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Planning a t56 swap and will be leaving the gears alone in the rear for a while. Question is what kinda rpms should I expect, and or behavior should be expected until the gearset gets changed. Tires are 28" tall.
I was thinking it would drive like a dry lakes car. lol. I want to get it in there, then do the super ten rear set up. I guess I'm asking if it would be manageable till the gear change. The motor is 500 ish hp big block.
I'm not very familiar with Tremec, but in a quick search, I came up with two GM versions. One has a 2.97 1st gear, not too different than the 700R4 auto. Leverage with that would be close to a stock '82 Vette. The other Tremec has a 2.66 first gear. That would be less effective, but still slightly more leverage than a TH350.
They sell a 2.97 first T56 It would help taking off. At some point on rear ends become inefficient because the motor is lugging in top gear. I owed a C-5 and I put a 4.10 rear to actually use 6th.
My present 5 speed I can go over 150 mph before shifting into 5th OD
I guess I'm asking if it would be manageable till the gear change. The motor is 500 ish hp big block.
What is the the 6th gear ratio? 0.50? If so you are talking about a 1.4 effective rear end ratio in 6th with 28 inch tires. That's pretty tall, about 1200 rpm at 70 mph. If you have any kind of performance cam in your BBC, you'll most likely be lugging it too much causing bucking and surging at anything less than some pretty fast interstate speeds.
Last edited by 71454Chevelle; Jan 3, 2016 at 08:11 AM.
Its just a small hydraulic roller. Motor is runnin clean by 900 rpm. Has very little chop at idle. Im goin to try it. Worst case Ill be limited to fifth. Its a 2.97:1 first gear trans so its still deeper first than my current trans.
I have a T56 Magnum with a 3.08. Which is ok for all gears 1st-6th.
It isn't a off the line launcher but I use the car for road track driving. 2nd-4th. Driving to the track is 5th & 6th driving. Close ratio starting @ 2.66 1st with a .63 6th.
Your setup would be 1525 RPM @ 70 MPH and 1575 with 27" stock tire size. Your setup is not the best if you like the 2 sec acceleration in first that most people seem to like.
The testing I did was looking at 2000 RPM - 5500 RPM in each gear to see if I liked it. for you this would be 20MPH - 54 MPH in first gear.
The ideal rear ratio as designed with the original factory design would be 3.28:1 and a 3.3 for the corvette would be great option to look at.
What tires do you have that measure 28" dia ?
Last edited by cagotzmann; Jan 3, 2016 at 11:25 AM.
I have a T56 Magnum with a 3.08. Which is ok for all gears 1st-6th.
It isn't a off the line launcher but I use the car for road track driving. 2nd-4th. Driving to the track is 5th & 6th driving. Close ratio starting @ 2.66 1st with a .63 6th.
Your setup would be 1525 RPM @ 70 MPH and 1575 with 27" stock tire size. Your setup is not the best if you like the 2 sec acceleration in first that most people seem to like.
The testing I did was looking at 2000 RPM - 5500 RPM in each gear to see if I liked it. for you this would be 20MPH - 54 MPH in first gear.
The ideal rear ratio as designed with the original factory design would be 3.28:1 and a 3.3 for the corvette would be great option to look at.
What tires do you have that measure 28" dia ?
215 75 15. These tires are somewhat temporary. Plans are 315 30 18 on a 18x10.5 on all four corners. These would be 25.4 inches tall.
Your car should have no trouble operating decently until you can change the rear gear. Is a 2.87 rear gear ratio 'good' for that transmission? No. But, unless you are planning on flogging it with that setup in the car, you will hurt nothing and it will operate O.K.
You won't like it. I have the T56 in my Cobra, with 26" diameter tires, and 3.55 rear. 70 MPH in 6th gear is 1800 RPM. I ONLY use 6th for 75MPH plus cruising on the interstate.
For you with the 2.87 gear and 28" tires, 70 MPH will yield 1351 RPM.
It'll work almost the same as your 4 speed, but shift much nicer and you'll have a gear you never use.
I would recommend quickly save up for a set of 3.55 gears.
I will be changing the gear set, but will likely be several months if not a year before I do. I just want a driveable car that will run the parkway. Im headed to the Rod Run In pigeon forge in march. This trip will be with a 350 turbo and the rallys. Im hopin this time next year it will be 6 speeds and the 18 inch wheels. And then I need to get with tracdog for a price on the super 10 diff. Sounds like it will be aight to go as planned.
You won't like it. I have the T56 in my Cobra, with 26" diameter tires, and 3.55 rear. 70 MPH in 6th gear is 1800 RPM. I ONLY use 6th for 75MPH plus cruising on the interstate.
For you with the 2.87 gear and 28" tires, 70 MPH will yield 1351 RPM.
It'll work almost the same as your 4 speed, but shift much nicer and you'll have a gear you never use.
I would recommend quickly save up for a set of 3.55 gears.
Useless in what regard? I have the 2.66 first gear, 3.55 rear, and 26" tires. even putting along at 1800 RPM, no clutch popping or stupidity, if I roll into to they'll light up. The ratio is more than low enough for off the line torque, but I wish it was a little lower so I had a creep speed for traffic without having to constantly clutch.
With the bigger vette tires and heavier car, I would say the 3.73 would be a better choice, or maybe even the wide ratio tranny and more like a 4.11
Six speed / 2.87 gear
If you have any kind of performance cam in your BBC, you'll most likely be lugging it too much causing bucking and surging at anything less than some pretty fast interstate speeds.
