• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

240 rear suspension

Marvelous3

Marvelous3

Who engineered this?
Joined
Nov 12, 2002
Location
Atlanta
I have poly up front with Kyoto coil overs, bens strut mounts and koni yellow. The rear has bens mounts, and koni yellow.

This car will eventually have a lsx in it so I want to go ahead and do the rear suspension to do with it. Should I do bens hybrid torque arms or the straight adjustable arms? I was going to get new trailing arms and box them. Spherical trailing arm bushings. And poly the rest.

Thoughts? This wont be a race car. Just a fun around car that Ill take to the 1/4 mile races every now and then.
 
Unless reinforced at the body, I thought poly was a no no on the front bushing of the lower control arm- even more so with Ben's mounts. With all that good articulation at the axle, the next bind will be at that body to arm connection. Now if you can get a compliant poly mount, that would be best. I know some of the aftermarket rubber have been flagged as not so good either. I have not checked mine after I installed the new lower arms that came with bushings, but will be addressing my rear suspension again soon. Look forward to want comes out of this thread.
 
PeaceEngineered said:
Unless reinforced at the body, I thought poly was a no no on the front bushing of the lower control arm- even more so with Ben's mounts. With all that good articulation at the axle, the next bind will be at that body to arm connection. Now if you can get a compliant poly mount, that would be best. I know some of the aftermarket rubber have been flagged as not so good either. I have not checked mine after I installed the new lower arms that came with bushings, but will be addressing my rear suspension again soon. Look forward to want comes out of this thread.
Click to expand...

where should i brace?? I just did poly everywhere ( except the rear lower axle cuz im getting bens bearings)... Its a 76 242 that i auto cross so it sees abuse. Id rather brace it now....
 
Marvelous3 said:
Thoughts? This wont be a race car. Just a fun around car that Ill take to the 1/4 mile races every now and then.
Click to expand...

The hybrid torque arms!

The rubber at the body connection will be more compliant than poly and will absorb more energy as well.

If articulation is it (and you're willing to find your compliance elsewhere) and you don't mind more energy transferred into the body, get the standard adjustable torque rods.
 
I ran the iPD arms for about 100k till the front bushing stretched (became oblong). I never really liked them very much frankly. They had a tendency to cause the suspension to bind as they didn't have any twist in them. Caused enough body flex on the front mount to damage the mount in the front on the passenger side. This was after I removed the poly TAB bushings on the axle and replaced them with Ben's spherical units. Prior to replacing the TABs, that bushing was the most limiting factor in axle bind. That's why the torque arm front mount bent after I swapped the TABs.

I bought a set of Ben's hybrid arms as a replacement. No more binding. I've got about 30k on the hybrid arms now. I have however worn out a set of front trailing arm bushings as those are now the most limiting factor. Based upon the clunking coming from the rear suspension, I've worn out another set of trailing arm front bushings in the last couple weeks.

Next step will be to replace the trailing arms with Ben's units to eliminate that bushing or build my own with a spherical up front. I have enough cores laying around it shouldn't be too damn difficult.

In your case, I would recommend you just go to where I'm going to end up. Get the hybrid arms and either buy Ben's trailing arm with a spherical up front, or build your own boxed trailing arm with a spherical up front.
 
classicswede said:
I have never seen an issue with the body caused by poly mounts. We have very rough roads here and if anything breaks its the arm itself
Click to expand...

I would say that is not good. The bushing should fail before a major suspension component gets broken. I really don't have a good answer on where to add additional bracing either. I would say though that Ben created the hybrid upper arm for a reason. NVH reduction and allows articulation too. The same can be mimicked on the lower arms. If 'whatever bushing material' doesn't allow movement, the suspension will not operate to it's fullest.
 
I have old yoshifab V1 torque rods on my car as well as a heim joint panhard bar. They hold up fine but the nvh is HORRIBLE. I'm getting rid of them asap and going to a stock style panhard bar and going to figure something out with the torque rods
 
quillc said:
I ran the iPD arms for about 100k till the front bushing stretched (became oblong). I never really liked them very much frankly. They had a tendency to cause the suspension to bind as they didn't have any twist in them. Caused enough body flex on the front mount to damage the mount in the front on the passenger side. This was after I removed the poly TAB bushings on the axle and replaced them with Ben's spherical units. Prior to replacing the TABs, that bushing was the most limiting factor in axle bind. That's why the torque arm front mount bent after I swapped the TABs.

I bought a set of Ben's hybrid arms as a replacement. No more binding. I've got about 30k on the hybrid arms now. I have however worn out a set of front trailing arm bushings as those are now the most limiting factor. Based upon the clunking coming from the rear suspension, I've worn out another set of trailing arm front bushings in the last couple weeks.

Next step will be to replace the trailing arms with Ben's units to eliminate that bushing or build my own with a spherical up front. I have enough cores laying around it shouldn't be too damn difficult.

In your case, I would recommend you just go to where I'm going to end up. Get the hybrid arms and either buy Ben's trailing arm with a spherical up front, or build your own boxed trailing arm with a spherical up front.
Click to expand...

Excellent post!

On this...

quillc said:
They had a tendency to cause the suspension to bind as they didn't have any twist in them.
Click to expand...

The funny thing is that this isn't anything new. The Grp A cars chose not to use poly for this reason.
 
So the big difference between the hybrid arms and the straight adjustable ones is some additional vibration out of the adjustable ones? And the hybrid arms are more expensive?
 
Marvelous3 said:
So the big difference between the hybrid arms and the straight adjustable ones is some additional vibration out of the adjustable ones? And the hybrid arms are more expensive?
Click to expand...

Additional NVH isolation as compared to straight Heim joints at either end. I would say having used both poly and hybrid, they have less NVH than the straight poly adjustable ones iPD sells.

Don't bind as the suspension flexes. As I stated in my post below, the poly adjustable ones actually bent the front passenger mounting ear. Don't have any issues with rear flex with the hybrid ones installed.
 
^^ Quicker than me. Haha
The upper hybrids are adjustable too, buy they only use the spherical bushing at the axle with a compliant bushing at the body to reduce the NVH. I have IPD upper arms, and do not care for them at all. Sure they are adjustable, but they will not "tighten" at the adjustment because of the flex that occurs because the poly bushings are too stiff. Basically, the threaded portion of the arm becomes a pivot. Every time on or off gas is a clunk due to the tolerance of the threads. Ben's mounts are on my wish list.
 
From my experience and testing for a DD situation where you want to minimize any vibrations transmitted to the body from the rear diff / driveline / wheels / etc. Its always good to have a rubber barrier between the body and the axle. Thats why I prefer to have a rubber bushing in the front of the trailing arms and the torque rods. I dont like how sloppy the rear feels with the factory axle bushings and full factory torque rods so putting a spherical in the axle and sphericals in half of the torque rod makes the rear react more quickly while keeping in the necessary compliance for it to reduce NVH.

One of the benefits that I noticed when going to the hybrid rods was it makes the car smoother in traffic if you get lazy with the clutch pedal. A full spherical torque rod transmits all inputs instantly, which makes smooth clutch modulation very important.
 
Also, to note with the rubber torque rod bushings in the hybrid arms... eventually that rubber will fail just like all moving parts on a suspension but the torque rods are easily removed and that bushing can be easily changed.
 
blkaplan said:
From my experience and testing for a DD situation where you want to minimize any vibrations transmitted to the body from the rear diff / driveline / wheels / etc. Its always good to have a rubber barrier between the body and the axle. Thats why I prefer to have a rubber bushing in the front of the trailing arms and the torque rods. I dont like how sloppy the rear feels with the factory axle bushings and full factory torque rods so putting a spherical in the axle and sphericals in half of the torque rod makes the rear react more quickly while keeping in the necessary compliance for it to reduce NVH.

One of the benefits that I noticed when going to the hybrid rods was it makes the car smoother in traffic if you get lazy with the clutch pedal. A full spherical torque rod transmits all inputs instantly, which makes smooth clutch modulation very important.
Click to expand...

Thanks for this post.

I've got poly motor mounts in it now so the vibration isn't really a big concern for me. I was interest if there was a performance difference or is the hybrids were strictly a comfort option for dudes not wanting race car race car stuff. So I think the full sphericals are the ones ill be getting.

I really really don't want to put rubber bushings anywhere. I don't want to have to pull the suspension apart in two years to replace a rubber bushing and I do like the stiffer ride of poly.
 
Giving the rear a little bit of float gives it more grip from what I experienced.

No matter what you use (poly, rubber, or sphericals) It will need to be changed eventually.

If you are putting a lot of load through the rear, the sphericals will be the strongest option.
 
Acceptance of the potential vibration (V in NVH) from poly motor mounts is one thing. The other N and H- noise and vibration are pretty annoying in the rear in my opinion. Harshness for sure as Ben alluded to above. It is tough to modulate the clutch to get a smooth take off. Of course, I am getting old YMMV. Haha
 
You must log in or register to reply here.
Back
Top