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Expectations versus reality


ksechler

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Since "finishing" my car last August I've had time to make a few observations.  In some ways the car has exceeded my expectations and in other ways it hasn't quite lived up to them.  That caused me to wonder if my expectations were realistic. My car is a 1976 280z and in 1976 I was 5 years old.  So I've never driven one in original condition.  In fact my car is the only 280z I've ever driven.  Mostly I drive my 2008 350z NISMO.  So I thought I'd list a few of my observations in hopes that folks would comment on whether or not they seemed normal for the car or something that might need fixing.  

1).  At highway speeds there is a lot of drivetrain noise.  The diffy and tranny are rebuilt and in good condition.  I think I am just hearing a harmonic from the driveshaft.  Is this typical?

2). The steering can feel a bit heavy during "aggressive" driving (hard cornering, quick transition from right to left, etc).  If I'm really on it I need both hands which makes shifting a challenge!

3). The car smells!  There are no emission controls and I elected to delete the fuel injection in favor of triple carbs.  I think I just forgot about the smell of an old car.  

4). The car is loud.  I used a ton of dynamat and heat mat.  I'm surprised it is still so loud.  

One other "unfortunate" consequence of finishing my 280z. My 350z seems slow now!  My 280z is quicker.  

 

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Those observations are pretty spot on, old Zs are loud, smelly and you can hear everything going on under the car. All of my Zs have been like that and I have had several. The only thing that would concern me is the steering, unless you have really fat sticky tires it should not be heavy at speed. Even with fat tires that does not sound right.

I had a ton of drive train noise in my last Z, ended up being both the trans and rear wheel bearings. But even after fixing those it was still loud.

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3 Tuning of triples is key to gas smell for you and for those behind you.  Most old cars stink from being too rich.  Test with a wide band sensor.  You should be able set the jets and fuel level  to go a bit lean at cruise but be in the rich sweet spot when you are accelerating. Best of both worlds

1 The differential couples to the flat panels of the rear deck and the glass window also reflects sound forward. It is a noisy design.  Using soft rubber bushings to decouple the differential helps. I noticed that my all stock 72 with 80,000miles has very little differential noise compared to others I have driven.  The low wear and the drive line alignment corrections help reduce noise (compared to 70 and 71).

2 Manual steering is manual steering.  The optional  ball and socket compression mounts help on bumpy corners.  If your compression rod bushings are too tight it also causes a poor feel. If the tension adjustment in the rack is too tight it will make steering stiff. Wide tires also make steering stiff but "rut grabby" too. I liked it when I installed a smaller steering wheel.  A loss of mechanical advantage but nicer feel.

4  A quick experiment: Throw pillows and sleeping bags in the back hatch area and see if it makes a difference.  A few layers of carpet or thick heavy rubber on the rear deck may help.  I also found that the cavity where the muffler resides can couple more noise into the cabin:  When I raised the muffler high into the cavity to hide it...wow it was loud in the cabin.  Just lowering it a little made a big difference.  Some sound proofing bituminous foil may help in this area..... just watch the heat and fire.

 

 

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Like you, my 280z is the only one I've driven so I don't have any direct comparisons to make, but I agree with a lot of that...

  • It definitely smells. I have to pass smog, and do easily, but there's still a lot of that smell -- no wonder smog was so bad a few decades ago!
  • I did a lot of soundproofing, and have cut road noise pretty significantly. It's quieter than my wife's 2005 Escape in that regard, but engine/drivetrain noise is louder than our other cars.
  • The interior is noisy as hell though. If I go over a bump or up a driveway, I think everything in the car rattles. I'm going to work on that, but I think it might just be the way things are.
  • Unlike yours, my Z is a heck of a lot slower than my DD (2007 G35S sedan). On the other hand, it is more fun!
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My biceps grew an inch in the first year after buying my 280Z. 225/50x16 Conti Extreme DW ties are a very nice tire but HEAVY steering. Autocrosss can be a challenge in a Z with wide sticky tires. You may want to consider electric Power Steering. SilverMine motors has just come out with a new kit that is a complete bolt in.

A friend of mine has 275/40 x 17's on the front of his 240Z with EPS. He can crank up the assist with a rheostat  so that  he can park it with one finger if needed.    

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no drive line noise, at least no whine if that is what you mean.

no smell (maybe I am just used to it).

heavy steering as slow speeds, yes.

interior is noisy, but no more so than I remember from back in the day when I drove one that was new.

did you replace bushings and if so did you go with rubber or PU?

 

 

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I work out with a round plate weight that I hold out in front of me at the same position (elbows bent) and turn it the same way one uses the steering wheel. While not as bad as spending time in a kart, a 3 day vintage event with 3-4 sessions a day on race slicks and my shoulders are burning.

I've seen a set-up that uses a rope and you can add/subtract the weight used. Nice but I can sit and watch TV with just a plate. You can start with an steering wheel.

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Drivetrain noise is normal for the 280Z especially when you compare it with the 350Z. What can make it worse or more noticable is PU bushings in the mustache bar, PU bushings in the transmission crossmember and/or a solid diff mount. The type of oil your using can make the diff a little quieter or noisier.

An RT diff bracket with the rubber stop touching the diff can transfer noise too.

Back in the eighties a common complaint about the 280ZX was it lost a lot of the sports car feel when they introduced all the creature comforts like power steering, electric windows etc. The car was much "softer". My 280Z is heavy, but I axcept it. My wife doen't like driving it because the steering is so heavy :)

 

 

 

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Howdy folks.  A materials person here.  Don't overlook that "PU" covers a huuuuuuugge range of physical properties, from goo to rock-hard.

These guys seem to have addressed the issue.  Don't know if they got it right or not, but they are aware.  https://whiteheadperformance.com/product/whiteline-differential-moustache-bar-bushing-kit-w91045-datsun-240z-260z-280z/  If I had the free cash I'd try a set just to see what they ended up with.

I reduced the diff warbling with my PU bushings significantly by extending the length of the inner sleeve for the mustache bar mount.  For whatever reason, many PU mustache bar bushings have a shorter inner metal sleeve than the PU bushing, which compresses the PU  against the washers, creating a solid path to the cabin for the diff noise.  I used washers to extend the sleeve.  Many of the aftermarket parts out there require a little bit of finishing work, in my opinion, to get them how you like them.

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I agree Zed. You se it a lot with PU rubbers. The mustache bar rubbers are a good example. If you look at the originals, they have a certain amount of flex before contacting the "star like" rubbers on the top and bottom. The original could isolate much better.

I might have a look at mine and try your idea on the extra spacers. One of the things I've regretted doing to mine.

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Not sure exactly when they added these to their catalog (sometime during the past year, I think), but it turns out that Whitehead Performance (Toronto) has introduced an almost-full line of own-brand poly bushings for the 240-260-280 Z's.  One of the key design features is the use of a material with a lower-than-usual durometer rating.  Here's their write-up:

"Whiteline Plus bushings provide the softness needed for street driven, low vibration, noise and harshness characteristics, while displaying extreme abrasion, tear and cut resistance, and near-zero compression set at a lower durometer reading of 70-80 (versus most poly bushings 100+ rating). In addition, Whiteline Plus polyurethane bushings are able to be bonded directly to the metal shell, which provide a method of flow control giving the bushing the characteristics of soft ride while on smooth roads, and when under cornering pressure cause the bushing to become firmer for improved suspension performance."

  • T/C Rod kit - C $43
  • Steering Coupler kit - C $73
  • Front Inner Control Arm kit - C $59
  • Rear Outer Control Arms kit - C $64
  • Rear Inner Control Arms kit - C $90
  • Moustache Bar kit - C $71

That totals out at C $ 400 (about US $300), so they're definitely premium-priced (and no 'master kit' is being offered at this time). The typical PU master kits being sold by 'others' (which also include Steering Rack and Roll Bar bushings, plus 4 bump stops) are going for as little as US $200 c/o American vendors.  Not saying that Whitehead is gouging on price.  Instead, I think their prices just reflect the cost premium that comes with a small-volume production run.

The sleeve-to-bush 'bonding' feature noted in the Whitehead write-up comes into play for the front-inner and rear-outer control arm pieces.  It looks like they've paid proper attention to the design of the poly and metal pieces, so that these control arm bushes will provide torsional resistance (rather than simply acting as a free-motion pivot).

It would be interesting to know what the durometer rating of the Nissan OE rubber bushes was in as-new condition.  Anybody?

It would also be interesting to know how the durometer rating of the OE rubber bushes drops with age.  I wonder, for example, what value it has sunk to by the time the rubber is 45 years old?

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I have 1976 280 and am the original owner and like you have only driven my car.

My car does not smell at all, you need the weather strips in the back hatch area and also good rubber seals around the tail light.

My car is not loud, I have a normal muffler on it, I have only the stock sound proofing..  The car does get hot inside because the exaust pipe runs along the trans tunnel under the driver.

I have 205 - 60 - 14 tires and they are simi hard to turn and very low speeds, at speed not a problem.

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Regarding the steering, I read an article from road and track about the new 280z when it was first introduced.  I believe they mentioned the steering was heavy compared to the earlier models.  This was caused by the additional 500lbs or so on the new 280z.  In the article, they felt it was time for power steering. 

Regarding the ride, I have an old 240 and it is stiff and loud.  I have always wondered what the impact of running low profile tires has on ride quality. I assume it would make it worse.

Edited by 87mj
typos
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On ‎2‎/‎18‎/‎2017 at 10:32 PM, Zed Head said:

Howdy folks.  A materials person here.  Don't overlook that "PU" covers a huuuuuuugge range of physical properties, from goo to rock-hard.

These guys seem to have addressed the issue.  Don't know if they got it right or not, but they are aware.  https://whiteheadperformance.com/product/whiteline-differential-moustache-bar-bushing-kit-w91045-datsun-240z-260z-280z/  If I had the free cash I'd try a set just to see what they ended up with.

I reduced the diff warbling with my PU bushings significantly by extending the length of the inner sleeve for the mustache bar mount.  For whatever reason, many PU mustache bar bushings have a shorter inner metal sleeve than the PU bushing, which compresses the PU  against the washers, creating a solid path to the cabin for the diff noise.  I used washers to extend the sleeve.  Many of the aftermarket parts out there require a little bit of finishing work, in my opinion, to get them how you like them.

I rebuilt my entire suspension with one of the Poly kits, I also lowered the car a bit with lowering springs.  The ride result is pretty harsh, but I expected it.  The one thing that however seems extremely harsh is the noise apparently coming from the mustache bar and so I would like to address this.  This noise is especially evident on short sharp bumps, small holes etc..  I have a spare mustache bar and was going to install a NOS set  of Nissan isolators.  I have since decided to try the White Head isolators with lower durometer.   Probably could have just drilled the harder bushings a bit to soften them as I did with the TC rods up front.

Edited by Jaymanbikes
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I used poly and rubber backs on the t/c rods after reading about them breaking from full poly.  Never thought of softening them with small holes.

That could be the solution for the poly steering rod coupler that is so hard and causes a twitchy steering wheel.  The OE rubber ones are NLA.

Good thinking!  Did you just drill 1/16, or close, holes around the outer part of the t/c bushings?

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4 minutes ago, siteunseen said:

I used poly and rubber backs on the t/c rods after reading about them breaking from full poly.  Never thought of softening them with small holes.

That could be the solution for the poly steering rod coupler that is so hard and causes a twitchy steering wheel.  The OE rubber ones are NLA.

Good thinking!  Did you just drill 1/16, or close, holes around the outer part of the t/c bushings?

Exactly

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3 hours ago, Jaymanbikes said:

 one thing that however seems extremely harsh is the noise apparently coming from the mustache bar and so I would like to address this.  This noise is especially evident on short sharp bumps, small holes etc..  I have a spare mustache bar and was going to install a NOS set  of Nissan isolators.  I have since decided to try the White Head isolators with lower durometer.  

The mustache bar bushings are known for transmitting gear noise from the diff in to the body and cabin.  Usually noticed on the highway when cruising along.  Or they're noted for being loose and letting the diff move when shifting, causing a thump.  Not really known for bump noises.  You might be looking at the wrong area.

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8 minutes ago, Zed Head said:

The mustache bar bushings are known for transmitting gear noise from the diff in to the body and cabin.  Usually noticed on the highway when cruising along.  Or they're noted for being loose and letting the diff move when shifting, causing a thump.  Not really known for bump noises.  You might be looking at the wrong area.

Good to know, I definitely have some of that going on as well although I rarely get the car past 60mph for any distance or on a highway.   Might be I just have something lose that is causing the noise.  Plan on checking everything out when I swap the spare bar.

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does the clunk happen on down shift or up shift? typical clunk sound as drive train is loaded and un loaded is u joints in drive shaft.  I read that the diff of a z can rise up in  the front as well if mounts are bad (down shift I think), making a clunk sound. Seems best thing to do would be get it on a lift and look for worn parts in drive line and mounts.

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1 minute ago, Dave WM said:

does the clunk happen on down shift or up shift? typical clunk sound as drive train is loaded and un loaded is u joints in drive shaft.  I read that the diff of a z can rise up in  the front as well if mounts are bad (down shift I think), making a clunk sound. Seems best thing to do would be get it on a lift and look for worn parts in drive line and mounts.

No, drive line is nice and tight, diff and trans isolators are also new.   Clunking happens on sharp sudden bumps, more prevalent when the car has less weight (fuel or another person) 

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