'91 M5 #06091 resto thread

[AHenry014]

avoid the bilstein sports. I had them with h&r's at one point. The rear bilsteins are OK, if not a tad soft, but the fronts crash over everything. I swapped the fronts to koni adjustables and the ride was immensely better. Go koni, you cant go wrong with them. I enjoyed my h&r springs as well.

[BleedsBlue]

avoid the bilstein sports. I had them with h&r's at one point. The rear bilsteins are OK, if not a tad soft, but the fronts crash over everything. I swapped the fronts to koni adjustables and the ride was immensely better. Go koni, you cant go wrong with them. I enjoyed my h&r springs as well.

Roger that, I read enough to know to avoid the Sports.

[Tre0Tre34]

I forgot to add, I also bought 44mm studs and nuts for a stud conversion, once I made sure they would fit behind the Turbine caps. I've had my wheels off 20 times already, and I hate lug bolts.



Thanks!

And yeppers, I priced out the GC kit for about $1800, but I will have trouble justifying the cost when my entire goal is just a lower ride height. I'm sure the H&R and Billie combo will look great, I just hope it's not too stiff. If I went with GCs I would get super soft (for coilovers) street-only spring rates.

Are you doing control arms, steering links, etc, at the same time?

I agree with the softer end of the spectrum. guess im getting old.

not doing any of the front end links as I replaced all of it a few years ago and they are holding up just fine. real motivation is the rear shocks have been a bit soft for a while, and I am now hearing a slight rattle telling me that my rear strut mounts are not so happy. will also get to the rear subframe bushings while im back there.

Edit: BTW Bavauto has a pretty nice deal on koni adjustables currently. paid $625 shipped.

[BleedsBlue]

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) 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

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).

[stoney85]

A suspension overhaul is one of the most rewarding things to do to a car for a better driving experience, nice looking old rear shocks too!

Good to hear about the moosehead sphericals, will be ordering a set soon.

Seeing that its an M5, we need more photos of it.

- - - Updated - - -

Also, looking at the old lower control arms, they don't look like E31 arms, they are alloy which the M5 also comes with, and it looks to not have the spherical bearing, rather just the standard bush setup which sits flush to the arm, the bearings have a more sunken look

[BleedsBlue]

A suspension overhaul is one of the most rewarding things to do to a car for a better driving experience, nice looking old rear shocks too!

Good to hear about the moosehead sphericals, will be ordering a set soon.

Seeing that its an M5, we need more photos of it.

- - - Updated - - -

Also, looking at the old lower control arms, they don't look like E31 arms, they are alloy which the M5 also comes with, and it looks to not have the spherical bearing, rather just the standard bush setup which sits flush to the arm, the bearings have a more sunken look

Roger on the pictures, I forgot to take some! Though to be fair, the drop was not significant since the rear was already sagging

I ended up setting the Mooseheads too loose initially and heard them clunking, so last night I jacked her up and was able to tighten them easily with hand tools.

The old LCAs are definitely E31 sphericals, they have the 477/8 part numbers. Perhaps they are an older style or different brand? The new Lemfs do have the sunken look.

[stoney85]

The old LCAs are definitely E31 sphericals, they have the 477/8 part numbers. Perhaps they are an older style or different brand? The new Lemfs do have the sunken look.

Shows my inexperience with the good parts these car can receive. What are you doing with the old set?

[BleedsBlue]

Shows my inexperience with the good parts these car can receive. What are you doing with the old set?

I was surprised to find them, since this car was such a mess from 3-4 owners ago. The old arms are why I brought up replacement ball joints. Those arms are ~$170US a piece! The E30/36 crowd has found replacement ball joints that are ~$20 and easily popped in and out via press. Then I could refurb these old arms and sell 'em.

[Tre0Tre34]

those rear struts look like they've had it!!! Will be interesting to see what mine look like when I get a chance to yank them out. I know they are anything but fresh.

Nice work with the continued refresh!

[Mr Tripp]

Very nice M5 you have nice to see that your vin is so close to mine (06073)

[BleedsBlue]

those rear struts look like they've had it!!! Will be interesting to see what mine look like when I get a chance to yank them out. I know they are anything but fresh.

Nice work with the continued refresh!

Still amazed how terrible and loose those old things made the rear end feel, and relieved the Billies fixed it.

Very nice M5 you have nice to see that your vin is so close to mine (06073)

Coolio! Just checked yours out on Mregistry, looks beautiful.

[Tre0Tre34]

Still amazed how terrible and loose those old things made the rear end feel, and relieved the Billies fixed it

i hope the konis do magical things to tighten my rear end (along with the subframe mounts, top mounts and springs of course)... That doesn't sound right.

The slight knocking sound from what I believe are fubar'd top mounts is now accompanied by a bit of a shimmy around 30mph. Damn I need to get in there. But this weekend is already not looking good.

let me know what you find with the replaceable Ball Joints. Don't need LCA's yet, but I might be interested in a set to have around for when I do. Especially if they have bearings.

[dizzythree]

Thanks for letting me drive the beast again.

Drove so much better than when I owned it.

And I swear those rear shocks were dry when I put them in 5,000 miles ago.

All 4 rotors were replaced by yours truly. Not sure what brand they were, but I think I got em from Bimmerworld? Maybe time to take em off and paint them up really quick, they did sit for quite a while.

[93FIM5]

Nice progress when is the next cars and coffee I'd like to see the beast in person.

[BleedsBlue]

i hope the konis do magical things to tighten my rear end (along with the subframe mounts, top mounts and springs of course)... That doesn't sound right.

The slight knocking sound from what I believe are fubar'd top mounts is now accompanied by a bit of a shimmy around 30mph. Damn I need to get in there. But this weekend is already not looking good.

let me know what you find with the replaceable Ball Joints. Don't need LCA's yet, but I might be interested in a set to have around for when I do. Especially if they have bearings.

I hope everyone tightens their rear end.

I'll admit, the ball joints aren't a huge priority, but I will check it out. These bearings apparently tighten up the steering feel even compared to fresh bushings, so the arms would be worth picking up if I can get fresh BJs in there. Aaaand it's accidently NSFW again.

Thanks for letting me drive the beast again.

Drove so much better than when I owned it.

And I swear those rear shocks were dry when I put them in 5,000 miles ago.

All 4 rotors were replaced by yours truly. Not sure what brand they were, but I think I got em from Bimmerworld? Maybe time to take em off and paint them up really quick, they did sit for quite a while.

Of course, mon frer. The shocks were dry, I can confirm that. I can also confirm that a few roads around my apartment could be used for damper testing for WRC Australia.

I mean the rotors and pads are solid and function perfectly, they're just an eyesore. Much less of an issue now that they're hiding behind Turbine covers. Of course, these just showed up, so there is that

Nice progress when is the next cars and coffee I'd like to see the beast in person.

It would be June 6th, but I'll be in CA for a wedding. So maybe July 4th, though it might be rescheduled for obvious reasons.

By then I'm SURE yours will be under its own power, yeah?

[dizzythree]

By then I'm SURE yours will be under its own power, yeah?

Nah, he's going to take it apart again long before then I'm sure.

[93FIM5]

Nah, he's going to take it apart again long before then I'm sure.

Haha! This is always a possibility!

[UnrulyGrace]

Little bump, wanted to ask how you're liking your suspension setup...I'm in need of UCAB and will pull the trigger on Mooseheads soon. I think they will compliment my setup well.

[de Witt]

Like the refurb . . . looking great.

[stoney85]

I'm patiently awaiting my set to arrive, found through a forum post that they are waiting another delivery of parts and therefor their deliveries have been delayed

[BleedsBlue]

Little bump, wanted to ask how you're liking your suspension setup...I'm in need of UCAB and will pull the trigger on Mooseheads soon. I think they will compliment my setup well.

You should definitely go for the Mooseheads, no doubt. I'm loving it, I have them dialed in correctly and while there is still a bit of noise on rough roads, there is no increase in NVH (at least compared to worn out stock parts) and you can only hear them working with the windows down at low speed. I didn't know beforehand that my LCAs were E31 already, so I can't really comment on the change in LCA (besides having new ball joints, which is obviously tighter and silent as it should be).

The thing that really sealed the deal for me w/ Mooseheads (and other spherical UCA bearings) is the serviceability, since apparently one can go through quite a few sets of stock and poly UCABs. I can tighten up the Mooseheads with them installed just by pulling the set screw and tapping the lock plate tighter, removing any play that develops.

Like the refurb . . . looking great.

Thank you! I haven't seen your thread/car, what do you drive? Ever come to meetups?

I'm patiently awaiting my set to arrive, found through a forum post that they are waiting another delivery of parts and therefor their deliveries have been delayed

Nice! Mine did not arrive quickly when they had parts in stock, so I imagine you might be waiting a couple weeks. It will be worth it. I can highly recommend E31 lowers to complete the front end.

[de Witt]

91 M5 and 88 M5 . . . 91 is ex Ken Little's. I haven't been to any meet ups, but maybe sometime soon.

[e24mpwr]

This...is a great thread. Congrats to the OP!

[BleedsBlue]

91 M5 and 88 M5 . . . 91 is ex Ken Little's. I haven't been to any meet ups, but maybe sometime soon.

Holy... mackerel, your 91 is clean and how I'd like mine to end up, especially with the stock black lower trim. Though I'm partial to my Turbines, now.

It'd be great to meet another E34 guy, I know there are a couple of us in the area.

This...is a great thread. Congrats to the OP!

Why thank you! Congratulations are not due to my wallet, but it's been worth it.

[de Witt]

Thanks. It is in pretty good condition for 217k on the odo, never babied though. I do like the turbines, though I dont run them. I always go with my staggered M parallels during the spring/summer/early fall, then switch over to the 8J M System wheels without any covers on some snow tires. I used to run t-star covers, but one shattered during a winter (it was -20F) and somehow punctured a tire.