Update to Jim Mulvey's project
 

TA rear suspension:

https://lateral-g.net/racetek

https://lateral-g.net/racetek/01.jpg

I swear to god.. that guy is as bad as I am.. lol

In the description it says FAST EFI, but in the picture its an Accel DFI unit.

Is the torque arm coupled or decoupled? I see the bolt and the rubber bushings but it looks awful short......but i'm no expert!

Coupled. Here's a pic of a decoupled torque arm. Decoupled arms are super slick but also super noisy.
http://homepage.mac.com/streetfytr/..../TorqueArm.jpg

Yes the arm is a bit short on Jim's car. But as with any multi-purpose carm there are packaging and application restraints.

It used to be a FAST system, now it will be Accel (DFI)

Hmm.. yea, that torque arm is pretty short. Any worries about handling due to that?

Love the car and they look to be doing a great job on it. Hey, were ever able to get me the front wheel specs?

Keep the pics coming along! :thumbsup:

Steve -
Is that some kind of vertical shock absorber in the pic, or just a way to adjust the length of the arm ?

I figured it was coupled...but couldn't tell 100%! thanks steve

I have seen that pic of the decoupled TA....it is in a real wicked el camino correct?

I don't know. I didn't build it. But too short relative to what? And for what application. And compared to what? The Torque Arm suspension replaces a tri-four bar set up. If the torque arm ran all the way to the front of the vehicle it would carry the front wheels thru the eighth mile. I'll have to get Todd to measure it, but pictures can be deceiving. That torque arm is at least two feet long.

I forgot abotu the front wheel specs. I'll ask Todd to pull a wheel and take some measurements.

I believe that's a shock. There are all kinds of different arrangements and combinations: Rubbers, springs, shocks. A controls forces under braking. B controls accelerative forces.

So back to Jim's car, the Torque Arm is coupled so it controls both braking and accelerative forces (Pinion rotation) The lower links control vertical movement and the J-bar controls lateral movement.

This was a quick, easy, real world mod that fit's within the existing crossmembers. My guess is that the torque arm will work awesome while the J-bar will be replaced at a later time with a longer Panhard bar.

Well generally I thought you wanted it long.. for example one in a newer Camaro goes way forward to the trans.

Something Katz said about a short bar (relative to the length of the car) having a low anti-squat value.. Anyway, I'm no suspension expert.. was just curious. looks strong as hell..

Here is the one from my old 2000 Camaro:
http://www.z069.us/00/Undercarriage/Torque.jpg

Anyways, I am really diging what they are doing with Jim's car.. gonna be one nice ride!

That suspension is exactly what Katz was talking about in this months PHR. You can really screw up an otherwise good design by poor execution.

am i gonna have to go buy this months PHR so i can read the article, or would you care to elaborate a lil.

my 65 mustang runs a long coupled T/A to the trans crossmember, similar to the griggs design, but it isnt a driver yet, so i dunno how it works in "real world"

A coupled T/A of less than 40" or so just begs for intense brake-hop. I'd also like to see the actual numbers for A/S as I am sure based on how the design was executed that they were not measured for or set during installation. I won't even get into the 20" J-bar...what the hell is that doing on a street car? This was very obviously a design put in place by someone who understands very little if anything about suspension design and should be stored as a classic example that just because you can do something (weld in this case) doesn't mean you should.

lol
 

lol denny, is this how you really feel, lmao. :D

Is this really the proper forum to critique the suspension choices on a car not even done yet? Maybe a new thread in the suspension area? I just don't want to be responsible for hijacking a thread.. :captain:

Also, in regards to the J-bar, if you read the post you would see that they are swapping that out for a PHR later on. Didn't mean to start a debate on T/A theory in here..

I wouldn't call it hijacking steveR, it was an update to the car and we are just discussing what has been done to it....

Seems kinda like wasted labor to put the j bar on...take it back off...put on the panhard bar. Why not just do the PHB the first time?

Maybe the design will work fine?

I know.. I just don't want to turn an update thread into a "bag on the suspension thread".. lol

I got the impression that the J-bar was already on the car from the previous owner. I can't imagine that they would put it on knowing that they were going to swap to a PHR later down the line.

No it had a TRI-4 bar before....no need for a J-bar. I wouldn't think anyway.......

Uhh.. Hello? Guys, if you have specific questions, just ask me. I'll do my best to find out the answers for you. As for the car, I'll take it for a spin--You know--in the real world. Brake hop is easy to test, right? I'll even ask Jim if he'll join us (or let me borrow the car) for the Pocono Track Day. If the car handles well, I don't care if the design looks good on paper or not.

That J-bar--as installed--only yields 1/16" of lateral deviation (to the left) in 2" of bump.

lol.. sorry for acting like you weren't in the room.. get us the scoop on what's up :)

I don't drive pieces of paper so I will be more concerned how it actually works in "real life".. Thanks for the info (now about them offsets.. :unibrow: )

Well there you go. Jim read the thread, then called and said we can take the car to Pocono in May. It's an open event, so we'll be able to able to compare the lap times against a variety of different cars.

Now if we could only get Dennis to attend charm school.

I thought that was Dennis's version of charming??? :rofl:

Can't wait for the track report.. will the PHR be done by then or will the J-arm still be in place??

The J-Bar will still be in place. Of course a full length PHB would exhibit less change. No $#!t. But the J-bar has such great packaging potential, that Todd wants to give it a try. Look at it. It's small, It's light, and it's in front of the axle. It leaves plenty of room for exhaust. So if the minimal deviation is acceptible, it stays.

well im probably at fault for asking :_paranoid

Yes, it is. The "bragging" photos of the suspension were posted here so here is where the critique should take place

.I'll critique that when it happens too. Based on what has been so far they will get that wrong as well.

No, it won't

Ahhh, probably not. Steve1969, that was a funny response, I almost laughed

Look, the bottom line is that the design obviously spent zero time on an actual spread sheet to see how it will respond dynamically (which is never wrong and should always be used as a starting point). It was about how pretty we can make this device that we probably don’t even know the name of. I hope it holds the axle place long enough to get it on and off the trailer. Maybe we’ll put it on a race track someday….of course as long as no other cars are there as one might throw up a rock chip or something.

OK, off soapbox. The design doesn’t work as installed, it doesn’t on paper and won’t on the track…or maybe even the street for that matter. It shour looks good though.

When someone uses the term "bragging" when someone is posting pics of thier car it just makes them sound jealous and bitter. The project update section is for.. well, updating info on projects.. If you think it's just the "bragging" section then why do you read it? I know you are a straightforward talking kind of guy so I am sure you will take this a constructive comment :)

So, what you are saying is that no matter what they do you will find fault with it since you know best.. gotcha.. way to keep an open mind :thumbsup:

Maybe, maybe not.. I guess if they try it on the track and it does work then they can challenge your slide rule to a race.. If it doesn't work I suppose they might rip the parts out and try again. This is like the bench racers that argue theoretical numbers to determin who is faster.. lol..

Like I said, I found the TA to look sorta short, but I'm willing to let someone finish thier project and wait to hear the results. Also, I was able to voice a concern over the set-up without coming off like a "ass".. this is an ability that everyone doesn't have. Then again, with some people that's sorta charming. lol

You laugh?? wow, learn something new everyday.. but seriously, you can't expect to be so blunt and well.. (I can't think of a nice word to put in here).. and not expect people to make note of it. Your known for having a certain lack of social skills but you provide good insight and tech on the board so people have learned that "that's just the way Dennis is". Life would be boring if we were all the same. However, that doesn't make the way you phrase things any less "assholian".. Then again I can be an ass from time to time as well. I suppose it's a matter of degree :)

I am sure that with your vast array of degrees in mechanical engineering and your boundless experience on the track that you know best. I guess we can add your physic mind reading powers to that list since you seem to know what everyone is thinking.

Again, the trailer and rock chip comments just make you sound bitter against people with money or nice cars, which is a shame since I doubt that is the case.

See, we all need a little time on the soapbox from time to time.. It's funny how many "experts" we have on the internet. You do know you could have accomplished the same "critique" of the system without bashing on the owner or the people that designed it.. right? A few people may think that being blunt like that is "cool" or "being real" but most people just see it as plain old being rude.

So, lighten up and learn that you don't have to hit someone in the side of their head with a baseball bat just to get thier attention. :D

I’ll behave now…unless this gets pulled into suspension.

lol.. god help us if it does.. Seriously man, there is nothing wrong with having an opinion or with critiquing someones "plan" but you get a lot farther with some tact than with clubbing them over the head till they are bloody. All that does is make people shut down and not listen to any insight you might of had.

Not everyone is a thick skinned as I am.. god help me though when you review my finished product ;)

Oh, and I just read you responses.. very good. and yes, you do get a quick response and you're ok in my book.. just take it down a notch or two and don't be so quick to assume..

<-- has many futile attempts at humor ;)

I think the productivity is gone from this thread...