84 with 4+3 looking for options
Thread Starter
Racer
Joined: Jul 2011
Posts: 387
Likes: 2
From: Austin TX
84 with 4+3 looking for options
Alright so i have a 84 with a 4+3 transmission, 150k miles.
The car is my DD but I don't drive everyday, its old a little rough and about to start making more power.
Iv converted from Crossfire to TBI, now in my quest for more power im going to be switching too a blowthrough carb and a turbo.
I have thought about keeping my 4+3, although i don't know how much power it will handle.. the transmission works flawless.. But if it did break i don't want to pay the price of rebuilding it, So i have been thinking about selling it or trying to trade it for a different transmission setup..
So my question is what should I look at? I want to keep a manual transmission, Im not paying the price of a ZF6..
Iv been thinking a superT10 might do the trick or any other 4speed transmission.. it should bolt right up if im not mistaken, But I would need a longer drive shaft correct?
or maybe I could trade someone even for a LT1 T56.. But with this option, wouldnt my 3.07 gears be too low?
Also isnt the going rate on 4+3 in working condition between 600-800 bucks?
Thanks
The car is my DD but I don't drive everyday, its old a little rough and about to start making more power.
Iv converted from Crossfire to TBI, now in my quest for more power im going to be switching too a blowthrough carb and a turbo.
I have thought about keeping my 4+3, although i don't know how much power it will handle.. the transmission works flawless.. But if it did break i don't want to pay the price of rebuilding it, So i have been thinking about selling it or trying to trade it for a different transmission setup..
So my question is what should I look at? I want to keep a manual transmission, Im not paying the price of a ZF6..
Iv been thinking a superT10 might do the trick or any other 4speed transmission.. it should bolt right up if im not mistaken, But I would need a longer drive shaft correct?
or maybe I could trade someone even for a LT1 T56.. But with this option, wouldnt my 3.07 gears be too low?
Also isnt the going rate on 4+3 in working condition between 600-800 bucks?
Thanks
Drifting
Joined: Apr 2011
Posts: 1,925
Likes: 441
From: Albuquerque NM
My understnanding of the DN 4+3 is that the "weak link" is the overdrive unit. The super T10 4 speed is a decently stout transmission. Depending on your level of abuse, if you isolate the hard usage to the
T10 (not flooring it when the overdrive is activated) then you should be good for a while unless you're talking big big numbers. I'm not sure how your overdrive works but mine only comes on when I press the button on my shift ****. If I am in "4+1" and mash the gas, the overdrive kicks off then returns once I let off the pedal. However if I am simply in 4th, the overdrive will not turn on until I actuate my **** button. Anyway, I am pretty sure that the T10 is rated between 300 and 400 ft/lbs torque and some drag guys in older cars do some hard launches
tldr; Don't abuse the overdrive and you may get enough life out of the doug nash to warrant leaving it in until the time comes to replace it. However if you're making big enough numbers to know that you'll kill it in short order, sell it while it works.
Once mine goes, I'm getting a TKO-500!
T10 (not flooring it when the overdrive is activated) then you should be good for a while unless you're talking big big numbers. I'm not sure how your overdrive works but mine only comes on when I press the button on my shift ****. If I am in "4+1" and mash the gas, the overdrive kicks off then returns once I let off the pedal. However if I am simply in 4th, the overdrive will not turn on until I actuate my **** button. Anyway, I am pretty sure that the T10 is rated between 300 and 400 ft/lbs torque and some drag guys in older cars do some hard launches
tldr; Don't abuse the overdrive and you may get enough life out of the doug nash to warrant leaving it in until the time comes to replace it. However if you're making big enough numbers to know that you'll kill it in short order, sell it while it works.
Once mine goes, I'm getting a TKO-500!
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The C4 doesn't have a transmission mount so just something like a Super T-10 alone won't work. There is nothing for the C-Beam to bolt to.
A ZF takes some work but it's doable and you can find them used. Others have done the ZF conversion from the 4+3. When the 87 Callaway Corvette was introduced, it had twin turbos and used the 4+3.
Keisler makes a bolt-in 5-speed for C4's but that will run something like $3K.
Don't engage the OD unit except for cruising/freeway and it should work assuming it's in good shape. Change the fluid and filter every 12K miles (do not use synthetic ATF) and the filter is the same one used in some Ford FMX auto trannies found in early 70's cars and some F-150's.
If you are going to add significant power and do an engine rebuild, then at 150K miles, you should be looking at rebuilding the trans and the diff at the same time. Probably a good time to consider alternate transmissions or rebuilding the DN. You should be able to find a ZF for about the same price as a rebuilt 4+3.
A ZF takes some work but it's doable and you can find them used. Others have done the ZF conversion from the 4+3. When the 87 Callaway Corvette was introduced, it had twin turbos and used the 4+3.
Keisler makes a bolt-in 5-speed for C4's but that will run something like $3K.
Don't engage the OD unit except for cruising/freeway and it should work assuming it's in good shape. Change the fluid and filter every 12K miles (do not use synthetic ATF) and the filter is the same one used in some Ford FMX auto trannies found in early 70's cars and some F-150's.
If you are going to add significant power and do an engine rebuild, then at 150K miles, you should be looking at rebuilding the trans and the diff at the same time. Probably a good time to consider alternate transmissions or rebuilding the DN. You should be able to find a ZF for about the same price as a rebuilt 4+3.
Thread Starter
Racer
Joined: Jul 2011
Posts: 387
Likes: 2
From: Austin TX
I know about the C Beam, couldn't a bracket/adaptor be made for use on a older 4speed? im handy.
That is a good point though about the twin turbo callaway vettes. Although I think they only put out around 350whp but probably alot of torque.
That is a good point though about the twin turbo callaway vettes. Although I think they only put out around 350whp but probably alot of torque.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
One problem with a "regular" T-10 is the floor tunnel and console would have to be cut up for a shifter. The C4 shifter bolts to the tunnel. The stock shifter is not as tall as something like a Hurst Competition Plus. Just some fabbing to do for that part. Also, there is not a lot of room between the trans and the side wall of the center tunnel. It could be that a shifter will wind up extending into (and very near) the seat.
I would think that somebody here did attempt a standard 4-speed install but for the amount of work involved, going with something that can be done with little work would be much better. Certainly less hassle.
IIRc, somebody did a T-5 install but I don't think those trannies are strong enough to handle your power goals. I think you would be much better off with a ZF6 or the Keisler TKO box. Both of these have been done in earlier cars and there is lots of information about the installs.
I would think that somebody here did attempt a standard 4-speed install but for the amount of work involved, going with something that can be done with little work would be much better. Certainly less hassle.
IIRc, somebody did a T-5 install but I don't think those trannies are strong enough to handle your power goals. I think you would be much better off with a ZF6 or the Keisler TKO box. Both of these have been done in earlier cars and there is lots of information about the installs.
Team Owner
Joined: Oct 1999
Posts: 31,977
Likes: 487
From: Guinness Its whats for B'fast JAWGA
CI 3-4-5-9 Veteran
Richmond also makes a 6 speed and there were swap parts out to mate it to the C Beam. The Richmond gear ratios would work better with your 3.07s than a ZF or T56.
Some don't like the way the Richmond shifts but I also have friends with TKO swaps in muscle cars and they say it shifts like a dump truck. To each their own. I love the way a ZF with a Hurst or a T56 shifts.
