transmission swap question
Thread Starter
Instructor
Joined: Jan 2015
Posts: 203
Likes: 2
From: Port Costa CA
transmission swap question
I have a 1988 C4 with the Doug Nash 4+3 trans and would like to know what other manual trans would be a bolt on swap? I don't want to change the bell housing or driveline. Thanks
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
None. The 4-3 is actually a BW 2nd design Super T10 4 speed with a Doug Nash overdrive unit. The 4 speed is very stout but not very common. Not wanting to change bell housing or driveline limits your options. The "C" beam supporting the rear of the transmission and the front of the rear diff is a concern requiring fabrication if not going to the ZF 6 speed.
Safety Car
Joined: Aug 2013
Posts: 4,429
Likes: 605
From: Minneapolis Mn
Well I don't know that's exactly true. I have an 86 that the 4+3 was replaced with a Tremec TR 3550 5 speed prior to my purchasing it. From what I can tell having been under it only a couple of times, it looks like the bellhousing, c-beam, clutch hydraulics etc are the oem style pieces. In fact I had to have the clutch master and slave replaced shortly after buying the car and they were standard 86 parts. It works and has been good to me. I talked to Tremec when I bought the car in 2013, though they said you couldn't buy that transmission new any more, it could be bought rebuilt.
I would think there would be a newer model that would be a direct fit.
You'll need to do your research to find out possible options.
Good luck.
I would think there would be a newer model that would be a direct fit.
You'll need to do your research to find out possible options.
Good luck.
Last edited by hcbph; Feb 9, 2016 at 09:26 AM.
Thread Starter
Instructor
Joined: Jan 2015
Posts: 203
Likes: 2
From: Port Costa CA
trans swap
None. The 4-3 is actually a BW 2nd design Super T10 4 speed with a Doug Nash overdrive unit. The 4 speed is very stout but not very common. Not wanting to change bell housing or driveline limits your options. The "C" beam supporting the rear of the transmission and the front of the rear diff is a concern requiring fabrication if not going to the ZF 6 speed.
Also it appears the ZF6 has a place for the "C" beam to mount like the Doug Nash.
Thread Starter
Instructor
Joined: Jan 2015
Posts: 203
Likes: 2
From: Port Costa CA
trans swap
Well I don't know that's exactly true. I have an 86 that the 4+3 was replaced with a Tremec TR 3550 5 speed prior to my purchasing it. From what I can tell having been under it only a couple of times, it looks like the bellhousing, c-beam, clutch hydraulics etc are the oem style pieces. In fact I had to have the clutch master and slave replaced shortly after buying the car and they were standard 86 parts. It works and has been good to me. I talked to Tremec when I bought the car in 2013, though they said you couldn't buy that transmission new any more, it could be bought rebuilt.
I would think there would be a newer model that would be a direct fit.
You'll need to do your research to find out possible options.
Good luck.
I would think there would be a newer model that would be a direct fit.
You'll need to do your research to find out possible options.
Good luck.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Some members have installed a ZF6 in the early C4's but you do need the bellhousing and most likely the C-beam. Your existing driveshaft can be used but it may require adapting the ZF6 yoke to the front of the driveshaft and possibly changing the length?? But any competent shop that does driveline work can modify and re-balance a driveshaft.
This company makes a Tremec TKO 5-speed bolt-in kit to replace the 4+3 that includes everything you need. Pricey, but it is a bolt-in.
The 4+3 shifter mounts to the trans tunnel and not to the trans itself. Doing a swap such as the ZF6 or even the Tremec trans kits will require some fabrication work to the tunnel.
This company makes a Tremec TKO 5-speed bolt-in kit to replace the 4+3 that includes everything you need. Pricey, but it is a bolt-in.
The 4+3 shifter mounts to the trans tunnel and not to the trans itself. Doing a swap such as the ZF6 or even the Tremec trans kits will require some fabrication work to the tunnel.
Thread Starter
Instructor
Joined: Jan 2015
Posts: 203
Likes: 2
From: Port Costa CA
Some members have installed a ZF6 in the early C4's but you do need the bellhousing and most likely the C-beam. Your existing driveshaft can be used but it may require adapting the ZF6 yoke to the front of the driveshaft and possibly changing the length?? But any competent shop that does driveline work can modify and re-balance a driveshaft.
This company makes a Tremec TKO 5-speed bolt-in kit to replace the 4+3 that includes everything you need. Pricey, but it is a bolt-in.
The 4+3 shifter mounts to the trans tunnel and not to the trans itself. Doing a swap such as the ZF6 or even the Tremec trans kits will require some fabrication work to the tunnel.
This company makes a Tremec TKO 5-speed bolt-in kit to replace the 4+3 that includes everything you need. Pricey, but it is a bolt-in.
The 4+3 shifter mounts to the trans tunnel and not to the trans itself. Doing a swap such as the ZF6 or even the Tremec trans kits will require some fabrication work to the tunnel.
