Transmission Puzzle -- Can You Help??

[Smirch]

Hello All -- I am looking for anyone with some insight on this little puzzle.

I bought a 94 4runner V6 4WD with a recent tranny rebuild.

It is shifting smoothly, etc. All fluids checked.

However, I have a shudder, or a series of clicks that I can hear and feel as I touch the shift stick area and console.

The catch is, it happens as RPMs increase, starting at 2800, but like clockwork they come on strong at 3500 RPMs -- Regardless of which gear I am in. I am told that means it is not a driveshaft problem, because the rotation velocity is different for each gear.

Three other clues -- It only happens during acceleration, not as I pass back down through the RPMs. Also, in neutral it is not really noticeable, but I have heard a few clicks at 3500 rpms there too.
And lastly, it seems to go away as I turn, however gently to the left, but get worse at all RPMs as I turn to the right.

My friend thought it would be something with steering pump, but there are no unusual noises as I turn the wheel while sitting still, and the steering is working fine.

It doesn't seem to be affecting anything, but I am worried it will put repeated stress on whatever is vibrating like that.

I hoped it could be something as simple as the transmission bracket to the engine, which I had to put on after that rebuild, but it appears tight. The rebuild warranty for parts is still in effect, although I don't know if it transfers to me as a new owner.

Any ideas you could give me would be much appreciated. Thank you very much! -- Brian

 

[Smirch]

One More Clue

Today, I tried it in 4wd high mode. The problem seemed to go away. No noise, etc. Does that mean it could be something in the transfer case?

When the noise happens it is almost like a repeated knocking coming from the shift stick console area. Thanks for any insight!!

 

[khaug]

The catch is, it happens as RPMs increase, starting at 2800, but like clockwork they come on strong at 3500 RPMs -- Regardless of which gear I am in. I am told that means it is not a driveshaft problem, because the rotation velocity is different for each gear.

Driveshaft rotational speed is related to vehicle speed only. The gear that you're in has no effect on driveshaft rotational speed.

 

[NCSCOTT]

[/B][/QUOTE] Driveshaft rotational speed is related to vehicle speed only. The gear that you're in has no effect on driveshaft rotational speed. [/B][/QUOTE]
:iagree:

As your speed increases (MPH) your drive shaft rotation speed increases at a linear rate. The faster you go the faster your drive shaft spins.

I am not very familiar with that generation of 4Runner. But, don't the front axles have a axle shaft with a joint similar to a CV Joint?? Have you had those checked? How many miles are on it? Are you sure there is Toyota fluids in the tranny and Transfer case?? Have you had the U-Joints checked in both front and rear drive shafts?? they can not be checked correctly unless you jack it up and take the tension off the shafts. Do you have limited slip axles and has the friction modifier been added if they are???

Just some brain storm Ideas. Hope it helps.

 

[Smirch]

Clarification

Thanks for your replies -- I understand -- I worded it wrong, I meant that the driveshaft is spinning at different speeds for each gear, yet the clicking always happens at 3500 RPMs regardless of speed.

In response to your suggestions -- wouldn't the front axle also be speed-dependent rather than rpm-related?

Also, does the fact that it goes away in 4WD mean that it is a problem inside the transfer case?

BTW, The truck has 120,000 miles.

Thanks again for all your ideas!! -- Brian

 

[JungleJim]

Re: Clarification

BTW, The truck has 120,000 miles.

The truck only has 120,000 miles and needed a tranny rebuild? That surprises me since it's a Toyota.

 

[NCSCOTT]

I had a rear end rebuilt on a 96 pick-up, about a month after I got it back all of a sudden while coming to a stop I could hear a bad grinding noise coming for the rear axle while coming to a stop. While accelerating it would go away but while coasting or breaking it would grind. I figured out the pinion nut had come loose allowing the pinion to move forward and backwards in the housing therefore allowing the pinion gear to slide back and grind againts the center of the carrier which the ring gear is bolted to. I figured out real quick if i kept my foot on the gas while breaking I could keep the pinion pulled forward in the housing in relation to the ring gear and stop it from grinding the gears to death.

I hope I explained it well enough??? But my point is could the same be applied in reverse to the front axle??? In my problem above when I turned either direction it was worse due to the diference in rotation speed between the right and left wheels. I am not sure about Toyota but someone else maybe able to answer this.

Does Toyota use a Central Axle Disconnect (CAD) similiar to Dodge or GM?????

If so when you are in 2WD one of the front axle shafts are not directly connected to the carrier. So when you put it in 4HI the transfer case engages and the CAD engages the front axle.

Could it be the front axle has a problem making you think it is the tranny.

This may be just a shot in the dark. So would someone please tell me if I am talking out my A$$ and I will Stop. :bigok: