jimlab

I do, but I'm still trying to decide if I'm using them myself. I do, however, have a pair of polished trailing arms with FEED spherical bearing bushings installed that I'm not going to use but haven't gotten around to putting up for sale.

maxcooper

Jim, keep the stock arms unless you think you are expecting wheel clearance issues. They're purdy all shined up like that. And the spherical bearings will probably last longer than the rod ends on the other arms.

-Max

jimlab

True, but I want to use my own Nylon bushings, and the FEED spherical bushings can't be removed without damaging the finish.

t-von

iTrader: (8)

So does anyone else sell a nylon bushing for the longitudinal arm?

jimlab

4CN AIR says he will be, and by odd coincidence, they'll probably look exactly like mine.

7racer

has anything come out of that BTW? Just curious about the "drama".

Jim, you might want to make sure you put a copyright or something on your instructions to incase they end up in another kit

maxcooper

Update: My new upper arms arrived from Malloy a week or so ago, but I was focused of dyno stuff last weekend so I didn't a chance to install them. They came loaded with stock rubber bushings and (of course) new ball joints. To recap, I bought some used upper arms but found that both my original arms and the used spares that I bought all had play so I ordered some new ones ($510 for the pair, ouch!).

I installed them tonight. I started with the driver's side and swapped the new upper arm in. I had previously replaced the lower arm with a used replacement that I bought. At that time, I had found that the ball joint and Unobtanium bushings on the lower arm all seemed to be in good condition (no play). But both the ball joint and the Unobtanium bushings in the upper arm had developed some slop. I didn't know what was causing the clunking when I started this, but that's what I found, and I assumed the same was true on the other side.

Fortunately, I did find the same thing on the other side. The bushings and ball joint on the lower arm were fine, and the ball joint and bushings on the upper arm were worn. So, I installed both the used lower arm (with rubber bushings) and the new upper arm on the passenger side of the car.

I need to get an alignment, but the clunking is all gone! Woo hoo!

I also removed my spare tire (doesn't fit over brakes front or rear) and installed some rollbar padding (for safety) tonight and then went out and tested the 80MPH-on-cruise-control sound level. I've got some sound deadening materials gathered up, but I wanted to get a baseline so that I could judge the results. I chose 80 MPH on cruise to keep things simple, and because that is my normal highway travel mode. The car has my SR midpipe in the middle (swapped in for dyno tuning), but I will replace that with a new cat+muffler midpipe I am working on soon. Anyway, I watched the meter for a while to see how sensitive it would be to the type of pavement, and I was pleased to find that the readings were pretty stable, varying only about 1-2 dB A or C as I cruised down the highway for a while. If I changed lanes and hit lane markers or pavement weirdness, the sound level would jump, but for the most part it was very stable. It didn't seem to matter much where the meter was, either, at least between the various places I could hold it with my arm while driving. The readings were much more stable than I expected. I'll use the same stretch of road (405S between Jamboree and Jeffrey) with similar traffic (pretty light, but still cars around, ~11:15PM Sat night) to gather comparable results in subsequent tests. Enough chatter, here are the results:

A-weighted, slow, Radio Shack meter: 82 dBA
C-weighted, slow, Radio Shack meter: 102 dBC

I think I'll try some of my McMaster-Carr sound deadening stuff on the hatch floor first.

-Max

rynberg

Christ, midpipes are loud. I'm never running one.

The very large difference between the A and C-weighted levels indicates that there is a large amount of sound energy in the lower frequencies below 125 Hz. I would not be surprised if switching to a hi-flow cat won't have much effect on the A-weighted levels, but will lower the C-weighted levels substantially.

pomanferrari

iTrader: (1)

Hi all, it's me, the guy who brought up this issue with the clunking (groaning like a wooden sail boat tacking into the wind). Car has less than 4000 miles since change to the Unobtanium bushing. I have moved to Scottsdale where it's Ferrari land galore but that is another story.

Anyway, I still haven't changed my control arms to new ones yet due to time constraint moving the whole family and three cars across the country. The front control arms are still making a huge racket. I did notice that if I go through a car wash (the brushless kind), the car is immediately quiet. Lubing doesn't seem to help at all.

Yeah yeah, I'll change them one of these days, after I replace the batteries on my noise cancellation headphone that I have to wear drviving with these bushings.

alberto_mg

i was wondering if you were going to chime in. FD still has nicer curves than most Ferraris

WaLieN

When you installed these bushings, did you put new dust seals in or did you reuse the old ones?

maxcooper

I used the old dust seals. I know I should use new ones, but I've never found a lot of dust in there. The grease surface was still clean, with dark coming from inside the bushing (metal wear?) rather than from the outside, which leads me to believe that it wasn't dust from the outside that killed them. So, I felt no strong need to get new dust seals. YMMV.

-Max

WaLieN

Thanks for that little bit of insight, Max. I ordered a new set of PBs and 3 dust seals. I was planning on only relplacing the seals that were either brittle, ripped, or warped. I'll be sure to check to see if there is any incoming dirt/corrosion.

travisorus rex

I want them...

Julian

iTrader: (14)

The nylon, delrin, rigid polureathane bushing question and the JimLab nylon delrin debate.

First yes, Delrin (r) is a DuPont tradename product and still only source for momopolymer Acetal just as MS is still sole source for "Windows (r)". A simlilar product ,"Celcon (r)", copolymer Acetal is available from Celanese, copolymers are easier to produce but have reduced mechanical properties.

This does not make Delrin better or worst than polyamides or nylon as it is known, only newer. "Nylon" was also a DuPont invention and tradename that was not protected as well. Delrin was later developed by duPont as a simliar application plastic that had outstanding abrasion and fatigue properties.

The attributes of these materials for the required application is what is important, not the source, name or price. In no particular order:

1 machinability - can you make the bushing as desired (Delrin best) (Polyureathane molded no machined)
2 abrasion restistance - will the bushing wear out with dirt and road grime (Delrin best)
3 stiffness - is it stiff enough for function, rigid without harshness (otherwise use metal on metal)nylon delrin similar, Poly softer
4 fatigue resistance - with it break down after prolonged use and get sloppy (Delrin best)
5 impact strength - toughest to weakest: Delrin 1.4, Celron 1.3, Nylon 1.0, Poly ~ .7
5 dimensional stability, dry wet, oiled, tared etc. - will it swell up and bind or srink and get loose
6 low friction, for linear stiffness - will it bind, does it need lubricating - Delrin more self lubricating than nylon which in itself is good.

You pick!

wanklin

iTrader: (2)

I have no desire to start a debate; however, I find your wording particularly biased so I am going to put in my own 2 cents in the name of fairness. Let me start off by saying that I do sell polyurethane bushings so I am biased to some extent, whether I mean to be or not. With that being said I have no interest in creating hype here, but I will express some of my thoughts which I have been keeping to myself of the past few months in the name of forum etiquette.

My main problem with the current material debate is that a lot of emphasis is being selectively placed on raw materials instead of the end product. I think prospective buyers need to see some testing, R&D or at least an objective review of a set of Delrins that have been installed on an FD for at least 10k miles. Please correct me if I am wrong, but it seems that the delrin bushings currently offered this forum were never even prototyped or tested prior to distribution?

The fact of the matter is that this all comes down to driver preference, but I find it curious that there seems to be an intentional downplaying of the resultant noise vibration and harshness associated with the delrin bushings. Just because a material is the stiffest, that does not automatically make it the best suited for a particular application. What some may label as "more responsive" others may consider "jumpy." The more balanced approach is to seek moderation and take advantage of the oscillation/shock absorbtion properties of a material while formulating it to be rigid enough to increase steering precision. One must also ask, "what net gain do the delrins offer that is worth sacrificing ride quality?" I would be on the delrin bandwagon if they equated to lower lap times, but I see no evidence of a real performance gain.

I have made this offer before and I will do it again. In the interest of providing accurate, unbiased information, I am willing to donate a set of SuperPro poly bushings to have them compared side-by-side with the Delrins by an unbiased party with significant driving experience. We can tout materials and label them as "exotic" all we want, but until the end user has an unbiased review providing substantive data about the end product, the rest is just hype as far as I'm concerned.

thanks,
Rob

Jodeny

iTrader: (3)

Finally...someone who makes sense.
Thanks Rob.
John

wanklin

iTrader: (2)

No, TY John. You also may want to keep this handy for your future customers: https://www.rx7club.com/showthread.p...59#post6026759

Rob