Minimising vibration when upgrading

[Aeroadster]

GRRRRRRRR the search doesn't seem to be working for me.

Ever since my fiasco with the near side brake caliper causing vibration, I seem to be more sensitive to the level of vibration coming through the wheel. It probably hasn't increased from normal, but I just notice it

From the last thread...
http://www.saabscene.com/saabforum/showfla...page/1#31588734

I've been able to confirm that wheel bearings are fine and bushes aren't showing visible signs of degradation.

Anyroad, looking forward to planning my next series of upgrades, I'd like to get views from other 9000 owners on best options for minimising that vibration I can feel through my wooden Anniversary steering wheel. It's always noticeable when I'm driving on the motorway. I don't notice it so much when I'm doing town driving as my hands are constantly moving across the wheel.

When I upgrade my front shocks to Konis (can I use the original bump stops - if they exist or do I have to buy new ones?) I'll be upgrading with the uprated wishbone rear bushes from Elkparts.

Is it worth replacing the two hydraulic mounts and both the upper engine torque mounts? If I change the mounts, is it worthwhile going for polys instead of the rubber ones? What are the benefits? Will this increase the vibration?

I'll definitely be changing the gearbox mount to a poly as the gearchange always feels unprecise.

Also considering changing steering rack bushes to poly for better feel, but again...will this significantly increase the vibration?

[mark e]

As a general rule, poly bushes are stiffer than rubber so you will inevitably get an increase in NVH. Add to that the fact that your rubber ones are probably a bit old and sloppy and it will be even more noticable.

I wouldn't necessarily assume that the sloppy gearchange will be cured by replacing the gearbox bush. Is it sloppy when stationary? If so then it's more likely to be a problem with the coupler or wear in the gearstick mechanism.

The steering rack bushes are a bit of a pig to do and TBH it's only really worth doing them if the steering rack is coming out anyway- it's just about as much labour. You'll get more "feel" (but also more NVH) by changing the drop link rather than the mounting bushes.

Have you tried experimenting with tyre pressure to reduce the NVH on the motorway? What tyre size/pressure are you currently running?

[Aeroadster]

The tyre pressure according to my local Tesco Express are 34PSI which of late has been checked weekly. I've tried 35PSI and the steering feels a little lighter. Also tried 33PSI and the tyres always looked flat on my drive and they were quite sluggish around town i.e. more feel through the steering wheel on slow tight turns.

Can't say I notice the difference in vibration though. Wheels and tyres are as per my avatar 205/55/16. What makes it worse perhaps is that I'm using the Dunlop SP Sport 9000 which is very quiet.

The car has done 96k now and I'm wondering whether all the engine mounts should be replaced with stock parts and put it down to wear and tear for an 8yr old vehicle. I saw the article on BILLJ's and was wondering how many years that car had seens and wheat mileage it had covered.

The sloppy gearchange is noticeable only when the car is moving. When it's just idling it feels great. I think I've been driving too many Beemer company cars in days gone by. Mind you, I'm due for a clutch replacement soon and have taken on board comments from "Saabben" about going for a SPEC clutch which he's currently using.

Is my best bet to avoid polys at the front, bearing in mind the Konis and H&Rs will be going in and just fit the upgrated the wishbone rears?

I have a spare set of drop links and track rods and ends, so maybe it's worth fitting if you feel they will make all the difference.

[cdcarlsson]

Here's my experience with upgrades/renewals and NVH.

Avoid poly drop links - they made my steering wheel vibrate over every small imperfction in the road - I went back to 'rubber' drop links.
Renewing the front anti-roll bar bushes (inner) along with the lower wishbone front bushes (the ones that not many people do) significantly lowered the Vibration / Harshness. Both these bushes were renewed with 'rubber' types.
The springs fitted to the car can make a HUGE difference, my current set are Abbott and are far smoother with less harshness than those fitted to the car when I bought it (also said to be Abbott, although I'm not sure they were).

I'm currently 80% satisfied with the vibration / harshness of the car, until I get in another car (I was given a lift in a new shape Astra the other day) and find that actually I'm being over critical of the feel, it's not that bad at all! It's more like some of the roads around here are diabolical.

In conclusion, if your gearleaver moves fore/aft on dipping the clutch then engine mounts, top and bottom probably need a good look at. Other than that consider changing all bushes over time as they all make a contribution to the feel of the car, especially through the steering wheel.

Nick.

[PHudson]

[ QUOTE ]
my current set are Abbott and are far smoother with less harshness than those fitted to the car when I bought it (also said to be Abbott, although I'm not sure they were).


[/ QUOTE ]

If they were green, they were probably Abbott. I can do someone a good deal on (IMO) over-harsh Abbott springs

P. (Planning to take a punt on the Kilen springs, since they're less than half the price of Abbott, Eibach etc)

[boosted ls1]

I had a lot of vibration caused by the rear wishbone bushes being shot. I fitted poly items and the car's a lot better but some play is still being transmitted via the steering wheel. Would I be better with rubber for the front wishbone bushes instead of poly?

Boosted.

[Aeroadster]

Boosted, I've been talking with my Saab indie and after much closer inspection of all bushes he agrees that I should do the following:

1) Replace all front suspension related bushes (including ARB bushes) with rubbers instead of polys. As previously mentioned, the Elkparts uprated rear wishbone butterflies will go in as a compromise between the standard kit and polys.
2) Replace both hydraulic engine mounts
3) Replace both engine upper torque arm bushes with standard rubber
4) Replace gearbox bush with Powerflex yellow poly version
5) Replace steering rack bushes with Superflex poly kit

May as well get the rear ARB bushes replaced with polys too since my rubber ones are shot to pieces. Looks like I'll be going for the cheaper Superflex kit as it's oodles cheaper than the Powerflex ones.

It's goes without saying that I'll probably seek to replace all the rear suspension bushes too.

The work done to the front should alleviate any vibration related problems as just about every rubber bush is hard, cracking or even worse - depleted

Overall, I'm expecting the combination of new rubbers, stiffer rear wishbone rubbers and rear poly ARB to improve the handling too.

Hmm...now when does the next pay cheque arrive? That lot will cost me nearly £300 in parts alone and I'm hoping that my sloppy gear changes improve, otherwise it might mean a new clutch too.

[PHudson]

[ QUOTE ]
I had a lot of vibration caused by the rear wishbone bushes being shot. I fitted poly items and the car's a lot better but some play is still being transmitted via the steering wheel. Would I be better with rubber for the front wishbone bushes instead of poly?


[/ QUOTE ]

Yes, in my experience. I changed back to rubber because of the vibration. If I did it again I'd use the Elkparts uprated rubber bushes (they didn't do them when I changed mine)