Yes, it's a basket case. No, I was not on drugs when I built it... (2001 Toyota Tundra 2->4WD Build)

[smokeysevin]

My truck started clicking and vibrating at about 65mph on the way to work this morning, I figured out it was coming from the transfer case once I made it off the highway and was able to get the noise to stop by switching between 2wd high, 4wd high, and 4wd low, then back to 2wd high. Unfortunately the noise came back and would go away after repeating the reset process. It would come back at shorter intervals each time.

I got home and blew apart the transfer case to try and find what was wrong and the only thing I found was that the synchro on the main shaft had the teeth ground down. I found lots of fine tooth shavings all throughout the case and planetary assembly.

With the case all apart, I cleaned and flushed everything out in my parts washer. Before I can get it back together though I have a few questions.

Can I order just the replacement synchro or is this a replace the case scenario?

Best guess on what happened is that somehow, the truck tried to shift into 4wd on the highway. I have manual locking hubs which were set to free and the transfer case was firmly on the detent in 2wd.

There should be no way for the truck to have the transfer case change from 2wd to 4wd while driving. There are no electronics in the case at all and the shifters are cable driven off a lever in the cab.

The only thing I could think of is that the 3 little detents plate things on the main gear that the synchro connects with for 2wd and 4wd were installed incorrectly when I reassembled the case after I modified the shift rails to for the twin stick shifter.

Is there anything I missed here?

Sean

 

[smokeysevin]

It looks like you can't order just a replacement syncro, you can purchase a replacement assembly but its $300 so I may try and gut my stock tundra case and swap the components over.

Can y'all think of anything that would have caused the transfer case to try to shift on its own? The shifter cables weren't rubbing and all the mounts were tight. When I took the case apart I didn't see anything that jumped out at me. The fluid still looked fine except for the excess brass in it. When I was limping the truck home anytime I shifted the case to reset it, the movement felt normal.

Sean

 

[Sal R.]

I looked through your old posts and it doesn't appear the cables are routed next to any heat sources.

I'll ask anyway.

Any chance the cables are stretching under normal operation?

 

[smokeysevin]

I looked through your old posts and it doesn't appear the cables are routed next to any heat sources.

I'll ask anyway.

Any chance the cables are stretching under normal operation?

Nope, same amount of end play as before. The internal detents in the case hold the shift rails in place anyways, the shifter I made doesn't lock or apply any pressure unless you are moving it.

Another question, do the fj cruiser cases use the same bolt pattern that the a340 trans uses? Pricewise, it looks like its going to cost the same to get just the part as it would to source another transfer case.

Sean

 

[Sal R.]

Nope, same amount of end play as before. The internal detents in the case hold the shift rails in place anyways, the shifter I made doesn't lock or apply any pressure unless you are moving it.

Another question, do the fj cruiser cases use the same bolt pattern that the a340 trans uses? Pricewise, it looks like its going to cost the same to get just the part as it would to source another transfer case.

Sean

? Man, what a mystery....

Based on what I've researched, yes, same bolt pattern. The auto coupler would need to be transferred over due to the difference in length. At least, that I've read. I've yet to do the mod.

 

[smokeysevin]

Man, what a mystery....

Based on what I've researched, yes, same bolt pattern. The auto coupler would need to be transferred over due to the difference in length. At least, that I've read. I've yet to do the mod.

Just to clarify, the auto coupler as in the input shaft to connect the transfer case to the transmission?

Sean

 

[Smileyshaun]

Now this is not the same setup but I have a buddy that’s been fighting his t case popping out 4 low from time to time for a couple years , he rebuilt both t cases , new mounts , shifters and it would still do it . Being a wheeling rig he just delt with it. Well not to long ago the trans let loose and on inspection of tearing it down turns out the output shaft bearing was just toasted and loose as all get out . So the only thing we can come up with is the trans was sending vibrations from all the extra play in the bearings , because it would usually do it after getting on it hard and letting off the gas . Don’t know if that helps but it’s something to look into

 

[Sal R.]

Just to clarify, the auto coupler as in the input shaft to connect the transfer case to the transmission?

Sean

If memory serves, yes, the input shaft.

 

[smokeysevin]

If memory serves, yes, the input shaft.

I just got off the phone with rock solid toys and it looks like the a340 has a different pattern than the a750 so I either need to swap the transfer case adapter or I need to get another 4runner case.

Oh well.

Sean

 

[Sal R.]

I just got off the phone with rock solid toys and it looks like the a340 has a different pattern than the a750 so I either need to swap the transfer case adapter or I need to get another 4runner case.

Oh well.

Sean

Damn. Really?

Well, that's new information. Thanks for helping confirm it.

 

[smokeysevin]

Damn. Really?

Well, that's new information. Thanks for helping confirm it.

Can't confirm it, just relaying what I was told.

Sean

 

[Sal R.]

Did a bit of browsing over in the FJ forums. It would appear that the AT TC would bolt up to the A750, but the MT TC would bolt up to A340 (40min search).

Low risk option is to probably try and source a T4R or Taco TC.

 

[smokeysevin]

Did a bit of browsing over in the FJ forums. It would appear that the AT TC would bolt up to the A750, but the MT TC would bolt up to A340 (40min search).

Low risk option is to probably try and source a T4R or Taco TC.

Interesting info, thanks for digging. I ended up just ordering a replacement 97 4runner case. Its the same as in there now so it should drop in after modding the shift rails for the twin stick.

I may try removing the syncro or knocking the teeth off of the current gear to see if I can save the case. Since I am using manual hubs and have locked the front add out I have to stop to swap to 4wd anyways so losing the syncro isn't that big of a deal. I still need to find out why it shifted though.

Sean

 

[smokeysevin]

Now this is not the same setup but I have a buddy that’s been fighting his t case popping out 4 low from time to time for a couple years , he rebuilt both t cases , new mounts , shifters and it would still do it . Being a wheeling rig he just delt with it. Well not to long ago the trans let loose and on inspection of tearing it down turns out the output shaft bearing was just toasted and loose as all get out . So the only thing we can come up with is the trans was sending vibrations from all the extra play in the bearings , because it would usually do it after getting on it hard and letting off the gas . Don’t know if that helps but it’s something to look into

Since I have the case off still, I will absolutely check that. Up until yesterday, I had no issue with anything shaking even above 90mph. I don't especially want to have to go through all this again so I am trying to get everything squared away and checked off before break something again and I toss another case in the trash.

Speaking with RST this morning, he also mentioned the case popping out of 4low into neutral but I never encountered that. He mentioned different detent springs on the low range selector which got me thinking that I may have mixed the springs up when I was removing the interlock to allow for the twin stick.

Sean

 

[smokeysevin]

2001 to 2005/6 throttle body adapter design and test fit.

After hearing a couple people speak highly of swapping to the 05/06 plastic manifold, I figured I would give it a shot. The 05/06 manifold has a different bolt pattern than the 00-02 so I took some measurements, made a cad template, printed it 1:1 and glued it onto some 3/16" aluminum. From there, I used my swag portaband table, a 3" hole saw, and proper drill bits for m6 and m8 threads.

I finished up the test fit a couple minutes ago and will be using some more time this afternoon to finish cleaning up the manifold, port matching the adapters to the manifold and throttle body, and fabricating a throttle cable mount.

Since my truck has 278k miles on it and has been throwing intermittent lean codes despite replacing the fuel filter, maf, bypassing the pcv lines, checking all the hoses for leaks. I figured it was a good enough excuse to swap the manifold (I prefer the gasket style from the new manifold) and upgrade the injectors to the 12 hole pinks.

Fingers crossed, I will have some good results when I get it wrapped up later this week.

I also think I have finally found the oil leak I have been chasing and it is not good news. From what I can tell, the oil pump housing is leaking between it and the block. From some reading and spending time under the truck pondering life, the universe, and everything, it looks like I will be pulling the motor to do that job whenever I get the time.

With how the 01 throttle body with adapter fits, the upper radiator hose rubs. This is not an issue on the 03/04 models because they don't use the same weird throttle body. Not sure precisely I am going to fix this but I have a few options.

1) cut the hose and try and fit a section of aluminum or stainless tube in its place. That may give enough clearance not to rub.

2) extend the factory water log closer to the fan. I don't want to do that just in case the fan rubs.

3) modify the crossover tube to come up next to the throttle body rather than in front. Requires welding and costs money.

4) add a 45 degree elbow to the silicone hose to kink it around the throttle body. This makes the most sense to me as of now. I need to measure the tube to find out if it will work though.

Sean

Wires for the throttle motor were hitting the water crossover pipe as was the throttle body coolant thermostat elbow. I had bypassed the cooling lines to the throttle body 10ish years ago so I just removed the elbow which gave me the extra clearance I needed to let the manifold sit flush.

The (modified) factory throttle body cooling hose routing was also fouling on the throttle motor so I stole some venair 1/2" silicone heater hose I had from my stash of jetski cooling lines and made a replacement. I think the horizontal leg is a little bit too long as it sits now but I will double check before starting it up. It clears the fan by a few inches but I would like it to be a little tighter.

I placed an order for some 1.5" silicone elbows and aluminum bends last night from verocious motorsports hopefully they will show up quickly so I can put this mess to bed.

All I can say so far is that this better be a sizeable increase in power/driveability or I am going to be pissed for having spent this much time and ~$500 on it so far.

EDIT: I ordered the water crossover pipe from a 2000 gs400 and will be trying that out to add the clearance I need. (https://www.lexuspartsnow.com/parts/lexus-joint-water-by-pass-front~16355-50070.html) It looks like it will swap but I will confirm when it gets here later this week.