Missy Good Wench
Wild Blonde from Cloud Mt
The 700R came into being in the 80's and replaced the TH350 in the 4x4's
The 700 started out life on a sour note and earned a very poor reputation from the gitgo
The input shafts on the early boxes were a 27 spline unit that was pressed into the input clutch drum.
These shafts would crack and break readily as they were drilled with several passages and holes.
Breakage almost assured the tranny would scatter all over the street.
The early trannies 82-85 in the 4x4's are a very poor choice to build.
The later boxes 87 on are the best choice. The "K"Case (has a big K on the bellhousing) are the best choice.
The 87 to 91 were hydraulic shifted and controled with a TV cable.
The later units were called the 4L60E and were all electronic.
The later units have a 30 spline input shaft that is pressed into the input drum.
Although better, even the late drums can and will fail in the spline area if used under rough conditions.
This condition can be corected and upgraded with the addition of a hard steel ring that presses over the hub area. There is a kit for this that comes with the ring, a new front piston and seals.
The front pump was originally a 9 vane pump and has been upgraded (aftermarket) to a 13 vane (13 is the gold standard)
There are also mods needed to improve the front pump bushing and seal area to prevent seal and bushing failure.
The reverse input clutch is the next item.
This clutch assembly is generally fine for most applications in its stock form.
There are some mods that are done during the installation of a "Shift kit" and are well covered By transgo.
The front sprag is weak and can let go under hard use.
Replacement with an HO unit is highly recommended.
The gear train in these boxes is not the greatest and the planetaries should be replaced with ones that have the 5 pinion carriers.
All bushings need to be replaced at the time of overhaul.
The rear roller lock (Low gear) needs to be replaced with an HO unit to enhance low gear.
The 2-4 band is another weak point. These are available in several incarnations.
There is a HD RED band that is good for most applications that are not all out race.
There is also a kevlar band available.
The 2-4 servo needs to be upgraded too (Round unit on TH side of case)
The servo piston under the cover needs to be upgraded to an aftermarket one with different sized piston heads to enhance the holding power.
The 700 having a very low first gear has a fairly broad spread between 1 and 2 this puts a fairly good amount of stress on the band when the 1-2 shift occurs and especially when things are happening under full throttle.
A broken 2-4 band kills second gear as well as OD (4th)
The3-4 clutch is another sore spot.
These clutches are too few and too light.
Thw aftermarket has some good parts available to remedy this situation.
A higher steel plate and friction plate count takes care of the failure in the 3-4 clutch.
The forward clutch is fine as long as the tranny is from a V8 model.
Do not use a V6 model in a truck, they are too light.
The Sunshell is also a weak spot.
The sunshell splined hub area is notorious for ripping out.
There is a fix.
Its called the "BEAST" and has a reinforced hub to eliminate the failure.
There are some companies that offer a kit that allows the use of needle thrust bearings throughout the gearbox.
This mod eliminates all the thrust washers. (weak spot)
The remaining mods are in the valve body and include valve changes and spring changes to improve reliability and durability.
Transgo makes some very good shift Kits as well as other good parts.
Transgo makes a KIT called then 700-LU
This kit will allow the 700R4 to opperate properly and lockup without the need for any electrical connections at all.
Them Kit allows the lockup to be custom tailored for shift speed.
The converter is fairly small in the 700 and with the included lockup clutch this makes the pump and the turbine small also.
A fully welded pump and turbine assembly are a must have in a 4x4 application.
The lockup clutch needs to be a HD one and there are even Kevlar clutches available.
With the above mods made expect to pay at least $1500 even if you do the bench work yourself.
A fully done 700R4 is not a cheap tranny (If you want it to live)
The biggest area of error is the adjustment of the TV cable.
Poor adjustment can and will result in failure even of a properly built tranny.
The cable must be adjusted by the instructions aupplied with the shift kit.
The test is a simple one.
Roll out on a very light throttle acceleration and as soon as the 1-2 shift occurs you mash the throttle to the mat, the tranny should drop right back to first gear.
If the tranny does not drop to first the adjustment is wrong.
The 700R4 is not at all a heavy duty box but can if built right handle some serious power.
The 700 can hold a 6.2/6.5 with a turbo and live fine.
Keep in mind though that the tranny needs all the mods to live.
I hope this info helps others.
Missy
The 700 started out life on a sour note and earned a very poor reputation from the gitgo
The input shafts on the early boxes were a 27 spline unit that was pressed into the input clutch drum.
These shafts would crack and break readily as they were drilled with several passages and holes.
Breakage almost assured the tranny would scatter all over the street.
The early trannies 82-85 in the 4x4's are a very poor choice to build.
The later boxes 87 on are the best choice. The "K"Case (has a big K on the bellhousing) are the best choice.
The 87 to 91 were hydraulic shifted and controled with a TV cable.
The later units were called the 4L60E and were all electronic.
The later units have a 30 spline input shaft that is pressed into the input drum.
Although better, even the late drums can and will fail in the spline area if used under rough conditions.
This condition can be corected and upgraded with the addition of a hard steel ring that presses over the hub area. There is a kit for this that comes with the ring, a new front piston and seals.
The front pump was originally a 9 vane pump and has been upgraded (aftermarket) to a 13 vane (13 is the gold standard)
There are also mods needed to improve the front pump bushing and seal area to prevent seal and bushing failure.
The reverse input clutch is the next item.
This clutch assembly is generally fine for most applications in its stock form.
There are some mods that are done during the installation of a "Shift kit" and are well covered By transgo.
The front sprag is weak and can let go under hard use.
Replacement with an HO unit is highly recommended.
The gear train in these boxes is not the greatest and the planetaries should be replaced with ones that have the 5 pinion carriers.
All bushings need to be replaced at the time of overhaul.
The rear roller lock (Low gear) needs to be replaced with an HO unit to enhance low gear.
The 2-4 band is another weak point. These are available in several incarnations.
There is a HD RED band that is good for most applications that are not all out race.
There is also a kevlar band available.
The 2-4 servo needs to be upgraded too (Round unit on TH side of case)
The servo piston under the cover needs to be upgraded to an aftermarket one with different sized piston heads to enhance the holding power.
The 700 having a very low first gear has a fairly broad spread between 1 and 2 this puts a fairly good amount of stress on the band when the 1-2 shift occurs and especially when things are happening under full throttle.
A broken 2-4 band kills second gear as well as OD (4th)
The3-4 clutch is another sore spot.
These clutches are too few and too light.
Thw aftermarket has some good parts available to remedy this situation.
A higher steel plate and friction plate count takes care of the failure in the 3-4 clutch.
The forward clutch is fine as long as the tranny is from a V8 model.
Do not use a V6 model in a truck, they are too light.
The Sunshell is also a weak spot.
The sunshell splined hub area is notorious for ripping out.
There is a fix.
Its called the "BEAST" and has a reinforced hub to eliminate the failure.
There are some companies that offer a kit that allows the use of needle thrust bearings throughout the gearbox.
This mod eliminates all the thrust washers. (weak spot)
The remaining mods are in the valve body and include valve changes and spring changes to improve reliability and durability.
Transgo makes some very good shift Kits as well as other good parts.
Transgo makes a KIT called then 700-LU
This kit will allow the 700R4 to opperate properly and lockup without the need for any electrical connections at all.
Them Kit allows the lockup to be custom tailored for shift speed.
The converter is fairly small in the 700 and with the included lockup clutch this makes the pump and the turbine small also.
A fully welded pump and turbine assembly are a must have in a 4x4 application.
The lockup clutch needs to be a HD one and there are even Kevlar clutches available.
With the above mods made expect to pay at least $1500 even if you do the bench work yourself.
A fully done 700R4 is not a cheap tranny (If you want it to live)
The biggest area of error is the adjustment of the TV cable.
Poor adjustment can and will result in failure even of a properly built tranny.
The cable must be adjusted by the instructions aupplied with the shift kit.
The test is a simple one.
Roll out on a very light throttle acceleration and as soon as the 1-2 shift occurs you mash the throttle to the mat, the tranny should drop right back to first gear.
If the tranny does not drop to first the adjustment is wrong.
The 700R4 is not at all a heavy duty box but can if built right handle some serious power.
The 700 can hold a 6.2/6.5 with a turbo and live fine.
Keep in mind though that the tranny needs all the mods to live.
I hope this info helps others.
Missy
