85: 4+3 problem
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Melting Slicks
Joined: Jan 2005
Posts: 3,003
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85: 4+3 problem
The 4+3 Overdrive was plagued with many design problems in 1984 to late 1985 cars. The main problems were an underdesigned bearing in the carrier assembly, a direct clutch thrust washer breakage problem, and a pump sealing problem. The carrier bearing failed because of poor bearing design, bad preload, and poor lube to the bearing. This was resolved with GM part number 14105940. It incorporated a heavy duty bearing, and feed oil to the bearing. It was up to the technician to preload it correctly. 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. The Direct Clutch thrust washer would break because it could spin in the case. Once broken it would jam in between the overdrive piston and case. This would cause the overdrive to get stuck in two modes and burn up. The new piston GM# 14091496 resolves this problem by putting anti-spin tangs on it. It was redesigned by us for GM again in 1997 to utilize better heat treating capabilites. The pump assembly on 1984 and early 1985 cars used a rear pump cover with no seal between the output shaft and cover. The new cover uses a teflon sealing ring to prevent pressure loss and pump whine. The GM number for the new spool is 14091349.
I have not had a chance or money to fix this problem and I have drove it serveral times for 30+ miles at 65 miles per hour. Is it to late to fix it, if so what are the simptoms it is to late? My reverse still works fine. Overdrive does not kick in. But when I turn it on it does get rid of the whirring noise.
thanks for the help
Instructor
Joined: Jul 2000
Posts: 203
Likes: 3
From: Galesburg IL
If your overdrive needs rebuilt, it is usually in the neighborhood of $1100.00. There have been some who have done the rebuild themselves. It's basically an automatic transmission. I didn't feel comfortable messing with that. I had enough fun getting it out of the car. If you have someone rebuild it, I would send it to someone who is familiar with this transmission. I used this guy.
www.pipersauto.com/4speeds.html
I believe S-K Speed comes highly recommended as well.
www.pipersauto.com/4speeds.html
I believe S-K Speed comes highly recommended as well.
Racer
Joined: Dec 2003
Posts: 277
Likes: 3
Originally Posted by jerander
Has anyone fixed his problem on there own, if so how hard was it? If you had it done how much did it cost?
I have not had a chance or money to fix this problem and I have drove it serveral times for 30+ miles at 65 miles per hour. Is it to late to fix it, if so what are the simptoms it is to late? My reverse still works fine. Overdrive does not kick in. But when I turn it on it does get rid of the whirring noise.
thanks for the help
I have not had a chance or money to fix this problem and I have drove it serveral times for 30+ miles at 65 miles per hour. Is it to late to fix it, if so what are the simptoms it is to late? My reverse still works fine. Overdrive does not kick in. But when I turn it on it does get rid of the whirring noise.
thanks for the help
