I am going to install a 200r4 with a 70 455... mild build up. I was told I should use a 3.73 posi. I have found a couple of 4.11 and a 3.64. Does anyone have any idea what kind of rpms I would run with either of these ratios?
Hi, don't know your tire size so here's the numbers with three different tire diameters: 4.11 gears - 26"=2490 27"=2400 28"=2310 3.64 gears - 26"=2210 27"=2120 28"=2050 All these rpm's are at 70 mph.
Figuring out what your effective gear ratio will be is easy. The 200R4 has a .67 overdrive, 4.11 gears would be 4.11 X .67 = 2.75 3.73 gears would be 3.73 X .67 = 2.49 3.64 gears would be 3.64 X .67 = 2.43 MPH X final drive ratio X 336/tire diameter = RPM For example: For the 4.11 gears with 27" tires @ 70 MPH, 70 X 2.75 X 336/27 = 2395 RPM
200r4 Hey guys... This information is GREAT! I am running 225x75rx14... 25" tall. I should have stated... I have found the following posi rear axles drum to drum... 1) 69 Chevelle 4.11 12 bolt (75 miles away) $1300 2) 69 Chevelle 4.11 10 bolt (75 miles away) $700 3) 70 GSX 3.64 10 bolt (150 miles away) $700 4) Later model posi set up new GM with new richmond gear set 8.5 posi installed in a 70 GS 455 (600 miles away) $725.00 I have a 68 GS400 conv... (actually my wife's car - I bought it for her). She wants a mild driver with good gas mileage... I want the power! So, at best, it is only a street racer on occasion. Just trying to figure which one to buy. Any more thoughts??? Thank-you very much... :TU: :TU: :TU: :TU:
I"m personally running a 3.73 with a 28" tire, so I'll really be cutting down on the rpm's this summer. All things equal, if it were me I'd go with option (4). Everything will be new and you'll know what you have.
200r4 I already put a 200R4 from a GN with the 2500 stall converter in my Stage-1 four door electra park avenue. I put a switch under the steering column to activate the lockup. I tried 3.42 posi gears with the 28" tall whitewall michelins but the car would not get on the cam in overdrive under 70 mph so I went to 4.10's and it was much better. Even cruised on the highway at 70 mph in the 2200 rpm range and was happy. Track times did not change but a couple of tenths between gear changes though. With the 4.10's and whitewall michelins I went 13.7-13.9 @ 102-104 mph (too heavy and square for more top end) with a 2.000 60'. This was a low compression well prepped smog motor with my stage one heads and B4B through the iron exhaust manifolds and 2 1/4" dual quiet exhaust system. I really like watching someone in a mustang pull the shifter out trying to catch up while my daughter waves bye-bye at them from the back seat or when I catch some Corvette or SS Camaro sleeping and it takes them 1/8 mile before they get bye. The best however are the rice cars they never give up. Those trannies are tough and it is stock but it has been in there for three years of abuse and the 1-2 shift is getting slow so I will have it rebuilt soon.
Wow, that's impressive! I'm toying with tranny ideas, I thought the 200-R4 wouldn't take a 455 without some serious strengthening, especially in a heavy car. Maybe there's hope yet!
Doncha just love inputting 3.23 with .67 OD and coming up with some ungodly top end at 5000rpm? :3gears:
LOL! How about my 29 inch tires, a 3.08 rear end with a T56 (.5 OD) at 5000 rpm? 280mph! I just need to do some streamlining...
I think there are a number of T56 transmissions with different ratios, and power ratings. http://www.keislerauto.com/gm/transmissions/builder.asp
200R-4 compatability Guys make sure you use a tranny out of a 86-87 TR or Grand National they have a tag on the passenger side with the letter code BR stamped on it. They have a different valve body and are far stronger than the stock 200R-4 and will live longer. Mine is stock out of a wrecked GN and went straight into my Park Avenue with the stock 2500 stall converter. I tried a 1700 stall but did not like it and went back to the 2500. I run 235x75x15 whitewall michelins with the 4.10 posi and the car is awsome. I get far less wheelspin with the 4.10's as the tire don't get spinning so fast as they would with the 3.42's when they do break. I also get 16-18 MPG on the highway @ 65-70 MPH and 12 around town if I keep my foot out of it. I am running the SP-1 club cam from the GSCA in the mild Stage 1 motor with my own home brew quadrajet that I enlarge the fuel passages on; no flat spots or lag. The only down side is there is not enough range in my column shifter to let me pull down to 1st gear and hold it there. My L on the column actually is 2nd in the trans so all the other gears, neutral, reverse and park are in the right place. But the GN tranny is goverened to 5200 by itself so there really is no problem. Michael
