Transmission TH700R4 - help
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
First, you will need to determine if the shift linkage/cable is actually rotating the shift shaft properly to move the shift valve into the reverse detent. If it is properly positioning the shift shaft/valve setting, then the problem is internal. If all the other ranges work properly, reverse should work also. Each range uses two [particular] clutch packs to allow proper function. Reverse uses the same packs used in other ranges...just in a different 'combination' than with the others. So the clutches themselves should be OK if other ranges work. I suspect a shift linkage/cable problem...but it could also be some electronic gizmo (i.e., solenoid operated valve) on the valve body/channel plate of the tranny. I'm not familiar enough with the 700R4 to know for sure about the electrical items.
Thread Starter
6th Gear
Joined: Sep 2007
Posts: 6
Likes: 0
From: London
Cheers
Thanks for your help. My first thought was that this was going to cost a lot of $ to fix but with your input it does not look that way. I feel a lot happier now and will drop the tranny and get my hands dirty
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
You going to wish you drained the fluid anyway, so I would pop the pan and look for some link bar from the shift lever/shaft to the hydraulic valve in the valve body....see that it has full range,
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Drop the pan. If the other gears work then it's not the manual part of the linkage- either inside the trans or out. the only electrics in a 700R4 are for the lockup convertor and or indications to the ECM about which gear it's in.
The low and reverse clutches are at the rear of the trans. There's a big piston that's the very first piece that goes in during a full rebuild. 3 seals on that one. IIRC, the fluid is ported to that and the input clutch for reverse. Step one needs to be drop the pan and see how much trash is in there.
The low and reverse clutches are at the rear of the trans. There's a big piston that's the very first piece that goes in during a full rebuild. 3 seals on that one. IIRC, the fluid is ported to that and the input clutch for reverse. Step one needs to be drop the pan and see how much trash is in there.
Advanced
Joined: Nov 2006
Posts: 64
Likes: 0
A few years ago I had the same problem, suddenly no reverse anymore on my 82. When I removed the oil pan I found the linkage loose (inside the pan). A small metall clip was broken which was holding a pin in place. Just reconnected it and secured it with a selfmade clip. No cost except some oil and gasket.
Hope nothing severe broke on your tranny!
Hope nothing severe broke on your tranny!
