17 replies to this topic

[Sol]

Hi, It's taking me a while to set up my suspension. I have an NA and many years ago I modified it to fit 195x45x17 Goodyear Eagle tyres on front and I fitted the Elise front suspension lowering brackets. All was fine, indeed very good on the standard Bilstiens. The slightly wider tyre and lowered front seemed to negate some of the under steer that the car had from standard. However, like me the car is getting old and the Bilstiens have given up! Both the rear and one of the fronts started leaking. So I decided to buy replacement gaz gold pro coilovers. I went for 425 front 475 rear spring rates. Fitted them over the weekend. I decided to start with the shock setting as soft because our roads are so crap and the continual crashing over the potholes is annoying. I started with settings 7 clicks from soft rear and 5 clicks from soft front. It was like trying to drive a bouncy castle! And bump steering. So I started to harden the ride. I'm now at 16 clicks from soft front & 14 clicks from soft rear. Still a crappy ride! Still a bouncy castle even down the motorway, so much movement. Only a few clicks to go until at fully hard setting. Now I'm beginning to wonder if there is more to setting these shock up than trial and error. I no that lowering the suspension induces negative camber my tyre wear bears witness, but cornering seems Ok. I'd just the bloody bouncing vibration that's worrying me. Does anyone have any ideas what to do or do I just continue to harden the shock setting?

[siztenboots]

lowering increases toe-out on the front, this would cause more uneven wear than -ve camber.

[JimmyJamJerusalem]

Always adjust coilovers from full hard rather than full soft. You can damage some shocks by winding them fully soft. Speak to Cliffie about settings as he's the Gaz man in these parts and can advise.

[SteveA]

You can damage some shocks by winding them fully soft.

Conversly I heard that you can damage them on full hard, the reasoning being that there is no give in the fluid so any wear is transferred to the body and/or pistons.

[JimmyJamJerusalem]

I'm not saying 'drive' at full hard, just use that as the basis for your adjustment.

[Sol]

Calling Cliffie, any advice please.

[Sol]

Anyone have any comments on my chosen spring rates? Getting close to having shock set hard and ride is virtually undriveable! At slow speed I can feel every stone in the road but still also bumpy. not much better as I go faster. Any suggestions appreciated. Thanks Sol.

[SteveA]

After reading you post properly I see that you want it firmer. Are they brand new shocks? I'm not sure how much harder you can go before you start under damping the shock. It might be a case of re-valving the shock or getting some more focused ones. I only really have experience of Nitrons and Sachs but IMO valving is key.

Edited by SteveA, 14 March 2012 - 09:42 AM.

[chris_uk]

How low have you set the car, i think ideal is between 110/120 (f/r) and 120/130 (f/r) (you want to keep your wishbones as flat as possible) Take them to standard ride height then try setting up the car, id probably say take it for a geo aswell. The spring rates should be fine aswell, possibly would of gone 50lbs softer all round for a softer ride but you probably wouldnt really notice on the road.

[mbes2]

Hi, Im running Gaz Nics, with the current setting of f425(Re040), r475(Re070), setting - 9 soft front, 18 rear... These work fine for me for road use... next time on track im changing to 11,20

[Sol]

Update, still trying by trial and error to get a decent ride. I believe that the springs behave uniformaly, that is to say if you put a certain load on them it will deflect a certain amount, if you double the load it will double the compression? Anyone know if that is correct. Anyway, car was virtually undriveable this morning, so after work I jacked the car removed the wheels (again!) placed supports under the discs and wound down the nuts to compress the springs. My thought was that the springs could be compressed until they began to support the cars weight. Then set the dampers to 7 clicks from soft front, 8 clicks from soft rear. Put the wheels on lowered it and looked at the ride heights IT WAS LIKE A 4x4!!. It looked stupid. However I drove it round the block and it was a much better ride? Returned it to the garage and reduced the spring compression to give me 126mm ground clearance front (chassis just behind wheel), 136mm ground clearance rear (chassis just forward of the wheel). Drove around the block and it seems promising? Not as low as I wanted especially considering I have the Elise front lowered shock mountings and smaller diameter front tyres. Not driven it further than 1/2 mile so far so not a lot to go on. - See what it drives like to work tomorrow. Beginning to feel a bit dissapointed in what these coilovers can deliver, although I'm sure someone with some expertise can get a reasonable performance from them. Bloody knackered now, probably jacked the car up & down, removed and refitted the wheels, adjusted the ride height and the damper settings at least 8 times. If anyone has a good set-up procedure - what to adjust first and to what dimensions then what settings to set the dampers to I'd love to see it published. Thanks for all the interest and replies. Sol.

[mbes2]

After I fitted my Gaz, I took my car to Plans to have the rideheight set and a geo... maybe its worth doing that to resolve quicker.. ?

[Sol]

OK, I still haven't set my suspension up properly yet but I've found a good guide that would have been very usefull from the outset. Maybe it'll be helpfully to others in my position: GAZ Shocks This article is intended as an introduction to the GAZ Shocks damper installation and basic setup tips. Gaz produce a number of variants for the VX220. Most are designed as a direct replacement for the early Bilstein dampers.   GAZ Gold Professional (GGP) GAZ Gold Professional dampers were introduced late in 2008. A development of the GAZ Gold the damper body is manufactured from aerospace grade aluminium and mounts via spherical bearings. This damper is more focussed towards track performance, the unit being lighter offering more precision using spherical bearings.   Installation The most significant difference with the GAZ damper is the twintube design. Bilstein Elise dampers are monotube.  Monotube dampers are fitted upside down where the body of the damper appears above the piston rod. Twintube dampers are fitted with the damper body nearest to the ground to ensure valving between the two tubes remains submerged in oil.   Setting Ride Height Ride height can be a little tricky to begin with but if you follow these guidelines then the job will be a lot more successful. The VX220 wishbones are mounted with rubber bushes that behave like springs acting on the wishbone when the pinch bolts are tightened. This means you need to tighten the wishbone pinch bolts at the desired ride height or the wishbones will be acting against the road spring or worse, the corners will be unbalanced.  The GAZ Gold dampers are mounted with rubber bushes similarly, the damper mounts should be fully tightened at the desired ride height. GGP dampers use a spherical bearing which is free moving. Dampers should be full soft when setting the ride height. Wind the adjuster right off (full anti-clockwise) and clockwise to the first confident "click".  Ride height is your preference and there is an open rage available to you. When setting the ride height try to obtain 5-10mm of rake, the rear being 5-10mm higher then the front. Lotus recommends the ride height is set mid-laden approximating to driver and passenger and a half tank of fuel. Assume a driver or passenger is 75-80kg.  Ride heights are obtained below front end of chassis siderail and below rear end of chassis siderail.   Note on nuts and bolts Where is it advantageous to replace old rusty bolts with new ones it is not always as simple as it seems. Lotus use zinc plated steel 8.8 M10 bolts with 17mm head for damper installation but have specific shank and overall lengths with may be difficult to source. If the original bolts are to be reused replace the nyloc nuts with new, identical nuts.   How to Set Damping Adjustment Not a black art but does require some trial and error, patience and experience.  Setting the dampers for the road is totally different to setting them for the track. Unfortunately, others peoples settings aren't going to work best for you but they can help as a guide.     Road Always start from full soft, wind the adjuster right off (full anti-clockwise) and clockwise to the first confident "click".  This is zero. Zero is very soft and you'll be able to bounce the car very easily. Start at 3 clicks front and rear and go for a short drive. Ideally on a private road, try some steady braking and weaving manoeuvres. There should be some initial body pitch and roll but you should then get the sensation that any further pitch and roll of the car is being controlled by the damper. Increase one click at a time both front and rear until the pitch and roll is firm and controlled but not abrupt. Once you've obtained a comfortable base road setting you will have to drive on a few typical roads, rough city roads, B-roads and faster undulating A-roads. City roads won't tell you much about well your setup is working but if the ride is too uncomfortable then you'll want to wind a click off. B-roads are typically quite undulating and rough. Again, if you're too stiff it will feel harsh and very uncomfortable. The faster, undulating A-roads will tell you if you're too soft. You'll notice a lot of pitch on initial braking and roll at turn in. Over undulating surfaces you may feel the car doesn’t "sit-down" well in which case you need to wind a click or two back on. If the car is not pitching and rolling a much but feels very nervous through corners with an undulating surface then it's possibly too stiff so try taking a click or two off. As a rule of thumb, go stiff then wind off. On the road tyres can influence the ride significantly. A tyre is essentially an undampered spring and is considered part of the suspension system.  Increasing pressure in the tyre can make ride feel firmer and if the pressure is reduced, more supple and less harsh.   Track Setting damping for the track is much easier and less time consuming but again, trial and error. Experience from your track settings may also help you tweak your road setup.  Use your road setup as a starting point wind on a couple of clicks to begin with and get your tyres and car up to temperature then progressively increase stiffness. To begin with add clicks to both front and rear. When the car starts to feel skittish (sometimes known as tyre hop, side hop or walking) through bumpy corners then you've passed the ideal so wind a click off. If you start to develop understeer then the front is probably a little stiff so take a click off the front. If the rear is very light or you're struggling to get the power down on corner exit then the rear is probably too stiff so wind that off a click.   Adjusting the Geo It is probable that your previous dampers weren't at the ride height you wanted or after years of use the old dampers had lost ride height consistency. If your ride heights have changed you will need to adjust the geometry. Specialist garages are best at doing this. If you do choose to do it yourself a useful tip is to set the desired ride height without "people ballast", set your geo then load the ballast and reset to the desired ride height. This means you don’t have to have people sat in the car while you attempt to set geo and then ride height (which can take some time).     

[TheStotts]

After I fitted my Gaz, I took my car to Plans to have the rideheight set and a geo... maybe its worth doing that to resolve quicker.. ?

My Gaz golds felt awful until Guglielmi adjusted the geo to compensate for the lower ride height. IIRC the front toe needed changing. Ended up 5 clicks front, 7 rear which feels good on road and track

[TheStotts]

Anyone have any comments on my chosen spring rates?
Getting close to having shock set hard and ride is virtually undriveable! At slow speed I can feel every stone in the road but still also bumpy. not much better as I go faster.
Any suggestions appreciated.
Thanks
Sol.

Think I'm running the same rates as you. When my car first went in Steve said the shocks were adjusted so hard that the tyre was effectively the only damping. Odd double bounce feel - perhaps that's what you are experiencing?

Geo adjustment made the world of difference

[snotvomit]

Installation
The most significant difference with the GAZ damper is the twintube design. Bilstein Elise dampers are monotube. Monotube dampers are fitted upside down where the body of the damper appears above the piston rod. Twintube dampers are fitted with the damper body nearest to the ground to ensure valving between the two tubes remains submerged in oil.

That's odd. My Gaz Golds were fitted at with the main body of the shock at the top. There's a fitting guide on here somewhere. It doesn't look like they would fit any other way.

I'm reading the above as suggesting that Gaz Golds should be fitted "thin end upwards" but that can't be right... can it?

[Sol]

My understanding is that they are fitted with the piston to the top, whereas the original Bilsteins are installed with the piston to the bottom. As stated in the guide the Gaz pro's have a valve between the two tubes that needs to be surrounded by the oil. Agreed it doesn't seem natural to install them this way as all the road dirt will collect around the piston shaft where it enters the cylinder. I have fitted mine the wrong way and I believe that is why I'm having so much trouble getting a good set up. Apart from the valve between the two tubes all the internal portage on the piston will be upside down and affecting the flow of oil. I think my car believes its in Australia at the GP. I'm going to invert my shocks tonight and re-set the bump & bounce. Aiming for ride height 120 front 130 rear. Will post results. Sol.

[Pidgeon]

A couple of thoughts after reading of your woes. A 'too bouncy' ride can be caused by excessive damping/spring rating as the damper is not moving enough or at all and what you are feeling is the undamped chassis flexing or movement of the tyre sidewall. This may be confirmed by what you experienced when you raised the ride height. The difference suggests you were running on the bump stops (so the experience would be the same as I describe above - the damper is not working). With coilovers, it is often the case the springs are loose on full droop, so adjust the spring platforms to achieve the desired ride height under load, nothing else. 425/475 is a little harder than the usual starting point (375/475?) but not excessive. I may have some 2 1/4 ID springs for sale in 275, 325 and 375 if you want to swap.