I have a driveline question on my 88 Chevy Blazer, full size (350 TH700R4)(thought this was a good place to get some info). Sorry about the length. I have recently purchased this truck and have run into some problems.

Problem: During acceleration or any situation where there is a load on the tranny/driveline I am noticing a vibration or shudder. It gets much worse as RPM's increase and is almost gone while decelerating or coasting, only slightly noticable during normal cruising. There is also a loud thump when coming to a stop and the tranny is shifting to low gear. Also happens when shifting from Drive to reverse (like there is play after the tranny) Tranny shifts fine in all gears with no slipping or floating.

I just changed the tranny fluid, which was in there for a long time by the looks of it. There was some metal powder on the magnet, more than I'm used to seeing but not that bad. I had also checked the transfer case fluid, which was only 1/4 full at most, found some metal shavings (the hard way) in the base of the case. U joints and rear seem ok.

My question is can a tranny actually shudder like that? Could it be the torque converter (truck pulls strong)? Is the transfer case my problem? It is hard to tell where the problem is as the tranny and transfer case are bolted together.

I would hate to start replacing these parts if they are not needed ($$$) and trany shops always rip you off. Does anyone have any ideas? Thanks for any help, I appreciate it.

 

I have a couple of ideas: On the shuddering, it could be the torque converter, or a bad plug wire. It happened to me once, and it only shuddered when a load was on it. I'm told you can check the T/C by driving in high gear up-hill, and lightly putting your foot on the brake, just enuf to set the brake lights off. If the T/C is good, it should just unlock. If it does anything else, that would be the problem.
On the rear clunking, I'm not sure what you meant by loud, but there will be some play in the rearend, especially if the truck has some miles on it. I wouldn't worry too much about it unless it scares people when you put it in gear.

I hope this helped you some. If you have any other questions, drop me a line.

Jeff

 

Jeff,

Thank you for the help. I wasn't sure if a tranny or converter would make that kind of shudder. I tried the uphill test and no reaction by my converter. Seems as it is not locking up at all. I'm going to wire a switch to the connector to check.

I have a converter that I recently removed from my Camaro (T-5 swap). It is the original converter and the car has 49K miles on it. Would this converter work in the truck? Car is a TPI 350 w/ TH700.

Is this something that would cause damage to the tranny/engine? Should I avoid driving until I fix the problem? I would not be able to replace the converter until the weekend. I don't want to do any damage to any other parts. Thanks again.

 

The camaro's converter should work fine, though it may be a slightly different stall. I've heard that when a converter goes bad, it can take the whole trans with it. Running the manual switch is a good idea, and I believe there are good instructions for that in the tech section of this site. I haven't tried it yet, but I will soon. I bypassed my computer so none of my stuff works. I'm glad I could help.