98 1500 4l60e clunk at 45-50mph - lockup?

[Jwill000]

dad got a 1500 with overheating issues, we pulled the engine, cleaned it up, replaced the rotten intake manifold(at coolant ports) and heads.

now it runs fine, but above 45mph if you let off the gas at all, it does a hard clunk. ujoints checked, suspension checked, no slop. I think it's the lockup converter kicking in. dad took it to a transmission shop, they said to 'run it till it blows' - he didn't like that suggestion so the truck is just parked. is there a way to prevent the converter from locking up to see if that's the cause?

again, it only happens above 45mph when you let off the throttle. I read somewhere to replace the valve body, somewhere else said the torque converter does go bad - but never saw the same symptoms as we have

thanks

 

[NickTransmissions]

dad got a 1500 with overheating issues, we pulled the engine, cleaned it up, replaced the rotten intake manifold(at coolant ports) and heads.

now it runs fine, but above 45mph if you let off the gas at all, it does a hard clunk. ujoints checked, suspension checked, no slop. I think it's the lockup converter kicking in. dad took it to a transmission shop, they said to 'run it till it blows' - he didn't like that suggestion so the truck is just parked. is there a way to prevent the converter from locking up to see if that's the cause?

again, it only happens above 45mph when you let off the throttle. I read somewhere to replace the valve body, somewhere else said the torque converter does go bad - but never saw the same symptoms as we have

thanks

Did you ever figure out this problem?

If no, do the 'clunks' coincide with a 300 RPM or so drop in engine speed as in they occur at exactly the same time? If not, the clunk has nothing to do with your torque converter. More than likely, it's the shift from 3rd to 4th where the 2-4 servo applies the band, which grabs and arrests the reverse input drum, which arrests the sun gear reaction shell which arrests the rear sun gear so the rear planet can rotate around it, giving you a mechanical gear ratio change from direct drive to overdrive.

The cluck itself may be the center support making contact with the anti-clunk spring and perhaps the spring is a bit worn...

Just a possible explanation...

 

[rzr6-4]

Mine has recently started doing this as well. Following...

 

[NickTransmissions]

Mine has recently started doing this as well. Following...

If im correct, both of you will be either rebuilding your respective transmissions or swapping them for good-used units. But if the clunk isnt producing any drivability symptoms like missing gears, slippage, etc I woudn't worry about it as there's nothing you can do short of ripping it apart on the bench to see what's up with it.

 

[DirtrdDiva98]

dad got a 1500 with overheating issues, we pulled the engine, cleaned it up, replaced the rotten intake manifold(at coolant ports) and heads.

now it runs fine, but above 45mph if you let off the gas at all, it does a hard clunk. ujoints checked, suspension checked, no slop. I think it's the lockup converter kicking in. dad took it to a transmission shop, they said to 'run it till it blows' - he didn't like that suggestion so the truck is just parked. is there a way to prevent the converter from locking up to see if that's the cause?

again, it only happens above 45mph when you let off the throttle. I read somewhere to replace the valve body, somewhere else said the torque converter does go bad - but never saw the same symptoms as we have

thanks

Torque converter, there's some stuff the sell in a red little tube. The name is slipping me.

 

[NickTransmissions]

Torque converter, there's some stuff the sell in a red little tube. The name is slipping me.

Lube guard.