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Discussion Starter #1 (Edited)
Quick intro: I'm Brent in CO, USA and I bought 1991 M5 BK06091 from a close friend in April 2014 (car was also FS on this forum). The car had 220k on it and was a mess, but the engine had an essentially zero-miles rebuilt head w/ S50B32 tensioner, good bottom end, and perfectly functioning driveline. Since I basically bought the car for the price of a working M5 drivetrain and the E34 M5 was on my automotive bucket list, I was able to overlook the mileage and issues (primarily suspension wear and cosmetics). The car was delivered with a ton of spare parts, many of which have made their way onto the car.

Completely irrationally, to fund this car I sold a dynamite Nissan B13 SE-R w/ factory sunroof delete, manual seats and windows, and a built SR20 (near 200fwhp, 2450 lbs) that I rescued from a buddy's yard, rebuilt the front end, and had running reliably for $800 total; and a '99 Saab 9-3 "stage 5" I bought built for far less than the cost of modifications, which had a dead-reliable (seriously) 300whp in a 3,000 lb hatchback shell. Both of these cars spank the M5 in a straight line, but neither were half as cool, either. Thankfully the SE-R stayed local and one of my best friends bought the Slaab.

This M5 was delivered with a light silver-grey interior, but a few owners ago it was swapped (mostly successfully) to black with Mitsubishi Evo 8 or 9 leather Recaros. Not my taste, but they are light, offer better headroom, and will be replaced with SRDs eventually. The car also had a full SLS delete. Bummer for originality (and my car nerdiness), but the 535i-based components that replaced the SLS has saved more weight. I bought the car w/o a spare wheel and tire, and in this configuration with a quarter tank of fuel, it weighs 3600 lbs sans driver.

Somewhere along the line the car also lost the original front bumper, trunk lid, and wheels. I bought it with E38 M Parallels, which have just been sold to fund proper M Systems w/ Turbine covers come springtime. I mention this to acknowledge that this will never be a numbers-matching M5 again, but at the very least, I hope to restore it to an extent that it can soldier on for many more years to come.

This thread will document my sloooow restoration and help keep me organized. It will be slow because I'm paying off student debt, other loans, and trying to buy a house in the next year. I learned how to wrench rebuilding a high mileage E36 M3, which I owned for 5 years and sold w/ 175k and not a single issue. The car is tracked regularly by the new owner and has only needed tires and brake pads in another 10k miles!

Some as-delivered pictures:

Can you say rock chips? This was after I replaced the kidney and headlight surround grills, the chrome kidney surrounds, and half-way successfully bent the dented nose panel back into a shape that would at least keep the kidneys in place.


The poorly color-matched (but OEM) spoiler-equipped trunk lid has been replaced w/ a spoiler-less lid. I hate the spoiler on this chassis. M-pars now gone.


After a new Interstate battery, the first real job to make the car daily-able was new strut inserts. After some research, I went with Bilstein Touring inserts, since I wanted to rebuild the suspension to primarily stock before I added suspension mods. This job also gave me a chance to evaluate the loose-feeling, clunky, shimmying front suspension, and confirm that basically everything needs replacement. Sorry for the potato-quality pictures in a poorly lit apartment garage. All the moisture on the fender liner was from the leaking PS reservoir, which turned out to come from both hose clamps on the bottom being finger tight. Go figure.


Demonstrating how shot the 220k mile OEM struts were. I could fully compress them with minimal effort, and they barely rebounded.


Both strut insert nuts (the big ones) did not budge from any combo of penetrating oil, pipe wrenches, torches, etc, so I took the struts to my good friend, the P.O., and he used a cutting wheel to cut a vertical (parallel w/ strut to avoid messing up threads) notch in each nut, and then hammered the nut further open. What a pain, but it worked and the new strut insert cap nuts threaded on perfectly. The Bilstein Touring struts at stock ride height are nice and compliant, and apparently valved about ~10% stiffer than stock.

After running the rebuilt engine for about a thousand miles, it was time for an oil change. Speakers and Brad Penn were for the 911.


The oil looked great, and I have driven enough that I can estimate the engine uses about 1/2 qt per 3k miles. Using Mobil 1, I will stick to about 7,500 mile intervals, to time every other oil change w/ valve adjustment.

The interior also needed some love since a bunch of issues were driving my OCD crazy. I did the shrunken weather stripping fix (new M dead pedal cover was installed after this picture):


No idea what happened to the center vent, but every slat was broken. I replaced it with the dustiest but functioning center vent. The dash looks rough in this area, I think during the interior swap someone put things together slightly off and gave up. I'll fix it in due time.


On the interior subject, everything was black-swapped below the A/C pillars, except for the rear parcel shelf, which was not only silver-grey but dirty.


Some fabric spray fixed that problem (the color is uniform IRL, the photo doesn't show it):


A couple of the dozen minor trim pieces missing that I've bought new (and still have more to buy):


Next I started tracking down a rear end clunk mainly related to engaging and disengaging the clutch. I checked and found the subframe bushings were somewhat compromised, so these went in:


The AKG subframe bushes reduced the clunk but did not fix it entirely. Without checking the existing component, I bought a Lemforder center diff mount and installed it. Unfortunately, the mount I pulled out was pretty solid still, and I kept it in case the Lemforder goes bad. I got a good deal on Lemforder dogbones, and jumped on them. The existing dogbones had a hilarious amount of deflection, and the new units keep the rear end far better planted. The clunk is still there, and the P.O. and I now suspect the driveshaft and/or CSB is at fault. Both are likely original, and I need to check them out. In the meantime, my rear end is finally solid and the only thing left to do back there is to reseal the diff. Woohoo.

This happened (the miles, not the low washer fluid. I just had to rotate the sensor 90 degrees to upright):


I decided I would winterize the M5 in preparation for the 2014/15 snowboarding and daily driving season, rather than buy a third car. Since the E34 M5 factory winter wheel option was 16x7 Style 5s (et20 IIRC), I picked up a beat set of much more common E38 16x8s and added Blizzak WS80s in 215 width. Annoyingly, for the same price as the beat wheels I bought on eBay, someone local to me sold a beautiful refinished set of the same wheels, but I just missed 'em.

Before I could install them, the cat acted like a cat:


I test fit them, worried about front strut clearance. It just barely fits w/o a spacer, but a wider tire would create problems. Note the tiny triangle of surface rust on the back of the fender, one of the areas I need to address come spring. And I can't get the damn chrome window trim at the bottom of the rear window to stay flush.


I pieced together a Yakima 1A gutter mount roof rack, and already had wide Yakima snowboard/ski racks that can fit four of each or two and two. Note the same triangle of surface rust on this side.


Then, after a few sub 30 degrees F drives, I opted to swap the M1 15w-50 out for M1 10w-40. With this oil the engine warms up in the usual time even in 10 F, whereas before it never fully warmed up under 30 F. When it gets above 50 F, I take the 911 out instead. I added BavAuto rubber floor mats, which fit great for the money and protect the carpet. I replaced many little bits including trunk shocks, the intake manifold M badge, etc etc. Added an M Tech 2 steering wheel. The car has been on several trips to Breckenridge and Keystone, including one with three passengers and a bunch of gear, and it's solid in the snow.

As I mentioned, for some reason I've always hated the rear spoiler on these cars. My non-original (WBA-vin) trunk lid also had a nice patch of rest under the driver side of the spoiler. I finally found a clean Alpine spoiler-less trunklid.

I stripped the spoilerless trunk lid, and then started stripping my current lid. Interesting components of the wiring harness including my favorite electrical part, INSULATED BUTT CONNECTORS, but it still works.


The cardboard was crucial, as the trunk is super awkward to lift off (and then reinstall) alone.


Can't find a direct butt-shot from before, but this is the rear end before (OEM spoiler now for sale):


Now, 10x better in my opinion:


I also figured out (preeeetty simple) how to adjust the trunk so that it fits perfectly when closed.

That about brings us to the present, right at 225k miles and still running like a top. I'm sourcing M Systems with Turbine covers for springs/summer, and continuing the suspension work as my first priority (though a windshield might come soon). I'm going with E31 spherical LCAs, Moosehead UCABs, and Lemforder steering links (already have a new Lemf center rod waiting for install), at which point the suspension should be autocross-ready and solid. I'll look into the drive shaft and components as well. The exterior will be addressed in time, which may necessitate a full re-spray but will definitely include proper black-painted lower trim. Maybe after the house.

I will update and attempt to take better and more pictures as I go along.
 

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I agree, looks tons better without the spoiler. I used one of those rock chip repair kits in Alpine White II and it works wonders--can still see the imperfections up close, but from afar it's a dramatic improvement.
 

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Discussion Starter #4
I agree, looks tons better without the spoiler. I used one of those rock chip repair kits in Alpine White II and it works wonders--can still see the imperfections up close, but from afar it's a dramatic improvement.
That is great to hear, where did you source the rock chip repair kit? I have a dilemma, since the car either needs rust repair and retouching (lots of work), or a full respray. If I respray it, I will no longer want to drive it in winter, and I already have a car I don't drive in winter (the 911), so then I would probably sell it. I'm leaning towards the arduous process of patching rust, repairing chips, and fixing clear coat.
 

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That is great to hear, where did you source the rock chip repair kit? I have a dilemma, since the car either needs rust repair and retouching (lots of work), or a full respray. If I respray it, I will no longer want to drive it in winter, and I already have a car I don't drive in winter (the 911), so then I would probably sell it. I'm leaning towards the arduous process of patching rust, repairing chips, and fixing clear coat.
I got this: Amazon.com: Dr. ColorChip BMW L7 Automobile Paint - Alpine White II 218 - Standard Kit: Automotive

Takes a lot of patience, and it won't be as good as a respray, but you can't see the little grey flecks from afar anymore.
 

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Discussion Starter #7
I got this: Amazon.com: Dr. ColorChip BMW L7 Automobile Paint - Alpine White II 218 - Standard Kit: Automotive

Takes a lot of patience, and it won't be as good as a respray, but you can't see the little grey flecks from afar anymore.
Thank you, bookmarked for future reference.

If you respray it properly, wax it now and then it goes many many winters.
My friend agrees with you Eero, he had his E36 M3 resprayed professionally and says that after the first new rock chip, one stops worrying about the perfect new paint.
 

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Hi,

Great work ! Congratulations !
One question, did you order your retrofit kit for the AC through BMW? I was told here that it had been discontinued... If by any luck you had a reference number i'd be much appreciated !
 

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Discussion Starter #9
Hi,

Great work ! Congratulations !
One question, did you order your retrofit kit for the AC through BMW? I was told here that it had been discontinued... If by any luck you had a reference number i'd be much appreciated !
Thank you!

I don't know if this helps you, but most BMW dealers and part suppliers here in the U.S. have this kit in stock. It is P/N 82 31 9 067 396, E32/E34 retrofit kit.
 

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Discussion Starter #11
I installed the R134a retrofit kit last night, pretty easy. I'll take it to a shop for a charge, and fingers crossed nothing is leaking. The only boner was when the washer tank pump detached momentarily while I was moving it, and I lost at least $0.50 of fluid on the floor. Darn.

I forgot to take a picture of the new red and blue adapter ports, sorry.

The kit: R134a compatible receiver/dryer, charge port adapters, new pressure switch, o-rings, and various charge labels for each model of car.


Old R12 receiver/dryer, with wires unplugged.


Hoses detached. Removing the old receiver required some finagling.


Old and new.


Finagling the new one back down.


New receiver installed, plugged in, etc, before putting the washer tank back. Don't forget to orient the washer level sensor with the wires pointing up!


Shiny new E34-specific sticker.
 

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Discussion Starter #12
Well, that didn't go well. I took the M5 to a shop to charge the A/C system, they found a leak, tightened a line that fixed the leak, then called me to say the A/C compressor is bad. And may have taken the condenser/evaporator with it. Since I had no idea what was up with the A/C, but knew it was empty and hadn't been run in years, I had a bad feeling something was wrong...

Researching now, but also looking for advice on the best course of action. Used M30/S38 compressor? One of the cheaper (~$200-300 Denso) aftermarket alternatives? Is the shop right about the condenser/evap being suspect, or is that unlikely? I've always hated (and thus been a noob about) A/C.

I want this car to be my daily this summer, and while it's not Texas hot, I really want A/C for those 90 degree days when the car is sitting outside.

Depressed now, so I "went shopping" to feel better:
 

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I went thru a/c work last spring on my son's E30 325. We originally bought a reman. compressor from one of the vendors the dealer uses for non-oe parts (world pac or ssf, can't remember who, but it was fairly inexpensive). Had it charged, and it blew out the front seal in maybe 2 weeks. Later talked to a friend who owns a shop who said yep, just get bmw reman or take your chances with used.

so, we bought a bmw reman compressor, with really good pricing (and the return of the bad compressor), it was still near 3x the cost (want to say around $700), but it's in, it works and he's got cold ac.

So the short answer, shop around the dealers and see how much a bmw reman compressor is. Not too hard to do the install yourself.

I'd think if they flushed out the condenser and evaporator, it should be fine.
 

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Discussion Starter #14
I went thru a/c work last spring on my son's E30 325. We originally bought a reman. compressor from one of the vendors the dealer uses for non-oe parts (world pac or ssf, can't remember who, but it was fairly inexpensive). Had it charged, and it blew out the front seal in maybe 2 weeks. Later talked to a friend who owns a shop who said yep, just get bmw reman or take your chances with used.

so, we bought a bmw reman compressor, with really good pricing (and the return of the bad compressor), it was still near 3x the cost (want to say around $700), but it's in, it works and he's got cold ac.

So the short answer, shop around the dealers and see how much a bmw reman compressor is. Not too hard to do the install yourself.

I'd think if they flushed out the condenser and evaporator, it should be fine.
Awesome Mike, thank you for the advice--particularly about the condenser and evap.

I have priced out the cheap rebuilt units to be ~$170 or so on eBay, a nicer rebuilt unit around $500, and a genuine BMW near $700 as you mentioned. Decisions, decisions. I would go for the eBay special if it lasted a few years, but two weeks? Ouch.

At least I know which model I need thanks to this thread: http://www.m5board.com/vbulletin/e34-m5-discussion/155963-c-compressor-parts-help.html
 

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Discussion Starter #15
Busy few weeks, with many purchases and a little work on the M5 as well as my other family cars. Tax refund season has allowed me to speed up the front end refresh.

Undeterred by the A/C compressor shot below the belt, I bought a rebuilt Bosch compressor, which is waiting for install and then another trip to the shop for a 2nd try at an R134a charge. Thankfully, it's been fairly cold here (and I have the gf's smoothly running S60R to bomb around in when needed).

Received the Lemf E31 LCAs and Mooshead UCABs (both gorgeous pieces). Also, I have long considered the M5's rear end w/ stock 535i shocks and springs to be too soft and saggy, so I decided to get matching rear Billies to go with the front. The BNIB H&R springs were a splurge, but I'm going to give 'em a try. The front end has stock M5 springs and is obviously high, but also a bit soft IMO. If the H&Rs beat me up, at least they have good resale value. This is really just a $250 appetizer to my $1800 coilover craving.



One of the responses to my WTB Turbine covers finally panned out, and I got a full set minus bolts (new emblems already ordered):



The cheapest BMW bolts I could find were $100/20, so Lowe's came to the rescue with identical bolts for about $20/20.

Random shot, this morning at the regular drinking hole:



No pictures of the following:

-Purchased a used ski bag. Mine was missing and it really helps minimize exhaust drone, particularly for back seat passengers, particularly particularly when not running a spare tire
-Done with the anachronistic Recaros (and my gf complaining about not being able to see over the dash), I listed the Recaros for sale and started searching for OEM sport seats. The Recaros sold locally in a day for a chunk of cash (with four buyers waiting in line), which almost covered a decent set of heated sport seats shipped

No pictures of the seats yet, since they look like every set of black powered, heated seats, but I'm very happy with them installed. The M5 gained ~60lbs unfortunately, but the comfort and adjustability (far more adjustments than my E36) is awesome. So are the indescribably cool powered headrests.

This week I need to press the Moosehead UCABs into the Lemf UCAs, and then I'll tear down the front end, install the new components, and install the rear Billies + springs. I'll also pull the bumper to install the fog delete panels I've had for a few months.

After that, my priorities are a new windshield, diagnosing the mild clunk I still get and have tentatively traced to the driveshaft, and then addressing the creeping door bottom rust. The mechanical restoration is nearing completion! I'm sure after this work, something unexpected will break

At this point I still want to postpone a respray ALAP and just drive the thing. I really hate the lack of Schwarz-lowers, and I might figure out a cheap solution to paint the lower trim, at least. I have only put 5k miles in the last year and since the S38 rebuild, and now my 911 needs some love. Nothing is broken on that car, but I've been wanting to waste money on it for awhile and just started by splurging on a pair of 16x8 Fuchs replicas for the 911. At $450 shipped, I'm happy with replicas when a pair of genuine 16x8s are now going for $2k.
 

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One of the responses to my WTB Turbine covers finally panned out, and I got a full set minus bolts (new emblems already ordered):
Congratulations! Im sorry i could not help you at this. May i ask how much you paid?

Cheap and easy schwarz-lowers solution might be Plast dip/Rubber comp RUBBERcomp -rubber coating, Maston - Car-Rep. Schwarz-lowers really makes car look right.
 

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Discussion Starter #17
I forgot to add that I ordered 44mm studs and nuts to do a stud conversion. I made sure they would fit under the Turbine caps (and my Style 5 center caps), and I am tired of lug bolts. I have taken my wheels off ~20 times already.

Congratulations! Im sorry i could not help you at this. May i ask how much you paid?

Cheap and easy schwarz-lowers solution might be Plast dip/Rubber comp RUBBERcomp -rubber coating, Maston - Car-Rep. Schwarz-lowers really makes car look right.
Thank you for your help, anyway! I paid $400, plus $25 in emblems and $20 in non-BMW bolts. The covers, fins, and caps are all intact, just with small scratches/imperfections.

I will probably Plastidip my lowers, that will be the easiest and cheapest. I agree that M5s need the lower color contrast, it sets them apart from the lesser models.
 

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Big old exciting update (at least for me). I've been busy but I was able to spread out this work over three two hour segments Wednesday-Friday night, mainly so I could make it to Cars and Coffee Saturday. Which was worth it, because the car was a big hit! Roland (REHaas, the previous owner) drove the M5 so I could take the 911, and the M5 got more attention than my 911 by far. Roland wants the car back :grin

The Install:

This was the trunkload to be installed Wednesday night (left hand box is the rebuilt a/c compressor, which I have yet to get to):


I started with the arms. 3/4 ball joints popped out with minimal effort (pickle fork + hammer), while the 4th took a solid 30 minutes. Here's a comparison between old and new. All the ball joints were shot, and the UCABs were fully compromised. I was surprised to find E31 lowers already installed! The bearings in those were obviously still fine, but not the BJs.


Bad picture, but here is a Moosehead installed. I oriented the set screw to point down, and the adjustment plate towards the center of the car (as recommended by Moosehead), so that I can tighten the spherical without disassembling in the future. These are seriously quality units.


Since the strut was disconnected from the plate, it was time to install the front H&Rs. This is my strut top nut tool combo, since I don't have air tools. It works perfectly!


Comparison between OE M5 spring, and the 540i P/N H&Rs. The M5 is already factory lowered ~20mm from other E34s, so the ~33mm drop cited for these springs on 535/530/540s is not fully realized on my car. You can tell the H&R is not much shorter than the M5 spring (the H&R is leaning more). I'm okay with this, since my main goal was just a stiffer front.


Buttoned up and torqued down. I love my TrackMat!


I don't have shots of the rear Billie + H&R install, but it was super easy (about 30mins per side, since I didn't need to swap springs). My suspicion about the rear end being soft and saggy was confirmed when I saw these OE 535i shocks & springs, and found I could actually depress them by leaning on them.


And while I had all the wheels off, I installed the Motorsport Hardware TUV-approved stud conversion. The studs are lifesavers, particularly because the Turbine covers obstruct your view of the hub when lifting a wheel into place. The brakes work perfectly, but the admittedly cheap rotors installed a few owners ago are already unsightly . I don't know how long I can take that, but at least Turbines hide the brakes.


The Verdict:
I knew the ball joints were bad because they clunked loudly over every imperfection in the road. I knew the UCABs were bad because of the shimmy, general vibrations, braking instability, etc. So obviously, with the new and upgraded control arms, it's a different beast. It tracks straight, makes zero noise over bumps, has LESS NVH, and feels like a sports car when I turn in. There are zero vibrations or shimmy of any kind.

I had been trying to diagnose an issue with the rear suspension: over significant bumps/potholes in a straight line, I was getting wheel hop and a nauseating unsettling of the rear end, and while turning even small imperfections caused the same sensation. I have poly subframe bushings, new dog bones installed correctly, and had pushed and prodded on everything back there and found no play. The RTA bearings are good as new. So, the big and happy surprise was that pulling those failing OE 535i shocks and installing Billies and H&Rs completely cured this wheel hop and rear end unsettling issue, verified over the worst roads near me and some power oversteer over bumps. After research, I found that this sensation is common with soft or blown rear shocks.

I find the H&Rs w/ the full-length Billies to be just the ticket. Over the roughest roads, it's firm but not jouncy and nowhere near the bumpstops, and I feel that the front end (and clearly, the rear) gained exactly as much stiffness as I wanted.

Next Steps:
The M5 has never driven better, and I plan to autocross it very soon. The fresh front end has made it clear that I could adjust the steering box, eventually replace the steering links (just need to buy tie rods and the pitman, since I already have a center link on hand) and swaybar links, and get it aligned. But it is really close, and the steering is still tight.

Now that my rear end is rock-solid over bumps and under power, I'm convinced the light clunk I get related to clutch take-up is purely drivetrain related, not suspension/bushing. I'll be investigating it more, as well as getting to the A/C system as it's warming up in these parts!

Depending on how long I own this car, I might figure out a good ball joint replacement strategy, since my Mooseheads will last forever, and I now have two sets of E31 arms w/ perfect bearings. The E30 and E36 guys now regularly press bad BJs out, and new ones in, so it's just a matter of finding the right replacement (since I know BMW doesn't sell them separately).
 

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Discussion Starter #19
The car has been running perfectly.

So $500 later (Safelite + new OEM windshield trim), I finally have a good windshield after driving around for 1 year+ with destroyed glass. To repay me, the driver side low beam euro Hella lens shattered a few hours later. And now my windshield cowls look bad, so I'll probably spray them black and will buy all of the clips for the cowls.

I have a late-model E34 driver wiper arm on order, and have now added a new Hella lens. I'll probably need to buy the pass. side lens soon (it's already cracked), but want to make sure I ordered the right part first. I will then lamin-x these things, which I should have done from the start.

Not expecting the Hella lens to shatter, I scooped up a used JC E34 M5 chip from eBay (thanks for the lead, Rolando aka Dizzythree) and look forward to trying that out. It's just money...

Discussing the cosmetics with friends, I do plan to book a respray in the next 6mos to a year; but until then I will probably sand down the bits of rust and cover w/ something like white Rustoleum to prevent further rot. I would rather have non-matching white spots instead of rust/bare metal patches (the spots are very small so far, anyway).

The new glass and black eye:

 
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