Are the genuine bolts on the E31 staggered style 5's made of stainless steel or not?
Does a magnet stick to them? Not definitive, depends on the grade of s/s, but I can't see BMW using anything but the best:-)
Just remember that stainless is softer than plain steel. The higher grade the stainless, the more chromium and hence the softer it is. I used to work in dairy industry engineering where the hygiene of stainless was a must, but there was a lot of maintenance changing out shorn or bound threaded parts. There's some parts on my car Ive switched out for stainless, and some I'd never go near, like the bolts that attach the strut to the steering knuckle, just because it would result in weakening the joint. Wheel nuts might be ok strength wise, but I'd be conscious of damaging threads. Each to their own though.
If I had a penny for everytime someone commented on my poor fuel economy, I'd have enough to get it to the petrol station.
I redid mine with stainless steel - no more corrosion worries, and they stay shiny if you polish them before installation.
'93 850Ci - Mineralweiß Metallic
2001 740iL - Titansilber
ALPINA B7 -Alpinweiß III
...the price of cool ain't cheap!
braincat:
I think you may have got a little mixed up, Plain carbon steel (mild steel) is softer than stainless, due to the chromium content of the s/s. S/S can be brittle compared to carbon steel, but not softer.
There's a big difference between austenitic (non-magnetic) and martensitic (magnetic) SS. Even within the non-magnetic SS flavors there are large differences in the properties. Use of SS in sanitary/food components is required but for something that is structural or is stressed I'd reconsider using it (JMO). Welding it tends to develop stress cracks at the weld, machining can be a PITA (gummy), and it's relatively soft compared to better grades of carbon steel. It does oxidize in the absence of atmosphere, galls on itself (and other metals too) and often just doesn't seem worth the "stain-resistant" properties unless used for marine applications. Most SS measuring instruments are made from martensitic SS. I made some machined shafts for the OEM jacking locations from 1" (non-magnetic) SS and they bend under the partial weight of the car after a couple of sessions of simply lifting, not holding, the car until I get a jack stand under the pads.
Thanks guys! I think I will get my bolts refurbished, and the company wants to know the material of them. Haven't got them out yet though, which leads to my next question. Is it a pain in the ass to get these 136 bolts out? I mean, is it worth the effort just because the bolts have some rust on them?
I redid 5 Style 42s for an e39 and I believe the bolts were titanium. There were 19 per wheel and the head was a triple square. I removed each one by hand with a small ratchet and kind of slowly pumped each one. They eventually all came loose and none of them broke. I put each bolt on a bench grinder with fine a wire wheel and they cleaned up nicely and I reused them. I retorqued them at quite a low pondage like 15 lbs.
After removing the curb rash with a coarse file around the rime I went from 80 grit sandpaper through 2500 grit and then a buffing wheel and hand Simichrome polish and they look like jewelry. Lastly, I hand wiped a coat of Sharkhide, about $59.00 a can. I plan to install them in the spring but the cost to refinish the wheels was under $100.00.
wheels 007.jpgwheels 008.jpg
If I had a penny for everytime someone commented on my poor fuel economy, I'd have enough to get it to the petrol station.
fair call but there are SS fasteners rated to the same 8.8 10.9 & 12.9 available out there. You might find some ARP SS bolts with the required spec of the same dimensions, some far exceeds normal HT fasteners. Also Google BUMAX fasteners, it's another alternative.
Galling is largely solved in "engineered" applications by specc'ing the right nut to go with the bolt. Usually by using different grades of SS, e.g. 4xx series for the bolt and 3xx for the nut. Problem is SS fasteners that are generally available off the shelf are all 3xx. You can also use lubricants against galling but you'll have to think about using nyloc, nord locks or similar to lock down the fastener as you can't use loctite (thread locker) if there's lube on them.
For stuff that I don't plan on disassembling ever I have used loctite as lube and just work quickly before it sets. remember you need to use an activator on SS or the loctite will not set.
Then there's also the elephant in the room - galvanic corrosion. That's another discussion altogether but in short if the total surface area of the SS fasteners compared to the substrate (e.g. the wheel or the engine you're bolting together) is insignificant then you shouldn't see much accelerated corrosion on the substrate.
Yes it's a lot more involved using SS "properly" which is why it's often advised against in forum-land. And yes, it's more expensive. But it's not some secret sorcery and discounting it carte blanche will just shut one out to a whole world of possibilities.
nice work!
Titanium can gall, just like Aluminum and SS as it's the surface oxide layer that cause galling (but it's also the layer that gives it's corrosion resistance).
You've already figured out to go slow when loosening and tightening. well done.
For others I'd recommend cleaning the threads the best you can and using some self wicking lube before disassembly as road grit and general junk in the threads can also kick off the galling process.
"But it's not some secret sorcery and discounting it carte blanche will just shut one out to a whole world of possibilities.-affa"
-Well I don't think that's what I posted so I hope that's not what others got from it. I consider the reasons for using it vs. the disadvantages. Often the drawbacks outweigh the benefits and I'll select another material when fabricating or machining something. That's all I was trying to contribute.
-Use of Ti for fasteners/components is another instance for weighing the potential problems vs. the benefits. Problems with using Ti are well documented and I know of several instances of dynamic shear deformation from using aftermarket components. Like using SS, can problems be avoided? Likely they can but that all depends upon the knowledge and measures taken by the individual.
-Is it worth the problems/risk? For me the benefits of both are often not worth the trouble if other materials are available that fulfill the requirements. That's all I'm trying to say here. YMMV.
Your least anodic reaction between the aluminum and the bolt will be with stainless steel. You can safely use the SS bolts and nuts without worrying about shear or deformation. Just remember that there are 34 bolts per wheel that hold the pieces together - the shear forces on the wheel and barrel are spread over these 34 bolts, unless you have 20,000 HP acting on this wheel, you should be more than ok. I have had my wheels up in the 150MPH range without so much as a vibration - you guys are overthinking this.
'93 850Ci - Mineralweiß Metallic
2001 740iL - Titansilber
ALPINA B7 -Alpinweiß III
...the price of cool ain't cheap!
^That about sums it up, I certainly wouldn't be putting rusty bolts in my wheels.
To answer the first question:
I believe the through-bolts on the Style 5 composite wheels are high-tensile steel, chrome plated.
If you want to restore the original look they can be re-plated, or buy new ones.
Stainless is a good option if you're not that fussy.
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