87 trans am, around stock weight 3300ish lbs. turbo 5.3 pushing 12/14psi on the street only via a VS gen 1 billet 78/75 2004R with 2500 stall (3k flash) and lockup. Ford 8.8 with 3.55s, upgraded trac lock, arp cap studs and a moser girdle, stock 28spline axles. Wheels are OE wheels repro Z06 aluminum 18x9.5s all the way around. The rear I had to swap on 285/45r18s to get the wheels to stop spinning in boost.

The car is only street driven and I want to put more highway miles on it and it does great on the highway. Guy who built my rear is no longer around and it’s got a leak on the front seal slinging gear oil over my tunnel and exhaust. I was going to pull it this winter to redo some brake lines and get the seal fixed and thought about putting taller gears in it. The 3.55s and the 28” DRs effectively make it a 3.42 ish. I was thinking of doing 3.08s to help with highway and loading the turbo a little more for better spool.

What is your guys thoughts? Would it be worth it? Car is kinda light and INJ duty cycle shows about 650crank Hp at 14-15psi. Figured the taller gears would also help with traction which the DRs helped a lot with.

 

Overdrive transmission or 1:1? I liked the 3.27's and a 27" rear tires on my last turbo Malibu.

 

OD .67:1 with a locked converter and 28” tall tires. Like I said it does great on the highway, 70mph is like 2k rpms. Which is why I don’t know if dropping to 3.08 is worth it. Given they will
act like 2.73 with 28” tires. I figured the 3.08 would help more around town with loading the engine but I still have the 2500 stall.

 

I’ve ran several combos. 3.08 and 28” tire with a th350 and a th400, as well as 3.31 and 3.50’s, and then 3.73 and 3.50 with my 80e. Imo I’d stay were you are. The 3.50 gear was my favorite in both combos, and my new car is also going back with a 9”
and a 3.50 gear. Sounds like your car is perfect honestly, I wouldn’t mess with it and add a bunch of extra stress to the trans and rotating assembly by dropping so low.

 

Not sure what your combo is doing torque wise, but I'd do 3.08s if I were you. With you being somewhat lightweight, it should pull well down low, and have nice legs up top, as well as cruise nicely.

 

Thanks for the input. I also feed that the car drives very well so far, but it could drive better with taller gears. You don't know till ya know. Which is why its a hard choice, I don't hate what I got or see any real problems and I would hate to spend the money and not be as happy as I am now.

 

These are the thoughts lingering in the back of my head lol. Torque isn't a huge problem, car feels and pulls great on the highway or town in locked 4th around 40mph and its lugging around at 1100rpms lol. My thoughts tho are with the converter stall. The converter currently stalls around 2500 in regular driving and will flash to 3000 depending on the throttle input. Will I even notice the 3.08s with the converter stall around town? I feel like I'm always in the 2000-3500 range which it has more than enough power to scoot around town. The 5.3 has a custom blower cam from Cam Motion, 218/228 .561/.561 114.5+5 and I feel like the turbo added more low end compared to my centri with big 1 7/8" primary Long tubes. The 862 heads are also ported by me, just cleaned up around the valves alittle and removed the swirl ramps.