i have a 91 yota p/u with a V6 with 35" tires.
so im driving to LA today, and i suddenly hear a violent RAPID knocking... coming from below the truck a lil to the passenger side. i pull off the freeway and take a looky and see no outside problems. so i turn around and head for home.

the knocking gets more rapid as i accelerate. not as the tranny gains RPMs.. coz i accell in 2nd gear and the knocking is the same rate as if im acceling from 4th great. so going 50mph in 3rd or in 4th, the knockin is at the same rate. if im in gear with the clutch depressed the knocking ceases, or significantly reduces... but the second i slowly release the clutch and as the engine engages the tranny, the knockin returns.

so me and my friend's deduction as im slowly driving home ... bad universal joints on the drive shaft. but i went home and checked the shaft and it seems ok. no real play or wobbling in it. so now im stumped. gotta take it to the shop 2morrow? ne ideas?

 

From your description, it is road speed related, not RPM. This would indicate a problem with driveshaft or universals (mabye the front shaft). Did you have the front hubs locked in? If so, try with them out. I'm guessing that with 35s, you have it lifted. This usually results in increased driveshaft angles, which can tend to shorten the U-joint/CV-joint life. You may have to put the truck up on jack stands and run it to better isolate the noise.

 

yeh i thought it might be coz of my front shaft, so i check them when i pulled over. it's unlocked. so maybe its still the shaft. it SEEMED ok. i even turned the shaft while under the car while in neutral and moved the car forward and back while i was under it. mayb it needs more stress on it like when the cars running. ill check it out 2morrow AFTER it stops rainin! thanks!!!!

 

how about the pilot bearing, that was what happened to my 01 tacoma...

 

Same sort of thing just happened to me over the weekend except it was more of a vibration. When I got home I found the rear most u-joint had alot of play in it so I dropped the rear DS. I'm just running FWD until I get time to replace the u-joint. The vibrations only occured when I gave it gas. The funny thing is that the vibrations could have been going on for a few days without notice since I just installed a new sub. strange coincidence

 

hm wat about the t-case? thats speed related yeh? it stays constant unless i dump into 4wdLo. it could be a broken tooth no? oh PLEASE dont be the t-case. i guess ill have to drain the tcase when i get home from work today

 

Could be a damper spring in the clutch plate?? My friend at work just replaced his and also found the pilot bearing decetegrated, ball bearings flotaing around in the clutch assy! I have seen those springs fail a few times.

John

 

sounds to me like a possible clutch problem. The clutch in my Supra did that before it grenaded. It didn't like 3rd gear powerbraking burnouts.

 

yeh i was thinking it might be the clutch. it is a bit old... its a centerforce. i was driving up and down the drive way today to try to find out where exactly it was coming fromg. as i was SLOWLY moving forward while in neutral with the clutch depressed, i release the clutch and i hear the thud. im in neutral.... so is it the clutch?

then i had my bro drive up and down the drive way and i walked along the side,... and the sound sounded more like it was coming from the back of the truck.... the rear difF? AHHHHH not again! this happened this time last year! OMG!

i drained my tcase and it was clean, and ill drain the rear diff 2morrow... i was to tired and it was cold and wet outside!