200R4
- Thread starter LJC
- Start date
What is the current ratio?
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Talking about rear end ratio?
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Might help if we knew what year and model the car is. If it has an original switch pitch, then it is a 65-67. Might be a 2.93. If you don't want to ASS-U-ME
, you could jack the car up and mark the tire and driveshaft, then rotate the tire one revolution while counting the driveshaft revolutions. Or, you could look for the axle code on the axle tubes, or if you have a tachometer, it will turn between 23 and 2400 @ 60 MPH with a 2.93.In any case, the 2004R has a .67 overdrive 4th gear and a lock up torque converter. It will like a 3.42 rear gear so that final drive will be 3.42 X .67 = 2.29. The 2004R 1st gear of 2.74 will give you a starting ratio of 2.74 X 3.42 = 9.37
Last edited:
LJC
Active Member
Anything missing?
The 200R4 is rebuilt and ready for install here is the list of parts what I'm I missing
cross member from 70 Chevelle
B&M converter lockup contoller
lokar TV cable currently installed on the 350TH / Edelbrock 1406
Dipstick can the one from the 350 be used?
Suggestions for speedo gears ?
Anything else
The 200R4 is rebuilt and ready for install here is the list of parts what I'm I missing
cross member from 70 Chevelle
B&M converter lockup contoller
lokar TV cable currently installed on the 350TH / Edelbrock 1406
Dipstick can the one from the 350 be used?
Suggestions for speedo gears ?
Anything else
LJC
Active Member
current is 1:3.55
Stray Tate
Active Member
If none of those checks work out, count the teeth on the ring gear, and divide that number by the number of teeth on the pinion gear. Larry called the transmission by its right name, 2004R. GM's other old RWD overdrive is the 700R4. I don't know why they were inconsistent with the order of their 4s and Rs, but there's my contribution for today to you trivia database. The 700R4 was thought to be the heavy duty unit, and to the best of my knowledge, wasn't made to bolt up to BOP engines, just Chevrolet ones. 2004Rs were less discriminating, and could be bolted to any old GM. They proved to be tough and durable, too.Might help if we knew what year and model the car is. If it has an original switch pitch, then it is a 65-67. Might be a 2.93. If you don't want to ASS-U-ME
In any case, the 2004R has a .67 overdrive 4th gear and a lock up torque converter. It will like a 3.42 rear gear so that final drive will be 3.42 X .67 = 2.29. The 2004R 1st gear of 2.74 will give you a starting ratio of 2.74 X 3.42 = 9.37
LJC
Active Member
The current gearing is 3.55
66 skylark
340/ with mild cam
225/70/14 might move up to 15" to swap drums to disc
Chevy 1970 cross member in case cant use the stock one
need speedo gears recommendation please
have several tv cables and brackets for use on 600 Edelbrock I might switch to this
66 skylark
340/ with mild cam
225/70/14 might move up to 15" to swap drums to disc
Chevy 1970 cross member in case cant use the stock one
need speedo gears recommendation please
have several tv cables and brackets for use on 600 Edelbrock I might switch to this
Summit Racing™ M2008 Series Carburetors SUM-M08600VS
Recommendations for the lockup would be appreciated I see there are a few with wide difference in $$I don’t know about a ‘66 but when I did my 1968 I used the original cross member and just moved it rearward to the holes for a TH400 that were already in the frame. I use an 1800 stall speed converter behind a cammed 350 and 3.43 rear gears. I like it but I think I would have liked 3.64’s or 3.73’s better.
Sorry I made a mistake. I’m running a 2000 stall speed converter. My wheels are 17” Year One Magnums. 8” in front and 9” in the rear with Nitto 225-50ZR17’s in front and 255-45ZR17’s in the rear. My 2004R was built by PATC, I think they are in Louisiana, to their Predator specification. I got my speedometer gears from them based on my rear gears and tire size.
I ran the 17’s to clear the 14” Baer Extreme Plus brakes that I have on all 4 corners.
I ran the 17’s to clear the 14” Baer Extreme Plus brakes that I have on all 4 corners.
Stray Tate
Active Member
There is a pretty simple wiring circuit to operate the TCC. No internal work is needed, A brake switch opens the normally closed circuit to unlock the TCC when the brake is applied, if memory serves me faithfully. I've used it for years (the circuit , that is) on the 700R4 in my 53 Pontiac, and intend to use it with the 2004R in my 40 Buick project, if I can. HydraMatic may well have changed the internals from model to model - dunno. Early TCCs, before manufacturers decided everything from soup to nuts had to be computer controlled, used a vacuum controlled switch. That could be to unlock the clutch when lugging. The TCC plug on the trans can hold 4 wires, but I'm thinking only one is in use on my 700R4. I have a vacuum switched harness from an 81 Caprice, which had the three speed automatic with TCC, and it has at least two wires to the plug. Maybe my 2004R will need that, but I'm not there yet. Some fun, huh?
3.55s should be a nice complement to that trans. You may want to invest in a limited slip center section at some point. It would distribute the power to the rear tires evenly.
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Maybe you can retrofit your housing with a limited slip center section using your current gears. It might be the lowest cost way to do it without changing out the entire rear.
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