antlee928

Hi,
Ok. At the risk of generating an oil or offset style of discussion, I finally checked the ride height of my S4 MY89 today and would like some assistance/input as follows.

Ride height results being:

Front Left = 145mm
Front Right = 145mm
Rear left = 170mm
Rear Right = 170mm

So the rears are a smidge out of spec (190mm-20mm) however the fronts are quite below factory spec (173mm+10mm).

I am running the 7 slot standard alloy wheels (16"). At the front with the car on level ground (my garage floor) I can almost get 3 fingers between the top of the tyre and the fender (about 2.5 actually). As a visual, the front looks to be sitting a little high if one takes a visual cue from the tyre versus fender.

I am running 15000km old Toyo Proxes T1Rs with 36PSI in front and 44PSI in rear (per factory recommendations).

I have (as far as I know) standard springs and Koni red dampers (installed about 5-6 years ago. The car has the following driving tendencies:

1. Some harshness over bumps and ruts (a little crashy);
2. Some mild understeer on turn in to corners at speed;
3. Mild tendency to creep to left at highway speed on major roads (although this could just be road camber or maybe a requirement to adjust toe - tyres are wearing quite nicely though).

So should I adjust front ride height to factory recommendations 190mm -20mm? Is there another preferred/recommended setting based on my wheels size, tyre selection, tyre pressures, etc.

I am wondering if due to the much lower ride height (over factory) if the sping rates and damper rates are being compromised and working outside their specifications??

Any assistance, feedback and informed commentary would be appreciated.

Cheers
Tony
S4 MY89 Guards Red

ammonman

I think you have your specs the wrong way round. Per the WSM page 44-05 dated 1993, the front axle height specification is 180mm +/- 20mm while the rear axle is 173 mm +/- 10 mm. There is an additional note at the bottom of the page stating that an additional 10mm of downward tolerance is acceptable "...after cars have been driven for a period.." but must be applied to both axles. Therefore the front has a range of max 200mm and min 150mm (180+20 and 180-20-10) while the rear range is from max 183mm to min 153mm (173+10 and 173-10-10). Since the additional 10mm of downward tolerance must apply to both axles, if you set the height below 160mm at the front you must set the rear height below 163mm. If you raise your front by 5mm per side and lower the rear 17mm you will be at minimum ride height specification. For the front I have my 1990 S4 set to keep the track rods (tie rods) parallel to the ground when the suspension is settled and the rear set within factory spec relative the height of the front. On my car this equates to 155mm front and 160mm rear. I have Bilstein shocks and Eibach progressive springs all around.

Mike

GlenL

It is very common for people to set these cars to a lower ride height than stock. Someone did this to your car. If you've got Koni's in there you might have aftermarket springs, too.

To your concerns:
1) Koni's are adjustable on rebound. That is, the same when wheel is going up and can be stiffer when extending. If they're set really stiff it'll add to harshness. Your tires play a big role in this.

You can try setting the shocks softer. Some Koni's are adjustable in the car using a **** on the top. You'd be fortunate to have this. Otherwise they come off. Some people use a long Allan wrench to do it on the car. Investigate your options on this.

Tire type and inflation is an easier approach. The given specs are really high. I'd try 32psi all around as see how it feels. You'll lose some handling stiffness but the ride will be less harsh.

2) This is in the alignment. The ride height is a bit lower than I'd do. 150 to 155mm for good looks works for me and on buddies cars. Make sure the shop doesn't lift it before they set the front alignment. This is odd and the techs will argue. Find a Hunter-brand machine or similar where it's not lifted off the wheels at all during the procedure. When they set it up they'll measure what you've got. That'll be telling. When the car settles after being lifted the toe in goes toe out.

3) Subtle alignment issues do this. Also imbalance in tire inflation.

I wouldn't raise the car unless it's too low and hits pavement and curbs. It's tough to get right and the adjusters often stick. Especially the fronts. The adjuster will turn and not go up as the sleeve is turning with the nut and sliding around the shock. Rears usually work fine once oyu get them turning.

Cheers!

Bill Ball

This does not add up. 2.5-3 fingers between the tire and fender would be at least 165mm ride height unless you have tires with rubber band sidewall heigh or someone cut an inch off the fender lip.

The actual ride height measuring surface in the front is essentially inaccessible on the ground. It's between the walls of the lower control arm rear bracket. I measure on the backside of that bracket, lowest spot, and add 10mm.

antlee928

Hi Mike, Yep got the specs around the wrong way. Damn finger problems ;-)

I will re-check the front to make sure I have measured from the correct point on the front.

Cheers
Tony

antlee928

Hi Bill, Obviously the finger measurement is just a quick and simple (certainly not accurate) way to check ride height however it does rely on the car being straight and aligned correctly. Ultimately the only way to teel for sure is to climb under the car and measure from each point.

Thanks for your help and advice and particularly on the measurements for older cars versus new specs.

Cheers
Tony

Rob Edwards

'Cause it never gets old:

Front ride height measuring point:




Rear point:





cheap way of making measuring sticks out of coathanger (Factory spec heights are asterisked - Front 180, rear 173. Preferred heights are all over the map, theres' a recent poll thread if you're looking for consensus.

https://rennlist.com/forums/928-foru...ight-poll.html

Bill Ball

Rob nicely shows the surface for the front ride height. I mentioned that is just about inaccessible on the ground, especially if you use a ruler like I do. That surface is 10mm higher than the lower lip of the bracket. So, for example, this is what 149mm ride height looks like.

Fogey1

IMO, it's easy to do.

Get one of these, a T-bevel:
http://www.ebay.com/itm/Stanley-8-T-...-/390321058435
and you can set it snug and with the apex of the triangle a little higher than the measuring point, reach under the car and slide it along the floor under and past the measuring point, which will push the apex down, then remove it and measure the height of the apex. Since you were holding the base flat against the ground, you can get a very accurate measurement. Works a treat.

I like it better than the coat hanger method because the technique of measuring pretty much eliminates the possibility/worry that you're not holding a little stick exactly perpendicular to the ground, directly under the measuring point. And it's easier to read the measurement on your ruler when it's not way under the car.

Thanks for the great pix, Rob.

Bill Ball

Will, I actually have one of those but never thought to use it for that. Good idea. However, I don't see the point of going to the trouble of trying to measure a spot you can't see when the lip is just as consistent as the as the measuring point. Slap a small ruler against it, add 10mm and you are done. I use the same ruler for the rear (shows 163mm).

GlenL

I'm a cut stick man (150,155, etc..) and can feel for the measurement spot. Gotta do it laying under the car. Find the shortest stick that fits, lift it up to touch and estimate the gap at the bottom. A bit imprecise but will be close enough.

Bill, Good point on that the OP is likely measuring wrong.

I'll reiterate: Leave it alone and get an alignment where they don't lift the car. Soften tire pressure to smooth rough riding.

Hilton

I just use a telescopic mirror - extend it until it's slightly too large for the gap, then while holding the upper end against the measuring point, wiggle it around in a few directions until the floor has pushed it in to the current length. Just make sure it'll wiggle on all four compass points so that you're confident its measuring the shortest distance to the floor.

Tony - if your height is off that much, you'll need to adjust it to spec (I use 170/173 front rear), and then get a new alignment (by an experience 928-aligning shop.. or at least somewhere who will actually listen to you when you tell them not to lift the car before aligning).

Also note that you'll get slight variation on each side depending on how much petrol is in the tank - I get alignments done with just over half a tank. Don't try and level the suspension heights left-to-right as you'll upset the corner balance of the car - if you count the threads exposed on each adjuster and keep them the same side-to-side it'll be reasonably close, or just find an alignment shop who can measure weight at each corner too. (or search landshark for John C's cunning scale-free home corner balancing technique - works very nicely).

ammonman

I also use a telescoping mirror to take the measurements. IIRC, the WSM height and alignment specs are supposed to be checked with a full load i.e. full tank of fuel, all tools, spare, compressor, etc. +1 on keeping the number of threads on the adjuster close to maintain corner balance. IIRC the WSM calls for no more than two full turns difference between adjusters on the same axle (this should be the 10 mm side to side limit in the spec chart.)

Mike

dr bob

If the car is anywhere close to correct height in front, its easy to see the measuring pads. I use the wire gauges as Rob does, pretty much a go/no go exercise with wire lengths bracketing target numbers by a few mm's. No guesswork, no parallax issues from the scale to the bracket.

I sometimes think we come up with seemingly elegant methods when simple might be better. I do have a set of telescoping inside micrometers I could use... no digital display so I'm not sure I could actually read them though. Its OK, I still have the wire gauges as a fallback. :-)

andy-gts

so can a person say one full turn of adjusters is 5 mmof ride height change?