TH350 and Differential
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
TH350 and Differential
I am putting 400 HP in my motor and will be rebuilding my TH350 to handle that power. I will be driving this vehicle around the city, as well as on the highway sometimes. The differential has a 3.08 gear ratio in it right now, but I am not sure I want to keep it that way. Will a 3.08 still get up and go with a 400 HP motor? I want it to accelerate quick, but not so quick that the engine runs at crazy RPMs. I was thinking about putting in a 3.36. I don't have the option to change the TH350 tranny. So what are your thoughts?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
Does it matter if I will be usig the stock TH350 for the tranny? I want this thing to take off more than I want it to go fast on a straight road - but I still want it to go fast. I guess you have to compromise...I can't decide. A 3.55 will take off faster than a 3.36...but how much faster in speed can you get using a 3.36 over a 3.55?
Last edited by stinger12; Dec 11, 2007 at 03:50 PM. Reason: wrong info
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
Does it matter if I will be usig the stock TH350 for the tranny? I want this thing to take off more than I want it to go fast on a straight road - but I still want it to go fast. I guess you have to compromise...I can't decide. A 3.55 will take off faster than a 3.36...but how much faster in speed can you get using a 3.55 over a 3.36?
But at some point you also have to address traction. If you have 400 HP, and 3.55 gears, will you be able to keep the patch planted to get that good launch or will you spin em before you start moving?
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I have a stock TH350 right now and will eventually be swapping up to an overdrive TH200R4. It has a very similar first gear to the TH350, so I will probably leave my gears at 3.08 or go up to 3.36. I like the 3.55 but I want to keep a respectable top speed.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Melting Slicks
Joined: Jul 2005
Posts: 2,545
Likes: 3
From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
This is not everyone choice, but our 79 has 378 rwhp, 4.56.1 gears, Th400 trans with a TransGo street/strip shift kit with 295X50X15 tires. It hooks up fine.
There are car owners here with alot more HP that seem to find the right combination to hook up, trial and error with gearing, tires, suspension.
There are car owners here with alot more HP that seem to find the right combination to hook up, trial and error with gearing, tires, suspension.
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
I'm trying to decide which tranny to go with...rebuild my stock TH350 strong or buy the 200r-4 tranny. I just bought stock crossmember to replace my bent one...so I don't want to have to replace it again. What modifications to the stock crossmember are required to fit a 700r4 tranny or a 200r4 tranny?
Thread Starter
Safety Car
Joined: Oct 2006
Posts: 3,930
Likes: 15
From: Calgary Alberta
Okay, so If I stick with my stock TH350, which gear ratio should I use? I want to e able to get pinned in my seat when I step on the gas...but I want to get decent speed as well.
Melting Slicks
Joined: Jul 2005
Posts: 2,545
Likes: 3
From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
You must decide what fuel mileage and top speed you can live with. I don't care to run 100 mph ever, but I do what to be set back in the seat when I pull away, and could care less about fuel mileage. Few cars can pull me from a dead stop, but will whip me down the road. (again RPM).
Some people like good fuel mileage and decent pull, thats the reason I mentioned 3.55.1
Drifting
Joined: Oct 2007
Posts: 1,458
Likes: 1
From: Collinsville MS
St. Jude Donor '08
I've blown some TH350s, but it took being really stupid on my part to do it. They will take a lot of abuse, I would prefer it for heavy duty way before the 200.
the 400 will take even more abuse but the weight becomes a factor on some.
the 400 will take even more abuse but the weight becomes a factor on some.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
TH350
2.52, 1.52, 1
TH200 4R
2.74, 1.57, 1, .64
I have the 3.55 in my DD car. I like it. It gives me enough torque on the low end and remains pretty respectable up top.
Drifting
Joined: Apr 2007
Posts: 1,892
Likes: 3
From: Springfield Illinois
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I said similar. Compare the TH350 to the TH200R4 and the TH700R4. Which is closer?
