92Yoda

ok so my 92 4runner has some insane vibration issues at 35mph up to 70mph and happens when i left off the gas, although it will keep vibrating after i press the gas pedal too, im almost sure its my transmission mounts, i recently just replaced everything in my rear axle from the differential to the brakes and i did the rear ujoints, so i wouldnt suspect that, the driveshaft has no play in it. what im asking is, if anybody has some insight on how to do the transmission mounts? is there any write ups? yes i have looked, but possibly not hard enough so i need your guys' help, thanks

rattlewagon

Loosen the mount bolts, then lift the tranny slightly and take the bolts and the mounts out, then put in the new mounts. Trail Gear makes "bomb proof" mounts..

You had both rear driveshaft u joints changed, correct? Checked all your link end bushings? Tiers or drive shaft out of balance?

92Yoda

Both ujoints done yes, not sure about its balance tho. Ive had since i bought it two years ago but in the last two weeks it has gotten twice as bad and im 98% sure its the tranny mounts aside from old mounts, nothing else has to be removed to do the tranny mounts? Thanks

stanprophet

Check to make sure that the drive shaft bolts have not come loose. Loose bolts will cause a hell of a vibration when you let off the gas.

Punchy

Also check Ujoint play (even if there new), I had some new ones installed and they were the wrong size (small) yet still the #s were in there book and thought they were right.

stanprophet

Yep that would do it also. I have never seen a transmission mount cause a vibration. Now having a bad transmission mount will allow drive train harmonics and vibrations to be transmitted to the body of the vehicle. But if the vibration is that bad you really need to be scrutinizing the joints and the bolts.

Just got done doing the rear joint in my 88, it was seized when I bought it, and causing vibrations. Usually I do them both, but the front was in perfect shape.

92Yoda

well i spent 5 mins underneath it after work today and found that the bolts on the front of the driveshaft came loose quite abit actually ahaha im emabarassed, i tightened them up and the vibration has gone 98% away, its back to the point where i bought it, there is still a very minor vibration i can feel still in my seat and it only occurs around 60-70mph. its so minor i think ill leave it for now

iliketoyota

weird, this exact thing just happened to me on the way home. Put new u joints in 2 weeks ago, then it has started shaking like it did before worse and worse until tonight on the way home to where it became reallly bad. I pulled over and crawled underneath with my t shirt in 15 degree weather and saw the front bolts came loose and tightened them with a ratchet and a pair of pilers, need to go out and tighten them better tonight. Not sure why they loosened, i double checked them all. Does it matter which way they go through? Maybe i just didnt get them tight enough.

Co_94_PU

iTrader: (-1)

Generally you want the bolt head facing the front of the vehicle, this way when the nuts fall off you have a chance the bolt will stay in.(Like in your frame crossmembers for example)

Parts explosions show them with the bolt head facing the middle of the shafts. Makes since here cause you probably can't get the bolts in the other way

Remeber to check drive train bolts and nuts after the first drive and again later, eg 20&100miles.

stanprophet

The nature of drive train harmonics can cause the bolts to come loose. Most factor service intervals have an lengthy inspection process and most also list to check the torque on the Propeller shaft bolts. Propeller shaft being the proper name for drive shaft.

Whenever I remove a shaft, I usually put a little dab of red locktite on the bolts, and torque them to factory specs, this works wonders to keep them in place.

Glad you got it all worked out OP.