How bad is the 4+3 Transmission?
03-19-2017, 05:24 AM
#1
How bad is the 4+3 Transmission?
I am considering picking up another c4, but this time it is going to be with a manual transmission. I'm reading stories of people saying that changing the fluid and filter every 10k miles will leave you with no problems. Then there are other people saying no matter what maintenance they do, the overdrive eventually dies. Beating on the transmission hard also eventually kills it. I know the zf6 is an overall better transmission, but I am also looking for a c4 with the l98 engine. Most of the l98 vettes around me have the 4+3 transmission.
03-19-2017, 08:03 AM
#2
The answer to your question will all depend on who you ask.
Some have had problems within 30k miles and others have went 100k miles with no issues. I'm sure driving style also impacts the longevity of the transmission.
My '84 has 36k miles and the 4+3 functions just fine.
I will agree with the suggestion of going no more than 10k between fluid changes.
Some have had problems within 30k miles and others have went 100k miles with no issues. I'm sure driving style also impacts the longevity of the transmission.
My '84 has 36k miles and the 4+3 functions just fine.
I will agree with the suggestion of going no more than 10k between fluid changes.
03-19-2017, 08:48 AM
#3
Safety Car
My OD went out at around 115,000 miles. And this is my track car.
Richard Newton
Rear Suspension on the C4
Richard Newton
Rear Suspension on the C4
03-19-2017, 08:48 AM
#4
Le Mans Master
The Doug Nash overdrive unit has been know to fail. With proper maintenance and care they do last much longer if left without maintenance. The T10 transmission unit is bullet proof! Its the overdrive unit that gets the bad rap. They really are a good unit though. I did fluid and filter changes on my 84 and I pressed the clutch pedal in any time I was going in or out of overdrive. I had zero problems with mine.
03-19-2017, 09:22 AM
#5
Race Director
I don't think the 4+3 is "bad", it's just less desirable than the zf6. And if you ask people here they will say the zf6 is less desirable than a t56. It's all a budget game.
There haven't been any Corvettes that I would say "never ever buy" compared to like, a vti saturn, a vw, an older northstar, or other cars with actual issues. Some of these cars are just less desirable than the others, and people will talk down about them as such. Crossfire and the 4+3 both get bad raps here but are still both great options. Would I rather have an lt1 zf6? Yes, and I do. But I wouldn't talk anyone out of either of those if that was what their budget allowed for.
There haven't been any Corvettes that I would say "never ever buy" compared to like, a vti saturn, a vw, an older northstar, or other cars with actual issues. Some of these cars are just less desirable than the others, and people will talk down about them as such. Crossfire and the 4+3 both get bad raps here but are still both great options. Would I rather have an lt1 zf6? Yes, and I do. But I wouldn't talk anyone out of either of those if that was what their budget allowed for.
03-19-2017, 09:54 AM
#6
Safety Car
Most, if not all the problems with the overdrive unit came from owners who beat on them, didn't know how to use them, or never took good care of them maintenance wise. Lots of bad information has been posted from people who have no clue about using them properly and some from people who never even owned one. There are a few of these types on this forum.
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Karvette (03-19-2017)
03-19-2017, 11:06 AM
#7
Melting Slicks
i don't think the 4+3 is "bad", it's just less desirable than the zf6. And if you ask people here they will say the zf6 is less desirable than a t56. It's all a budget game.
there haven't been any corvettes that i would say "never ever buy" compared to like, a vti saturn, a vw, an older northstar, or other cars with actual issues. Some of these cars are just less desirable than the others, and people will talk down about them as such. Crossfire and the 4+3 both get bad raps here but are still both great options. Would i rather have an lt1 zf6? Yes, and i do. But i wouldn't talk anyone out of either of those if that was what their budget allowed for.
there haven't been any corvettes that i would say "never ever buy" compared to like, a vti saturn, a vw, an older northstar, or other cars with actual issues. Some of these cars are just less desirable than the others, and people will talk down about them as such. Crossfire and the 4+3 both get bad raps here but are still both great options. Would i rather have an lt1 zf6? Yes, and i do. But i wouldn't talk anyone out of either of those if that was what their budget allowed for.
l48
03-19-2017, 05:03 PM
#8
Race Director
03-19-2017, 05:57 PM
#9
Melting Slicks
I've owned two L48's (both 79s) and they are still great cars. In their day they were decent power. Everything back then was being choked off by primitive emissions.
As to the OPs question on the 4+3. I shied away from them because a failure leads to problems getting it repaired.
If those that really know them could provide advise on telling how to spot abused cars it might help those shopping.
As to the OPs question on the 4+3. I shied away from them because a failure leads to problems getting it repaired.
If those that really know them could provide advise on telling how to spot abused cars it might help those shopping.
03-19-2017, 06:27 PM
#10
Melting Slicks
03-19-2017, 10:01 PM
#11
Melting Slicks
See this page: http://www.5speeds.com/nash.htm
The '86-'88 had most of the issues fixed. In particular the carrier bearing. Many of the 4+3 owners never even realized that the OD had to be serviced separately. Neither did the fast lube places. With no service they tended to die early since there isn't much of a fluid reservoir.
The '86-'88 had most of the issues fixed. In particular the carrier bearing. Many of the 4+3 owners never even realized that the OD had to be serviced separately. Neither did the fast lube places. With no service they tended to die early since there isn't much of a fluid reservoir.
03-20-2017, 04:54 PM
#12
Melting Slicks
See this page: http://www.5speeds.com/nash.htm
The '86-'88 had most of the issues fixed. In particular the carrier bearing. Many of the 4+3 owners never even realized that the OD had to be serviced separately. Neither did the fast lube places. With no service they tended to die early since there isn't much of a fluid reservoir.
The '86-'88 had most of the issues fixed. In particular the carrier bearing. Many of the 4+3 owners never even realized that the OD had to be serviced separately. Neither did the fast lube places. With no service they tended to die early since there isn't much of a fluid reservoir.
Abuse is another thing... anything will break after enough abuse.
03-22-2017, 06:42 AM
#14
03-24-2017, 10:50 AM
#15
Drifting
'88 4+3 with 162k on it with no issues. I've read the overdrive is somehow tied in with the reverse so if it goes bad they both go?
What if you drive it like a normal 4 speed? My **** is out of adjustment but the overdrive worked fine before I messed with the **** and I am planning on using this with my turbo 5.3 swap.
What if you drive it like a normal 4 speed? My **** is out of adjustment but the overdrive worked fine before I messed with the **** and I am planning on using this with my turbo 5.3 swap.
03-24-2017, 03:09 PM
#16
Safety Car
Factory equipped - AFAIK that is true. I've also seen some 4+3's listed as 4 speeds so it happens (assume they just looked at the shifter). Now in fact not every pre ZF manual is a 4+3, but that's usually the result of some change-out. Mine for example had a Tremec in it when I bought it, so it was oem 4+3 but currently a 5 speed.
03-24-2017, 03:21 PM
#17
Team Owner
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St. Jude Donor '05
And if you ask people here they will say the zf6 is less desirable than a t56.
Threw a bunch of $ upgrading a T56 and bet a stock ZF would still outlast it. Parts are cheaper for the T56 though
Far as L48s btdt talk about disapointment
Last edited by cv67; 03-24-2017 at 03:22 PM.
03-24-2017, 04:57 PM
#18
Not bad at all. Had a 1988 w 4+3 and loved it. Miss it and still regret selling that car, but had to trim the herd at the time.
Great on highway, flying along in relatively low reving OD, to pass just a bit of a jab on the accelerator, car would momentarily drop out of OD, throw me back in the seat, and once I passed or whatever, just let off the gas a tad and right back into relatively low rev OD.
Useful when an actual clutch in downshift might be overkill, but a burst of speed is needed.
Never understood complaints about 4+3, think it is a great idea, would not hesitate to buy another 88 with it.
Great on highway, flying along in relatively low reving OD, to pass just a bit of a jab on the accelerator, car would momentarily drop out of OD, throw me back in the seat, and once I passed or whatever, just let off the gas a tad and right back into relatively low rev OD.
Useful when an actual clutch in downshift might be overkill, but a burst of speed is needed.
Never understood complaints about 4+3, think it is a great idea, would not hesitate to buy another 88 with it.
06-23-2021, 05:00 AM
#19
1st Gear
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Most, if not all the problems with the overdrive unit came from owners who beat on them, didn't know how to use them, or never took good care of them maintenance wise. Lots of bad information has been posted from people who have no clue about using them properly and some from people who never even owned one. There are a few of these types on this forum.
i did my apprenticeship at a gm dealer back in 1985, in Vancouver bc, Canada, which i had worked on those 4 plus 3 corvettes many times. . as far as the transmission problems went, there was almost non regarding the overdrive unit. the most common repair was with the input shaft bearing. it was too loose and required bearing preload by shimming , reason was to put a slight rotation resistance on the clutch disk when disengaging the clutch, stoppng the input shaft from spinning so that the reverse gear will engage without grinding., the real reason for the overdrive unit damage was exactly what you said...abbuse...and impropper operation. the damage was mostly caused by shock load. Popping the clutch on power