need help with 4+3
Thread Starter
Racer
Joined: Oct 2008
Posts: 253
Likes: 6
need help with 4+3
hi, guys as iam sure you can tell iam new to this site. i got a 1984 vette, with the 4+3 trans. i figured before i have someone look at it, i was wonder if there is a common problem with them? mine seems to shift hard, but not all the time, and when i mean shift hard it seems to slide into gear ok, it just seems like its more of the shifter that gets stuck? any help would be appreciated and iam about to go take some pics before the sun goes down...if you guys are like most forums i know you love pics lol 
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
I'm assuming that you mean that shifting is difficult and requires a surprising amount of force to go in and out of gear. I also assume that your overdrive unit is functioning OK.
The oil or lubricant that you use in the transmission makes a difference with the quality of shifts. The 4+3 transmission is an interesting case because it calls for gm 1052271 and Dexron II in the overdrive unit. The problem is that 1052271 is really for use in the differential as a GL4+ or GL5. You don't need the sulfur in the transmission and it might even be corrosive. A GL4 is OK for the transmission and Redline and Royal Purple have options. I like the Royal Purple option, MaxGear I think, GL4 lubricant. It has worked very well for me on track days and daily driving. The Redline product wasn't quite as good in my novice opinion.
The oil or lubricant that you use in the transmission makes a difference with the quality of shifts. The 4+3 transmission is an interesting case because it calls for gm 1052271 and Dexron II in the overdrive unit. The problem is that 1052271 is really for use in the differential as a GL4+ or GL5. You don't need the sulfur in the transmission and it might even be corrosive. A GL4 is OK for the transmission and Redline and Royal Purple have options. I like the Royal Purple option, MaxGear I think, GL4 lubricant. It has worked very well for me on track days and daily driving. The Redline product wasn't quite as good in my novice opinion.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
shifter
Try adjusting the reverse lockout rod and readjusting the shifter arms on your trans. Also, when you push the overdrive switch, be sure you push in the clutch like you would if you were actually moning a lever instead of pushing a switch.
Sometimes the rod ends wear and the shifter isn't quite in neutral when you are passing through neutral when you pick up another gear.
wiggle the rods in neutral, and check for excessive play and or tight link rods.
The gear oil in the trans part is regular 90W gear oil.
The overdrive unit has auto trans dexronIII in it. make sure you drain and refill both units and then recheck after a short drive.
To fill the overdrive, turn the wheels so the internal pump will draw from the overdrive pan and reveal the true fluid level.
Sometimes the rod ends wear and the shifter isn't quite in neutral when you are passing through neutral when you pick up another gear.
wiggle the rods in neutral, and check for excessive play and or tight link rods.
The gear oil in the trans part is regular 90W gear oil.
The overdrive unit has auto trans dexronIII in it. make sure you drain and refill both units and then recheck after a short drive.
To fill the overdrive, turn the wheels so the internal pump will draw from the overdrive pan and reveal the true fluid level.
Last edited by coupeguy2001; Oct 12, 2008 at 01:53 AM.
Pro
Joined: May 2007
Posts: 659
Likes: 5
From: Holden, MO
Cruise-In IX Veteran
The 4spd portion uses 90wt gear oil. The overdrive uses atf. The 4+3 is really two transmissions. A 2spd automatic mated to a 4spd stick. Overdrive is available in 2nd through 4th hence the 4+3.
Hope this helps.
If you don't already have one get the fsm and an owner's manual. The owner's manual will tell you what fluids to put where.
Mike
Thread Starter
Racer
Joined: Oct 2008
Posts: 253
Likes: 6
Try adjusting the reverse lockout rod and readjusting the shifter arms on your trans. Also, when you push the overdrive switch, be sure you push in the clutch like you would if you were actually moning a lever instead of pushing a switch.
Sometimes the rod ends wear and the shifter isn't quite in neutral when you are passing through neutral when you pick up another gear.
wiggle the rods in neutral, and check for excessive play and or tight link rods.
The gear oil in the trans part is regular 90W gear oil.
The overdrive unit has auto trans dexronIII in it. make sure you drain and refill both units and then recheck after a short drive.
To fill the overdrive, turn the wheels so the internal pump will draw from the overdrive pan and reveal the true fluid level.
Sometimes the rod ends wear and the shifter isn't quite in neutral when you are passing through neutral when you pick up another gear.
wiggle the rods in neutral, and check for excessive play and or tight link rods.
The gear oil in the trans part is regular 90W gear oil.
The overdrive unit has auto trans dexronIII in it. make sure you drain and refill both units and then recheck after a short drive.
To fill the overdrive, turn the wheels so the internal pump will draw from the overdrive pan and reveal the true fluid level.
i was pretty sure i saw in the manual that if you are just driving around to always leave it in overdrive? what do others do?
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Drifting
Joined: May 2006
Posts: 1,428
Likes: 7
From: Chewelah Wa
I use overdrive mainly on the highway. I use the 4 speed in town, on the highway I treat mine like it is a 6 speed, with 3rd OD as "5th gear" and 4th OD as 6th. There is also a kickdown feature, you can just stomp on the gas and the OD unit disengages, so you can go from 4th OD down to regular 4th gear for passing without having to shift.
