Suspension/Brake Upgrades
I have decided to do a true adjustable coil over conversion. I don't really NEED to, I was pretty happy with my
Eibachs but I wanted to see what it would really cost to get a set onto
my car using DIY skills and not buying anything off the shelf. I recently found out that Eibach springs were rated at 104lb/in front (not progressive) and 97/180lb/in rear (progressive). That's not as stiff as I had expected so I have decided to modify my original plans for 300lb front/220lb rear springs.
Rear Coil Overs:
Here's what I used:
1 pair of new AFCO #1073, steel, large body racing shocks with welded on bearing ends. $75 delivered, normally at least that much each before shipping.
1 pair of AFCO coil over sleeves, top spring cups and shock clips. about $25-they came in a larger lot of coil over shock parts for $58 delivered-some of these parts will be used on the front. Coil over kits are $50 for each shock new.
1 pair of modified stock upper spring mounts. $0, just some metal I had on hand and some TIG time. It DID take me 3 tries to get the upper mount right, first was a really nice aluminum disk but it was too thick and messed up the shock travel.
1 pair of QA1 14-200 2.5" coil over springs. $48 delivered, normally $50 ea. before shipping.
Throw in $10 for misc. hardware and some extra shop time to turn upper and lower mount spacers.
So that's $158 for the rear and that INCLUDES new shocks!
Here's some more info on the parts:
Racing shocks have an industry standard for dampening, it's a 1-10 scale with 1 being the softest dampening. The shock number reads like this-the 10 is the shock model (AFCO steel, large body), the 7 is the shock travel in inches, the 3 is the dampening-if there is only one number the compression and rebound are the same, if it something like 1073-5 that would be the same shock with 3 compression and 5 rebound dampening.
The QA1 spring is easy 14-200 is a 14" spring with 200lb per inch rate.
Some will ask "Why the soft spring, lots of people use 300lb or more on the rear?" This is primarily a street car and I don't want my kidneys knocked loose on the crappy roads around here. I DO plan to come up with a larger rear sway bar to increase the roll rate while retaining the softer springs that will keep the tire in contact with the rough pavement and my kidneys in their original location. The 7" travel shocks are close to the stock shock compressed and extended length. I don't intend to slam the car so they will work well. If you want to do something similar and go really low you will need a shorter shock.
#3 dampening MAY be a little light, a different pair of shocks for cheap will allow me to test other dampening without a large expense. You CAN'T tell how stiff a shock really is by moving it by hand, that's not fast enough to get a true sense of the dampening. Good coil over springs are readily available on ebay in a multitude of lengths and rates.
For more money you can get aluminum threaded body single or double adjustable shocks and only have to worry about dialing in your preferred spring rate... I'm a low buck guy so these will work for me.
Front Coil Overs: These are more work than the rears. First you need to strip the struts down to just the tube and spindle. You need to choose the spring rate and length you plan to use. I will use 12" long 220lb springs.
Using the common 8" springs doesn't make sense to me unless they were very strong springs that didn't compress much with the weight of the car on them-but that causes problems when chassis comes up from a bump and the suspension goes into "droop". The spring would come away from the upper end and slam back into it as the car came down. If you hit a large bump the spring would coil bind with much more than 4" of travel, not a good situation either way.
12" 220# springs with the adjustment sleeves positioned to put the strut insert close to the center of it's travel should be compressed a couple inches which will allow some droop before the spring looses contact with the upper mount. 12" springs would also be unlikely to coil bind in compression.
Here's a pic of the struts stripped to the bare tubes, I used a thin cuttoff disk to remove the stock spring perches, brake backing plate and hose brackets. A 4" grinder with a flap disk cleaned up the remains and some quality time in the blast cabinet cleaned the paint and crud off. This strut insert is a KYB with the custom upper spring perch installed with the stock upper bearing and mount. When I do the final assembly of the struts I will install a set of Koni adjustable inserts.
Here's a pic of the front strut mocked up with a spring in place.
MONSTER Big Brakes: How does Wilwood Superlite calipers on the front with 11.75"(1.25" thick curved vane) rotors and Wilwood Dynalite calipers and on the rear with 10.75" (.81" thick vented) rotors sound?? That's some race car quality stopping power for a 2400lb car on the street! I will likely loose the OEM brake power booster in favor of a correctly sized master cylinder/cylinders with the appropriate pedal ratio.
BIG Wheels/Tires: After the crash I decided that more grip was in order. Here's the solution- xxr 513 16x8 0et wheels. They weigh just over 16lb ea. The purest say running any wheel dia. over 15" dia. is a "travesty" and not period correct, well-you may have noticed I'm not a purest and believe in function over "correctness". The monster brakes should easily fit inside these wheels.
225/50/16 tires ought to be a good match but 245/45/16 would be even grippier! This tire/wheel combination will take some work to get on the car and will likely include enlarging the factory wheel well bulges or maybe some all steel e30 M3 style box flares. I'll have to see which appeals to me more, time to get out the poster board to whip up some mock ups to check the fit and look. I'll start a page on body modifications when I get that far.
While on the subject of wheels and fitment here's a quick tutorial on wheel width and et offset:
So, what does that et number on wheels really mean? In simplest terms it's the distance in mm that the wheel to hub mating surface is from the true center of the wheel dia. ET0 on the wheels above means the wheel to hub mating surface is exactly in the middle of the 8" wide rim, or 4" from the back lip. How do you figure out the distance on a wheel such as the 15x7 et12 wheels commonly used on an e21? Grab a calculator and do some math with me: There are 25.4mm in an inch-that's a critical number to remember.
7x25.4= 177.8mm total rim width 177.8/2=88.9 now add the 12mm for the et of the wheel 88.9+12=100.9mm total back space, divide that by 25.4 and you get the back space in inches.. 100.9/25.5=3.97" As you can see my 8" wide et0 wheels have nearly identical back space as 7" et12 wheels, that means there will be no fitment issues on the inner side of the wheel/tire combination-that also means the extra 1" width is all on the outside of the wheel and will cause interference with the sheet metal=more work for me! Now you know how the et numbers work so you don't have to post on the forums things like "I found these great wheels cheap, they are 15x7 with an et35-will they fit my e21?" Just do the math and figure it out.
June 5 2008-Wheel lug bolt to stud conversion: I've been wanting to convert this car to wheel studs/nuts for a while and finally got around to it. I bought a set of 16 studs on Ebay from jjboy925, it's a ricer tuner supplier on the east side of SF bay. They are 12mm x 1.5 press in studs with 3.25" under head length and made by OBX-they make a ton of ricer stuff. The price with shipping was less than Summit Racing, Jegs or other ebay dealers and being local shipping was quick. The knurl area is .485" dia. so I drilled the threaded holes in the rear hubs to 15/32" and pressed them in place with a hydraulic press. Sounds easy doesn't it.. The rear hubs were a pain to drill, they are pretty tough but the key is to block them well on the drill press table and clamp them down very tight-the drill bit will try to grab the metal and spin the hub. The front hubs drill slightly easier but the rule of clamping them very tightly to the drill press table still applies.
This is a rear hub in place with an aluminum rotor hat installed. I scored 4 of these hats for $25 on ebay. They were claimed to be genuine Wilwood #170-8643 but are knock-offs. These came with 1/4x20 threaded holes for the rotor and real Wilwoods use 5/16" bolts. It was easy to drill and re-thread the holes. These are commonly used on Honda/Acura big brake upgrades. These take a vented 10 3/4" dia. 6 bolt pattern rotor .81" wide (Wilwood #160-5839). The fronts will require a different hat (Wilwood # 170-8405) and rotor as I want 11 3/4" dia. rotors up there. The larger rotors use a more common 7" 8 bolt pattern available through several sources like Summit Racing, Speedway Motors and more.
July 17 2008- 11.75x1.25 Rotors: Last week I was poking around the AFCO racing site and checked out their close out/specials page and found some great stuff. I ordered a pair of big directionally vented rotors for $8.00 ea.!! They are made by US Brake. Wilwood disks the same size and quality go for about $80 ea. The cheapest I have found are from Speedway Motors and are $25 and are NOT directionally vented.
These rotors are seriously beefy at about 8.5lb which is good for stopping. How well a brake rotor works is directly related to it's weight. Brakes convert the engergy of motion into heat so the more heat a rotor can absorb the more braking you can do without overheating the rotor and pads.
As with all things high performance there is a trade off. The more a rotor weighs the better it works but the trade off is greater unsprung weight. That's the weight NOT supported by your suspension such as brakes, tires and wheels. The higher your unsprung weight the harder your suspension has to work to control it which reduces handling. A second side effect of the higher weight is slightly reduced acceleration due to the greater mass to get rotating. I would have preferred .81" thick rotors for the reduced weight because this is still a street car and 1.25" thick rotors are overkill but when a smokin' deal shows up you gotta go for it and the calipers I found a great deal on are designed for 1.25" thick rotors.
A front rotor hat and rear rotor are on order so I can begin to fit the calipers. I have yet to find a really good deal on either of those parts.
28 July 2008: The rear rotor arrived and is mounted on the hat. The caliper may interfere with the wheel with these low offset hats, .66" may not be enough. Once I receive a Dynalite caliper and get it mocked up I'll test fit a wheel and see.
I had to remove the rear sway bar to get the gas tanks out and while I was under there I decided to go with a larger adjustable bar. There are no reasonably priced upgrades on the market so I have a couple ideas I'm looking in to.
31 August 2008, Re-think the brake system: I got the hat a couple weeks ago and finally have the rotor bolted up, it feels much heavier than I expected so I threw it on the scale and... "Holy Crap, Batman-that suckers really heavy!"
11 lb is too much of a sacrifice in un sprung weight and rotating mass. I will go to a pair of these-
These are .81 thick and weigh 5 lb. ea. so that cuts the un sprung weight in half for the front brakes. The trade off is not as much mass for repeated stops and more cost - about $90 each. This definitely takes the big brake project from the low buck to the high end with rotors and hats costing about $249 for each corner including shipping. Handling and better acceleration is a higher priority than repeated hard stops.
I also ran into a problem with mounting the Wilwood Superlite calipers to the front struts. Their bolt pattern is 3.5" and the strut has the 3" bolt spacing of the stock calipers. OK, so I'll just build an adapter-well it's not that simple using 11.75" dia. rotors because the mounting ears on the caliper interfere with the mounting points on the strut making the adapter more complicated than I want to mess with. The solution is to run Dynalites on front as well as rear.
The other rotors and Superlite calipers won't go to waste. They will sit on the shelf until I get to my 4X4 project when this BMW, the VW and the Motorcycle are all done.
People always want a cheap big brake upgrade kit. I can see why the vendors sell them for $1000 or so. Let's look at the cost of a set of 11.75" brakes for the front using new parts.
Hats- $140 each
Rotors- $35 each for normal 8lb straight vane rotors
Wilwood Dynalite Calipers - $135 each
Caliper adapters - custom machined from aluminum $100 each
You would also need new flex hoses and some adapters $60 or so.
That's about $880 in parts alone! If you bought in bulk you MIGHT save some on parts and if you had several sets of the caliper adapters made at one time you could save about half of that cost. Most retailers mark up their parts at least 100% of their cost so to me a $1000 big brake kit starts to look like a deal!
Dec. 2008: I just received a pair of new 11.75 x .81 scalloped front rotors from Speedway Motors. These are a new product that they recently brought out.
These are virtually identical to the Wilwood versions pictured above but sold under the Speedway name. As you can see they are a significant weight savings over the 11.75 x 1.25 rotors pictured above. These cost $46 each as opposed to $89 each for Wilwood's. I could have saved about .5 lb more by getting the drilled version for about $10 more ea. but I'm happy with these.
More suspension and brake parts will be arriving in the near future so progress should pick up soon.
May 2009:
I finally got off my butt and ordered the wheels. The 513's look more like the Panasports/minilites in person than they do on the web. I tossed one on the rear hub to check clearance to the coil over spring and decided to go with 225/50/16 tires to ensure I have adequate clearance. 245's might be too close depending on the MFG, there is great variation between MFG's when it comes to tires with the same size markings. I will order a set of Falken 502's next week. I also need to scrounge up some lug nuts that will fit the wheel recesses.
Here's a wheel on the hub:
The spokes clear the caliper by .25" so I'm quite happy about that.
There is enough clearance to the coil over to clear 225's easily but 245's might be too close. You can see the shock mount spacers are offset for a little extra clearance.
Clearance to the trailing arm is more than adaquate as the arm angles inward away from the rim as it goes forward.
Once the tires are mounted I can finish the front struts and get all the suspension installed and the car back on the ground.
End of May 2009:
The tires arrived last week but have not been mounted yet. They are Falken 502's. They have an 8" tread width and should fit these wheels nicely.
I drug out the solvent tank, cleaned up the front hubs and bearings then installed them dry without the seals for test fitting the wheels, brakes and coil overs. This pic is NOT the coil over sleeve I will use, this is a 5" sleeve and I will use 7" sleeves. The new sleeves and adjusting collars will be ordered soon.
The disks are held to the hats with 180,000psi socket head bolts and hardened flat washers all kept in place with Locktite. The bolts were ordered 1 1/4" long so they go all the way to the far edge of the aluminum hat for maximum holding power.
The coil overs will clear the wheels/tires nicely.
I picked up some steel to fabricate the front caliper mounts with. That's the next project.
July 15th 2009:
This project has taken a turn so the suspension will be re-adjusted to suit the new direction. The spring rates will be increased to support the higher weight of a S50 6 cylinder and a fuel cell in the trunk area. I'm thinking the fronts will need 325-350lb springs and the rear 250-275 lb springs.
July 26th 2009:
I dropped the rear suspenison, differential and crossmember out today. I will clean the crossmember and weld on some gussets to strengthen a few spots I see that might be a little weak.
The rear trailing arms will get cleaned, painted and urethane bushings from Top End Performance. I was suprised at how much the rubber bushings bind up the movement of the trailing arms.
I will start looking for a 3.64 rear differential to put my limited slip from the 3.91 into.
I am thinking about a more rigid rear differential mount to replace the rubber bushed "dog bone" that suports the rear of the differential. Maybe a steel link with urethane bushings.
August 1 2009:
The mail carrier delivered these today:
These will be the new rear shocks, the steel shocks I had planed to use have #3 valving and with the expected greater vehicle weight and higher spring rates I felt that the valving would likely be inadequate so these are #5 valving. Of course the adjusters and upper spring cones I have on hand won't fit these shocks so I'll have to buy some new parts to make these work.
I scrubbed up the rear subframe a couple days ago and welded on some triangular gussets to strengthen the control arm mounts. I also welded up some areas of the differential mount the factory left un-welded. Welding cost's $$ so the bean counters make them weld only what they feel is necessary to do the job to help maximize profit. I shot it in satin black.
Today I scrubbed up the rear control arms, shot them with satin black and tried to install some urethane bushings I bought on ebay. I'm VERY disappointed in the fit of these bushings. They appear to be high quality until you try and install them-they don't slide into the control arms and if you force them in the inner steel sleeves bind up. The point of urethane bushings is to have the suspension move freely with no binding. The way these are made the only part that can pivot is the bolt on the sleeve - metal to metal is NOT good, especially when you can't grease them easily. I thought I might be able to open up the trailing arms some and get the bushings to slide in so I grabbed my drill and brake cylinder hone and went at it for 30 minutes or so on one side of a control arm. Here's an action shot:
It cleaned up the bore nicely as expected and the bushings slide in easier but the sleeve still binds. Part of the sleeve issue is the finish on the sleeves. They should be nice and smooth but these came with the mill finish still on them, I cleaned them up and smoothed them out with some sandpaper:
I think the final solution will be to run a drill or reamer through the bushings once they are installed and open them up to the correct finish size.
When you pay for a product like this you shouldn't have to mess around to make them work!!
TECH TIP: How DO you remove those old stuck rubber bushings from the control arms so you can install urethane bushings?
The obvious easy answer is to use a press but as usual it's not that easy. The bushings must be pushed out from the inside of the control arm due to the rubber shoulder on the outside edge. I HAVE a press that could easily push out the rubber bushings but I could not figure out a way to get the control arm in the press in a position to work. I came to the conclusion that a press is NOT the answer.
Here's how I removed them:
I used a band saw to slice off the larger outer end of the rubber bushing-you could do it with a hacksaw, takes longer but works just as well.
I clamped one end of the control arm in a large bench vice-you could have a friend hold on to it.
I fired up the oxy/acetylene torch - you could use a common propane torch - and heated the control arm, it didn't take much heat to get some reaction. In a very short time and with MUCH less heat than I anticipated the rubber began to react. The first indication was a high pressure release of gases and smoke from between the rubber and control arm. I turned off the torch and grabbed a large steel punch and BFH (Big F&##!*% Hammer) and easily drove out the bushing with less effort than expected. 3 of the 4 came out easily, the 4th took a little more heat but not much.
Front suspension update: The FEDEX guy delived some Afco 7" threaded coil over sleeves today so I can get back on the front struts. The new sleeves have a slightly different design than my older 5" sleeves so I will have to design a new way to support them at the bottm. No big deal, just time on the lathe.
August 9 2009:
The rear control arm urethane bushings have been installed. I used a reamer and drill to remove material from the ID so the steel sleeves fit correctly.
I decided to try my hand at casting the rear mounts in urethane. I used a 3/8" drill to remove a large portion of the rubber around the center aluminum core of the mounts:
I then used poster board and re enforced shipping tape to build up the ends:
My goal was to avoid the leaks that others have experienced during the casting process. I was MOSTLY successful with that, only a little minor weeping from a couple spots. The poster board stuck to the urethane but came off easily with a soaking in warm water and scrubbing with a green pad.
I used the 94A urethane from McMaster Carr. They sell it as a quart but you really only get about 1/2 a quart once it's mixed and there wasn't much left over.
I'm pretty happy with the way they turned out. Another day to cure and I'll put the rear suspension back it minus the differential so I can get to work prepping the engine compartment for the s50 installation.
Aug 10 2009:
I installed the rear subframe this evening and tried to install the rear trailing arms, those urethane bushings have got to go. I'll order another set from BMP or TEP in the next day or so. I hate having to buy the same parts twice!
Aug 13 2009:
BMP is out of stock until the end of August so I ordered a set from TEP. They arrived today. When I tried to fit them to the control arms they have the same issues as the Internet bushings, the steel sleeve could not easily slide into the urethane. I'll have to come up with something on my own like make some from Delrin on the lathe or maybe some steel sleeves with Nyliner bearings. I'll have to think about that for a while.
Aug 15 2009:
I dropped the steering rack and front crossmember today for cleaning and paint.
21 Aug 2009:
The rear coil over parts finally arrived yesterday and the rear shocks are assembled:
The rear crossmember will be coming out today or tomorrow so I can modify it to hold a 3.25 LSD rear gear housing from a 5 series. With a 1-1 5th gear the 3.64 e21 rear gear I had planned would not be tall enough and the engine would be at about 3500rpm at 70mph. That is too high to run down the highway for long, it would get tedious very quickly. The rear axles will likely have to be modified to fit the larger differential. I'm sure it's wider and the flanges are likely larger dia. also.
Aug 24 2009:
I picked up the 3.25 limited slip differential last weekend. It's a BIG sucker and will take a lot of work to get mounted into the e21:
The drive flanges are larger dia. and wider spaced so there are two problems that will have to be delt with. I may be able to make some adapter plates that will allow the e21 CV joints to bolt up and the axles may have to be shortened.
Sep 8 2009:
After a couple tries I finally got the correct front springs from Summit Racing. I wanted QA-1 progressive coil over springs with 175/350 rate 12" long. The first set they sent were part number HAL-12-175/350, they were listed and shown as 12" long 2.5" ID coil over springs but what arrived were conical shaped with 2.5" id at the bottom but 5" id at the top. Apparently those are for a coil over conversion on late model Firebirds. After returing those and the Summit rep calling QA-1 I got the correct springs with part number 12-175/350:
One of the major drawbacks to coil over suspension using short stiff coils is the coil looses contact with the spring seats during suspension droop causing violent contact when the suspension comes out of droop. I fist saw this when an e36 autoX car was put back on the ground from a lift and I heard violent banging as the springs snapped back into the seats under pressure.
These coils should pretty much eliminate that problem.
The softer part of the coil will likely be completely coil bound with the vehicles weight on them but that's ok. This is called a "tender coil" and is often used in rock crawlers. Eibach uses the same concept on it's lowering springs for the Scion Xa-that's where I got the idea with clarification from the Eibach tech rep. The coil bound part of the spring has no function other than to keep the ends of the spring seated during droop. In England a car will not be allowed on the road if the spring looses contact with the seat during suspension droop, it's unsafe for highway cars. I don't think anyone In the U.S. has even thought of adding that requirement to a safety inspection.
Feb 24 2010:
I finally got around to buying some new Suspension Techniques 25mm/19mm sway bars and got the front suspension installed, tires/wheels bolted on and the front end on the ground (the rear is still up in the air).
Left side:
Right side:
The coil overs are adjusted so the lower control arms are level and there is plenty of ground clearance:
The tires barely fit in the wheel wells and the sheet metal will require MAJOR modifications to make the car driveable, those will be documented on the Exterior Modifications page
Here's a shot of the brake rotor through the wheel, the caliper is not mounted yet.
The rear suspension is up next but will take a bunch of work to mount the new larger differential and adapt the axle shafts to it's flanges. The axles MAY need to be shortened also due to the width of the differential. I just received the 245/50/16 tires for the rear and they will be mounted up soon.
July 22 2010:
The rear differential is finally mounted to the crossmember and the crossmember/suspension is installed, not including the sway bar which will go on shortly.
Yes, the trunk floor and stamped sheet metal crossmembers have been cut out.
The mounting ear on the aluminum cover hit the crossmember so out came the cutoff wheel and "Presto", plenty of clearance.
The cover mount will be tied into the shock towers and side rails for support. I will fabricate a new trunk floor and use my new bead rolling tool to ensure it not only looks good but is strong and doesn't "oil can" or vibrate.
Rethink the brakes part 2:
I have decided the car needs a real cable operated parking brake system so the Wilwood Dynalites are NOT going on the rear. I will install some GM metric single piston calipers with parking brake levers as often used in hot rod brake systems. The Dynalites will go on the front. The clutch and brake pedals will be lengthened 1" to increase the pedal ratio and improve the braking using a non-power master cylinder.
August 15 2010:
I bought a pair GM metric calipers with parking brake levers from Speedway Motors for $150 which included pads and mounting bolts. I also picked up the banjo fittings for -3 braided brake lines. To mount the calipers I used some "weld on" caliper mounts hotrodders use to install disk brakes on axle tubes. I also bought some new parking brake cables on Ebay. I had to modify the mounts slightly and add a spacer to get the calipers lined up on the disks correctly then welded everything solid to the existing drum brake mounts on the swing arm.
I will have to fabricate a mount for the parking brake cable end and modify the lever to fit the cable end but it won't be too much work. Next up is plumbing the rear brake system to the front and mounting the Dynalite calipers to the front struts.
I also threw on the Suspension Techniques 19mm rear sway bar.
January 12 2011:
I trimmed the trunk floor some, installed a new crossmember and braced up the differential to the shock towers.
I decided the rear frame rails needed strengthening to support the fuel cell mounts so I added .090" steel sheet to the inside. With the new steel welded over the old frame rails there is a good chance of rust forming between the two pieces so I coated the inside of all the pieces with coper "weld through" primer.
Jan. 27 2012:
The steering rack is connected to a new Ididit tilt steering column:
This was not easy or cheap, I was not able to find a company that made a lower U joint that would slip on the stock splines so I made it a DD (double D) shape with careful application of a grinder. The upper U joint incorporates a vibration isolator. The steering column, U joints and shaft total about $700!! Fitting the column through the firewall required some pretty serious surgery as it's larger dia. than the stock steering column.
I have a nice Strange Engineering 1 1/8" bore dual master cylinder that bolts to the side of that bracket above the steering shaft. and a Wilwood master cylinder for the clutch. The mount for the clutch master cylinder had to be completely rebuilt to accommodate the Wilwood unit in the stock location.
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