thunder_hamilton

i recently got this odd vibration from 50 miles per hour and up. if im driving with the truck in 5th gear i can get it to decel with out shaking by just applying the breaks but if i engage the clutch and brake my truck shakes all to hell having all the plastics in my dash vibrate and my change to rattle around in that cubby hole. it gets worse with she speed to the point where if im doing 65-70 miles an hour my rear view mirror is unusable do to the vibrating. the stearing wheels chatters as well but i beleave its just due to what ever is causing this shaking. im not to sure what the problem is because all my tires seem to be wearing even and the truck tracks very good. my trans mounts on the bottom seem to be in good shape as well. its a 91 4x4 ext cab with 240 000km on it or 150 000 miles. any ideas or common issues/cures would be greatly apreciated.

Tubbyfatty

If it shakes when you are on the brakes, its mosly caused by a warped rotor.

I dont know about that other shaking you were describing. Could be alot of things but hopefully someone will comment on that.

snobdds

I once had mud caked on the inside of the front wheels and it shook like crazy above about 40 MPH becuase the tires were out of balance. I had to stop on the interstate and get in there with a flat headed screw driver and scrape mud. It did the trick...

Check for wheel balance and like fatty said...your rotors are probably warped.

thunder_hamilton

its all fine and dandy braking its just when i have the clutch in it shakes more violently. also if i tap on the gas real quick and let off doing hwy speed it makes the truck shake to for 2 seconds or so. There was/is no mud in any or my rims either. The front tires seem to be cracking around the outer lugs on the face of the tire if that helps at all?

equalxlength

Maybe a weight came off

Plumbrbob

check you rear drive line....mine shook hard when I let off the gas or pushed in the clutch petal.....then suddenly BAM my rear drive shaft flew off LOL it scared the hell out of me I guess the POS was loose.

other wise I woudl say have your tires rebalanced maybe you hit somthing? or a weight fell off.

yoterr

also your trucks a 91 didint they have the front end disconect deal so your cv's are turning all the time? maybe cv is going bad?? bud def check out the driveshafts

Plumbrbob

that brings up other possible problems

you are sure your in 2wd?

also are your hubs locked in?

sometimes hubs dont unlock jack the truck up and spin the tire see if they are sticking

ayron

also make sure to check the large bolt that holds the flange protruding from the transfer case which is used to bolt the driveline on. mine was loose and I tried everything to stop the shaking not knowing about this bolt. the shaking caused my speed sensor plastic gear to break, ujoints to go out and now my transfer output bearing is shaking even after tightening that bolt. It is quite large 30 mm I think and you cannot see it until you unbolt the driveline 4 bolts.. anyone know which bearing in my transfer case is most likely to be shot after this loose bolt? this will be low hanging fruit after this dang head gasket job.. almost together.. whew

thunder_hamilton

Ok so I found my rear drive shaft was loose in the fact that I could spin it and it had side to side play as well. What van I do? Should I find a replacement shaft?

1990mudslut

I don't mean to jack your thread but it would be dumb having the same topic again.

I have always had shaking in my 90 ext cab with bfg a/t 31x10.5.I have the basic ideas of why it would shake from reading around and can eliminate some of the ideas.The cv are a great possibility truck is almost 20 now and to my knowlege they have never been replaced.How can you tell if they are giving out?I know for a fact im in 2wd and my hubs are unlock.I get my tires balance every 3k miles and that seems to eliminate a good bit of shake but still jary.I just checked the front and rear driveshafts both seem tight not loose or anything nor are they caked in mud.my bushings and shocks are stock which could be my problem.The bushings look dry rotted.I havent checked that bolt in the transfer case that was talked about a few post up.Do yall reccomend me checking?I have searched and searched and newver heard anything about this bolt cuasing shake at all.

Plumbrbob

what exactly is loose it it the u-joint (the cross thingy)?

Plumbrbob

or do you have a two peice drive line and its the carrier bearing (the donut looking thingy)?

thunder_hamilton

Naw it's the u joints. Is it ok to replace just the one or should I get both front and back?

Plumbrbob

if the other needs it then do it.