Urethane bushings

[drunkenmaster]

I have heard from one source recently that the firmness of these can causes structural failure of other related systems and welds.

Any opinion on this?

[biker]

With the stiffer type of bushing, it may contribute.

Look around the race track and you do see a lot of Zeds with stress cracks around the roof line particularly near the hatch.

biker

[260DET]

On the 260Z anyway, the stock anti-sway bay mounts are inadequate and should be beefed up, even when using stock rubber bushes. Using urethane suspension pivot bushes is questionable given the compliance designed into the stock bushes, at the very least they could inhibit normal suspension travel which possibly could lead to component cracks.

On rear pillar cracks, they are the direct result of body flex, nothing to do with urethane bushes.

[drunkenmaster]

So we are getting negative feedback for urethane bushes?

Anyone for them?

[260DET]

For anti sway bars and tension rods they are excellent, providing as I said the former mounts are beefed up. Try the following test on the stock rear bar mounts.

Jack the rear up so that you can remove one wheel. Then remove the bar end suspension arm connecting link from the same side as the removed wheel. Lower the car so that the other wheel is sitting firmly on the ground. Place a piece of pipe over the end of the exposed bar to gain some leverage and push it up/down, at the same time observing the bar mount on the body. You can actually see the mount moving around under load.

[2ManyZs]

I've seen numerous Z's that were raced and many of them never had any problems with the mounts or any structural problems due to using urethane bushings. I think a lot of it may have to do with the condition of the chassis in question as it sits before the modifications are done.

FWIW, I raced a 75 280Z for 5 years with urethane bushings with no problems... and the car was a street car for many years after the first owner rolled it on its side and a friend of mine replaced the bent suspension pieces and straightened the roof. Nothing was ever done to the sway bar mounts, and it is now on the track again after sitting in my backyard unused and neglected for 8 years...

[SledZ]

Ok I am new to the Z and it's suspension. My car is completely stripped of it's suspension and I have all new urethane bushings waiting to go into it. Should I stop and re-order rubber? Am I in for that much of a rough ride compared to rubber?

I have read about all the posts in about all the forums on the web and the majority of the Z's all put in Urethane and I assumed it was the way to go...:paranoid:

Also my Z is in great shape, bit's of surface rust and 51k miles

[2ManyZs]

I'd go for the urethane.... last longer than rubber and you'll get better handling without sacrificing too much ride comfort. The biggest thing that will affect the ride will be your spring/shock choice anyways....If you were planning on adjustable coil overs with 200+ pound springs etc. then I'd say you were heading for ride problems...Stock or close to stock springs with the urethane bushings should be fine for the street. Also, you have to remember that tire size and profile contribute greatly to your handling and ride comfort as well, the lower profile you go, the harder it will ride yet will more than likely handle better.. It's all in how you choose the rest of the components that will give you your best results.

Just remember to lube the bushings with a good grease to prevent squeaks and you shouldn't have any problems.

[SledZ]

Thats reassuring. I am keeping it stock. I bought the KYB struts because they were close to stock and am only going to ride it on the street. Not sure about the wheels yet. I have both stock rims and another set that came off a 280 "I think". I'd really prefer the slotted dish cause thats how I remember them!

Thanks!

[260DET]

Re stock rear sway bar mounts, sure they won't usually break using urethane bushes. But since strengthening them on my 260, rear end breakaway on the track has become much more predictable and progressive, plus, a lighter rear bar can be used.

But if people are happy with the stock setup then thats OK by me.

[drunkenmaster]

I went to a reputable suspension place and spoke to a guy who uses a 240Z in targa tasmania and he was of the opinion rubber all round for the rear with some urethane up front.

Decisions decisions...

[260DET]

It would be interesting to know the reasoning behind the rear rubber sway bar mounts idea. From everything that I have read and from a little practical experience, all sway bars should be as rigidly mounted as possible from a performance perspective.

[drunkenmaster]

He runs a 240Z and thus no rear sway bar.

He was referring to the 8 control arm bushes and the 2 diff mount bushes.

[zed240au]

Must say im complexed by this discussion everything you read says the more rigid controlable your suspension the better the handling I would guess nissan only used rubber when zeds were built because it was cheaper than urathane its only in the last 10 years that urathane bushings have become cheapa nd easy to get that they are being used more by manufaturers Im sure that nissan woul build zeds with it today the ride quality is better the handling is better they last longer not easily ruined by oils so all round much better

I would say most flexing in bodies is through the bodies not being strengthed to take horsepower upgrades When i rebuilt my car I fully seam welded every seam in the car not flex in my zed

(of course im told ill never repair it if it has a a major accident but thats a risk i have taken)

Mick

[sjcurtis]

I use urethane on my 240Z 6/7 73, on all positions on both sway bars. On both steering rack mounts and the steering shaft joint and both radius rod adjuster ends for the street. I also run all four srtut urethane bump stops. Highly recommended, go get them you wont regret it

my 2c

Steve:classic:

[drunkenmaster]

rear control arms are the real 8 bushes in question i suppose?

[sjcurtis]

With those pivot positions, I went with "Factory New". When I installed my fresh R200, the shop techs told me that factory rubber units for those positions was best then they showed me why with demos of condition and movement from race/road/and rally use. Reason + the existing system works and is not subject to early failure, after viewing my original items I considered that opinion as on my rubber units only light distortion was present with zero movement from original production.I installed as stated circa 1991 never had to revisit these pivots.

So for the rear go rubber.

Cheers

Steve :classic

[drunkenmaster]

Thats similar to what I was being told earlier.

Thanks for the confirmation.

[=Resurected280=]

This is a piece of information that I picked up from the JTR conversion manual so im not sure if it applies here but they said that removing the rear sway bar is good because it will keep a high horsepower z car from spinning its inside rear tire during hard cornering. But this is for a V-8 Z mind you :-)

[Bambikiller240]

intersting bit of info, but I'm not sure it has anything to do with the subject of this thread.

[thehelix112]

sjcurtis,

I'd be keen to see these demonstrations you were shown? Or atleast a description thereof?

I will be going full urethane in the rear, but my car is more track orientated. For a street car I can't see it making half a lick of difference either way.

Dave

[sjcurtis]

thehelix112,

Dave the demonstrations I was shown was interestingly enough a comparison of one season running Sydney Oran park in modified production and sport categories for track only cars and a visuals of factory rubber assemblies pulled from other cars of various histories cars that had been wrecked out and my own car in tear down. On this particular car up on the hoist with the struts disconnected from the swing arms the rate of effort to move the swing arms was vastly different. after full tear down visual galling and distortion on one side was evident do not know why and all the cups where nice and shiny. Even the old stuff in my own car seemed better so I went with factory rubber again. Still only use my car for street though no problems, with race application you may have different loading on your car to the car I saw, that will maybe give you a more even effect.

hope this will help

Steve