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VW suspension primer/FAQ with MkIV focus

A MkIV "coil-over" strut assembly:


Phatvw's master DIY/FAQ list:

What is this FAQ all about?
I wrote this FAQ to help save people money and get the most fun and utility out of thier VW's. Use it to decide how to restore an old suspension or to upgrade to something even better.

The Internet is full of useless opinions - especially mine
# Do a little hands-on research and seek test drives in modified cars. That's the only way to really find what you like. You may need to try several times to get it right. Formula-1 teams go through hundreds of design iterations when preparing a car for a season and still go through dozens of tweaks just to setup for a particular race track.
# Bottom line is you have to make a decision. Don't get caught up researching for too long. Save up the cash, pick something, and have fun!
# The focus of this article is on PERFORMANCE. Not lowering, aesthetics nor comfort.
General info:
# shocks=struts=dampers A strut is basically the same as a shock except it has an integrated spring perch and is used only is specific suspensions like the MacPherson design. Damper is the more generic term.
# Under-steer is the tendency of the car to go straighter when you want it to turn - i.e. plowing straight off the road. Over-steer is the tendency of the car to turn when you want to go straighter i.e. spinning out. Neutral is a delicate balance right in between.
# ANY car can be made to under-steer OR over-steer depending on the conditions and driver-inputs.
# In a front-heavy, front-wheel drive car such as most watercooled VW's, there are two kinds of under-steer. The first is chassis/suspension-induced under-steer. By design, the front wheels lose grip before the rears when we go into a tight turn. The second is power-induced - when you add throttle (gas pedal) at the limit of grip, the front wheels start slipping and you get under-steer.
# This is the opposite of many rear-wheel drive cars where adding throttle promotes over-steer.
# Not all RWD cars over-steer. Under steady-state conditions many RWD cars under-steer and will only over-steer when you add more throttle to break the rear tires loose. For untrained drivers, under-steer is far safer than over-steer and is thus the majority design-choice of automakers.

What to upgrade first?
# Tires and driving technique affect ultimate grip more than anything else. Upgrade those first if you're serious about good handling, otherwise you're wasting your time.
# Do you think you're a good driver? Why not prove it by taking a high-performance driving skills class on a closed-circuit. You are probably a crappy driver and you don't even know it. The amount of money you spend on upgrades has nothing to do with your driving skill. Ask in your regional forum for more info.
# High-school drivers-ed courses are a joke - they do not teach you how to drive at all. They only teach you the rules of the road and the very basics of operating a motor vehicle.
# Even if you take all the courses in the world, driving in traffic is unpredictable. Be safe and enjoy your car responsibly.

The prioritized suspension performance upgrade list (biggest bang-for-buck):
# optimized tire pressures (usually 3-5PSI higher than OEM rating)
# fix worn or broken parts such as tie-rods, ball-joints, bearings, bushings, mounts, bumpstops, etc
# performance alignment (usually max negative camber, 1/8th toe out on front axle)
# driver skills
# performance tires
# dampers
# sway bars
# springs
# camber plates
# re-located suspension points via optimized spindles/steering knuckles (such as Audi TT or H2Sport for MkIV cars)
# upgraded bushings/bearings
# strut bars/roll cages/chassis & frame stiffeners
# aerodynamics, limited slip differentials and 4WD conversions can have a huge impact on handling & grip, but they are not strictly suspension modifications and are beyond the scope of this article.

Is lower really better? Roll-center vs Center-of-Gravity
# Lower is not always better. Formula-1 cars are low, but they also have a design budget of several million dollars and never encounter potholes.
# Center of gravity (CG) is not the only consideration - it is just one small part of the picture. Other parts include roll-centers (RC), camber curves, and suspension travel. CG is the easiest concept for manufacturers to convey in advertising so they always imply that lower CG = better handling. While this is an easy sell to the un-enlightened masses, it simply isn't true for all cars For some car designs this may be true, but not for the specific McPherson Strut design on most VW cars. Get technical
# Lower does look cool to a lot of younger folks, but when you get older, higher looks better since you're less concerned about impressing your friends with your suspension and more interested in actually using your car and getting your money's worth from it. A low car just isn't practical.

What if I still want to lower but maintain or improve handling?
# A lot of folks ask this. The bottom line is that if you want to do it right, its going to be expensive. Don't expect to out-handle a Subaru STI by slapping on a set of $100 ebay lowering springs. Figure out your priorities. Do you really want handling, or do you just want to feel cool? Or maybe you just want to spend money? Figure that out first and you'll get a lot more help on the forums. To really impress your friends, there are some creative alternatives to lowering springs.
# You can modify the fenders and side skirts to look lower while maintaining your suspension height.
# You can correct some of the geometry, camber curve, and bump-steer issues of a lower suspension by swapping out the oem spindles (aka knuckles or hub-carriers) for Audi-TT or H2Sport.com units in the case of MkIV cars. Hint: check the main FAQ.
# You can cut and weld your car and totally modify the suspension pickup-points.

What do road-holding and handling actually mean?
# Handling feel and road-holding are two entirely different concepts: handling is subjective while road-holding is objective. Both contribute to better lap times at the race circuit, but road-holding is more important. If you are familiar with popular car magazines, road-holding roughly translates to the skid-pad and slalom test scores while handling-feel translates to the test driver's comments about the car.
# Any spring kit will change handling-feel and make you think your car is faster, but when you record your lap times, you may actually be slower. You won't know for sure until you test it out. Don't assume that a modified suspension is better than the OEM suspension. Those Volkswagen engineers know what they're doing believe it or not!

Comfort, suspension travel, and bump-stops
# You need suspension travel for maximum grip on rough/bumpy surfaces. Look how much suspension travel rally cars have! When you go lower, you may lose grip and speed on the street.
# You need suspension travel for good comfort. There is no way around this.
# Bump-stops (rubber things at the end of the damper shaft) act as secondary springs which prevent damage to the damper and increase spring rate.
# Many lowering kits "ride" on firm bump-stops meaning there is no free suspension travel. This makes the car feel stiff and sporty, but road-holding is worse on bumpy surfaces and comfort is greatly reduced.
# Some lowering spring kits require that you cut a section of the OEM bump-stop out, so that you do not "ride" on them. For each inch of lowering, remove an inch from the bump-stop. For best results, remove a section from the middle of the bump-stop rather than the top or bottom. This helps preserve the non-linear ramp-up of the bump-stop stiffness for comfort. Use crazy glue to stick the two end-pieces back together.
# Dampers affect ride comfort a lot more than springs. You can have springs that are double or triple oem stiffness, but with proper suspension travel and specially tuned dampers, you can be comfortable and controlled.

Can I keep my OEM dampers?/I think my dampers are wearing out
# Stiffer springs generally do not work well with OEM dampers, especially when the springs are lower. Ever see Honda kids bumping up and down on the highway? That's because they chose not to install proper dampers for their springs. Not only is it wearing out all the parts of their suspension, it is a road hazard waiting to happen because when you're bouncing around you're not in control.
# If you can't afford dampers, wait. You'll end up paying more later if you use OEM dampers with stiffer or lower springs. The OEM dampers will wear out and then you'll be sorry about your crappy ride.
# OEM dampers on OEM springs last a long time for non-enthusiasts. However, many enthusiasts notice that the performance decreases over time and some folks believe their dampers are completely "shot" after 20-40k miles. Testing on this is inconclusive, but dampers, and especially the oil inside them, wear out eventually. If your car is a few years old, chances are the dampers are not "shot" but then they probably don't perform like day-1 either. The best bet is to replace them with a quality aftermarket brand. You'll pay more than the oem replacements, but unless you're planning to sell the car real soon, its worth it in the long-run.

Can I swap my current OEM suspension for another OEM suspension from another VW car?
# Many folks believe swapping out their OEM suspension for a 337/GLI or similar lowered OEM suspension will improve handling. It really doesn't do much except change the look. You still have the low-quality dampers which will wear out. From a return-on-investment perspective, it just doesn't make sense to pay money to install another OEM suspension. You are much better off getting aftermarket dampers and keeping your existing springs.
# Ok you understand all that, but you still want to do the swap. What will fit? Any OEM suspension from the same platform (i.e. MkIV) will fit. For example you can swap Golf/Jetta and 1.8/VR6 springs no problem. Your ride height may be a little weird and your handling balance may not be the same due to different weight distributions between cars. But if you've decided to do the swap, you probably don't care about the performance implications.
# Some folks like using the 20thAE/337 suspension (~150# all around) on the MkIV VR6 cars: http://forums.vwvortex.com/zerothread?id=3148512

Gap between the strut tower and the top plate in engine bay?
# Don't worry, that is normal. Turn your steering wheel all the way and you'll see one gap grow larger as the other one becomes smaller. If the gap gets much larger than 1/2" or so, you may need to replace the strut bushings/bearing (see below), however, even a brand-new car has that gap.

What about OEM hardware and suspension rebuild kits? Poly bushings?
# Strut bushings and bearings wear out and should be replaced every 4 years /50,000 miles for best performance. Also, any time you install a new suspension it is a good idea to inspect or replace the strut bearings/bushings regardless of their age.
# Lower-control-arm bushings wear out and should be replaced with OEM equivalents every 4 years/50,000 miles or so for best performance as well.
# Polyurethane bushings are not a good choice for the VW design despite what aftermarket companies say. They generally feel stiff and sporty for a while but wear out quickly. Plus many need to be lubed regularly while oem bushings are maintenance-free. If you want the stiffest-and-sportiest setup, and the most expensive, you do not want a bushing at all; you want a spherical bearing. Get Technical | LCA bushing DIY | Discussion
# tie-rod ends, ball-joints, and rear upper shock mounts should be replaced every 100,000 miles for best performance. Rear-axle bushings can also be replaced, but the process is much more involved.
# Alignments are important. As tires and parts wear, it is more important to get routine wheel alignments. Most cars do well with zero toe or 1/8th toe-out up front and even camber/caster side to side. Unless you have AWD/4WD don't worry about the rear as there usually aren't any adjustments.

Clunks or other noises from suspension?
# Suspension noises can be difficult to diagnose. The most likely causes of suspension noises are the following rubber bushings and bearings:
Front:
# upper strut mount - clunks, BIG gap in engine bay
# upper strut bearing - clunks when steering
# LCA bushing - clunks when braking, erratic steering feedback under heavy acceleration/braking
# swaybar [email protected] rack- clunks when corning, especially 90° parking-lot turns over curbs, etc
# swaybar end-link - clunks
# ball-joint - bunch of different symptoms
# steering - tie-rod end (outer & inner) - alignment issues
# axle - CV joint - clicking when turning and accelerating slightly
# wheel bearing - whirring noise that increases with speed - whole wheel assembly has play
Rear noise?
# 99% of the time, it's a loose 16mm bolt on the shock- there are 3 of them per side
# Sometimes the upper shock mount goes bad internally - there is a metal plate surrounded by a rubber bushing. If the rubber wears too thin, the plate will clank against the outer housing. This should be replaced Check the shock nut which fastens the mount to the shock shaft as well. It need to be torqued to spec.
# aftermarket swaybar - check those bushings & clamps especially H&R which are notorious for wearing out and snapping.

Do I need to replace my front sway bar (FSB)?/Do I need a FSB?
# Your car comes with an OEM FSB aka stabilizer bar. When you lower, there is a chance that the drive axle will hit the sway-bar when riding over bumps. There are a few options.
# You can try aftermarket swaybar end-links to position the FSB further away from the drive axle. Note, this solution works for most cars, but some cars with extreme lowering will still have clearance issues. Refer to the manufacturer regarding how to adjust the links for your particular swaybar setup.
# You can replace the oem bar with an aftermarket bar that is shaped a little differently. If you get a thicker bar, the car will feel flatter in turns, but will under-steer more. Some successful auto-x setups use large front bars, but this is not popular for street or road-racing.
# You can also remove the FSB altogether, but this can make your car's handling unpredictable in emergency situations on the street and is only recommended for track/closed-course use.
# Yet another alternative is to use aftermarket steering knuckles.spindles which change the pickup points of the suspension to correct these issues such as http://www.h2sport.com
# For drops less than 2", you won't know if you actually need end-links or a new bar until you try it. Many folks take the wait-and-see approach. After you install the suspension, listen for clunks while driving. If you don't hear clunks, great! If you hear clunks, drive slow, don't corner hard, and take it REALLY easy going over any sort of potholes or speed bumps. Its ok to drive for a couple days like this while you wait for your new parts to arrive in the mail.

Coil-overs are better, I mean they cost more so they must be... right?
# Adjustable "coil-overs" are good for one thing: balancing the diagonal cross-weight so that left and right turns have equal grip. This is called corner balancing Sounds neat - but it doesn't really do a whole lot for street performance and only helps for pro drivers in competition where every millisecond counts. Other than that, coil-overs are just a spring and a damper like any other kit. Nothing special.
# You can use coil-overs to adjust ride height instead of corner-balancing. You generally cannot do both since the act of corner-balancing will throw your ride heights all wacky and vice versa.
# When you change ride-height with coil-overs, even an inch, you may need to get an alignment. Hint: invest in a lifetime alignment at Firestone or get some DIY camber gauges and toe plates to check your alignment at home. You don't want to chew through your expensive 19" tires in 3 months do you?
# Its official; bragging about how much drop you have on your "coil-overs" is lame. Go record your lap times at the local race course instead.

Do strut/stress bars/braces help handling?
# Yes and no. In mony cases its not worth the extra weight from a performance perspective but some folks like them for the look and feel. In any case, these should be the last item on your mod list since the return on investment is usually quite small.
# There are exceptions. Some bars can reduce cabin vibration which is important to some folks. In older cars where there is a lot of chassis flex, these bars can actually make a big difference, but the effect is generally minimal on a new car.
# Update: MkIV sub-frame stiffening can yield impressive results.

What about a roll cage? I like it stiff!
# Not for a street car!!! Unless you wear a helmet driving around town, getting a full roll cage is about the dumbest mod you can do to a street car. Heads and steel tubes don't mix. You think a half-inch of foam padding is gonna protect you? Get your friend to whack you in the face with a padded steel pole as hard as they can. If that doesn't hurt, by all means get a roll cage.
# If you want to get a half-roll cage for the rear of the car, thats fine as long as you don't have rear passengers. A full roll-cage will protect you much more than a half-cage.
# You will need a 4 or 5-point harness and appropriate harness bar if you have a roll cage. A regular factory seatbelt just doesn't cut it and you probably won't pass safety inspection at most race tracks.

Do I need a camber kit?
# For VW's you generally don't need a camber kit when modifying suspension. Unlike Honda cars, the camber doesn't change a whole lot when lowering. Camber is mainly for performance tuning. You still need an alignment though.

MkIV Stock spring rates (courtesy Pyce)
Front
Rear
 

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Re: VW suspension primer/FAQ (phatvw)

Nice writeup! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif
Now how do we get this added to the main FAQ thread?
 

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Re: VW suspension primer/FAQ (briang)

I particularly like your line of trying things several times before getting it right. On my A4 I've gone from stock to Shine to Stock springs with Bilstein HDs to Stock Springs with Koni Reds. From 15" wheels to 16" back to 15. I'm on my third set of springs on my A3, second set of dampers, and bought my third (!) set of tires today. And I'm signed up for two driving schools this spring.
Trial and error. Fortunately it's fairly easy to sell used suspension components.
 

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Re: VW suspension primer/FAQ (phatvw)

Great write up! Thanks. You're quite candid in some spots, so one needs to read with a grain of salt.

In your opinion, what is the better way to go:
Car is Mk2. Person wants to lower a decent and understandable amount. Person wants an good improvement in performance, but does not want the ride to be overly harsh. Coilovers of a quality brand or Strut/Spring combo of a quality brand?
 

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Re: VW suspension primer/FAQ (phatvw)

Nice write-up http://****************.com/smile/emthup.gif .I'm new to suspension tuning but looks like I'm doing things in the right order. Tires were first. Next are coilovers.
 

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Re: VW suspension primer/FAQ (phatvw)

I have a new GLI and I read somewhere that the European version is about 2" lower than the US version. Is that true? If so, what are we looking at for $$$ and effort to change over?
 

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Re: VW suspension primer/FAQ (phatvw)

Great writeup! Jus acquired a 97 Jetta GLX with blown struts and shocks. Really like the Shine RSS and have read a lot of good stuff about them.
My main suspension goals for the car are:
*streetable
*will barely see the track (haven't tried an event yet)
*keep stock height for suspension travel, be able to drive car during the harsh winters in MI
After reading the testimonials on the Shine setup, I'm pretty much sold but I am still open for ideas since it's going to be a while before I can even consider buying a set for the car. I may just consider buying performance dampers to cure my "cadillac" ride.
I have a questions re: the statement below
Quote »
Strut bushings and bearings do wear out and should be replaced every 4 years /50,000 miles for best performance. Also, any time you install a new suspension it is a good idea to replace the bearings/bushings too. They are cheap.

Are you referring to jus the strut bushings/bearings? What others would your recommend. I apologize for the newbish q's and thanx in advance
 

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That was beautiful!!!
It is nice to read something like this since I am interested in tuning my A4's suspension.
I don't want to lower it, but I do want it to not be so soft. My other car is a 92 integra LS and the suspension is very firm, but your butt does not hurt after driving 400 miles.
This wagon tends to get on my nerves when it does a little 'shimmy' when I get on the brakes hard while in a slight turn. Also, the nose drops too much during hard braking.
I think stiffer sway bars are the answer along with a slightly stiffer damper. Because the nose also drops hard without rebounding, would springs be reccomended? Is there a complete kit for the whole 9 yards?
 

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Discussion Starter · #12 ·
Re: (Al_)

Quote, originally posted by Al_ »
bars are the answer along with a slightly stiffer damper. Because the nose also drops hard without rebounding, would springs be reccomended? Is there a complete kit for the whole 9 yards?

Try the Shine kit: http://www.srsvw.com
 

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i have a quick question ive been searching everywhere for, my car is lowered and i noticed that the front sway bar is rubbing the passenger side drive axle and i ordered adjustable end links. Question is: should i make the endlinks longer or shorter than my current stock ones to allow for more clearance? need help asap. thanks ! !
 

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Re: VW suspension primer/FAQ (seesquared)

Nice thread. Learned quite a bit.
But lets take this a bit further. If the TT bushings are a good+ upgrade, wouldn't also upgrading the LCA to the TT version w/ these uprated bushings be even better? Or is the TT Lower Arm not a direct bolt on. I heard rumors that this was possible, but would like to confirm this.
 

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Discussion Starter · #15 ·
Re: VW suspension primer/FAQ (AndyBlk18t)

Quote, originally posted by AndyBlk18t »
Nice thread. Learned quite a bit.
But lets take this a bit further. If the TT bushings are a good+ upgrade, wouldn't also upgrading the LCA to the TT version w/ these uprated bushings be even better? Or is the TT Lower Arm not a direct bolt on. I heard rumors that this was possible, but would like to confirm this.

I try to refrain from having long discussions in these FAQ threads, but your question has been asked a few times so its fair game. I have added some more info the the LCA bushing thread to address this: http://forums.vwvortex.com/zerothread?id=2300853



Modified by phatvw at 11:46 AM 9-28-2006
 

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Re: VW suspension primer/FAQ (AndyBlk18t)

http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif
 

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Re: VW suspension primer/FAQ (phatvw)

I read every word of this, thank you for this gem of wisdom!
One thing I was wondering about ... the amount of negative camber that can be squeezed out of a Mark 4? I know this is very minimal, but I was hoping one degree could be coaxed out by a good technician?
 

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Discussion Starter · #19 ·
Re: VW suspension primer/FAQ (Shinex1)

Quote, originally posted by Shinex1 »
I read every word of this, thank you for this gem of wisdom!
One thing I was wondering about ... the amount of negative camber that can be squeezed out of a Mark 4? I know this is very minimal, but I was hoping one degree could be coaxed out by a good technician?

You're most welcome. ~1° +/- 0.5° is the OEM setting on all four corners. If you want a little more check out:
http://forums.vwvortex.com/zerothread?id=1432095
 

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Re: VW suspension primer/FAQ (phatvw)

Quote, originally posted by phatvw »

You're most welcome. ~1° +/- 0.5° is the OEM setting on all four corners. If you want a little more check out:
http://forums.vwvortex.com/zerothread?id=1432095

Thanks ... I had a similiar post on the 20th/GLI forum and got zero response. Glad to have those numbers - getting an alignment tomorrow! That other link looks like a gem too - will check that out
 
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