I took mine to a local race shop. Their fabricator was very good, but had never installed one of Randy's kits. Because Randy supplies VERY good documentation (and is open to phone calls), any experienced fabricator should be able to install the kit with no problems.
You could see is Randy would be willing to send you a copy of the instructions so you can let your guy read through it to see if he is comfortable doing the work.
Last edited by khammack; 06-25-2017 at 10:49 AM.
2002 M Roadster, Steel Gray Metailic, Gray Nappa Leather, Black Soft Top, Steel Gray Metailic Hard Top, TC Kline Double Adj Shocks with H&R Springs, Stromung Exhaust, SSR Type C Wheels. Looking for a new home.
2022 Z4 M40i, Misano Blue Metallic, Prem Pkg, Driver Assistance Pkg
2023 X5 M50, Phytonic Blue, Black Extended Merion Leather, Driving Asst Pro Pkg, Park Asst Pkg, Exec Pkg, Climate Comfort Pkg.
Sorry if this has been answered many times before. I'm new here and am looking for a good condition mid-price/mileage Z3 M roadster and would like to know exactly which spot welds in the trunk floor to check. I would like to see all welds holding and I know about the group of welds just over the diff mount. What about far left (driver's side) and far right? I've only looked at these on-line so I've not gone under to see the diff mount itself. Any help is appreciated.
Keith
Hi Keith, it will depend on what year M Roadster you are looking at as to whether there is sound deadening in the way, but basically you are looking at the spot welds that fasten the trunk floor to the cross member underneath that has the differential mount spot welded to it. It runs side to side across the floor (as opposed to front and rear), and is partially covered by the tool trays and battery cover, if that helps. You should also look at the floor welds spreading out from the ends of the cross member where it attaches to the side rails. As a separate investigation, you can look under the car at the differential mount itself to see if there are stress/fatigue cracks developing, if any of the welds attaching it to the cross member are letting go, or if the cross member appears to be breaking free of the floor. It is tough to look at without a lift however. Use good light and take pictures for additional help.
Amazing thread!
So my turn on this. I took it my buddies shop and we looked pretty good around and couldn’t catch any bad welds, but then again, it was was kinda fast and the more I read, the more I’m worried, since I’m hearing more noises back there. even after a good cleaning.
I purchased this Coupe with 42k miles on it, and it was owned by my friends mother. She BARELY drove the thing and said she never beat on it. She purchased the vehicle from an older gentleman with about 5k miles in 03'. I know its almost impossible to say without seeing, but whats the chances on it having bad welds?
Last edited by z3m.casey; 11-07-2017 at 02:54 AM.
So here is a great photo of just what you are looking for when it comes to bad welds--this is where they most typically show up and what they look like (originally posted bu Member Gomanual in this thread):
Very helpful. Thanks!
Do you ever see breaks/cracks in the diff mount when the spot welds in the trunk look perfect. Looking at a 40k mile 2000 M Roadster with perfect appearing spot welds in trunk photos but I don’t have a good shot of the diff mount itself. Shopping long distance!
Thanks
Keith
There are two (2) distinctly different problems in the rear end; the differential mount can crack across its width, and the spot welds holding the trunk floor assembly together.
Yes, I have seen cars with an essentially perfect floor assembly, with zero failed spot welds but with a crack propagating across the differential mount.
And yes, I have seen cars that have a perfect mount, but with several failed spotwelds.
Usually, by the time a car gets sent to me__even when the owner thinks they're being proactive and reinforcing it before any damage starts__there are already signs of problems in both areas.
Gary got your kit last month and had a place called touring cars in Charlotte NC install came out great the shop was real impressed with the kit and the workmanship of it so again thanks Wayne
Hello , new to the forum . I just bought a Z3 2.8 and found pulled rivets in the trunk floor and one ear of the diff bracket cracked . I saw the problem of the trunk prior to buying but missed the bracket . However I did not pay much for the car so I am not too upset . I have contacted Randy already and he has been very helpful . I will be ordering the kit shortly . I live in the Montreal area and wonder if anyone has done it themselves ? I am torn between doing it on my own or taking it somewhere to get it fixed . Thanks all .
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People have done it themselves--you need the facility, tools, and skill--but if you possess these and the time, there is no reason you can't tackle it yourself. I had all but the time when I had Randy do mine. Randy has excellent photo gallerias, so you can check out every step of the job in assessing your facilities, tools, and skills.
Yes, lots of people have! One (1) of the ways I shame people/build their confidence (take your pick ) into taking on the job it to tell them about the then fifty-some year old woman that was then living in Florida__several years before we moved here ourselves__that did her own M Coupe! I had a chance to inspect her work at one of the last few Homecomings (held at the plant in SC) and she did a very impressive job! Shawn and an M Rdstr owner were doing their cars simultaneously, and I believe Gordon helped her with some of the out of position welding, but she did the bulk of it herself.
Soooo, if she can do it, should be a walk in the park for an airframe mechanic...
Besides the (67,294 and counting) pictures online for reference, you can also call me if feel like you painted yourself into a corner.
Hello,
Aside from a visual inspection of the spot welds and the differential mount can you tell me what symptoms to expect while driving the car. I have a 1998 Z3M Roadster with perfect spot welds. I have not put my car on a lift yet but, using a flashlight and getting fairly close to the diff I couldn't locate any cracks. When I drive the car, however, I hear something loose from beneath me. A bit difficult to describe in words. Almost like something is moving around or back and forth, beneath me.
It is very common for the rear shock mounts to disintegrate and bang around back there. It is also common for the hanger bearing of the drive shaft and/or the giubo to go bad and make noise. If you can hear the trunk floor/differential mount/subframe issue it's because the differential cover is scraping along the pavement and you won't have any doubts about that.
Okay, I’ve read through this entire thread and have two questions. The sticky on this subject mentions an effective preventative preceeding any failures. My M Roadster has 20k on it from its original owner who babied it from day one.
1) If there are no signs of failure in all of the prone locations, can I simply replace the bushings with poly to avoid any future failures?
I know as long as I own the car, the style of driving and miles driven per year will be pretty much unchanged. The only variable I can’t compare or control are road surfaces utilized, but I’m assuming failure is caused by engine torque versus stiff suspension.
2) Is there still a highly recommended first choice for which vendor and poly bushings to use?
Thanks.
Last edited by Tigershark48; 01-05-2019 at 07:42 PM.
From what I've read and think, replacing the subframe bushings with poly should stiffen up the rear and thus should minimize the chances for the failure. I would still continue to monitor the welds but you should be good to go. I just put Ireland Engineering on my M this summer, it had the originals still. BTW- my welds had failed prior to my ownership, whoever repaired it just put the metal back together and rewelded it. I am planning on reinforcing this over the winter with Randy Forbes kit. I can tell you that you don't want to wait until it really fails though.
Good luck!!
The general consensus is that poly subframe bushings will in fact prevent future damage in that no one has ever reported a car with poly bushings put in before damage surfaced ever suffering trunk floor/differential mount/cross member failure after. Ireland Engineering are the presumptive best, although look to be sure they are new and newly manufactured--not NOS--as there was a bad batch produced several years ago. I believe you can buy them directly from Ireland to be sure of this. http://www.iemotorsport.com/bmw/item...bfrmmount.html
Consider new shock mounts while you're at it from Rogue Engineering http://www.rogueengineering.com/Rogu...E46_p_270.html
Do not go with poly rear control arm bushings as these tend to squeak--OE is best for them.
I concur. You know what to look for, so a couple times a year take to look. Roadsters are so easy to inspect, there's no excuse not to!
IF things go south, and I'm still looking down and the dirt, you know what you can do to resolve the situation.
Great advice gentlemen, including the squeak avoidance tip. Thank you. Tomorrow I inspect for failures.
Is there a relatively easy procedure for doing the poly bushing upgrade? My goal is to buy the Ireland Engineering components and do it myself. The alternative would be to order the same and have my BMW tech install.
This spring I plan to get all fluids changed to establish a base point for future service intervals. As the second owner, it makes sense to re-establish the proper intervals. This would be a good time to change bushings. I have a retired service manager friend who recommended an excellent tech to ask for anytime I need someone to go to.
Randy,
Do you have pictures of your reinforcement installation? I haven’t actually seen the installed modification and would very much like to see how it looks on the vehicle. Thanks.
It's a Hybrid--Burns Gas and Rubber
Good news. Checked the welds on mine today and, as expected, they are still in showroom new condition.
Last edited by Tigershark48; 01-06-2019 at 03:52 PM.
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