polyurethane rear control arm bushings

[Bambikiller240]

Originally posted by visionary

the car has an 'updated' feel to the ride and handling and is very solid.

sorry about the delay in responding...

keith

Good Deal! Enjoy the Ride!

PS On cold winter days (cold for N. CA that is. 40-50 degrees or less), my car still squeeks a bit though I believe that is due to me not getting grease EVERYWHERE that I should have. Since it's minor and not noticable with with the radio on........ I gladly live with it until the next "required" teardown.

[Zvoiture]

First of all: Every single bushing in my 77 is PU. AND: The 73 I am building is getting every single bushing replaced with PU. Just telling you this up front so you know what side of the fence I am on.

However, in defense of DET:>>>>concerning the ride and handling, it is true. the handling is much more positive and the ride is improved a thousand percent. one thing that has also improved substantially is the "clunking" from the rear end. i also installed the tension arm kit from motorsport as well and the alignment and positive feel in the steering wheel is very noticable as well.

the car has an 'updated' feel to the ride and handling and is very solid<<<<

A. When you replace 30YO rubber bushings with ANYTHING, it will be positive, and the ride improved.

B. The PU bushings did not stop the 'clunking'. A new rubber bushing would have worked equally as well.

C. You replaced the front bushing on the T/C arm with a chunk of delrin mated to a chunk of AL (yes I have one too!!!). Perhaps this was just a side note, as including it in a discussion of Rubber Vs. PU and stating "improved feel" is a bit unfair.

Sorry to rave on about this, but it is somewhat of a pet peeve, and I have ranted about it before. Go to a Z show. Get on your knees and look under these beautiful cars. You won't believe how many you find with cracked, chunked, disentegrating 25-YO stock bushing on them.

steve77

[Bambikiller240]

Originally posted by Zvoiture

C. You replaced the front bushing on the T/C arm with a chunk of delrin mated to a chunk of AL (yes I have one too!!!). Perhaps this was just a side note, as including it in a discussion of Rubber Vs. PU and stating "improved feel" is a bit unfair.

I could be wrong, but I thought he meant that he installed PU in the Tension Compression rods. (I did this also) The Aluminum/Delrin TC kit that I had on another Z was too harsh for driving on the street. (we have pot holes galore up here in the Bay area)

PS to 260DET: I never said rubber bushings caused any problems, I simply maintain that with PU bushings you get more performance out of your suspension.

[260DET]

Originally posted by BambiKiller240

........................

As for shear loads, it's the spindle pins and Inner Transverse link bolts that handle the shear. Just like the rubber bushings, there is no place for the bushings to "shear", since they are surrounded by steel.

PS

1. Everyone is welcome to their own opinion
   
2. I'm not selling anything here, I'm relating personal experience gained over 28 years of owning, driving, modifying and maintaining 240Z's
   [/list=1] Not quite clear on that Carl. The OE inner bushes are in shear but these poly ones are not? So do they rotate during suspension movement, if so what surface do they rotate on? By 'rotate' in this context I refer to anti-sway bushes as an example, they rotate on the surface of the anti-sway bar itself, they are not in shear.

[260DET]

Good points Zvoiture, what I'm trying to establish is whether new poly bushes are superior to new OE bushes. The poly bushes squeaking bothers me because that COULD indicate a potential problem.

Incidentially, I designed and had made up a new set of rear suspension arms with rod ends running on modified outer shafts. Now the rear suspension is fully adjustable for toe and camber, presently set at 1.5 degrees negative camber. And used new OE inner bushes. Sorry, can't post any pics, all my spare money goes on the car, not on computer accessories.

[Bambikiller240]

Originally posted by 260DET

Not quite clear on that Carl. The OE inner bushes are in shear but these poly ones are not? So do they rotate during suspension movement, if so what surface do they rotate on? By 'rotate' in this context I refer to anti-sway bushes as an example, they rotate on the surface of the anti-sway bar itself, they are not in shear.

Hi Richard:

I don't believe that the inner A-arm bushings rotate. They slide onto (over) the threaded part of the A-Arm inner pivot point (sorry if I'm not clear here on the name) and then are clamped by the U-shaped brackets. The A-arm tube rotates within the bushing, and it is the rubbing of the two surfaces that make the squeek.

As for the Anti-sway bar mount bushings, the bar rotates within the bushing which is held stationary in the same way as described above. Same squeek is possible there.

This is the way I understand it to be. Now I'm not Einstein, so if you have differing idea of how it works, jump in and tell me (us) as I (we) are all open to learning new stuff. Maybe we should ask www.ground-control.com or another company that specializes in suspension about this. Too bad you don't have a digital camera (I don't have one either:() as I'd love to see these suspension arms you designed and had made up. I saw some at the MSA West Coast Nationals and they were really neat. For Optimum handling and adjustability they are certainly the way to go.

To reiterate, there isn't anything "wrong" with OEM rubber bushings (unless they are 30 years old and trashed). The PU bushing are a very popular replacement item in the US for folks who want a bit more positive feel to the handling, but can't go to solid suspension bearings (heim-joints, spherical bearings, Aluminum/Delrin Off-set bushings, etc) due to the conditions of our public roads.

[visionary]

the ploly bushings contributed to the reduction of clunking not because they are ploy rather because of corrected alignment of the moving components.

i have balanced, rebuilt and replaced half shafts, u-joints; installed solid mounts, etc.

the sum of the total is directly proportion to the factored input.

i will stay with the poly, machined metal and fabricated updates.

they work...

i also enjoy my 4channel 150 watt cd player over original mono am...

i have learned a great deal from this thread,

thanks again for all the great input

[260DET]

Thanks for clearing that up Carl, my original negative comment on poly inner A arm bushes was based on an assumption that they would be in shear like the OE bushes are.

Learn something new every day, good stuff.

[Bambikiller240]

Hi Richard:

Please tell me about the OEM bushings being in shear. My understanding (which COULD be wrong, as I'm not perfect) is that they are not in shear. Can you educate me?

Does anyone else have input here?

[260DET]

Carl, my understanding of the OE bushes is that they are in shear because compliance (movement) occurs as a result of deformation of the rubber part of the bush. The outer rubber surface is locked against the body by the locating brackets, the inner metal surface is locked on to the suspension arms when the large cap bolts are tightened up.

With the OE bushes, the range of suspension arm movement is limited by the capacity of the rubber to deform (twist) up to a point. Past that point and the rubber would shear due to its elastic limit having been exceeded.

[Bambikiller240]

Originally posted by 260DET

Carl, my understanding of the OE bushes is that they are in shear because compliance (movement) occurs as a result of deformation of the rubber part of the bush. The outer rubber surface is locked against the body by the locating brackets, the inner metal surface is locked on to the suspension arms when the large cap bolts are tightened up.

With the OE bushes, the range of suspension arm movement is limited by the capacity of the rubber to deform (twist) up to a point. Past that point and the rubber would shear due to its elastic limit having been exceeded.

I see what you are saying about the outer surface of the bushings being "locked" to the body by the locating brackets.

I have a new pair OEM inner bushings in my hand (P/N 55555-E4100) and I see that the inner metal sleeve has "teeth" at each end which would work in conjuction with the large washer and cap bolts to lock them down as you describe, since the sleeve and the rubber of the bushing are built as one unit.

But, with PU bushings, I'm not so sure about the large cap bolts "locking" the inner metal surface, thus limiting movement to any great degree.

I don't recall the metal sleeves (which come in the kit as separate pieces *loose* from the bushings per se) having these "teeth" (they had smooth ends AIR). So, with the inner metal sleeve not being solidly attached to the actual PU bushing material, I don't *believe* that the PU bushings are in shear.

I usually don't work on my Rear Suspension this way, but there was an occasion when I needed to change strut cartridges quickly, and I was able to simply undo the 3 bolts at the top of the strut assembly and pull the whole strut assembly down and out of the wheel well, so it didn't seem to me that movement at the inner bushing was limited "very much". (of course, I disconnected the half shaft, the brake line and E-brake cable as well ) The suspension didn't just "fall" down, but I was able to pull it down, and out without too much effort as I recall.

Interesting discussion though. I hope someone else will jump in here who can shed more light, confirm or not, what is actually going on there. If the PU are in shear, I understand your concern and acknowledge it's validity, as PU will certainly have less capacity to deform. It's that lesser capacity to deform that makes the handling feel more positive than as delivered from Nissan.