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E21, E30General discussion and technical help for 1975-1991 3 series cars.
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Your Ride: bmw E31
Good job...want to share some tips on replacing struts? I'm finishing this mod this weekends and one thing on the list is replacing bmw struts..I'll use anti-seize on the strut-to-knuckle bolts to make future alignments easier.
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Your Ride: 1991 318is
I am not trying to steal your post but I ran across this a few days after i got my 318is...
I was wondering what some of you may think about these mods.
Not sure what I will do until I get a new daily driver. How ever I am trying to put together some kind of plan and begin collecting all the bits and pieces I will need.
Thanks for your input....Jami
You've found a very fun and economical Bimmer. I just happen to have some experience with it--about 100,000 miles worth of experience.
The E30 318is, produced in 1990 and 1991 as a 1991 model-year car, is a great deal more like the E30 M3 than the 325is. At a svelt 2,602 lb, it is the lightest "modern" BMW by a substantial margin. And while it's M42 1.8-liter dohc engine is clearly underpowered with a scant 138 hp at 6000 rpm and 129 lb-ft torque at 4500 rpm, it will rev up like prom date on Stoli, easily provide trouble-free six-digit mileage, and get over 30 mpg in the process. The Getrag 240 five-speed overdrive gearbox and small-case 4.10 differential are no-brainers given the occasional synthetic oil change. Even driveshaft parts last longer on the 318is, due to the relatively low torque.
However, you have touched upon two major 318is failings--low power and the need for suspension improvement.
Engine power can be improved noticeably with the addition of a good chip. High-octane gasoline is required even with the stock chip, owing to the 10.5:1 compression ratio as well as this engines lack of knock sensors. The chip gives the motor a new rev limit of 7000 rpm, which you probably won't use except on the racetrack. Don't miss a shift, either, because the vibration damper on the front of an M42 engine will disintegrate at precisely 7200 rpm.
A high-performance chip bumps ignition timing so that high-octane gasoline will become critical. And the lack of knock sensors means that some M42s, if they have carbon buildup on the tops of the pistons, may experience detonation with a chip. However, you can get rid of carbon buildup on the tops of the pistons through aggressive use of a good fuel system additive such as Red Line SI-1, BG44K, Chevron Techron or BMW Gasoline Additive. My regimen for this job is one full bottle of Red Line SI-1 before a full tank of fuel, and 1 ounce of the same product in every tankful after that--forever. U.S. gasoline additive packages suck, and when detergency is of paramount importance, such as in a car with 10.5:1 compression, no knock sensors,and aggressive ignition timing, we need to mix our own gasoline additive package--that is the simple harsh reality.
No, you can't add knock sensors to an old M42. You have to pony up for high-octane gasoline, and, with a chip, mix your own additive package. On the bright side, the 318is doesn't use much fuel. There is no need to do anything with the ignition system, except perhaps a preventative igntion coil replacement in the 120,000-mile range (also a good time for a new E30 fuel pump and new main and fuel pump relays). Wowie-neato ignition wires are, in my opinion, unnecessary on BMWs. The factory parts are high-performance parts.
A good high-performance exhaust system, such as the Supersprint cat-back system, can also net you a few more ponies. While the power increases are slight on this car, they are easy to notice because output is so low to begin with. Another modification that can net you a nice increase in acceleration is a differential swap. The E30 318i convertibles had a 4.27 differential. Naturally, they're hard to find on the used market and a limited slip is even harder to find, but they are available rebuilt from BMW if you want to spend the money. A 4.27 diff was the first thing I did to my 318is.
You might also consider a good short shift kit, as the factory parts are rather sloppy and long of throw.
The chief problem with the 318is is the factory springs, as you have so astutely recognized. For some reason, BMW gave the U.S.-specification 318is great shocks--BOGE units actually shared with the E30 M3--combined with positively horrible coil springs, particularly at the front. The front of an E30 318is looks like it is set up for the Dakar Rally--it is way too high. Bilsteins are a wonderful upgrade to any BMW, but whether you can use your existing Bilsteins with shorter, stiffer, aftermarket coil springs depends upon whether you have Bilstein Heavy Duty shocs or Bilstein Sport shocks. The later are compatible with shorter springs, while the former are for use with stock springs. You'll have to check the rears for part number stickers, but I suspect you have HDs. So, unless you want to buy new shocks, you'll be using the horrible stock springs. I care for a friend's 318is in the same predicament--it has Bilstein HDs installed by a previous owner, and the present owner simply cannot bring himself to remove them.
Well, there is something to be said for ground clearance I suppose. Not much, though. And all is not lost. You can lower the front of this car and any E30 except the 325iX by 10mm using ingenious upper spring hats from BMP Design (www.bmpd.com), pn 139009 ($160). These wonderful parts, also available for non-M E36 3 Series cars, including the Z3, are total no-brainers. You simply remove the strut assemblies, compress the stock coil springs, remove the factory upper spring hats, fit the BMP Design units and bolt the assemblies back in. And yes, they can be used with aftermarket springs, too, for an additional 10mm drop. I would recommend these parts for your car unless you are into buying Bilstein Sport shocks and aftermarket coil springs. I note, however, that doing the later will significantly stiffen ride quality--something you mentioned you did not want to do.
While you're working on the front suspension, you need to make one other improvement. Swap out the stock control arm bushings for solid rubber offset units for the E30 M3. In addition to being a great deal stronger, E30 M3 offset control arm bushings provide some extra caster for greatly improved high-speed stability. You can get these from almost any BMW parts house, from BMW itself, and from BMP Design under their pn 56812 ($100). They're worth every penny!
After either or both these suspension modifications, you will need a front-end alignment.
Larger sway bars are also an easy upgrade for the E30 and other BMW models. And if you're running the stock 16x14-in. alloys, consider upgrading tires to 205/60-14, and also consider the Yokohama AVS ES100 in this size--these tires will rock your world.
Life without a bimmer is No life at all
Last edited by Jami318is; 06-27-2007 at 03:15 AM..