Making the A650e transmission survive on the cheap.  Part 2

One of the most common misconceptions about the IS300 (and other cars that share the 5 speed Lexus automatic) is its ability to handle some real power.  In this article, I will outline what it takes to make it handle some power on the cheap, mods that almost anyone can do.  Everyones mileage will vary, no doubt, and part of its longevity rests with you, the driver, but this will be the best thing you can do without spending a ton of money.

There are a few theories on how to make automatic transmissions last.  I knew, going in, that my stock transmission might not last too long, so I was prepared to do some experimenting.  What I have ended up with is a transmission that was amazing at a 560 whp level (over 500 ft lb of torque also), and today, is still holding up to 650 whp, once in 3rd gear and above.  I have not modified the valve body in any way and the transmissions guts have never been removed.  The transmission pan and valve body will need to be removed, but that is it really.  How, you say?  Well, I did a bunch of research and found that it is a delicate balancing act to make these transmissions work right with some real power behind them.

The first problem I ran into was hitting the rev limiter under power.  Stock rev limiter is around 6200-6300 and the transmission starts its shift around 6100.  Doesn’t really give much time to do its thing, but it works just fine at the rather anemic stock power level.  There are two ways around this – raise the rev limiter or make it shift faster.

The best way without a full transmission build, and even without a valve body replacement is to modify the accumulators.  Accumulators are the small piston like devices that allow fluid to accumulate, in order to dampen shifts.  The springs need to be stiffer to make the shifts firmer, but they still need to be in place to maintain a little bit of shift damping.  There is no need to be chirping tires for a quarter throttle 2-3 shift.  I was never able to find good information on stock spring rate, or even find a good source for stiffer springs that would fit properly.  Instead, I simply shortened the space the spring could travel.  Unfortunately, I do not have measurements, as I simply did not take them when I was performing this mod 3 years ago.  Some day, I will pull her apart and get exact measurements.  To shorten the travel, I simply made bushings for the springs.  Anything metal that fits inside the accumulator will work.  I shimmed all 4 of mine approximately 15 mm.  That was attempt #2.  Attempt #1 was about half of that and though it helped, shimming more helped more, but is still not harsh.  There are small holes inside the accumulators that you do not want to block, but the a650 design prevents that to an extent.  One more quick mod related to this is to simply turn line pressure up.  On the side of the valve body, there is a pressure control – simply use a straight edge screwdriver to push in and rotate to the next detent.


here are the accumulators in an a340 circled – the a650 is extremely similar

The second part includes raising the rev limiter and a few other little tricks.  Even with the above listed modifications, getting the trans to shift too quickly will not be good.  At the power levels required for these types of modifications, hopefully you are running some sort of standalone already.  The 2jz is very capable of spinning higher than the stock 6300 rpm redline.  That redline is put there because the stock cams and naturally aspirated motor just simply don’t make much power past that.  We can safely spin a stock head / cams / valvetrain car past 7500 rpm, and probably higher than that if necessary.  I have my redline set up through the AEM Infinity I run at 7300 rpm.  One other thing I do is retard timing during the shift.  Since no standalone will control the auto trans, what I’ve done is drop timing to 0 at the shift point.  This reduces power just slightly (low timing keeps the turbo spooled though) until the lower RPM after the shift point is realized and the timing is obviously much higher there.  These mods are enough to allow my transmission to survive at 650 whp / 610 ft lb.  It doesn’t do so well in 1st and 2nd, mainly because the power comes on so strong, but once in 3rd, it holds together extremely well, all the way to redline in 5th.

Bad ideas – One of the most popular “mods” to these transmissions is the rods that go in the accumulators.  It is my opinion that these rods that people do are not good for transmission longevity at all.  The fact is, they make the transmission slam into gear pretty much every single shift.  This is not good on the internal components of the transmission.  Things like this are what causes the infamous sprag gears to roll over.  An instantaneous hit of power is much harder on the sprag than applying the power smoothly.  (Drop a hammer on a piece of glass versus lay a hammer on a piece of glass).

Good ideas – Don’t let the transmission slam into gear.  Use the transmission selector buttons to maintain the gear you want.  Prevent the transmission from downshifting if at all possible under full throttle.  If the engine is below 4000 RPM, applying full throttle will invoke a downshift, no matter what gear you have selected.  There is one way around this – the snow button.  If you have snow mode activated, you can go full throttle as low as 3000 rpm, but will be limited to 60% throttle until snow mode is turned off.

Making the A650e transmission survive on the cheap.  Part 1 – Cooling

One of the most common misconceptions about the IS300 (and other cars that share the 5 speed Lexus automatic) is its ability to handle some real power.  In this article, I will outline what it takes to make it handle good power on the cheap, mods that almost anyone can do.  Everyone’s mileage will vary, no doubt, and part of its longevity rests with you, the driver, but this will be the best thing you can do without spending a ton of money.

Part 1:  Transmission coolers – Keeping transmission fluid cool is one of the most important keys to transmission longevity.

The stock cooling system for the transmission lives in the lower portion of the factory radiator.  Fluid is simply pumped out of the transmission, through the radiator (you’ll notice two 5/16” hoses along the lower edge) and back into the transmission.  There is very little fluid pressure here – the return essentially falls into the transmission pan.  There is a factory temperature sender on the outlet of the transmission.  This can be monitored by obd2 scan tools with live data ability.


A wide variety of external transmission coolers exist on the market place.  You can’t have one too large, with regards to cooling, however, there isn’t a whole lot of space for large coolers without some ingenuity.  Many will simply attach to the front of the condenser, behind the intercooler (on a forced induction car).  Behind the drivers rear tire, there is some room for auxiliary coolers as well.  Some have fans as part of their design, some will add external fans.  No matter which you choose, it is a good idea to plumb the cooling system in such a way so that the fluid flows through the radiator based cooler first, then through the additional coolers.  This provides for the best chance for the fluid to cool before returning to the transmission pan.


My personal setup has transmission fluid routed through the radiator, then to the rear of the car.  Behind the drivers side rear tire, there is an unused space, away from anything else that produces heat.  Here, I have two transmission coolers stacked, with an 8” cooling fan on them.  Ideal transmission fluid temps are 175-225 degrees.  I monitor transmission output temp through the AEM Infinity, and when transmission temps reach 175 degrees F, 80 degrees C, the auxiliary cooling fan is turned on.  Sustained operation above 225 degrees will shorten transmission life, and any operation above 240 degrees is extremely detrimental, as the fluid itself begins breaking down.

20140901_211627(excuse the poor picture and dirty shield)  

A few key things that everyone needs to know with regards to this.  First off, make sure any fluid lines used are rated for transmission fluid.  More commonly available at parts stores is fuel injection hose, which will break down over time when used with transmission fluid.  It is a good practice to use high quality fuel injection hose clamps instead of the more traditional worm gear clamps.  I can’t say this is all I’ve ever used, but these are stronger, provide more consistent clamping pressure and once you use them, you will understand why I advocate for them.  Next on the list is fluid type.  Toyota T-IV fluid is the only transmission fluid to be used in most Toyota transmissions.  It is relatively inexpensive at the dealer and it works great.  Many manufacturers do make generic import transmission fluids that will work, but in general, they are the same price or even more expensive than the genuine fluid.  Last but not least, no amount of cooling will help if you are are hard on the transmission and do high powered pulls and races back to back.  Monitor temperature and allow the fluid to cool if it is getting unnecessarily high.


2JZ VVTI Cam Tech


  • Camshaft lobe seperation theory and advantage/disadvantages.
  • VVTI advantages over standard fixed position cam engines
  • VVTI Cam noise with aftermarket cams
  • VVTI Cam gear noise with aftermarket cams / valve springs.
  • VVTI Tuning for best spool and top end power.
  • VVTI Tuning for a quiet smooth idle.

Aftermarket Cam Options

  • Kelford (T202 is a standard 2JZ cam, V202 is the vvti version.  Kelford makes all of their standard cams in vvti grinds as well.  Available since 2005)
  • GSC (S1 S2 and S3 are available in a vvti option as of 2008)
  • Titan Makes a custom Grind 272 vvti cam.  As far as I know its made by GSC.
  • BC makes 264/272 vvti cams… the ramp rate and half durations are very low.  These cams are built for top end power with high duration/lift with low ramp rate
  • Tomei makes some small 2jz cams, in between everyone else and stock.


VVTI System