Time to SAS Hawairish's truck

[system_f]

As for your speed, the gears don't matter one bit, remember we are getting speed directly from the tone ring which is always spinning at wheel speed.  Stock tire size is probably close to 720-740 RPM per mile and the speed will always be set to see "TONE RING TEETH" * (720 to 740) = pulses per minute at 60 MPH unless you can get into the ECU and change that in the firmware.  

 

No matter what the gearing your speed will always be off "Stock tire size" + or - "new tire size".

 

 

Edited September 4 by system_f

[hawairish]

On 9/3/2025 at 12:53 PM, system_f said:

It's been a minute, and I haven't been up to date on where your R50 was before the SAS.  So anything done that isn’t pictured I am not aware of and it may make the comments seem redundant.  I have a couple of questions and some comments.

1. Rear vibration you are experiencing.  Did you do a hack and tap slip yoke on your rear driveshaft?  That was the only way I could get rid of the rear vibration when I was 6" ++ lift.  

2. Steering: Toe and Camber, you'll find the right settings.

I have two questions for you.  These aren’t criticisms, I’m in no place to criticize this kind of work, but I am curious about your thought process?

1.    What about side-to-side bracing, under the radiator support?  Something to replace what the subframe did.  This may be completely unnecessary, but what are your thoughts?
2.    Strut tower bracing.  Do you think the strut towers are strong enough?  I know they were designed to handle the vehicle load, again, your thoughts.

 

Now there's an old-timer name I recognize from the forums!  caR50!  Your truck surfaced here a few years ago with its new owner, if I recall correctly.  Your old ARB front locker before your SAS got passed around, ended up in my truck pre-SAS, and is now in TowndawgR50s hand...an exchange for all his help on my project.  Welcome back, man.

 

To answer your questions:

1. The vibration was there long before the project.  Honestly, I think one of the tires just needs to be re-balanced, but it could just as easily be from the 6" of lift and the pinion angle.  I get a slight driveshaft rumble when coasting and decelerating still, but it's subtle (it used to be pretty bad).  I will eventually be correcting a few things back there with longer upper and lower trailing arms.  I do have a tapped output shaft on the t-case, plus a Calmini SYE on hand for whenever I get around to tackling things.  
2. Toe and camber...I hope so.  I pulled the drag and tie-rod off over the weekend to get a feel if maybe the ball joints were too tight...but they seem ok.  I was hoping to adjust the preload on them, but that didn't go well so left it alone.

No worries on any criticisms!  They're accepted here, for sure, especially since I know you've done the work before.

1. Crossmembers and other support in general was something I put a lot of thought into, and honestly, I think I need maybe one more support somewhere.  One thing I considered was trying to square-up things up where the chassis rails meet the radiator support because of where the steering box was mounted...but the location of the box itself is what made it difficult.  Eventually, when I do a bumper, it'll likely have an integrated skid that will reinforce the radiator mount.  Though, the subframe didn't really add any support under the radiator, but it did stiffen things below the engine.  That is something I would like to restore, but it'll have to be directly under the engine without interfering with the diff snout, and space is pretty limited.  I'm considering two approaches, though...one that would be bolt-on using the motor mount perches.  The other is one of those "in hindsight" things where I'd have to remove everything to do, but would be the best approach...I'm just not ready to take it all apart!  Notably, during the design process, I really wanted to just to a simple support bar running from the upper panhard mount to the passenger rail, but there really wasn't a straightforward way to do that, so I instead opted to C-box the entire rail and put whatever I could in place to prevent any twisting from the leverage at the panhard.  All said...I'm not sure how necessary all this is at this point, but I think I would like to have it eventually.
2. I think the towers are strong enough, yes.  But I have considered a strut tower brace a few times.  My biggest problem is that space is such a premium on these trucks, and the passenger strut area eventually ended up being the most suitable place to mount my compressor and all my solenoids.  The compressor mount already mounts using the strut tower, so I'd have to get really crafty to make it work.  For now it'll have to suffice.

On 9/3/2025 at 5:51 PM, system_f said:

As for your speed, the gears don't matter one bit, remember we are getting speed directly from the tone ring which is always spinning at wheel speed.  Stock tire size is probably close to 720-740 RPM per mile and the speed will always be set to see "TONE RING TEETH" * (720 to 740) = pulses per minute at 60 MPH unless you can get into the ECU and change that in the firmware.  

 

No matter what the gearing your speed will always be off "Stock tire size" + or - "new tire size".

 

Fck.  You're right.  I didn't even think about it like that...been so used to dealing with speedo sensors on my other Nissan and tire-gear corrections that I didn't even realize the disconnect here.  Or hell, how I didn't realize that when I jumped to 4.63's long ago?

 

Well, now I know.  Thank you for enlightening us!

 

So, I guess the good news is I've still accounted for performance from the engine's perspective, just not from the computer's perspective.

 

Custom tone rings with more teeth would've done the trick then, and I would've had everything apart at one point to change them (including the rear)...but that's extremely impractical now.

 

I guess I need to see what sort of inline module I can find or make to bump up the voltage on the signal then.  OR, I could go back to stock tires!!