posted on March 15, 2012 00:00
Project Hypermiler Part 4: Suspension Techniques, Whiteline, Enkei and Nitto Install
By: Steve Rockwood
The door handles and mirrors on Project Hypermiler came painted, and swapping out the sad excuse for shocks and springs on this car was absolutely necessary to keep them that way. On top of that, the stock wheels and tires left the car looking like a grizzly bear riding a skateboard, making it an unfathomable proposition to retain these pizza-cutters after going through the trouble of upgrading the suspension. Luckily, Suspension Techniques, Whiteline, Enkei, and Nitto had off the shelf solutions to help Project Hypermiler actually turn a corner at ludicrous speed while keeping its mirrors and door handles painted.
|Yep, she rolls like a canoe in high seas. Yar.
That's not to say that it was a simple matter of firming up the car's roll-resistance, throwing some big meats on there, and calling it a day. Project Hypermiler presented some unique requirements and some compromises needed to be made. The suspension needed to be firm, but not kidney blasting units that generated more Aggravation Per Mile (APM?) through squeaks, rattles, and shivers than a sports talk radio show the Monday after the home team lost. The wheels and tires needed to improve handling, feel and appearance, but still make sense with the project's daily driver status and 60mpg tank average goal, throwing R-compound steamrollers right out the window.
Lastly, all of these items had to jive with the car's $3500 purchase price. Magnetorheological shocks, top of the line Michelins, and forged magnesium wheels would've certainly met the Project's goals, but also would've eclipsed its buy-in by a considerable margin. Sensible yet fun was the name of the game here.
|The stock wheels and tires leave lots to be desired from a performance and aesthetics standpoint.
Sensibility comes into play immediately when selecting suspension modifications for the VW MKIV chassis, and foremost among these comes when determining ride height for the vehicle. While the ability to slam the vehicle certainly exists in the aftermarket VW world, keeping the front suspension geometry as happy as possible was paramount, so lowering would need to be limited to as close to stock as reasonable. Fresh from the factory, the VW MKIV chassis is set up with a very poor camber curve on the front of the car. The outside front tires lose camber any time the car rolls when cornering because the control arms are pointed at an upward angle at static ride height. Out back, however, is a different story. While a beam axle lacks in sophistication, it does have the benefit of having a nearly perfectly matched camber gain to roll ratio. This means that any MKIV chassis car will always be subject to understeer without re-engineering of the suspension's hard points because the car is set up to lose camber more quickly on the front than it is on the rear.
|The MKIV chassis front control arm angle is far less than optimal at stock height.
Why purposefully sabotage the front to rear camber gain ratio and condemn the car to a life of continual understeer? The reasoning VW likely used actually makes some sense. Loss of grip through camber is generally a very progressive process, mainly because cars gradually lose camber as they roll. The MKIV chassis, with a rear-skewed camber gain ratio, will gradually increase the amount of grip lost on the front of the car the harder it is pushed, giving the inexperienced plenty of warning before the fecal matter hits the ceiling-mounted air handling device. This method of introducing understeer is much more gradual than using a balanced camber gain ratio and using spring rates to determine chassis balance. A balanced camber gain ratio would place most of the responsibility of informing a driver he's about to fly off the road on the tires. With a set of ultra-sticky high performance tires, this may not be immediately apparent until it's too late. Nothing is more scary than sudden and terminal understeer, as there's almost nothing that can be done to immediately regain control of the car. In the end, the goal for Hypermiler's ride height choice and suspension modifications was to mitigate the front suspension's inherent flaws, not remove them entirely, while also improving aerodynamics for fuel economy purposes. Mild understeer with plenty of warning is a good thing in a car that spends the vast majority of its time on public roads.
Since self-preservation is a very strong instinct, keeping ride height reasonable would help the car on the road. The oil pan, which doesn't sit very far off the ground, is made of cast aluminum.
|The cast aluminum oil pan sits very low in the car. Ours showed evidence of repair from impact damage by the previous owner.
Thursday, March 15, 2012 8:25 AM
Did you say those Enkeis and Nittos weigh more than the stock wheels and tires?
Thursday, March 15, 2012 8:52 AM
@ Dusty: Yep. Stock wheels were 15x6 and tires were 195-65-15s, aluminum (16.5lbs, not bad for OEM), and the tires were ultra-cheap Chinese models with hardly any sidewall support. They were technically too light (weight rating wise) for the car.
Going to a 225-45-17 with 7.5" wheels, I was expecting a minor weight increase.
Thursday, March 15, 2012 9:48 AM
Those are some very light OEM wheels!
Thursday, March 15, 2012 12:13 PM
Aye matey, ye needs to trim yer sails a bit in dat first pic! Yar...xD
Thursday, March 15, 2012 12:56 PM
I heard roxy stickers add a few mpg.
Thursday, March 15, 2012 1:11 PM
@ Steve: This chair be high, says I. Yar.
@ Steve Choi: Kiss my entire ass. :)
Thursday, March 15, 2012 2:50 PM
Steve, I know wheels (most of the time) are choose based on price and strength-lightweight criteria.
Any reasons why you didn't go with the proven RPF-01?
Thursday, March 15, 2012 3:12 PM
How many Steves do we have in the house today!?
Steve R - Excellent coverage of your build! I was starting to think (around page 6) how much I'd like to see some comparative data and then you totally pull through :-) Despite your attempt to justify your fairly "unscientific" method, I still find worth in the data despite any arguements against. Now, I'm looking forward to how you get those front tires spinning again :-p
Thursday, March 15, 2012 3:38 PM
@ JDMized: There were a number of reasons. Chief among them was budget for the car. The Fujins are part of Enkei's new lower priced line of tuner wheels. Not as light as the RPF-1, but definitely cheaper:http://www.amazon.com/Enkei-FUJIN-Silver-17x7-5-Wheels/dp/B005ME9GOK/ref=pd_sim_sbs_auto_5http://www.amazon.com/Enkei-Silver-17x7-5-5x100-Wheels/dp/B005KDUBG0
Same quality and MAT construction, so for me the extra couple of lbs was a fair tradeoff. Since the budget for this build is extremely tight (the car's primary reason for existence is to save me money), the Fujins made more sense.
Second, I like how these wheels look. Always been a 6-spoke wheel fan (my SE-R has Kosei K-1s on it).
Lastly, the RPF-1s only came in a 48mm offset in the 5x100 pattern and 17x7.5 size I knew I wanted. I didn't want to run spacers, and with the 40mm Fujins I have, the tire is about 10mm away from the strut. The RFP-1s would've definitely required spacers.
@ Der Bruce: I would say that I took an unscientific test, and made it as scientific as possible. Much like dyno charts, it's only reason was to measure improvement, not for winkie measurement. ;-p
Thursday, March 15, 2012 7:14 PM
Steve, impressive grip. Over a full g and serious improvement, wow. And, those rear sway end links are SO cute, I know a cute blonde with a white Jetta who will...oh, sry nvm xD
Thursday, March 15, 2012 8:21 PM
Nice writeup! Your project reminds me of an article in a German car magazine where they kind of ghetto tuned a Golf 3, maybe you can get some inspiration from there -> http://tinyurl.com/6lzyeuo (watch out for google translator).
I am looking forward to the rest of your build! WPC treat ALL the parts, I guess...
Friday, March 16, 2012 8:42 AM
@ Steve: Yep, though that full g would likely show up as somewhere around 0.90-0.95 on a real 600' skidpad test. My numbers were skewed a little being peak numbers. Either way, the grip this thing has impresses me. There really is no need to get a summer-only tire with these things unless you're actually going to drive them on the track regularly.
@ Julian: Err, I hope the only reason this car reminds you of that one is that it's also a TDI-powered VW... ;-p
The entire build is street-oriented and budget friendly, but nothing embarrassing. No duct tape visible to the outside, non-matching coroplast, stripped interiors, etc. This car is to be nice, comfortable, quick, and REALLY fuel efficient.
Friday, March 16, 2012 9:47 PM
no worries ;) I was just surprised how much fuel saving they were able to achieve with those crappy methods when I read that article, so I wanted to share it. Many of them don't qualify for street use, of course.
There were a few ideas I liked though, like closing up the front as much as possible to reduce cd, and trying to make the underbody as flat as possible.
Monday, March 19, 2012 2:40 PM
Yep. I plan to use some of those ideas, just not so ghetto.
Funny, but one would think something like that would be verboten with ze Germans... :)
Tuesday, March 20, 2012 6:46 PM
Cool right up. Why did you ditch the oem wheels? Was it tire options, appearance, or something else?
Just concerning the wheels and the ability or inability to put a similar tire on the oem wheel: Ignoring the aesthetics, with everything else you did, could you have skipped the aftermarket wheels and upgraded the tires on the oem wheels with similar results?
Wednesday, March 21, 2012 9:53 AM
@ eeeen: I upgraded from OEM wheels for a number of reasons.
1. Fitting a 225mm wide tire would require a 7" wide wheel. Fitting them on a 6" wide wheel wouldn't have really improved handling.
2. Available tires. Not much that is higher performance is available in the 195-65-15 type sizes. I could've gone wider/lower profile, but even still, not much is available.
3. Aesthetics. The stock wheels looked undersize for the vehicle.
Ignoring aesthetics, I don't think I could've been able to combine the all-season capability, treadwear and performance of the Motivos with another tire on the OEM wheel. The Motivos don't come in 15" sizes, and most of the offerings in those sizes aren't the greatest tire. I've been REALLY impressed with these tires so far.
That being said, I probably shot myself in the foot with my MPG goals a little by going wider and higher performance with my wheel/tire combo (though the mileage penalty hasn't coalesced so far), but the tradeoff was worth it to me. We'll see if I can make it up elsewhere.
Sunday, April 22, 2012 9:20 PM
My e30 has a similar strut setup.
I found a 13/16 spark plug socket and a combo wrench with a hex key worked great. No need for a pair of vice grips.
Tuesday, April 24, 2012 4:10 PM
Ah, that would've probably worked as well. Didn't even think of that.
Then again, this method is far more dangerous and ghetto, so it's much more in line with my thinking anyway... ;-p
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