My new to me 1988 IROC 5.7 has a 9 bolt rear end and 2.77 gears.
First: does this have a different rear disc brake system that will interfear with installing the 89 bigger brakes vs the disc braked typical 10 bolt unit? What about routing the rear lines?

Second: I see many posts with people really happy with their 3.*# gears, but little mention of the 2.77. Did it have a specific marketing attraction for GM? What is it best suited for. Any reason not to keep it????

Third: what was the estimated fuel mileage in this setup compared to a H.O. 305 stick shift???

Fourth: Does the normal 3 link system work and all the other suspension parts?

Thanks on this one. There's a lot of posts out there that hint at things but none popping up with detailed information.
Nitro

 

First: 88 had the Delco Moraine iron calipers which were famous for not working. Even after installing GMs kit for these brakes results were 50/50 at best. You'll have to swap everything from the backing plate out for the 89-up discs. Contact Ed Miller, he can set you up with everything.
Second:2.77 was the gear set that most of the 5.0 auto cars came with. The 5.0 5 speed cars came with 3.45 while the 350 cars were supposed to come with 3.27. Maybe someone swapped a 2.77 into yours at one point.
Third: I have no idea.
Fourth: the rear will bolt into any third gen from 82-92 with no hassles and is a good upgrade from the standard 10 bolt.
I swapped my old 10 bolt drum rear for a 2.77 9 bolt and swapped to the 1LE brakes at the same time. I personally wanted the 2.77 as I was tired of the 3.73 gears in the 10 bolt.
Hope this helps.

 

Stock gear ratio for 88/89 350 TPI Cars was the 9-bolt BW 2:77. The 9-bolt BW 3:27 ratio was the G92 option on the 350 TPI at a additional cost.

 

I was unaware of that. Thanks for the correction.

 

Mongoose- Thank You for your reply, it was/is going to be helpful. It's taken a lot of search clicks to find out what I actually have and how to improve it.

May I ask if you noticed a significant difference with the gear change and if there were any adverse affects? Nitro

 

s-plane lucy?

 

Does it really make that much of a difference? I've just never explored gearing ratio's yet. (emphasis on the word 'yet')

I wouldn't think it would effect final freeway cruising speed/fuel mileage much with the 4-speed automatic. But I did have an issue once with one hot rod mini truck I built where at 55mph I had to choose 4th or 5th gear to drive in. Fourth was to high of RPM and Fifth started lugging the engine....
Nitro

 

use the calculator on the main page and see the differances, the higher the ratio the lower your top speed but the quicker you accelerate (and dump gass) I don't do alot of gear playing but trust me think about how you plan on using your car before you swap something huge in. the way gas prices are now a high gear ratio could cost a pretty penny to drive to and from work. with my Th350 and 4.10's i was getting horrible gass milage, i think it was in the range of 5 mpg but no one could touch me off the line, now i got a 5spd and 3.08's and im in the teens and civics eat me off the line. they are both extremes just figured i would give you something to think about for your future gear swaping exploration

 

I hadn't really thought much on the around town issue, only freeway cruising. Also, I missed the computer option on the main page, thanks for pointing it out.

I live near the ocean and mountain redwoods; lots of winding roads. Although I really enjoy the 1/4 mile runs, my true love is tossing around curves and quick freeway passes, along with some Interstate high speed cruises. *** I love this board; everybody really shows maturity and knowledge!!!! Nitro

 

gearing makes a HUGE difference. The calculators help. You need a ratio that suits your needs/driving.
- Also remember, lower gears(numerically higher) can many times equal better gas mileage. Too low of an rpm and you get under the cam and loose gas mileage....

 

Shagwells on to something. I have a destroked (3.25") 400 with Vortec heads. I'm running a T5 with a 4:10 gear. The flywheel is a factory lightened unit. I believe 18 lbs. I'm running a CompCams hydraulic roller cam that specs out to something like .480" intake/.510 exhaust with a 112 degree lobe seperation. 1.6 ratio roller rockers. Despite the light flywheel, the car can leave a stoplight with the smallest application of throttle, thanks to the 4:10 gear and good torque. It can be short shifted under normal street use to keep the RPM's down and pulls down respectable 15 city/21 highway mpg's. When it's time to rumble, you better be pointed in the direction you want to go because at 3500 rpm, she pulls like a train to 6000.

 

Here's what I get for only buying imports this past 15 years. When I sold my 78 Z28 for a reliable college Toyota, I was hardly able to change my own spark-plugs and had never heard of 'indexing' or 'anti-sieze' at that point. It's been very cost effective to stay with imports, as I love to rack up 25-30 thousand miles each year touring and exploring anywhere I wanted to. Now I can see how much fun I've missed learning how to match so many seperate mechanical aspects up Into my own unique dialed in package.
"Too low of an rpm and you get under the cam and loose gas mileage...."
Well, I can tell I'm just blah-blah-blahing. It's just that I've come to really love working on my own vehicles. There are plenty of contributors on this board who have the teaching talent. It's not that there isn't a huge amount to learn on a basic Toyota 4 cylinder, but the choices over the years of available bolt on 'go-fast' options were so few and far between. It didn't take much thinking and planning; more of just a cookie cutter menu (till the Supra/Turbo scene came on nationwide). Again, I just want to thank you all for guiding us newbies along. Nitro

 

You guys with big modded motors go to www.autoweldchassis.com and check out what they offer. I installed there big fully adjustable kit the end of last year and it is the best you will ever see.