Thread: Discuss TDMimports Rear Adjustable arms

TDMimports is offering a group buy on their adjustable rear suspension arms.
http://www.sr20-forum.com/classifieds-group-buys/75365-gb-tdmimports-rear-adjustable-arms-extra-free-gift.html#post995531

I've always hated the cheesy factory rear control arms on my B13 and sometimes wondered if they're not tweaked.

These are made of Chromoly Steel SCM435 and the bushings are high durometer rubber so suspension bind shouldn't be an issue like it is with some poly bushings.

The arms are adjustable and notice they adjust from the center instead of the ends. It reminds me of the factory adjustable rear arm set up on the early 90's Maxima.

I see they describe the bushings as "super hard rubbers". This will make the rear suspension bind WORSE than factory, just like the polyurethane bushings do. This is a bad idea.

I don't know what other adjustable arms you're thinking of that "adjust at the ends" and why this set "adjusting from the center" makes for an improvement?


If you want camber adjustment and can live with more bind than factory I guess these would be a good idea? Otherwise I would spend $10 more and get the TurboFx solution that provides camber adjustment, and also eliminates the factory bind.

The TurboFx arms are a good example of what I miss out on seeing. I've wanted rod ends like those and would have bought them a long time ago if I knew they were there.

The TDMimports are a nice alternative to stock and are what the factory could have used from the beginning. Like I said they remind me of Maxima arms.

Thanks for pointing this out. For what I have planned I'll be moving out of the Group Buy and reading through the long thread link you posted.

Well I am not sure about the bidding theory, but these do serve its own purpose. Why the reason why we adjust from the center. It is because for easy access rather then going from both ends.
Arms itself do have built in hard rubber bushings just like Nismo does. I adapt the same ideal from Nismo and if they are easily binding from the side to side then I guess Japanese engineers must be doing wrong since decades ago!
Arms have been installed on my car for over 18 months and I don't see any significant binding nor SOFT feelings.
I also do get extra cambers from these arms without hassles!

Your product has a poor design for most cases. Defend it if you must, but you would do yourself a service if you understood your product and its limitations and owned them instead of showing your ignorance by waving your hands around in the air.
These things provide one benefit. They allow for camber adjustment. They do that at the expense of making the stock suspension bind worse (same as the Nismo units you're describing). The Ingalls product provides camber adjustment with the similar binding as stock (not worse) so they are a better design. The TurboFX design provides camber adjustment (from the center as well if that's important to anyone) while eliminating the stock suspension bind all together. There are potential NVH issues with the TurboFX design, but they own that.

How many cambers does it take to get the roll center?

After installing my Road Magnet/AGX combo I had to have camber bolts installed on the rear struts. I don't see camber bolts as a long term solution.
So I did a lot of research and gave this a lot of thought. I needed a better way to adjust camber.

The B13 rear is not the best design. The parallel arms move up and down as the strut compresses but the trailing arm is a fixed length so it moves in an arc in relation to the up down motion of the parallel arms. The results is that the trailing arm pulls the parallel arms forward as the suspension compresses. The frame end bushings of the trailing arms are very large and allow for some deflection but not enough.

A simple way to demonstrate this Trailing arm movement is to take a yard stick,(or tape measure). Hold one end against a door frame with the other end touching the opposite side of the door frame, and the stick horizontal to the floor. Now, keeping one end "fixed" but allowed to pivot (like the large end of a trailing arm) move the stick up and down simulating the suspension compression/rebound effect on the Trailing arm.
You'll be able to easily see how the distance between the end of the stick and the opposite side of the door frame increases and decreases as the stick pivots through an arc movement.

The Trailing arm is a necessary part of the suspension system but it is also the main culprit in the suspension problems, especially if the large bushing is replaced with polyurethane. Parallel arms with heim joints on the end seem to be the best solution as they allow a greater range of motion in response to the trailing arms arc of movement.

When I read some other posts in this thread I got the impression they thought if a magazine, like GrassrootsMotorsports, did a before and after comparison of stock vs TDMimports arms, the driver would get out of the car and say "Oh My Gosh, the rear end is a catastrophe! I could barely keep the car on the track."
To the contrary, after reading the Bushing Section of the B13, B14, B15 Suspension Information... I find it difficult to believe that the difference in durometer between TDMimports bushings and factory bushings makes any appreciable difference as far as suspension bind is concerned. I also intend to follow everyone's advice and leave the trailing arm bushing stock.

My B13 is not a track only car. I use it as my primary driver. I drive it to work every day and take it on long trips so heim joints were not the best solution for me.
I didn't want to turn up the radio to cover the noise/vibration of heim joints at work. I also didn't like the wear factor. To quote another source: "with heim joints, it's race em and replace em".

So...I ordered the TDMimports rear adjustable arms. I won't be able to install them until summer comes but I'm not anticipating suspension problems. Here's why.

The TDMimports arms use Nismo type rubber bushings, not polyurethane. Research on the 240SX forums indicated they are successfully using Nimo bushings in places polyurethane won't work. Polyurethane in 240SX rear ends are a tangle of suspension binding problems, worse then ours even.

With the TDMimports arms I should get the camber adjustment I need, along with the lack of noise, vibration and wear factors I wanted to avoid.
The arms arrived last week and I'm impressed with the quality of everything from the welds to the bushing inserts to the powder coating.

All this debate is fun but what we really need is for a few good drivers, say at the next convention, to take a B13 with TDMimport arms on the track and give us some driving impressions.

It's not just the durometer of the bushing, the shape of it matters maybe more. The stock ones are oval to help minimize the binding. More deflection is better.



@NI SER-1, were you aware of the TurboFX solution when you bought these? If so, why did you choose not to buy them if you don't mind me asking?

Hey Ben, I knew about the Turbo FX solution. but first let me address your opening comment:
"It's not just the durometer of the bushing, the shape of it matters maybe more. The stock ones are oval to help minimize the binding. More deflection is better."

Take a look at the pictures of the TDMimports bushings here: http://www.sr20-forum.com/tdmimports-kuo-s-garage/66634-sale-tdmimports-b13-p10-rear-adjustable-arms.html

You'll notice the TDMimport rubber bushings are "oval" like stock, and may even allow more deflection. They are definitely not flat ended like your typical polyurethane bushing.

What caused me concern about heim joints, was what javier b14 posted in his Turbo FX solution thread.

"Quote Originally Posted by javierb14 View Post
They will definitely transmit more noise and vibration from the suspension to the chassis...this is more of a "race car" part since the bushings and their damping characteristics are being removed. Streetable is relative term, I would run them in a daily and just turn the radio up a bit."

This caused me to do more research on heim joints, including actually talking to track drivers and mechanics who work on track cars. What javierb14 said is true.
The consensus seemed to be, Unless you have a dedicated track car, the benefits of heim joints for this type of application do not seem to out weigh the negatives of noise/vibration and especially wear.

Going through the B13, B14, B15 Suspension Information thread, Mike Kojina didn't find that even polyurethane bushings were a significant issue. A lot of what Steve Foltz posted had to do with the 240SX rear end suspension bind. It seemed everyone agreed that the trailing arm was the problem in a B13. Here are quotes from Steve and others.

"Quote Originally Posted by 98sr20ve
You do relize that you really don't want to replace every control arm bushing in the rear with ES bushing. Leave the trailing link one alone. Don't do es on that. Search around the site about suspension bind and you will find the info."

"Quote Originally Posted by Johnand
There was a thread that I posted a while back about the rear suspension bind and the consensous was the trailing arm frame bushing should remain rubber as it need to move fore and aft."

So I decided I didn't want heim joints, and that I would be fine with rubber bushings in the parallel arms as long the trailing arm large bushings were stock. That's why I went with the TDMimports parts.

We should probably start a heim joint vs bushing thread, but I think it's a matter of what your goals are.
By the way, I think you made the right decision when you left the ES bushing in your rear hubs. That is the Progress rear sway bar bracket mounting point so I'm can imagine a lot of stress is placed on that bushing. I was also wondering if you ever followed up on the possible difference between the SE-R and the GA16 B13 trailing arms.

I'm not seeing the same images you are. They are effectively rectangular, and provide no articulation due to shape like the stock units do.