86 OD unit rebuild?
Thread Starter
Intermediate
Joined: Sep 2012
Posts: 46
Likes: 0
From: Oro valley AZ
86 OD unit rebuild?
I have a 4 + 3 its working as it should but.. new vette owner.
there is some slop in the OD unit. I thought it was a ujoint going bad. I jacked up the car and the sound im hearing when shifting up or down shifting is coming from the OD unit. the car has 99k miles on it so i guess its time for a rebuild soon.
i can get the unit out and in.. but is there a place you all use to have them rebuilt? or do I chance it with a local transmission shop? what should i expect to pay?
I am going to change the filter and gasket soon and am hoping i can get a better look into what the problem might be. but im sure its just something that I am going to have to have done. I am not sure I can take one apart and get it back together again.
thanks for your input.
there is some slop in the OD unit. I thought it was a ujoint going bad. I jacked up the car and the sound im hearing when shifting up or down shifting is coming from the OD unit. the car has 99k miles on it so i guess its time for a rebuild soon.
i can get the unit out and in.. but is there a place you all use to have them rebuilt? or do I chance it with a local transmission shop? what should i expect to pay?
I am going to change the filter and gasket soon and am hoping i can get a better look into what the problem might be. but im sure its just something that I am going to have to have done. I am not sure I can take one apart and get it back together again.
thanks for your input.
Racer
Joined: Dec 2003
Posts: 277
Likes: 3
If you can get it in and out you could rebuild it yourself with help from a factory service manual. There are some good tutorials on the unit by DAvid Fulcher, parts are going to run you in the $500 range, that is what I spent on the last 2 I did.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
You can get it off the trans without removing the trans.
If it works, then I say run it till it quits. The clutches will wear out before it can self destruct.
Then take it apart and rebuild it.
At this present time, you are describing the sprague clutch as worn. If you take it apart, you will be able to get it back together easy if you take pics with your phone, send to your computer or printer, and make yourself a little binder of how it came apart.
you will need to remove the three pipe plugs at the back of the unit, screw in metric all thread, and then spin nuts down onto the all thread to relieve the spring pressure to get it apart. be sure to have about 3 inches of all thread poking out of the trans.
After that, everything else is being able to identify what is worn/broken, and replacing those items.
Also, get yourself the rear tailshaft bushing at the back of the overdrive, and get that replaced. that is probably another source of noise and vibration.
There are bearings in there, but normal pullers will get them off and on.
Good luck with the O.D.
If it works, then I say run it till it quits. The clutches will wear out before it can self destruct.
Then take it apart and rebuild it.
At this present time, you are describing the sprague clutch as worn. If you take it apart, you will be able to get it back together easy if you take pics with your phone, send to your computer or printer, and make yourself a little binder of how it came apart.
you will need to remove the three pipe plugs at the back of the unit, screw in metric all thread, and then spin nuts down onto the all thread to relieve the spring pressure to get it apart. be sure to have about 3 inches of all thread poking out of the trans.
After that, everything else is being able to identify what is worn/broken, and replacing those items.
Also, get yourself the rear tailshaft bushing at the back of the overdrive, and get that replaced. that is probably another source of noise and vibration.
There are bearings in there, but normal pullers will get them off and on.
Good luck with the O.D.
Last edited by coupeguy2001; Oct 22, 2012 at 11:29 AM.
Thread Starter
Intermediate
Joined: Sep 2012
Posts: 46
Likes: 0
From: Oro valley AZ
I know this is English... But half of sounds like Greek 
I willd do some more reading on the subject, can you suggest a website? And a book? I understand that the 86 is different than 84 and 85 models?
Maybe i will buy an 86 od unit that is bad or used and rebuilding that
I willd do some more reading on the subject, can you suggest a website? And a book? I understand that the 86 is different than 84 and 85 models?
Maybe i will buy an 86 od unit that is bad or used and rebuilding that
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
http://www.corvetteactioncenter.com/...Overdrive+Unit
This info page
http://www.5speeds.com/nash.htm
from 5speeds is from '99. They past their O/d rebuild service onto to Brian @ SK Speed
http://www.skspeed.com/
who according to recent posts on here is giving up servicing and supplying parts for 4+3's
Finding a parts source for the rebuild is going to be one of the biggest problems if Brian is gone
Possibly
http://www.pipersauto.com/4speeds.html
Later units were upgraded to overcome the problems found in the early units and did not have the TV cable to the TB found on early ones
http://www.5speeds.com/dne.htm
This info page
http://www.5speeds.com/nash.htm
from 5speeds is from '99. They past their O/d rebuild service onto to Brian @ SK Speed
http://www.skspeed.com/
who according to recent posts on here is giving up servicing and supplying parts for 4+3's
Finding a parts source for the rebuild is going to be one of the biggest problems if Brian is gone
Possibly
http://www.pipersauto.com/4speeds.html
http://www.5speeds.com/dne.htm
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Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
"When a carrier goes bad you will hear bearing noise in direct drive and it will go away in overdrive.
Sometimes it can sound like a tire whirring noise".
Read
http://www.5speeds.com/dne.htm
http://www.5speeds.com/carrier.htm
Sometimes it can sound like a tire whirring noise".
Read
http://www.5speeds.com/dne.htm
http://www.5speeds.com/carrier.htm
Thread Starter
Intermediate
Joined: Sep 2012
Posts: 46
Likes: 0
From: Oro valley AZ
Do u know the cost of the tko? I would like this also, but i cant find prices for them
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
$3K+
http://www.ebay.com/itm/1984-1987-CO...f73f52&vxp=mtr
http://www.proformancepowertrain.com...tte_84-88.html
Many have installed the ZF6 6 speed BOX from a later C4 as a cheaper alternative
Can reuse some of your 4+3 parts
http://members.cisdi.com/~anesthes/zf6/
Do a search on here , the swap has been well documented
Burning Brakes
Joined: Jun 2005
Posts: 1,191
Likes: 15
From: Wallingford Vermont
As someone who has been down this road before...
1. Don't let a "local" transmission shop touch it (as most NEVER even heard of a DNE 4+3).
2. If you are not mechanically competent don't mess with it. There are some special tools required depending how "deep" you need to go (spring compressor, depth micrometer).
3. The FSM is great until you get to the chapter on the 4+3 (missing are line pressure values, valve diagrams, etc).
4 If your OD is making noise or shifting funny, STOP DRIVING IT! Try to diagnose what is wrong with it. If it is an internal failure, remove the unit and get it fixed. Driving it will only compound the damage and turn your repairable core to a pile of scrap.
you have been warned....
1. Don't let a "local" transmission shop touch it (as most NEVER even heard of a DNE 4+3).
2. If you are not mechanically competent don't mess with it. There are some special tools required depending how "deep" you need to go (spring compressor, depth micrometer).
3. The FSM is great until you get to the chapter on the 4+3 (missing are line pressure values, valve diagrams, etc).
4 If your OD is making noise or shifting funny, STOP DRIVING IT! Try to diagnose what is wrong with it. If it is an internal failure, remove the unit and get it fixed. Driving it will only compound the damage and turn your repairable core to a pile of scrap.
you have been warned....
Last edited by DanZ51; Oct 21, 2012 at 10:38 AM.
Thread Starter
Intermediate
Joined: Sep 2012
Posts: 46
Likes: 0
From: Oro valley AZ
As someone who has been down this road before...
1. Don't let a "local" transmission shop touch it (as most NEVER even heard of a DNE 4+3).
2. If you are not mechanically competent don't mess with it. There are some special tools required depending how "deep" you need to go (spring compressor, depth micrometer).
3. The FSM is great until you get to the chapter on the 4+3 (missing are line pressure values, valve diagrams, etc).
4 If you OD is making noise or shifting funny, STOP DRIVING IT! Try to diagnose what is wrong with it. If it is an internal failure, remove the unit and get it fixed. Driving it will only compound the damage and turn your repairable core to a pile of scrap.
you have been warned....
1. Don't let a "local" transmission shop touch it (as most NEVER even heard of a DNE 4+3).
2. If you are not mechanically competent don't mess with it. There are some special tools required depending how "deep" you need to go (spring compressor, depth micrometer).
3. The FSM is great until you get to the chapter on the 4+3 (missing are line pressure values, valve diagrams, etc).
4 If you OD is making noise or shifting funny, STOP DRIVING IT! Try to diagnose what is wrong with it. If it is an internal failure, remove the unit and get it fixed. Driving it will only compound the damage and turn your repairable core to a pile of scrap.
you have been warned....
Racer
Joined: Sep 2008
Posts: 387
Likes: 2
Looks like the TKO transmission only is around USD 2200...2300.
TKO 500 at Summit
TKO 600 at Summit
I unfortunately have no idea at this point what else is needed.
TKO 500 at Summit
TKO 600 at Summit
I unfortunately have no idea at this point what else is needed.
Burning Brakes
Joined: Jun 2005
Posts: 1,191
Likes: 15
From: Wallingford Vermont
Originally Posted by Rontopia;1582129676I
If i cant fix it, nand i cant trust a transmission shop with it, what should I do with it? Im not trying to be a smart ***. Judt not sure what to do with it.
You gotta go to the man
O/d rebuild service onto to Brian @ SK Speed
http://www.skspeed.com/
http://www.skspeed.com/
Thread Starter
Intermediate
Joined: Sep 2012
Posts: 46
Likes: 0
From: Oro valley AZ
Looks like the TKO transmission only is around USD 2200...2300.
TKO 500 at Summit
TKO 600 at Summit
I unfortunately have no idea at this point what else is needed.
TKO 500 at Summit
TKO 600 at Summit
I unfortunately have no idea at this point what else is needed.
Advanced
Joined: Oct 2012
Posts: 76
Likes: 0
From: San Diego CA
Go pay the piper for a rebuilt unit from SK or someone that does them and install it yourself, take yours back in for a core fee.
There are other swaps out there like the TKO and ZF, but they will end up costing you more money, way more time, and will nickel and dime you to death in small parts and frustration. Keep that 4+3 setup and enjoy it. It's a fun transmission when it works right.
There are other swaps out there like the TKO and ZF, but they will end up costing you more money, way more time, and will nickel and dime you to death in small parts and frustration. Keep that 4+3 setup and enjoy it. It's a fun transmission when it works right.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
Orange County Transmission did mine in a single day turn around.
Usually, when the O/D is out, reverse stops working. That is the tell tale sign.
Whining usually means that the Super 10-T 4spd is on the fritz.
I'll wager that your clunk is just the slop in that drive system from being 25 years old. You are just hearing it from the
Usually, when the O/D is out, reverse stops working. That is the tell tale sign.
Whining usually means that the Super 10-T 4spd is on the fritz.
I'll wager that your clunk is just the slop in that drive system from being 25 years old. You are just hearing it from the
Thread Starter
Intermediate
Joined: Sep 2012
Posts: 46
Likes: 0
From: Oro valley AZ
the first time i noticed the sound, to me it sounded like a spindle arm bushing that was just no longer there. so if you can imagine that, you have a good idea of what this sound is that im hearing.
this week, I will have it up on jacks again as I plan to service the od unit this weekend. with the cover off maybe more will be understood.
from what I have read, and understand, the od unit I have now works exactly as it is supposed to. there is a little bit of a grinding sound in 2nd gear at low RPM with the od off. i assume this is the counter shaft barring in the t10.. which means I will need to do something about that soon as well.
thanks for your time