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I recently bought another roadster - a '01 with 67K - and the diff mounts / subframe look pristine. How important / urgent is it to install the reinforcement kit? Any other preventative steps that can be taken before that work is done?
It's not the years in your life that counts, it the life in your years...
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Check your trunk floor spotwelds for cracks or separations and your differential mount for cracks. If there are any failures in those areas, the reinforcement should be considered urgent. If not, you have time to read all the other posts and think about it. Factors affecting your decision include how aggressively you will be driving it.
My newly acquired M is like new, including the areas of concern. My plan is to to put the second 20k miles on the car over the next 20 years the same as the last owner. I doubt that a kit will be needed during my ownership.
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My M Coupe has got over 104K miles on it, no signs of welds cracking yet!
Marty, hoping I didn't just jinx myself .....
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Why risk it though given the considerable worse costs of a failure? Even with 20k miles, all that rubber is 20 years old and could allow enough movement for things to crack possibly
Originally Posted by Tigershark48
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Forgive me if I'm telling you something you already know: Poly subframe bushings are preventative against the failure. They are far cheaper, and should be done anyway for handling and road "manners". Also, not all Z3s develop this problem. My 98 M has 112k miles and no signs of failure. I don't do burnouts (no idea how POs drove it), so I'm hoping to never have to do the reinforcement.
Last edited by zellamay; 03-11-2019 at 11:36 AM.
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From what I've heard its actual lateral forces from hard turns that usually cause the tears, not burnouts. I'm sure they can't help though haha
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Rubber looks good everywhere, but still planning on poly bushing excluding the differential mount. If nothing
else, it will make handling even better than it already is.
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I was watching mine while the RF kit sat waiting. In the winter last year I noticed a change (drivers side welds looked different) and checked against my 5 year old “original pictures. It was starting, just the slightest of hairline type cracks around the spot welds. I thought I had time. Two months later that spot weld was cracked all the way around and others were also starting. And that was driving it easy.
However this does not answer your question. It depends on what your car is like. In the case of MartyBtoo, it’s not important at all (fingers crossed that it continues) & in my case it wasn’t for 5 years. BTW mine has 88k miles.
One last note. I think you are far better off to fix it before it gets bad. What’s bad, depends on how much you want to pay to get it put back to normal. With little stress cracks it’s still a cut and weld job. I would think that gets WAY harder the more the bodywork self destructs.
Last edited by catimann; 03-11-2019 at 07:10 PM. Reason: More info needed.
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Catimann,
Were you running poly bushings or still original rubber?
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To some, not it's not very important at all. There was dealer service reports among the trash strewn throughout the interior declaring the car unsafe to drive dating several years apart (addressed to different members of the same family).
To each their own, ymmv!
Last edited by Randy Forbes; 03-11-2019 at 08:17 PM.
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Everything looks original. Thinking of installing poly bushings in the sub-frame and all four corners.
It's not the years in your life that counts, it the life in your years...
Member
Sounds like a good place to start. And that very well could be enough.
Member
Yikes! Likely clueless owners who paid practically nothing for a sportscar they couldn’t afford to maintain.To some, not it's not very important at all. There was dealer service reports among the trash strewn throughout the interior declaring the car unsafe to drive dating several years apart (addressed to different members of the same family).
To each their own, ymmv!
Member
Yes my car is all original but that picture from Randy is not my car. It has 88k miles on it. A 98 US car with no winter driving on it since 2000 when the PO bought it.
edit: I noticed I didn’t say how I drive, nor did I mention the history of the car other than summer driving.
The car was first leased and as I understand leases, bringing the car back in bad shape will cost you. I assume the car was in great shape because the second owner was VERY particular about it and had EVERY last little thing looked at while it was under warranty. It was garaged and virtually never saw rain. He was more interested in the expensive stereo and the sensitive alarm. It was nearly perfect when I bought it.
I did more damage to it in 3 months than he did in ten years. I don’t do burn outs but often launch fairly hard and cornering is what I live for. When the tires start to squeal or it starts to squirm out of the arc it’s traveling along then I must be having fun. Drifting it is also fun but I mostly do that in the rain. I can’t say how many times I’ve had the car snap back from an almost total loss of control. (I only do this with no one anywhere near me. Not even in sight of me & not in town.)
Last edited by catimann; 03-13-2019 at 05:30 PM.
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I'm much more of a 'grand touring' type and while I often drive at an 'elevated' pace, I look for smooth and flowing rather than attacking and maximum g-forces. As Tigershark48 suggests I think a bushing update is the way to start and may be enough. I'll closely monitor the spot welds and diff ears as the miles roll by.
It's not the years in your life that counts, it the life in your years...
Member
Sorry to harp on this, but no matter your driving style/needs, do the poly subframe bushings. It improves cars manners in all situations; makes it a better car. Once you do it, you'll wonder why they ever built one with rubber there.
Member
I understand why some people have reservations about upgrading subframe bushings. It's a significant cost if you outsource the repair. Moreover, once you drop the subframe, all of the items that fall into the, "while your in there, how about replace this and that" are in-play. And since you dropped the subframe, why not spend a little more and install the RF kit.
Z3 enthusiasts are the exception and are willing to put in the time and money to preserve and/or improve a car they love.
Tony
"You can't sign away negligence."
Member
Right, like I said I'll be upgrading all the bushings: sub-frame, trailing & control arms. Now I need to decide if I pull the subframe myself or pay to have someone do it for me. As I don't have a lift will probably pay for the rear but do the front myself.
It's not the years in your life that counts, it the life in your years...
Member
I dropped my subframe without a lift. The biggest issue is removing the existing subframe bushings. They're pressed in and have locking tabs. Many, including myself, used a bit of heat and a custom bushing puller to removed the OE bushings; the poly bushings just slip in.
The attached picture shows the OE bushing removed using my customer puller
.bushing.JPG
Tony
"You can't sign away negligence."
Member
I also dropped the sub-frame without a lift and removed the bushings with a home made bushing puller and a heat gun. Though I am mechanically inclined, I am a complete novice when it comes to cars. Lots of information in the FAQ to help guide me and I used "Clint's IE Install Tips" as an almost step by step guide.
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How did you guys raise the car enough to work on it without a lift? I know there are ways, but curious about yours in particular since you dropped the subframe.
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I just put mine on jackstands. That's enough room to lower the sf enough to do the job. I used the homemade puller described on this site. I think a heat gun is better. Less danger, easier to apply locally. I applied pressure with the puller, then heated all around until I could see the bushing move, then tightened the puller some more. Came right out. ADDED INFO: thread for homemade puller: https://www.bimmerforums.com/forum/s...frame+bushings
Last edited by zellamay; 03-15-2019 at 02:37 PM. Reason: to add puller thread ref
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As I am in the process of putting the car back together I have the whole thing kind of fresh in my mind. I KNOW this has been discussed to death many times over and you could read for weeks about it, start here: https://www.bimmerforums.com/forum/s...-mount-failure
I have formed the opinion that bushings will not help. If they have an effect on the ear and body welds then it is very small. The Diff is mounted at three points. Two bolts to the subframe and the ear mount to the body. I think the repetitive torque motion from the diff slowly but surely pulls apart the body welds. Now that I have had this R.Forbes kit installed (I prepped the car and got a welder to install it) my thought to your question "Any other preventative steps . . . ?" is this. The body welds and the sheet metal the body is made of is not thick enough to deal with the added HP of the 6cyl. If you add more welds it my help. Add extra ear metal (like the R.F. install recommends) and perhaps some extra metal in the area the problem starts at and it could be ok. And after you got to the period of that last sentence you already knew the answer was Just do the R.F. kit. All this said here is a quote from the above link.
"It is generally agreed that a part of the overall problem (and this does involve the subframe) is that the subframe bushings mounting the subframe to the body are too soft, allowing too much play, and placing an undue stress on the differential mount. There are polyurethane subframe bushings available in the aftermarket to address this aspect of the problem, with the Ireland Engineering (IE) bushings being generally recognized as the best option. Many believe, and there is anecdotal evidence to back this up, that going to the IE poly subframe bushings can prevent the problem from developing in the first place." I am so convinced of my opinion that I would love to hear from the guys who did just this as a preventative and then spent the next 5 years driving the crap out of their cars. If you find five cars that survived this I would change my opinion.
If you set up the work place and have a welder ready to go I would think you can have the R.F. kit in the car and on the road in 3 days. Not me but procrastination is my middle name.
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Standard harbor freight jack stands are plenty tall on the second setting to get ground clearance. But what made the real difference in my garage was the atv/motorcycle lift. Plenty of surface area and clearance to balance and lower or raise the subframe and diff.
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I only jacked up the rear of the car and as zellamay said that gave enough room to lower the sub-frame and perform the work. I also completely removed the fender liners instead of just bending them back.
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