Closely spaced gears make a street car fun to drive. So my vote would be 2.66 trans and a 4.10 rear.

Phew. Seems like a 50/50 split on this. Guess I'll just flip a coin and change rear end gears as I see fit lol

skwerl said:

In my Bullitt with well over 600hp to the wheels I had 3.73 gears and the 2.97 first gear. It was too tall for me to run a 28" tire at the track, I'd bog first gear every time. I was ready to go to 4.10 gears just so I could run a normal size tire.

Avoid the 2.66 first gear unless you have some insane horsepower level or you want to run 4.30 or 4.56 gears.

Click to expand...

So you're thinking with more aggressive gears like 4.56 (possibly with 28"/29" tires) that the 2.66 ratio is a good compromise for civilized street driving and solid performance at the track?

palanza7 said:

So one thing I don't know crap about is figuring out the best gear ratios and tire sizes I should be sticking to. Thinking I'm going to be putting a magnum XL trans in here that has the option for 2.66 or 2.97. I currently have 3.55 gears in the rear end and 28.46 DIA tires.

Current Setup -

3.55 Rear End
28.46 DIA tires
Probably 20# boost from a supercharger setup (maybe going to go back to the ole TVS route)

So do I get the 2.66 or 2.97 first gear in the magnum?
Do I need different rear end gears?
I have a leaking seal in the rear end I have to fix and I plan on putting in a truetrack so doing gears isn't the worst thing in the world.

The focus would be on street drivability.

Click to expand...

I'm reading: go with the Magnum geared at 2.66 with slightly more aggressive gears.

Not to hijack the thread but I was thinking the 6-speed would be detrimental at the track compared to a 5-speed (more shifting).

MassMustang said:

I'm reading: go with the Magnum geared at 2.66 with slightly more aggressive gears.

Not to hijack the thread but I was thinking the 6-speed would be detrimental at the track compared to a 5-speed (more shifting).

Click to expand...

You still only use 1-4 on the track. You don't use 5th and 6th. With the longer 1st gear you might be shifting less.

Sent from my SAMSUNG-SM-G935A using Tapatalk

I'm not super worried about the track otherwise I'd just go with that 4w70 or whatever ive read about lol

palanza7 said:

I'm not super worried about the track otherwise I'd just go with that 4w70 or whatever ive read about lol

Click to expand...

I hear ya! I don't go to the track often but I know I need to upgrade my setup. I was dyno'ed last year around 540rwhp/530rwtq with my 326, Novi 2200SL (12#) and 4.56 gears. The setup is just a bit too aggressive for around town. I have to slip the disc on my TR3650 and Exedy Mach 400 Stage II in 1st gear (or sometimes just start in 2nd).

Looking at the ratios below (I googled this) I think the T56 Magnum or a TR6060 with my aggressive gearing would really improve my driving experience around town. I need a twin disc clutch too.

Here is a ratio comparison:

TR-3650 OEM gear ratio
1st 3.38
2nd 2.0
3rd 1.32
4th 1.0
5th 0.675

TR6060 (stock GT500 2007-2009)
1st 2.97
2nd 1.78
3rd 1.30
4th 1.00
5th .80
6th .63

TR6060 (stock GT500 2010-2012)
1st 2.97
2nd 1.78
3rd 1.30
4th 1.00
5th .74
6th .50