I have an 87 k5 with a 700r4 transmission, I usually drive it in drive instead of overdrive on the highway because it has 37 inch tires and will try to hunt between drive and overdrive if I don't. Lately the trans. Has refused to hold in drive and shifts on up into overdrive regardless of which gear I'm in. I can shift into 1st and 2nd just fine and it will there tho. I thought this could be a linkage problem but I'm not sure since all other gears work correctly. Any help would be greatly appreciated.
CK5
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700R4 question
- Thread starter ODK5
- Start date
You sure it's just not the convertor locking?
I drive mine in "D" too (3.42's and 35's)
Rene
I drive mine in "D" too (3.42's and 35's)
Rene
I have never heard of this before. You could drop the pan and look at the link from the selector shaft to the manual valve to see if it's bent. And look at the spring arm with the roller tip that hits the selector detents. Maybe the bolt is backing out or something? Any chance you are confusing the converter lock-up with a shift to 4th gear?
Maybe the forward sprag or the overrun clutch is failing? Take a look at this chart:
Maybe the 4-3 sequence/ 3-4 Relay valve or the 3-4 shift valve is sticking?
Maybe the forward sprag or the overrun clutch is failing? Take a look at this chart:
Maybe the 4-3 sequence/ 3-4 Relay valve or the 3-4 shift valve is sticking?
British Slave
1/2 ton status
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Could it be the TV cable adjustment? I know when I changed throttle bodies, the little bit of difference between the old and the new made it do crazy things when shifting. Adjusted it and no more crazy shifts.
I'm not sure what the torque converter lock up would feel like so you guys may be right, I'm not really even sure what that is but I know I can shift from D to OD while on the highway and it never downshifts unless I accelerate. Thanks for the input, I just wanted to get some ideas before I spend the money on it.
Well the OD is a difference of 0.7 - maybe more if it locks at the same time. So for example, if you are at 2500rpm in 3rd, OD will drop it to 1750rpm (or lower if it was unlocked in 3rd). If the change is more like 200rpm, that is just the converter lockup. What gears do you have with your 37s? If they are something awful that starts with a 3, you may never be getting enough governor pressure (i.e. driveshaft speed) to shift to OD anyway. Do you have a tach?
Well i dont have a tach ive just been going on feel and I'm not sure what gears my blazer has, I haven't investigated the axles yet. If I were to guess I'd say they are 3.73 - 3.42ish, probably whatever was factory. I've thought about 4.10's but I really don't want to invest in my 10 bolts. If I find a 3/4 ton donor for the right price an axle swap might help my shifting problem. I just can't figure out why it started acting different two months after I bought it out of the blue!
700s get depressed about stock gears with tall tires and tend to commit suicide. If the 10-bolts are stock and not from a military truck, the lowest the gears could be is 3.73. With 37" tires, this is barely drive-able and trans torture. It's going to need 70 MPH before you can trick it into 4th gear with a nearly closed throttle anyway.
4xcrazy
3/4 ton status
you sure about this statement?
