Project Thread Supercharged 1UZ Bangkok Drag Truck

[HarperRacingBangkok]

My Bad!

Well, every project needs a major miscalculation, and I have had mine. Nobody to blame but myself . . . . sort of. My builder/shop guys 'could have' caught it, but I'm the guy who supplied what were suppose to be the "right" parts. The part in question is the 1UZ bell housing which is "suppose to" be able to mount the 1JZ automatic transmission "perfectly". Well, the mounting surfaces and bolt pattern of the 1UZ bell housing are identical to the 1JZ, the only problem is that they are not the same DEPTH! No Good! Of course this means that the splines of the trans input shaft do not engage the torque converter or ride in the pilot bushing. No good! I made various inquires on the Internet with experts, visited a ton of sites, and even called up legitimate, big name experts on the subject at reputable transmission shops and was assured by all that the 1UZ bell housing would mate the 1JZ automatic trans. Nope. I am guessing that there are more than one 1UZ bell and more than one 1JZ auto box involved here and that I have the novel combination. My fault was not measuring (let that be a lesson to us all!) or simply placing the bell housing side by side.
Yes Virginia, the 1UZ and the 1JZ automatic trans bell housings have the same mounting . . . . .
. . . . they just are not the same DEPTH.


So, what to do. There are two possibilities: one -- (best, but not what I am going to do) is to disassemble my 1JZ built racing trans and install the input shaft (and pump) from a 1UZ of the correct input shaft length (assuming that they fit . . . . and I do not know that they do); or two -- make a spacer ring (with a pilot bushing allowance) between the current flywheel (ring gear) to ANOTHER flywheel which will have the torque converter bolted to it, and bolt it all onto the crankshaft. The length of the "spacer ring" is about 2 inches. It will work, and only adds the weight of the spacer ring and the additional flywheel (it will fit inside the 1UZ bell housing). I will do this at the machine shop using a dummy block for measurement.


What would YOU recommend?

 

[JustenGT8]

Oops

10 char

 

[cribbj]

What about using a thicker torque converter?

David (Lextreme) might be your man for this as he's had custom torque converters built in the past in order to couple the UZ to the TH400's.

 

[scotturnot]

What a let down, sorry to hear this. I am not sure if I like the 2 inch spacer idea. Thats a lot of rotating mass. Depending on how you fasten it, it also opens you up for possible vibration. I guess it depends on the design, I will wait to see it before I make a call.

 

[SuperRunner]

The input shafts are interchangeable.

I have had to do this for truck swaps, and turbo vs/non-turbo setups. You will also have to change the pump as well.

 

[HarperRacingBangkok]

Ok, alright already: I will do it the right way -- exchange the input shaft and pump from a 1UZ into my current race-built 1JZ A342 trans (it has the right output for my drive shaft, and the case is of the right length so I can use the motor mounts already in the car). My shop has a pile of 1UZ A340-series transmissions laying around (and complete 1UZs), so no problem with sourcing the parts. Everything will be measured prior to assembly. The only remaining imponderable is whether or not the 1JZ torque converter on a 1UZ ring gear is 'indexed' to proper torque converter-to-input shaft spline engagement. I will send along a 1UZ bare block with crank to the trans shop to test fit it all together when the trans has been refitted with the longer input shaft and pump. I will get photos. Thanks again for this group's care and concern.

 

[HarperRacingBangkok]

OK . . . . the input shaft and pump from a 1UZ auto trans has been swapped into my 1JZ race-built auto trans. No problem. The "final" reassembly is now in progress. Wish me luck.

 

[cribbj]

Very interesting, I wonder if your 1JZ A/T is the same as the A/T in a 2JZ-GTE powered Supra? Is your tranny an A340E?

 

[stevechumo]

Very interesting, I wonder if your 1JZ A/T is the same as the A/T in a 2JZ-GTE powered Supra? Is your tranny an A340E?

Another interesting thing is when I ordered the hi-performance rebuild kit for my SC400 A341, the engineer at Alto said the tranny internals are the same as A340E. My A341E now runs fine with that kit.

 

[spf_lexus]

the a340 is used in a lot of different vehicles. I'm in the process of getting a friend hooked on a 1uz swap for his cherokee. His 98 has an a340 in it from the factory so swapping over is cake.

Steve-


Do you know if there are more part options/brands for the 340 versus our 341?

 

[HarperRacingBangkok]

Thanks for the messages. Yes, the excellent A340 series auto box is used on a lot of cars and trucks, including the 2010 made-in-Thailand Toyota Vigo pick-up truck and turbo Supras. There are different gear ratios for different years, different numbers of clutches and steels, and different input shaft lengths (!). But they all share the same problem for high performance use: a somewhat 'weak' 2nd gear sprag. Some of the racing trans shops (like MV in Australia that I use) tailor their valve body modifications to 'soften' (still hard, but not 'maximum' hard) the hit on the 1-2 shift, others make billet sprags ($$$). This weakness is not a problem on high horsepower street machines on street tires where you can get tire spin to ameliorate the effects of torque. However, the weight of your car, the rear gear ratio, and tire size (grip) all play into whether or not you will break one of these transmissions' sprags. With slicks, spool, and 500hp I lift the front tires on my 1-2 shift without any problem (for five years!) . . . but at only 1800 pounds. Michael at MV Automatics also told me these transmissions are good to 800hp, and at 1800 pounds and a properly set-up valve body to take care of the weak 2nd gear sprag, I believe him. My 1JZ trans has an "A342" tag on it. I like the early 1JZ trans because it has a 'TV' cable to control shift firmness (line pressure), instead of electronic control, which I would not use - I also used brass tubes to make solid all accumulators (no springs): since my truck is 'race only', I just bolt the TV cable down at full firmness at all times, and do not connect it to the throttle body linkage. I use a PCS programmable trans controller (http://www.powertraincontrolsolutions.com/transcontrol.php ) to actuate the shifts according to rpm. The PCS is WAY MORE than I need (although it has excellent features for a street trans . . . . highly recommended . . . you can make it into a paddle shifter), but I can really dial in my car to my bracket by changing shift RPMs in 10 rpm increments! More later.

 

[stevechumo]

Steve-
Do you know if there are more part options/brands for the 340 versus our 341?

Besides Alto, there're a few more options like www.importperformancetrans.com , www.levelten.com. I think Boostlogic may be able to build the Lexus V8 with stronger parts, too.

 

[HarperRacingBangkok]

I am also using the MV Automatics 3800-4200 stall converter.

 

[Zuffen]

I would have shot the monkey who bolted the torque conveter up and didn't notice 2" of slop.

Even the apprentice has a responsibility to ensure what they are doing makes sense.

 

[HarperRacingBangkok]

You got that exactly right Zuffen! The Neanderthal who bolted it up later replied that there didn't seem to be enough 'clicks' when he bolted it up. There are many brilliant and skilled Thai mechanics and shop workers, but they are brilliant only 90% of the time. You have to check everything over.

I prefer bludgeoning.

 

[HarperRacingBangkok]

The only remaining imponderable is whether or not the 1JZ torque converter on a 1UZ ring gear is 'indexed' to proper torque converter-to-input shaft spline engagement.

Yep, you guessed it . . . the splines did not match up. I'm pretty discouraged. The on-line "experts" on this topic were no help. The 1JZ auto trans does not have a long enough input shaft, and . . . if you swap in a 1UZ input shaft that IS long enough . . . it doesn't fit the 1JZ torque converter because of a mismatch in spline location. I know the solution is a 1UZ torque converter on the 1UZ input shaft mated to the 1JZ trans . . . . . . . But I already have a good race torque converter (1JZ) . . . . so I am back to the double ring gear with the doughnut spacer. to make it all work. Wish me luck.

 

[JustenGT8]

Sell the JZ converter mate, surely a market for them? The torque and shock loads this tranny will see mean you can't cut corners on this one!! Do it right or it will bite you for sure....and no doubt end up being x10 as expensive as well.

Plenty of good UZ converter options.

 

[HarperRacingBangkok]

JustenGT8 -- Well, yes, new parts are always better than used parts . . . but I will actually be running about the same horsepower and torque with this motor as I did with my former 1.5JZ. It is an MV torque converter. Yes, I know, "Famous Last Words." Shipping heavy stuff to Thailand is expensive.

 

[JustenGT8]

I'm not worrried about the used converter

It's this bit, "so I am back to the double ring gear with the doughnut spacer." that i'm not keen on?

 

[HarperRacingBangkok]

Oh, OK., point well taken. I am looking into a race 1UZ torque converter . . . . . but in the meantime . . . . . I want to race.