4+3 opinions
Thread Starter
Pro
Joined: Jan 2010
Posts: 677
Likes: 39
From: Southern Indiana
4+3 opinions
I am going to go look at an 86 with the 4+3 manual tranny. Car is low miles and looks to be in great shape, but have read some iffy stuff about this tranny. What's the skinny on it?
Melting Slicks
Joined: Oct 2000
Posts: 3,426
Likes: 4
From: Heidelberg PA
Cruise-In V Veteran
They can be iffy - if it is low mileage ask if filter & fluid has been changed on OD. This is important maintenance on the 4+3. As long as you use the OD on the highway and the 4 speed in normal driving you should be fine.
The car has the Dana44 rear, and from my experience the early Dana44's are stronger than the later ones.
Also depends on what you will be doing with it. Weekend driver - OK, if you want to man handle the car the tranny will not last.
The car has the Dana44 rear, and from my experience the early Dana44's are stronger than the later ones.
Also depends on what you will be doing with it. Weekend driver - OK, if you want to man handle the car the tranny will not last.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The key to long life with the overdrive unit is regular maintenance. It's a good idea to change the filter and fluid every 12K miles or so. The filter is the same one used in the Ford FMX auto trans from the early 70's. The fluid is Dexron II/III and takes about 2 quarts.
The 4-speed portion is a Borg-Warner Super T-10 and is very strong, The Super T-10 was used behind lots of high perfomance motors from the late 60's and early 70's.
The OD does not like abuse like shifting while at WOT. It's designed to upshift and down shift automatically in normal driving. It will downshift like a "passing gear" for freeway use and then upshift. It can also be manually be used for each gear if you desire. I use the OD in my 87 for boulevard cruising where the speeds are 40 to 50MPH For example, 3rd and OD is a lowere RPM than 4th and no OD. When manually using the OD, it's best to use the clutch just like shifting the 4-spped part.
Here's a link showing how the various years work and the parameters.
You can do a search here for "4+3" and you will get lots of information on the trans.
The 4-speed portion is a Borg-Warner Super T-10 and is very strong, The Super T-10 was used behind lots of high perfomance motors from the late 60's and early 70's.
The OD does not like abuse like shifting while at WOT. It's designed to upshift and down shift automatically in normal driving. It will downshift like a "passing gear" for freeway use and then upshift. It can also be manually be used for each gear if you desire. I use the OD in my 87 for boulevard cruising where the speeds are 40 to 50MPH For example, 3rd and OD is a lowere RPM than 4th and no OD. When manually using the OD, it's best to use the clutch just like shifting the 4-spped part.
Here's a link showing how the various years work and the parameters.
You can do a search here for "4+3" and you will get lots of information on the trans.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
no such thing as a 'perfect' trans.
oem 6-speeds (zf , t56, etc) actually have 4 useful ratios, one useful o/d, second higher ratio that is good only to pass fed emissions lab testing...even modded cars go faster in 'first over' (5th gear) than 6th gear ('possible' exception; salt flats), 6th gear failures are common to street driven vehicles with extended use and early under increased load...zf repair costs, if service can be found at all, is so expensive that total replacement is more attractive.
aftermarket 5/6 speeds offer little/no service or factory support, high initial cost...some offer increased torque capability, some not.
4-3 'second design' (86+) is more reliable than 84/85...all suffer oem 'attempts' to automate control of the o/d (ez to bypass to manual control but some 'operator grey matter' must exist)
oem 6-speeds (zf , t56, etc) actually have 4 useful ratios, one useful o/d, second higher ratio that is good only to pass fed emissions lab testing...even modded cars go faster in 'first over' (5th gear) than 6th gear ('possible' exception; salt flats), 6th gear failures are common to street driven vehicles with extended use and early under increased load...zf repair costs, if service can be found at all, is so expensive that total replacement is more attractive.
aftermarket 5/6 speeds offer little/no service or factory support, high initial cost...some offer increased torque capability, some not.
4-3 'second design' (86+) is more reliable than 84/85...all suffer oem 'attempts' to automate control of the o/d (ez to bypass to manual control but some 'operator grey matter' must exist)
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
The 4x3 is cantankerous and there are many "inputs" that can make it not want to work.
I suspect that a lot of "rebuilds" are at the hands of unscrupulous shops.
All My issues have been able to be properly diagnosed using the FSM trouble shooting guide and then attacking some electrical input.
If you are a "See what the mechanic says" type of guy, then maybe you should'nt get a 4x3. but if you are a hands on engineering type then you should be fine.
Mine has "Needed a total rebuild" 3-4 times in three years but truth be told......only to find that a $45 switch fixed it right up. Had I listened to "the experts" I would have been relieved of $1500 rather than $45......
Once you understand the thing and all it's inputs, it's a nice unit....
The T10 is easily rebuilt by any shop.....
I suspect that a lot of "rebuilds" are at the hands of unscrupulous shops.
All My issues have been able to be properly diagnosed using the FSM trouble shooting guide and then attacking some electrical input.
If you are a "See what the mechanic says" type of guy, then maybe you should'nt get a 4x3. but if you are a hands on engineering type then you should be fine.
Mine has "Needed a total rebuild" 3-4 times in three years but truth be told......only to find that a $45 switch fixed it right up. Had I listened to "the experts" I would have been relieved of $1500 rather than $45......
Once you understand the thing and all it's inputs, it's a nice unit....
The T10 is easily rebuilt by any shop.....
Former Vendor
Joined: Nov 2006
Posts: 2,482
Likes: 3
From: Carmichael ca
I have an 86 with a 4+3. I've done 23 track days and about 50 1/4 mile passes and never had an issue with it. I rigged a switch to control the OD so I only turn it on on the freeway and I always use the clutch when I engage it.
Like everyone says, change the fluid regularly, you have to pump it in from under the car, and it should hold up OK.
Like everyone says, change the fluid regularly, you have to pump it in from under the car, and it should hold up OK.
Slingshot
Joined: Dec 2001
Posts: 3,817
Likes: 24
From: Charlotte NC
I have an 86 with a 4+3. I've done 23 track days and about 50 1/4 mile passes and never had an issue with it. I rigged a switch to control the OD so I only turn it on on the freeway and I always use the clutch when I engage it.
Like everyone says, change the fluid regularly, you have to pump it in from under the car, and it should hold up OK.
Like everyone says, change the fluid regularly, you have to pump it in from under the car, and it should hold up OK.
I've had mine for 24 years of spirited driving and other than replacing a solenoid and a switch I have done nothing more than regularly change the tranny oil and the overdrive fluid & filter. If the car that you are looking at has been reasonably maintained, I would not shy away from it because of the tranny. Finally, Royal Purple gear oil in the T10 will make it shift a lot smoother. Works great for me.
Good luck with your decision
Drifting
Joined: Jan 2001
Posts: 1,347
Likes: 4
From: Slidell La
I have an 86 with a 4+3. I've done 23 track days and about 50 1/4 mile passes and never had an issue with it. I rigged a switch to control the OD so I only turn it on on the freeway and I always use the clutch when I engage it.
Like everyone says, change the fluid regularly, you have to pump it in from under the car, and it should hold up OK.
Like everyone says, change the fluid regularly, you have to pump it in from under the car, and it should hold up OK.
However...
1) I always locked out the OD in town and ONLY used it on the highway
2) I changed pan and fluid ever 25,000 miles to make sure no gear oil from the 4 speed went into the OD unit
3) Mine was bought used and the OD fill plug is aluminum and was galded into the side of the OD. I could only add oil by pulling the oil cooler line and pumping in enough to come out of the other cooling line.
So I would check the OD fill plug to see if you can get it out. Otherwise if you lock it out except for highway use it was a solid transmission for all of my driving.
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Drifting
Joined: Dec 2003
Posts: 1,493
Likes: 94
From: Westfield MA
I agree with redrose on the std shift transmission situation for C4's, no perfect situation. One of the problems the way I see it is that both the ZF and the 4+3 are orphans used only on C4's. Not very many people know how to work on them. I had an 86 with a 4+3 and it worked fine, was actually a neat trans once you got used to it. I used it basically like a 5 speed shifting normally through the gears and engaging the OD like it was a 5th gear.
For me, I like to go on trips and if I have a problem when I am 1000 miles from home, what do I do with it? As jhammons01 said, if you get to know the ins and outs, most of the problems can be easily fixed, I was more worried about the situation where I am not in a position to work on it. I think the ZF is better but still an expensive trans to work on.
The 86 and later are reasonably solid units if properly maintained and not abused. Most of the criticism you will hear comes from people that have not owned one.
For me, I like to go on trips and if I have a problem when I am 1000 miles from home, what do I do with it? As jhammons01 said, if you get to know the ins and outs, most of the problems can be easily fixed, I was more worried about the situation where I am not in a position to work on it. I think the ZF is better but still an expensive trans to work on.
The 86 and later are reasonably solid units if properly maintained and not abused. Most of the criticism you will hear comes from people that have not owned one.