[graaja]

Installed: Tough Dog Foamcell Adjustable Suspensions in my Toyota Fortuner 4x4 AT

In July 2024, I bought an Attitude Black Toyota Fortuner 4x4 AT. One of the weak points of the car is the suspension which I felt to be very harsh at low speeds on bad roads. Last week, I upgraded the suspensions to the Tough Dog Foamcell Adjustable suspensions.

This thread is to document the complete installation. I will divide this thread into various sections. Please skip to the section of interest.

The decision to change the suspension and the selection process
Installation of the suspensions
Comparison of the Suspensions using Physical Data and Analytics
Low Speed Comfort Tests - Effect of Z-Axis GForce on Comfort
Low Speed Comfort Tests - Effect of Pitch and Roll on Comfort
Pitch and Roll Measurements - A Failed Test Case
Final Thoughts and Conclusion

Before I proceed with details of installation, I would like to thank:

• My daughter for helping me with the data collection and analysis in comparing the OE suspension with the ToughDog. She is a Physics graduate interested in data analysis and we had lots of discussions on how to collect, analyze, and present the data.
• Friend and TBHPian Mr.Boss provided lots of inputs on suspension testing. He has experience in the automobile industry in suspension design and testing. He gave me lots of tips on how to avoid errors in data collection, and suggestions to improve data collection. He also gave me the tip about keeping the stiffness of the suspension on the driving axle (in this case the rear), slightly stiffer than the other axle.
• Friend and TBHPian RobiMahanta who first suggested the Tough Dog foam cell suspensions.

[graaja]

The Need for a new Suspension:

Following are the problems or area of improvement in the OE suspension.

1. The ride is very harsh at low speeds, and the car crashes into potholes and speed breakers.
2. There is some body roll in the corners. This is expected for a BOF SUV with high center of gravity. But there is room for improvement
3. Though the car handles well at high speeds, there was some floating feeling at high speeds on roads with undulations.

So, I decided to change the suspension to a more comfortable option. I listed the following requirements.

1. A suspension that improves the comfort and low-speed ride quality on bad roads.
2. A little improvement in body roll in the curves
3. More stability at high speeds

I was not looking to make the car behave like a sedan. I just wanted to improve the performance within reasonable limits imposed by the BOF SUV architecture.

I was also aware that low-speed comfort and high-speed handling don't go hand in hand. An increase in low-speed comfort will increase body roll and the floaty feeling on highways. Improving high-speed handling will result in harsher low-speed comfort. So, I wanted an adjustable suspension that I could adjust to depending on the road conditions I expected to drive on.

Selecting the suspension:

I spent a lot of time reading about various options available for the Fortuner. There were so many options and features to choose from, like:

Nitrogen struts: These types of struts have both nitrogen and oil in a single or dual chamber design. These are the most commonly available struts, and these work out cheaper, too. One drawback of these struts I read in various reviews is that when the car is driven on bad roads for a long duration, the increase in heat results in the nitrogen mixing with the oil, forming bubbles. This, in turn, reduces the viscosity of the oil, resulting in reduced dampening. However, I am unsure if this is the real situation or just some marketing used by the foamcell manufacturers.

Foamcell struts: This is a new technology where a foam based layer infused with nitrogen is placed in the outer chamber. This foam prevents nitrogen from mixing into the oil at high temperatures, thus preventing the reduction in damping.

Adjustable struts: These suspensions have a provision to adjust the rebound damping force. Some suspensions come with 16 way adjustment and the Tough Dog comes with 9 way adjustment. The advantage of these struts is that they can be set to various levels depending on the type of road being driven on - like softer setting for rough roads for better shock absorption, and stiffer setting for driving on the highways that can reduce rolling and pitching.

Electrically adjustable suspensions: Some suspensions like Tein have a stepper motor attached to the struts which can be operated using a controller from inside the cabin to adjust the damping.

Lift: Almost all the 4x4 suspensions result in some lift in the car. I could not find any option that did not result in a lift. This was the biggest discouraging factor for me. I was concerned that a lift will increase the already high center of gravity which can worsen the high speed handling etc. However, all reviews suggested otherwise. So, I decided to take a leap of faith here.

Based on various reviews and suggestions from friends, I shortlisted the following.

Old Man Emu (OME):

From older threads in Team-BHP, I found that Old Man Emu was the de facto standard for aftermarket suspension upgrades. However, I read several user feedback that these suspensions were stiffer than the OE suspensions. These suspensions are nitrogen based.

Ironman Foamcell:

The Ironman suspensions had very good reviews online and I found some good feedback in Team-BHP as well. These suspensions are based on foamcell technology, which is an advantage. However, these are fixed suspensions and reviews mentioned these to be on the stiffer side.

Tein 4x4 with EDFC: A couple of friends suggested Teins. One of them has it installed in his Endeavour and another in his previous generation Fortuner. These come with EDFC (Electronic Damping Force Controller) with 16-stage adjustment. However, I could not find any reviews or videos on the performance of these suspensions other than a few Instagram videos from an installer in Kerala. Also, if I did not opt for the EDFC, then the car has to be lifted to make adjustments to the struts.

Tough Dog Foamcell Adjustable Suspension: I found lots of positive reviews about the Tough Dog foamcell suspensions, and I found that these suspensions are tuned towards comfort. My friend and TBHP'ian RobiMahanta has installed the ToughDog suspensions in his Thar and he had very good feedback about their performance. Unlike the Ironman suspensions, which are fixed, Tough Dog has a variant with 9-way adjustable struts. Also, adjustments can be made without lifting the car. It takes about a minute to adjust all four struts.

Of the four, I dropped OME and Ironman as they did not have adjustable damping. Between Tein and Tough Dog, I chose Tough Dog for its foam cell technology and the easy access of the damping adjustment.

Tough Dog foamcell adjustable comes in two sizes - one with 40mm bore and another with 45mm bore. The 45mm is mostly used in heavy applications. It also comes with various spring rates like 0-300 kilograms, constant 300 kilograms, or 500 kilograms. The spring is selected based on the load requirement on the car, accessories like bullbars, winches etc. As my car does not have any off-road gear or accessories, decided to go with the 40mm struts and 0-300 kilogram comfort rated springs.

[graaja]

Installation of the Suspension:

The dealer for Tough Dog is 6th Mile Customs in Indra Nagar, Bangalore. I talked to Mr. Thomas, who owns 6th Mile Customs, and he readily answered all my questions about choosing the correct variant, installation, adjustments, warranty, etc. I decided to drive to Bangalore and have the suspensions installed at 6th Mile Customs. I fixed an appointment on Friday, the 15th of October. Reached 6th Mile at 11:30 AM. Luckily, only one other car was in the workshop, and they completed the installation by 3:30 PM.

A few pictures from the installation.

6th Mile Customs, the Tough Dog dealer and installer. The owner Mr. Thomas is very knowledgeable about these suspensions and installation.


Customary picture of the car with all the suspension components.


Ride height measurement is being done before the installation. After installation, they check if the ride height is the correct expected value.


The car goes on the lift for suspension change.


The OE front suspension.


The OE rear suspension.


Comparison of the OE and new spring. The new spring is longer than the OE spring.


Comparison of the OE and new rear struts. The new strut is thicker and longer than the OE strut.


The new suspensions are installed in the front.


The new suspensions are installed in the rear.


The adjustment knob for the rear struts. These are easily accebile from below the car. One has to just squat by the rear wheel and reach below the car to adjust.


The adjustment knob for the front struts. These can be accessed behind the wheel. If the wheel is turned to one side, these become easily visible. But I have got used to reaching them without the wheel turned.


Ride height before and after. The front has increased by 50mm and the rear by 40mm. Mr. Thomas said once the springs settle down, there will be a small drop in height.


A mechanical wheel alignment machine. This is the first time I am seeing such a mechanical machine. Wonderful engineering, this is.








Alignment being done. They did a few rounds of adjustments and test drives to get the right adjustment.

[graaja]

Comparison of the Suspensions using Physical Data and Analytics:

When I read the reviews and tried to determine whether various suspensions would be more comfortable than the OE suspension, I found that all the reviews were very subjective. For the same suspension, some reviews called it soft, while some others called it stiff. So, I had to take a call based on the majority of opinions.

This got me thinking. Say I feel that the suspension is comfortable or has less roll compared to the OE suspensions. How do I know that what I feel is real and not a placebo effect because of my trying to justify the 1.8 Lakhs I spent on the suspensions? Is there a way I can record some data and back up what I feel with the analysis of this data.

There are three parameters that decide how good or bad a passenger feels inside the car.

1. The force that is transmitted from the road to the person's bottom - the GForce on the Z-Axis
2. The roll - the sideway oscillations of the car
3. The pitch - the front-to-back oscillations of the car

While #1 directly corresponds to how harsh the ride is, #2 and #3 contribute to being thrown around in the car while driving on bad roads at low speeds and the floating feeling while driving at high speeds on highways with irregular surfaces.

#1 can be measured with an accelerometer, and #2 and #3 can be measured with an inclinometer. All these sensors are available in cell phones.

For fun, I decided to do some measurements using my cell phone under standard conditions with the OE suspensions and later with various damping settings on the Tough Dog.

I took my daughter’s help in recording and analyzing the data.

Test Cases:

We decided on two test cases.

1. Select an unpaved road with an uneven surface and drive the car over this road at various speeds (30kph, 40kph, and 50kph) and record accelerometer and inclinometer data. This will be helpful in quantifying the comfort levels on bad roads.
2. Drive the car on a smooth road with curves and undulations and record roll and pitch data. This can be used to measure the floatiness of the car at high speeds.

Of the two test cases, we were able to collect good data for test case #1 to analyze low-speed comfort on bad roads. The second test case was a failure, as I could not find a traffic-free road section where I could drive the car at the same speeds for all test cases. We collected data for this test case, but it was useless due to various uncontrolled situations like not being able to maintain the same speed in the curves due to traffic, not able to maintain constant speeds on straight stretches due to traffic etc.

Tools used:

1. Physics Toolbox Sensor Suite app on my iPhone to collect data. We placed the phone firmly on the handrest and my daughter started and stopped data recording as I drove the car. The phone was firmly held on the handrest to prevent any relative motion of the cell phone with respect to the handrest.
2. Microsoft Excel for performing math operations like STDEV, d/dt analysis etc.
3. GNU Plot for plotting graphs

Caveats:

Before I proceed with the details of the data collected and the analysis, there are a few caveats:

1. The data can contain errors, such as the accuracy of the sensors on my iPhone, the slight change in positions of the phone between sessions, the relative motion of the phone itself against the handrest, etc.
2. The data can contain errors due to variations like changes in road surface between test drives (I may have taken a slightly different path on the same road)

Because of the above, the absolute values measured are meaningless. I do not have any standard or reference point to translate a particular value of a sensor to how a passenger may feel. For example, 1-g measured on the accelerometer may be harsh for some people and comfortable for some others. For this reason, all my conclusions will be based on comparisons of the values between various test conditions.

Also, the relationship between some of the numbers like STDEV or RMS and the way we perceive comfort will not be linear. For example, the STDEV of GForce between OE suspension and Tough Dog with damping 0, will look quite small. But the actual improvement in comfort level between these two is significant. For this reason, the meaning of the data has to be taken in conjunction with what the passenger feels in terms of comfort.

I do not know if the metrics that I have analyzed and presented are the right ones to assess the suspensions. I read many articles which pointed to other types of analysis like measuring natural frequency of the suspensions, performing frequency domain analysis on the pitch and roll data and find if the peaks fall under frequencies that generally create discomfort etc. I could not do these tests as I do not have enough data for this.

Finally, this is more of a fun project that I enjoyed doing with my daughter, than a proper experiment with tightly controlled variables. Please take these analysis with a bucket of salt

[graaja]

Low Speed Comfort Tests - Effect of Z-Axis GForce on Comfort:


The picture below shows the raw data collected while driving on a bad road section. This road has almost zero traffic. The data contains the Z-axis accelerometer data in G and pitch and roll data in degrees.



A total of 24 data sets were collected.

1. Original suspension - 30kph, 40kph, 50kph
2. Tough Dog suspension, damping 0 - 30kph, 40kph, 50kph
3. Tough Dog suspension, damping 2 - 30kph, 40kph, 50kph
4. Tough Dog suspension, damping 4 - 30kph, 40kph, 50kph

For each of the above test cases, 2 sets of data were taken. This was for redundancy. In a couple of test cases, first pass data was corrupted - like a dog decided to sit in the middle of the road.

As we were collecting the data, I and daughter also recorded how we felt about the ride - comfortable or harsh.

The Accelerometer Data to Measure Harshness

The Z-Axis accelerometer measures the force that is transferred from the road to the seats. Higher the force, the harsher we perceive the ride. To numerically quantify the harshness, we decided to apply a Gaussian distribution to the accelerometer samples.

The median and standard deviation can directly indicate the comfort or harshness of the ride. When the standard deviation is small (narrow Guassian curve), it means more samples are closer to the median (which is close to zero), making the ride comfortable. When the standard deviation is high (wider Gaussian curve), this means more samples are away from the median making the ride harsher. The three pictures below show the side-by-side comparison of the OE suspension and ToughDog suspension damping setting 0, 2 and 4, for speeds 30kph, 40kph, and 50kph.

Click on the images to view the full resolution image full screen.







Analysis:

We felt the ride to be the most comfortable (cushiony) in the lowest setting in the Tough Dog and the data supports this feeling.

From the graphs, it can be seen that damping setting 4 in Tough Dog is slightly better than the OE suspension in comfort (smaller SDEV) at 30kph and 40kph. Setting 2 is more comfortable than 4, and setting 0 is more comfortable than 2.

Effect of Tire Pressure on Comfort:

We also wanted to check how tire pressure affects comfort levels. I usually keep 30psi all round. To see how a higher tire pressure would affect comfort levels, we did a few tests with the tire pressure increased to 33psi. Below is a comparison of the original suspension with 30psi tire pressure and 33psi. It was very harsh and the same can be seen in the graph. The STDEV is almost 30% more compared to 30psi.


We did not test the Toughdog suspensions with 33psi tire pressure, as the result would be relatively bad in the same way.

[graaja]

Low Speed Comfort Tests - Effect of Pitch and Roll on Comfort:

In the previous post, we analyzed the G-Force data from the Z-Axis which represented the force that was transmitted from the road to the passenger's bottom. The other parameters that contribute to the discomfort are the pitch and roll (bottom part of the graph below).



The rate of change of angle is what is perceived as the sideways and up and down movements. So, for this analysis, my daughter proposed using the d/dt method to calculate the rate of change of roll angles (angular velocity). We did not analyze the pitch angles as we felt the roll was more and significant than the pitch. However a complete analysis would take the pitch data as well.

The picture below shows the raw roll data at the top and the rate of change data at the bottom.


It is difficult to judge the intensity from this graph, so we decided to use the RMS of the d/dt values, which will directly indicate the intensity of the roll.

The three pictures below show side-by-side comparison of the OE suspension and Tough Dog suspension settings 0, 2 and 4 for speeds 30kph, 40kph, and 50kph.







Analysis:

When we were doing the tests, my daughter and I observed that at the lowest speed, 30kph, though the ride was very cushy, there was increased horizontal motion compared to the higher speeds. This was not the harsh "getting thrown around" kind of movement, but in a much softer way. This can be seen on the graphs as well. At 30kph, the RMS value of OE suspension is 3.981, whereas that of Tough Dog at damping 0 is 4.366. But in spite of this horizontal motion, we felt that the softest setting was the most comfortable at all speeds.

I also remember reading some articles where it was mentioned that ideally in an independent suspension, a bump or rut on one side should be absorbed by the suspensions on that side and should not be transferred to the other side. However, the anti-roll bar that is provided to improve high speed handling results in the force being transmitted to the other side as well, which in turn result in pitching and rolling. In extreme off-road situations, this coupling can restrict wheel articulations and that extreme off-roaders change the anti-roll bard to delinkable ones and delink the bar when going off-road.

I did some more digging and found that there is a standard ISO 2631-1 which documents how human body reacts to various physical parameters. I was not able to access this document as it has to be purchased. But I did several searches on the internet and found various information that correlated to the data we had.

Below is a small compilation of some points I gathered from various sources.

• Humans generally tolerate slow rotational motions (like pitch and roll) better than sharp vertical impacts.
• Even if the RMS values of pitch and roll are higher, these changes may occur at lower frequencies that our body perceives as natural or less intrusive.
• Our bodies quickly adapt to the oscillatory pitch and roll because they are more gradual and rhythmic compared to the harsher jolts from vertical accelerations.
• Softer damper settings tend to filter out high-frequency vibrations (sharp impacts), leaving behind smoother motions. This "soft" feel can mask the discomfort from increased pitch and roll.
• ISO 2631-1 uses the RMS value of weighted accelerations to quantify discomfort. Lower RMS values of vertical accelerations (Z-axis) correlate directly with improved comfort. Rotational motions like pitch and roll are included in the analysis but have less weight in terms of discomfort if their RMS values are relatively low or their frequencies are outside sensitive ranges.
• Crest Factor: The crest factor (peak/RMS) measures how sharp or spiky the vibrations are. Softer damper settings reduce the crest factor of vertical accelerations, smoothing out the jolts, which are particularly uncomfortable for the body. Pitch and roll typically exhibit lower crest factors and thus contribute less to perceived discomfort.

In summary, I found that the high frequency vertical oscillations play a major role in ride comfort than the low frequency pitch and roll motions.

[graaja]

Pitch and Roll Measurements on Curves and Straight Road Sections:

For this test, I selected a road section that had a few sharp curves and one long straight section. The road section is shown in the map below and marked by the two red markers.



I wanted to measure the roll in the curves and the pitch and roll on the straight section at relatively higher speeds (60kph in this case). However, due to several uncontrollable factors like some two-wheeler getting ahead as I approached the curve or the presence of other vehicles on the straight stretch, I was not able to maintain the same speeds over various parts of this road between test cases. Because of this, it was not possible to come to any clear conclusions from this data.

Just for record, I am sharing the data we collected. The four graphs below show the time vs. pitch/roll data over this road section. The first is with the OE suspension and the other three are with Tough Dog damper settings 0, 2, and 4.









As can be seen, the curves and straight road sections are not easily identified from these graphs. Even the magnitudes are not consistent as I was not able to maintain the same speeds. For some of the test cases, I had to slow down at the curves due to traffic and for other cases, I was able to take the curves at a higher speed. I tried performing FFT on these data to find if there is some correlation of frequency peaks that get shifted for various suspension settings, but could not get any conclusive results. I am sure this is because of bad data.

The best way to collect this data would be to drive on a highway at constant speed with cruise control and record this data over the same section of the high way. As it takes more than an hour to reach a 4 lane highway from my home, I decided to not pursue this test.

PS: Do not get alarmed by the big change in roll angles in the graphs. The large changes happen over long time periods like 15 seconds. These variations are due to the change in road conditions itself over a longer duration. What is important is the smaller variations over a period of 1 to 2 seconds. These are the movements that are perceived by our body.

[graaja]

Final Thoughts and Conclusion:

After the installation of suspension, I have driven the car for about 500 kilometers with various settings and road conditions. Below is the summary of my experience with the suspensions.

The installer had set the suspensions to a soft setting of 1 all around. I drove with this setting on the Bangalore to Salem. The drive was through 4 lane highway with several diversions with bad road sections. The car just soaked in all the bad roads in those diversions. Rumble strips would not even rumble. In spite of the soft setting, I did not feel any bounciness or oscillations at highway cruising speeds of around 100 kph.

From Salem I drove to Yercaud where some friends from Coimbatore had also come for an overnighter. We all grouped near Salem and proceeded to Yercaud. A friend rode shotgun during the drive from Salem to Yercaud. This friend is sensitive to motion and told me that he felt some motion sickness and had this floaty feeling. Midway during the climb, I stopped and adjusted the dampers to setting 4 all around. After this adjustment, he was very comfortable and did not have any of this motion sickness.

In Yercaud, I had a chance to discuss with Mr.Boss about suspension dynamics and he told me that it is standard practice to tune the suspensions on the driven axle a little stiffer than the other. In this case, the Fortuner is a rear wheel drive most of the time. So, I set the front struts to setting 2 and the rear struts to setting 4. I drove the next day from Yercaud to Coimbatore with this setting and found this to be a fantastic combination. The car felt very comfortable in bad road sections, felt very stable on the highway, and the body roll was very controlled in the curves in Yercaud. I felt the steering response also to have improved.

During the return from Yercaud to Coimbatore, my friends and TBHPians batterylow and DRIV3R joined me. batterylow drove the car from Avinashi to Coimbatore, and I used this opportunity to check out the rear seat comfort with the new suspensions. The car was very stable and I did not experience any bounciness on the highways. batterylow also gave a positive feedback about how stable the car was at highway speeds.

I am also planning to check the combination of 2 in the front and 3 in the rear and keep it if it gives me a balanced ride. After this, I will mostly change the settings only if I have to drive through really bad road sections, where I will set it to 0 or 1 all around, or long highway trips, where I may go for 4 or 5 all around.

Conclusion:

I took a calculated risk in choosing the Tough Dog Foamcell Adjustable suspensions, and I feel the risk has paid off very well. I am very happy with the improvement over the OE suspensions and also with the flexibility of being able to adjust the suspensions in under a minute. The Tough Dog suspension has nine-way adjustments. Setting 4, which is halfway, is almost similar to the OE suspension in stiffness. I have four settings below for better comfort and four settings above for better handling.

I can confidently say (with data to back up) that the ToughDog suspensions are more comfortable than the OE suspensions.

I also greatly enjoyed working on the data collection and analysis with my daughter, which was a fun project.

I am not sure about the long-term reliability, but from the various reviews I have read, these suspensions should easily last at least 70K to 80K kilometers. Also, I have not made any tests on the suspensions from an off-roading point of view. My main use case is touring, which includes lots of driving through bad roads. I have not yet explored off-roading. When I do some off-roading, I am sure these suspensions will perform well.

Before-after comparison. The increase in height is clearly visible with the increase in the wheel-well gap.


A few pictures of the beast to close this thread.








That's all folks I have on the Tough Dog suspension upgrade on my Fortuner. I will update the thread if there is any major update. Hope this thread is of use to someone in the same situation as mine in the future.

[megazoid]

As expected, comprehensive and useful information. Actually surprised to read that tough dog for the Fortuner is so good. Will borrow your car sometime to understand things better. Great job with the data and tools. Also, cheers to your daughter for helping out enthusiastically and putting her subject to good use.

[graaja]

Originally Posted by megazoid

As expected, comprehensive and useful information. Actually surprised to read that tough dog for the Fortuner is so good. Will borrow your car sometime to understand things better. Great job with the data and tools. Also, cheers to your daughter for helping out enthusiastically and putting her subject to good use.

Thank you

Yes. I feel significant improvement with the ToughDog. I was a little worried it would perform to my expectations, but it has definitely exceeded them.

The freedom to adjust the damping in under a minute is the biggest advantage, IMO.

Let's meet soon. You can drive the car in various settings under various road conditions and see its performance.

[cruzindeep]

Good one.. thanks ����
A couple of questions ..
1. Air pressure plays a role in the comfort feel in the car. What pressures are you trying with? And what are your findings?
2. Any thoughts on non adjustable suspensions on the front & adjustable at the rear? I feel the “drop feeling” more on the rear.
Thanks in advance.

[jfk1975]

Originally Posted by graaja

Yes. I feel significant improvement with the ToughDog. I was a little worried it would perform to my expectations, but it has definitely exceeded them.

Congratulations on the upgrade.

It doesn't look like you got the adjustable UCA (sold separately) for caster adjustment. How is the alignment holding up? I am sure that Thomas must have told you (besides your research) that the factory alignment settings are pretty much out of the window with this and you might want to get the right settings/values from 6th Mile.

P.S:- Speaking from personal experience - I swapped the stock setup on my Hilux to Tough Dog at 6th Mile and haven't regretted it

[graaja]

Originally Posted by cruzindeep

A couple of questions ..
1. Air pressure plays a role in the comfort feel in the car. What pressures are you trying with? And what are your findings?
2. Any thoughts on non adjustable suspensions on the front & adjustable at the rear? I feel the “drop feeling” more on the rear.
Thanks in advance.

Yes. We tested the effect of tire pressure on comfort levels too. I run all the tires at 30psi and all the tests were done with 30psi. Just to understand how tire pressure affects comfort, we did some tests with the OE suspensions at a tire pressure of 33psi. The harshness was quite bad. Below graph shows the comparison. The STDEV is almost 30% more compared to 30psi showing the ride is much harsher than 30psi.



When I discussed this with Mr. Thomas of 6th Mile Customs, he mentioned that he prefers 28psi. I plan to set the pressure to 28psi and drive for a few days. Maybe the combination of 28psi pressure and a damping setting of 2 or 3 will give still more balanced performance.


I would not recommend having fixed in the front and adjustable in the rear. It is better to match the settings of the front and rear struts for a balanced ride. In a RWD car, the rear has to be a little stiffer than the front, or at least equal. If you use fixed suspension in the front and make the rear soft, it may spoil the handling dynamics. So my suggestion is either go for fixed suspensions for all four or adjustable for all four.

Originally Posted by jfk1975

Congratulations on the upgrade.

It doesn't look like you got the adjustable UCA (sold separately) for caster adjustment. How is the alignment holding up? I am sure that Thomas must have told you (besides your research) that the factory alignment settings are pretty much out of the window with this and you might want to get the right settings/values from 6th Mile.

P.S:- Speaking from personal experience - I swapped the stock setup on my Hilux to Tough Dog at 6th Mile and haven't regretted it

Thank you for the kind words.

Yes. I discussed with Mr. Thomas if an UCA is required. As the lift is less than 2" and as my tires are stock size, he said it is not necessary to change the UCA.

Great to know you have changed the Hilux suspensions to ToughDog. I have heard about how these suspensions improve the comfort and handling in a Hilux.

[Cliff9091]

How Does this effect the warranty of the Fortuner, and can the same be fitted for the 4x2 variant ?

Great analysis @graaja helps us owners a lot to take an informed decision about the same.

[graaja]

Originally Posted by Cliff9091

How Does this effect the warranty of the Fortuner, and can the same be fitted for the 4x2 variant ?

Great analysis @graaja helps us owners a lot to take an informed decision about the same.

Thank you for the kind words.

I think the warranty for suspensions and suspension-related components will naturally go when installing these suspensions. Other than that I don't think there will be any other warranty issues.

And yes, these suspensions can be fixed for a 4x2 variant as well.