To re-gear or not to re-gear? (1 Viewer)

[CharlieS]

For those who have regeared, are there any horror stories out there as far as gear failures or other mechanical issues associated with the regearing?

Negative. It is an awesome upgrade.

 

[TeCKis300]

This is very helpful, thanks a ton!

While I understand gears don’t equal HP your comment about ‘access to the power band’ is a far better way to sum up my issue. This is precisely why I can’t maintain speed while climbing, once hitting 5k in second shifting into 3rd is 2.5k’ish which is short of the power band.

I believe the 3.9 are Toyota gears so that’s another selling point for them for me.

I know that hole well. On the 6-speed, on really steep grades and elevation towing, I'd get stuck in the shift to second gear where it falls on its face out of the powerband. It's a giant step in gearing in the 6-speed putting me in no mans land. Not enough gearing to accelerate or access the meatier part of the powerband. So I'd sit at ~25mph at ~3000rpm, with max access to 180hp (~135hp at elevation), waiting for the grade to ease up before I could accelerate again. Granted this was at 8k elevation, 7% grade, on 33s, at 15k total rig weight with stock gearing. An extreme scenario by most measures.

4.3s have made a world of difference there. Both allowing better access to the powerband. But also more access to strong engine braking.

 

[linuxgod]

For those who have regeared, are there any horror stories out there as far as gear failures or other mechanical issues associated with the regearing?

Yes. Finding a good shop who knows how to properly set the gears up is key. If you don’t have one nearby I suggest sending your 3rd members to Zuk, though I think he may be on sabbatical.

 

[kcjaz]

Yes. Finding a good shop who knows how to properly set the gears up is key. If you don’t have one nearby I suggest sending your 3rd members to Zuk, though I think he may be on sabbatical.

his website says "out for 2022"

 

[duncancsu]

2008 here, and 34's. Regearing was the best mod I've done. Not the first, and with a limited budget it might come towards the end of the list, but when I got mine done, the truck felt like it had new life. Night and day difference and I wish I'd done it much sooner.

Off the line is like stock. Offroad and downhill you rarely need to hit the brakes. If you have the money and plan to do it sometime, then just do it now and enjoy the experience.

Sorry old thread but what did you regear to?

 

[kcjaz]

Anyone have a hp/torque curve for 3UR-FE? I'm googling but haven't found a good one. I assume a Tundra version is essentially the same? All the hits I am finding are Tundra. All I want to do is look at it while I play with different GR and tire sizes.

 

[TeCKis300]

Funny sorta but @kcjaz and I are talking past each other cause he blocked me long ago. And why he doesn't see my threads or posts. Prob too much AHC

 

[linuxgod]

Anyone have a hp/torque curve for 3UR-FE? I'm googling but haven't found a good one. I assume a Tundra version is essentially the same? All the hits I am finding are Tundra. All I want to do is look at it while I play with different GR and tire sizes.

The Tundra one should be close enough. Only ones I’ve seen from an LC involved a supercharger

 

[Artie]

I know that hole well. On the 6-speed, on really steep grades and elevation towing, I'd get stuck in the shift to second gear where it falls on its face out of the powerband. It's a giant step in gearing in the 6-speed putting me in no mans land. Not enough gearing to accelerate or access the meatier part of the powerband. So I'd sit at ~25mph at ~3000rpm, with max access to 180hp (~135hp at elevation), waiting for the grade to ease up before I could accelerate again. Granted this was at 8k elevation, 7% grade, on 33s, at 15k total rig weight with stock gearing. An extreme scenario by most measures.

4.3s have made a world of difference there. Both allowing better access to the powerband. But also more access to strong engine braking.

Those terrible 2nd and 3rd fear climbs wouldn’t be as bad if the torque converter would lock and the trans temps fell. A few times I’d get a lock in 2nd or 3rd but it was random and I couldn’t make it repeat, it just happened. I never had to pull off but I was close, tc temps got to 255 a few times before the grade leveled off. It was humiliating to be passed by big rigs or full ton dually pulling a house sized 5th wheel while going up hill.

 

[TeCKis300]

Those terrible 2nd and 3rd fear climbs wouldn’t be as bad if the torque converter would lock and the trans temps fell. A few times I’d get a lock in 2nd or 3rd but it was random and I couldn’t make it repeat, it just happened. I never had to pull off but I was close, tc temps got to 255 a few times before the grade leveled off. It was humiliating to be passed by big rigs or full ton dually pulling a house sized 5th wheel while going up hill.

I should probably respect tranny temps more than I do. I've seen 265°F+ on extended climbs riding 5500+ rpm and can't say I let up. IIRC, the AT temp warning light is at something like 306°F. Not saying that it's okay to go all the way to that point and a vehicle in good working order won't likely, with self protections probably coming into play before that point. I don't mind pushing machines hard, coming from my track days which is even more abuse. In return, I service them at appropriate intervals with good fluids. I expect modern fluids to have more tolerance to heat.

The torque converter not locking is expected as it's actually a strategy the ECU uses to get more incremental gearing. You'll notice the rpm ticks up by 100-200rpm when it unlocks and that's additional leverage. Since the ECU knows tranny temps, I would imagine it will manage heat by locking up more if necessary.

The Land Cruiser, more than most cars, should take it. I trust that it's been developed and validated for hard use and that's what I bought it for. I'll let you guys know if I manage to blow it up.

 

[linuxgod]

I should probably respect tranny temps more than I do. I've seen 265°F+ on extended climbs riding 5500+ rpm and can't say I let up. IIRC, the AT temp warning light is at something like 306°F. Not saying that it's okay to go all the way to that point and a vehicle in good working order won't likely, with self protections probably coming into play before that point. I don't mind pushing machines hard, coming from my track days which is even more abuse. In return, I service them at appropriate intervals with good fluids. I expect modern fluids to have more tolerance to heat.

The torque converter not locking is expected as it's actually a strategy the ECU uses to get more incremental gearing. You'll notice the rpm ticks up by 100-200rpm when it unlocks and that's additional leverage. Since the ECU knows tranny temps, I would imagine it will manage heat by locking up more if necessary.

The Land Cruiser, more than most cars, should take it. I trust that it's been developed and validated for hard use and that's what I bought it for. I'll let you guys know if I manage to blow it up.

Light goes on at 302F, shuts off at 275F. 265F is hot, but apparently Toyota isn't concerned enough to warn you at that temp.

The ECU does know trans temp. If you get above 266F *and* the coolant temp exceeds 203F it will force you into 3rd and will lock up the torque converter in 3rd (which otherwise never happens) until the ATF gets below 230F and the coolant below 203F.

 

[TeCKis300]

Light goes on at 302F, shuts off at 275F. 265F is hot, but apparently Toyota isn't concerned enough to warn you at that temp.

The ECU does know trans temp. If you get above 266F *and* the coolant temp exceeds 203F it will force you into 3rd and will lock up the torque converter in 3rd (which otherwise never happens) until the ATF gets below 230F and the coolant below 203F.

View attachment 3097780

Great sleuthing. Thanks for that specific data!

 

[lx200inAR]

Light goes on at 302F, shuts off at 275F. 265F is hot, but apparently Toyota isn't concerned enough to warn you at that temp.

The ECU does know trans temp. If you get above 266F *and* the coolant temp exceeds 203F it will force you into 3rd and will lock up the torque converter in 3rd (which otherwise never happens) until the ATF gets below 230F and the coolant below 203F.

View attachment 3097780

Who wants to put a switch on their ATF temp sensor to short it out so that you can get lockup in 3rd on command (assuming the 203 coolant temp).

 

[linuxgod]

Who wants to put a switch on their ATF temp sensor to short it out so that you can get lockup in 3rd on command (assuming the 203 coolant temp).

I suspect the lock up is a CANbus signal. Unless you can decide and modify it you’ll likely have to settle for triggering a sensor misreading the temp, which may cause other failure modes (change in ATF pressure or engine air/fuel mix or who knows?) you don’t want.

Being able to force the TC to stay locked would be nice though. I don’t care much about 3rd gear but it would be nice when towing to allow the transmission to pick 4th or 5th gear depending on the power needed without worrying about whether the TC is locked. Really that’s what the PWR button should do for us…

 

[bloc]

Don’t the Aus market diesel guys often install a TC lockup switch? Could probably be done on a gasoline rig just as easily..

@VooDoo2 any input?

 

[linuxgod]

Don’t the Aus market diesel guys often install a TC lockup switch? Could probably be done on a gasoline rig just as easily..

@VooDoo2 any input?

Is the transmission ECU the same?

It’s be awesome if it worked

 

[bloc]

Is the transmission ECU the same?

It’s be awesome if it worked

I believe both are integral to the ECU, so it wouldn’t surprise me if it’s similar. Obviously different control systems for the fuel injection side.

I think it might even be the same transmission..

 

[linuxgod]

I believe both are integral to the ECU, so it wouldn’t surprise me if it’s similar. Obviously different control systems for the fuel injection side.

I think it might even be the same transmission..

Well there goes my weekend…

 

[duncancsu]

Don’t the Aus market diesel guys often install a TC lockup switch? Could probably be done on a gasoline rig just as easily..

@VooDoo2 any inpu

Don’t the Aus market diesel guys often install a TC lockup switch? Could probably be done on a gasoline rig just as easily..

@VooDoo2 any

Well there goes my weekend…

Don’t the Aus market diesel guys often install a TC lockup switch? Could probably be done on a gasoline rig just as easily..

@VooDoo2 any input?

I had this same thought and o reached out to a couple of shops and both said to change out my Valve Body. I never dove deep into that but assume this would change potential shift points etc.

 

[steenh]

Sorry old thread but what did you regear to?

I went with 4.88's