A343f Transmission: manual Torque Converter Lockup..anyone tried? (1 Viewer)

[geanes]

98 LX (A343f transmission). It seems that the only time my torque converter locks-up is when it's in overdrive (4th). Even then, it does seem to "adjust" while cruising and disengage the lockup (even in 4th). It does not seem to lockup at all in 2nd or 3rd. This is not normally an issue for me. However, when towing, my trans temps fly all over the place (138-190). Cruising on the highway at 70mph with overdrive on and the converter locked, I see 138 on the temp (Scangauge) and a consistent 188 on the engine temp. I try driving in 3rd (OD off) as many have suggested, but the temps continue to climb into the high 170s. When I let off the gas, the trans temps shoot higher still. Seems clear to me that 3rd never locks the torque converter. The revs also climb over 3k and drive engine temps to 191-193. In Texas (where it's relatively flat), this isn't too much of an issue. But, I go to CO all the time and am about to start my trips up there later this month. For the first time, I'll be towing a small camping trailer. I'll need to be in an O/D off state most of the time. Can't afford to the let the engine temps and trans temps climb too high. Seems that maybe a manual torque converter lockup could be the ticket to keeping the trans temps and engine temps lower when towing in the mountains. I would gain better engine braking as well on the descents. Here's a link to the one I'm looking at. Cruiser Brothers has them too and they will lockup both 2nd and 3rd along with locking in 4th ($600). In order for 1st to be locked, I'd need to buy an entire heavy duty valve body for like $1300 which I don't intend to do. Curious peoples' thoughts on this?

GENII Torque Converter Lockup Control Kit to suit Toyota LandCruiser 100 Series 4 Speed

Designed to give you manual control over the factory lock-up torque converter, while still allowing the transmission to change up and down through the gears as per normal.

automatictransmission.com.au

Trailer I'm looking at buying: Black Series Dominator....3400lbs dry/4400lbs GVW

My current trailer: PakAll (Morris Mule knock-off) with Smittybilt Overlander tent and ARB 2500 awning....1200lb total.

 

[abuck99]

Cruiser Brother's imports and distributes the Wholesale Auto Transmission product range for North America- they can probably give you some good information & feedback.

That is one beast of an off road trailer; I think you'll be wanting a diesel conversion to pull that thing up & down hills and through the sand.

 

[geanes]

Cruiser Brother's imports and distributes the Wholesale Auto Transmission product range for North America- they can probably give you some good information & feedback.

That is one beast of an off road trailer; I think you'll be wanting a diesel conversion to pull that thing up & down hills and through the sand.

Yeah, the trailer is sick. Saw it in person and it's really impressive. Fully boxed galvanized steel chassis with beefy independent trailing arm suspension. The body is fully seam-welded aluminum (no tack welding anywhere) and completely waterproof. The entire underside is metal (aluminum) and coated with a thick raptor-liner like coating. 12" brakes, full pullout kitchen, Dometic fridge, 200ah AGM batteries with solar, etc. I walked away very, very impressed. At 3400lbs, it's a monster for sure.....in both weight and impact on the wallet (roughly $5.25/lb)! My poor 98 will probably do 30mph up some of the paved passes....if I'm lucky. Guess I should invest in a Supercharger while I'm breaking the bank

 

[ga12r1]

Yeah, the trailer is sick. Saw it in person and it's really impressive. Fully boxed galvanized steel chassis with beefy independent trailing arm suspension. The body is fully seam-welded aluminum (no tack welding anywhere) and completely waterproof. The entire underside is metal (aluminum) and coated with a thick raptor-liner like coating. 12" brakes, full pullout kitchen, Dometic fridge, 200ah AGM batteries with solar, etc. I walked away very, very impressed. At 3400lbs, it's a monster for sure.....in both weight and impact on the wallet (roughly $5.25/lb)! My poor 98 will probably do 30mph up some of the paved passes....if I'm lucky. Guess I should invest in a Supercharger while I'm breaking the bank

If you don’t already have headers they really made a difference towing my TT. It’s 3400 dry too. With my 2000 I couldn’t hold grades very well in 3rd but with the headers it holds. I can’t tell much of a difference daily driving but Towing they really shine.

 

[geanes]

If you don’t already have headers they really made a difference towing my TT. It’s 3400 dry too. With my 2000 I couldn’t hold grades very well in 3rd but with the headers it holds. I can’t tell much of a difference daily driving but Towing they really shine.

I wanted the Thorley headers, but have been told many times that, for whatever reason, they don't work on the 98-99 100s. Not sure at all why not. If it were confirmed to be compatible with my 98, I'd do it in a heartbeat.

 

[ga12r1]

I wanted the Thorley headers, but have been told many times that, for whatever reason, they don't work on the 98-99 100s. Not sure at all why not. If it were confirmed to be compatible with my 98, I'd do it in a heartbeat.

Yeah, I don’t know why they wouldn’t work. Probably something small that could be worked around
They do help though. I paired the DT catback with the headers and love the setup just a little more every time I drive it.

 

[geanes]

Ok, so Cruiser Brothers confirmed that the manual Torque Converter Lockup will work on 3rd and 4th on the A343f. They said I'm probably not seeing 3rd lockup (which it should according to them) because of the strain the engine is under pulling my nearly 7800lb rig AND the 1200lb trailer. In order to get 2nd (and 1st) to have manual lockup control, I'll need to add the valve body. So, looking at about $2k. But, that seems like it would be less money than potentially breaking my transmission and/or destroying my brakes (current trailer has no brakes, just idler hubs).

 

[ga12r1]

What about regearing?

 

[slacker24-7]

That trailer shouldn’t be a issue ,after you get the tranny straightened out, I have a buddy with a similar built 98 ,100 pulling a very similar trailer, a Kimberly, all over the place just fine

 

[geanes]

That trailer shouldn’t be a issue , I have a buddy with a similar built 98 ,100 pulling a very similar trailer, a Kimberly all over the place just fine

Probably being overly cautious (prone to do that from time to time). Here in TX it isn't that big a deal as there are no long climbs or descents, just rolling terrain. But, on the long extended passes (Raton, Monarch, etc), I could see my transmission going well over 200 degrees (hit 250 once already) and without proper engine compression braking, burn my brakes out or over-rev the engine on the 10-12 miles descents.

Hadn't really considered re-gearing yet. I was thinking of doing that in conjunction with going to a 295/70/18 tire from my current 275/70/18. But, a re-gear (I'd add lockers at the same time) would be a big investment. Still considering it though.

Those Kimberly trailers are super nice! Probably the best made off-road trailers on the market.

 

[ga12r1]

Uneducated question here. Towing in 3rd(OD off) how does one know if TC is locked or not?

 

[geanes]

Uneducated question here. Towing in 3rd(OD off) how does one know if TC is locked or not?

I can feel it and the trans temp on the Scangauge is a dead giveaway. Hard to explain the feel thing, but it is noticeable when towing when it locks up. Never notice it when I'm not towing. On the Scangauge, you can tell it's locked up the moment the temps either stabilize or drop. They immediately climb the moment it disengages and allows slippage either under more pressure or when decelerating.

 

[ga12r1]

I can feel it and the trans temp on the Scangauge is a dead giveaway. Hard to explain the feel thing, but it is noticeable when towing when it locks up. Never notice it when I'm not towing. On the Scangauge, you can tell it's locked up the moment the temps either stabilize or drop. They immediately climb the moment it disengages and allows slippage either under more pressure or when decelerating.

When towing at a steady speed, say 65mph, does the RPM change when TC locks/unlocks?

 

[geanes]

When towing at a steady speed, say 65mph, does the RPM change when TC locks/unlocks?

No. RPMs stay about the same, but it suddenly feels more "engaged" Hard to explain. Definitely notice it when towing. In 4th, it's very recognizable as the RPMs drop quite a bit and things get smoother.

 

[ga12r1]

I have never towed in 4th, but I don’t really ever notice anything different in 3rd either. I set my cruise at 65mph and run 3200rpm. It feels solid. The only time things change is if I’m going up a steep grade and the speed and RPM start bleeding down. Once it gets down to about 61mph it will down shift to 2nd.

I do see a sharp rise in trans temp when let off the gas or slow down. I don’t know why but I always assumed that was just less airflow through the cooler, but now I know.

When I’m not towing at 65, and the Rpms are lower in 3rd, say 50-60mph, weird things seem to happen. Maybe that’s the TC unlocking/locking?

3200 seems like a good rpm to tow at in 3rd, much less and it struggles.

 

[geanes]

Yup! That's the torque converter unlocking and allowing some slippage so the vehicle can slow down without stalling. Basically think of it like lightly riding the clutch in a standard transmission...the friction that then occurs builds heat which transfers to the fluid. When fully locked up, there is no friction and no heat buildup. I had originally attributed the sharp rise to air flow as well. If I add the full lockup converter, you would have to disengage it before coming to a stop. Otherwise, it would behave like stopping in a standard transmission in gear without depressing the clutch.

You probably are feeling it lock and unlock. I'm a little more attuned to it now and notice it.

I tow in 4th quite a bit. I generally leave OD off until I hit the highway. Since it's mostly flat here, I can tow a light trailer in 4th. RPMs stay relatively low and trans temps stay very low. They immediately climb if 4th needs to unlock.

 

[ga12r1]

Are you planning to do the TC lockup kit and the heavier trailer before HIH? I would like to see both.

 

[geanes]

Are you planning to do the TC lockup kit and the heavier trailer before HIH? I would like to see both.

Probably going to do the TC lockup for sure. Not sure on the Black Series trailer yet. That has to be approved by the spousal unit. Things under $3k are generally "slush fund" money and acceptable. But, a $17k trailer is something that needs to be discussed. Hopefully she won't approve it based upon me getting her something of equal or greater value In order to get my patio, I had to put in travertine tile in the kitchen

 

[geanes]

Here are a few more pics of the Black Series...

 

[geanes]

And the suspension and armored 200liter water tank.