Transmission
Modifications
Index:
Introduction:
I recently had some
transmission work done and learned a lot from it. One
of the most important things I learned is how
expensive the automatic transmission in the 4Runner
is to overhaul when it fails. I also learned what can
be done to make it stand up to the increased output
the supercharger provides.
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The Problem:
The stock transmission,
although very durable, does have its limitations. I
had about 75,000 miles total on my 4Runner and about
31,000 miles with the supercharger. One day I was
accelerating and when it shifted into second, the
RPMs increased and the rev limiter kicked in. It was
clear that the second gear clutch slipped.
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Prevention:
I always wondered if there was
anything that could be done to beef up the
transmission so it will stand up to the increase in
output provided by the supercharger. I had been
looking for some time.
JD from OZ
told me about a company called Level
10 that does
performance work on the Toyota transmission. With a
quick Internet search I found their URL. (
http://www.levelten.com
). I called and spoke to Pat the owner.
After telling Pat what
modifications I had made to my 4Runner, he told me I
had better get the valve body modification done ASAP.
I made an appointment for a couple of weeks later. He
also talked me into a torque converter upgrade.
Between the time I made the
appointment and went to Level
10 is when my
transmission slipped. I parked it until it was time
for the road trip to Level 10.
The problem is that the
transmission is set up to provide a slow, soft
"luxury" shift. Well that may be nice on
the stock engine, but when you crank up the power the
luxury shift is bad. The stock unit is set up to
slowly engage the clutch packs to give that soft
shift. The longer it takes the clutches to engage to
more they wear and the more heat is generated. With
more power you just add to the heat and wear.
Level 10
reworks the valve body so that the clutch packs
engage much faster. This reduces wear and heat
generated. Because it also applies more clamping
pressure, the clutch packs can hold more power.
Pat told me that the better
after market supercharger kit makers recommend this
upgrade to prevent damage to the transmission. He
said that Stillen makes a kit for the Maxima and they
flat out tell people not to install the belt on the
supercharger until Level
10 reworks the valve
body in the transmission. Pat says that if the
upgrade is not done on the Maxima’s transmission
it will be ruined with just one full throttle
application with the supercharger.
I arrived at Level
10 at 0700 hours and
Pat jumped in for a test drive. He mashed on it from
a standing stop. "Wow, it is real torquey!"
Then it started to shift into second. "One
thousand one, one thousand two, that’s not good.
We are going to have to open it up." Remember it
only slipped one time before without any warning.
My 4Runner was pulled into one
of the bays and within a couple of hours my
transmission was torn down and I was handed a stack
of second gear clutch and reaction plates and told
"you blew through second."
I could clearly see where the
fiction material was worn through on the clutch
plates and the heat damage on the reaction plates.
The metal on the surface of the reaction plates was
blue and galled.
Pat made it very clear that if
I had had my valve body upgraded it would have
prevented the damage to the clutch pack and
eliminated the need for the expensive overhaul.
The upgrade is more involved
then installing a "shift kit" in a domestic
transmission. On the domestics you just change the
separation plate and install new springs in the
valves and you are done. The transmission used in the
4Runner (not made by Toyota by the way) has a much
more complex valve body. It requires in shop
modification by Level
10. I was lucky, I only
live five hours from them so it was easier just to
drive there.
For those of you that live some
distance away you can remove the valve body yourself
and ship it to them. They will modify it the day they
get it and FedEx it back to you.
It is real easy to remove from
the vehicle. Remove the pan and filter. Pull out a
small metal pipe that is pressed in the valve body
and the case. Remove 12 10 mm bolts and let it drop
down a bit. Unhook the kick down cable from the
pressure valve. Wrap it up in plastic and ship it
off. You will also get three new valve springs to
install with it when you get it back.
I wish I knew about this BEFORE
I smoked my second gear clutch pack. A $600 valve
body upgrade could have saved me a few thousand $ it
cost me for the overhaul.
Do yourself a favor and get
this done if you have a supercharger or do a lot of
towing.
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Overhaul:
With the second gear clutch
pack "blown through" there was no question
that I needed the transmission overhauled. Pat sat me
down and went over my options. I ended up going to
most expensive route because although Pat and his
guys are great to hang out with, I really did not
want to have to visit with them again.
I chose to have the best clutch
plates available installed. They are made by Raybestos
and are only available through Level
10 for this
transmission. Pat calls them the "Blue Plate
Specials." The special fiction material is
bonded to the plate with a resin that gives them a
blue color and that is where the name comes from.
These plates also require
special reaction plates called Kolene steels. The Kolene
reaction plates are much thicker then the stock plate
to absorb more heat and the surface is specially
treated.
The Blue Plate Specials are
available in an overhaul kit that Level
10 sells so you can
have it done by your local shop if you want.
Pat allowed me to watch the
entire process and I learned a lot from the
experience. His guys are great.
The transmission used by Toyota
is a very complex unit and I was impressed on how
meticulous the Joe at
Level 10 was that
worked on my transmission.
Although Level
10 has lots of bays,
most of their work is shipped to them from all over
the world. Transmissions arrive by truck on pallets
and they do their thing and ship them back out. Pat
say that about 70% of their business comes from the
middle east so their work has to be done right the
first time every time, it is not like the customer
can just bring it back.
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Torque Converter:
Pat sold me on the idea of
having my torque converter upgraded to a performance
version. The trouble was they could not find a core
to modify before I got there. I guess the stock
Toyota converters hold up real well and there are not
a lot of bad ones out there to use as cores. Pat
rented a car for me and let me drive my torque
converter to Pro
Torque in Long Island,
New York. Pat called ahead and told them exactly what
was to be done and worked it out so I could watch the
whole process. This is not normally done to protect
the trade secrets involved. It was made clear that no
pictures were allowed. I did feel honored.
With in minutes of arrival my
torque converter was cut open and disassembled. The guys commented that it look like I
had been babying it due to the little amount of wear
and how extremely clean it was on the inside (I have
my transmission power flushed every 30,000 miles).
I can not tell you exactly what
they did to modify it. They asked me not to. I can
speak in general terms. The angle of the blades on
the impeller is changed. The stator is machined down
and the distance between the impeller and turbine is
changed.
They also modify the lock-up
clutch. In the stock converter the fiction material
is in the face of the turbine. Pro Torque grinds this
off and modifies the face of the turbine and applies
a ceramic friction material to the face of the
pressure plate.
The whole thing goes through a
final inspection and then it is placed in a special
jig that holds everything together and it is tack
welded. This is a custom jig that was developed in
house. The converter is then placed in a custom
automatic welding machine and the seam is welded. It
is then pressure tested for leaks, balanced, painted,
boxed, and handed to me for the trip back to Level
10. I was really impressed with Pro Torque’s
facility and hospitality.
There are some terms you might
want to know so you will know what I am talking
about.
Stall Speed- When you apply
full power and hold the car still with the brakes the
stall speed it the maximum RPM the engine will
produce with no forward movement.
Flash Speed- Without holding
the brakes, snap the throttle full open from a
standing start and the RPM will quickly run up to and
then hold briefly as the vehicle starts moving. The
RPMs will then start to climb again. This pause is
called the "flash speed."
Torque Multiplication- I am not
completely sure what this is or how it is measured.
The engine will run ahead of the torque converter and
then the converter quickly catches up. I think is
like a sling shot effect. I have been told that the
stock converter has a 1.6 to 1 multiplication factor.
My modified one has a 2.5 to 1. When I know more I
will update this section.
I think my stock converter had
a stall of about 2200 RPM with a flash of 2500. I
found it hard to test the modified one. The tires
start smoking way to soon. I had to place it in 4x4
so I could use the front brakes to help hold the
tires still. The stall was 3700 RPM. I still could
not check the flash. I found it hard to watch the
tachometer with the 4Runner going sideways.
The ideas here is to allow the
engine to quickly rev up to the point of maximum
torque without load and then dump the power to the
wheels. It is like revving it up with a stick shift
and then quickly letting out the clutch.
After driving it a while I have
decided the high stall of the modified torque
converter is perfect if I was doing nothing but drag
racing. I do not drag race and feel that a lower
stall would be better suited for my style of driving.
I think a stall of 3000 RPM would be perfect for me.
I called Pat at Level
10 and talked to him
about it. Pat offered to install another modified
converter at no charge. I can not ask for anything
more. He had me call Pro
Torque and I spent some
time talking to Joe. He had me email him some of my
dyno runs so he could figure out what he needs to do
to get the stall just right for me.
He made the same modifications
to my converter as they do on the turbo Supra. It
does appear that the modification has had close to
double the effect on my supercharged 4Runner. This is
most likely due to much more instant low-end input
torque. Joe says he has it nailed down and has a new
converter waiting for me at Level
10.
I returned to Level
10 and had the new
converter installed. Pat and I jumped in for a test
drive. We were both very pleased with the way it
turned out. This converter is absolutely perfect. It
has very close to the same performance increase as
the first one without that "spongy,
disconnected" feeling below 3500 RPM.
I have spent some time driving
with the new converter. I have can not find and
negative side affects at all. There is dramatic
performance increase over stock and it is completely
"streetable." I can drive it in stop and go
traffic and really take advantage of the performance
increased when I want to. This is the perfect torque
converter for the supercharged 4Runner. I’ll bet
that it would be nice for the normally aspirated
4Runner.
In a straight line on level dry
pavement, I can quickly apply full throttle and the
tires bite hard and there is instant acceleration
with this new converter, unlike the first one. With
the same throttle application the tires would just
smoke and there was very little acceleration unless I
had it in 4H.
Here is a side by side
comparison of the converters:
Converter
|
Flash
|
Full Brake Stall
|
Stock
|
2200
RPM
|
2500
RPM
|
First performance
converter
|
3500
RPM
|
3700
RPM
|
Current converter
|
3000
RPM
|
3500
RPM
|
For those of you that want to
get this Torque Converter it is available through Level
10. Just tell Pat you
want the "Gadget model" (PTC T040-20RS).
Pat and Joe, I just want you to
know you have done a great job getting my converter
"just right" for me. I also want to thank
you for the personal attention you gave me on my
visit to your shops. Your customer service is second
to none, thank you very much!
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Transmission Cooler:
Have you ever wondered whether
you need to add an auxiliary transmission cooler? It
looks like you do. A while ago I installed a
transmission temperature gauge. What I learned from
this is that the temperature in the transmission
varies quite a bit. When I am accelerating from a
standing start I can see the temperature gauge climb
almost as fast as the speedometer. Once I reach
highway speed and the clutch in the torque converter
engages the temperature will drop right off quickly.
Aggressive stop and go driving will cause the
temperature to climb very high. I have had it as high
as 300 degrees. It is clear that when the torque
converter is active it does generate a lot of heat.
I asked Pat of Level
10 if I should install
an auxiliary transmission cooler. He suggested I
install the largest transmission cooler that will fit
behind my grill. He also said that it should be a
stacked plate type and to stay away from the tube and
fin type. He then handed me an 11x17 inch stacked
plate cooler rated at 30,000 pounds made by Hayden to
take home with me. Pat says that 9 out of 10
transmission failures are due to excessive heat.
There is two lines of thinking
on how the cooler should be installed. One is so the
fluid goes from the transmission to the auxiliary
cooler, then through the stock cooler built into the
radiator and then back to the transmission. The
second method is to have it flow through the stock
cooler, then the aux cooler and back. That is the way
mine is currently installed at the suggestion of the
pros at Level 10.
Level 10
is in a mountain area in NJ and on my way home
driving through the mountains I just could not
believe how hot may transmission got. I think this
was mostly due to the high stall of the new
converter. I think that it should be a close
approximation of what it must be like to tow
something. It gets very hot.
I installed the cooler the
morning after I got home. It does a great job of
keeping the temperature where is used to be with the
stock torque converter. I expect that when I install
the converter with the lowered stall I will change
the routing of the aux cooler so that the fluid will
go to the aux cooler first then the stock cooler.
This way it won’t over cool in the winter.
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The Result:
The shifts are instant and very
crisp and feel rock solid. I no longer worry about
the transmission being the weak link.
I have been told that with my
transmission shifting faster and putting more power
to the wheels quicker, I have cut my ¼ miles times
by at least a full second. I guess that would be
important if I was a drag racer, I am not. I do love
the way it feels when I drive it. The occasional tire
chirps during shifts are a real kick in the pants. It
also turns the heads of many of the traditional
hot-rodders.
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