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Suspension work: Reusing Nuts and Bolts, Nuts only, Nuts + Bolts

22K views 48 replies 19 participants last post by  occhis 
#1 ·
Whenever I do a whole front suspension on any car, I always use new nuts and bolts (pinch bolts/nuts, bolts/nuts for control arms).

However, I was at the bmw dealer today and was told by the parts salesman that when doing suspension work, their bmw mechanics keep the bolts and only replace the self-locking nuts.

So I am just curious for you guys out there who have done the front suspension (could be any car, BMW, MB, Volvo etc. etc.), what do you do?

- Reusing both Nuts and Bolts (I don't think this is good idea).

- Replacing only the Nuts (This seems to make sense because when you look at wheel studs, very often the nuts go bad but the studs are still good for the life of the car).

- Replacing both the Nuts + Bolts.
 
#7 ·
I replace all self locking nuts, Usually add a bit of blue locktite as well. Usually reuse the bolts, unless there's I think they're damaged, and in that case, I usually suspect the components they fastened too...
 
#8 ·
Thanks!

That is what I thought, but every single repair manual, from Volvo, MB to BMW specifies that both the bolts and nuts should be replaced when working on suspension components. I guess this is because these bolts are tightened with much higher torque values than other nuts/bolts.

However, I am happy with replacing the nuts only.
 
#10 ·
Replace all the fasteners. Its simply good practice. You do not know the fastener's history.

It could have been over-torqued, or over stressed from hitting a pot hole or such, it could have any number of micro fractures or other faults. Looking at the fasteners are not enough. They will never tell you their history, good or bad.

A failing fastener in the suspension could cause a crash and cost lives. Its not worth it.

Replace both the bolt and the nut. Its highly improbable that the used bolt is defective and not the nut or just the nut and not the bolt. You can not tell by looking at them.
 
#11 ·
Wouldn't it depend on the grade of the bolt as to wether or not to replace it? Grade ten and higher probably are ok in my opinion...just replace the nuts? Then you thread a new nut onto an old bolt which may "rethread" the darn thing then your back to square one...on suspension work, I have actually pulled all the bolts off, gone to the hardware store and replaced with stainless steel hardware...a little overboard, but there is nothing like climbing under your car and seeing new stainless hardware let alone piece of mind.
 
#12 ·
I got a call from the BMW dealer, their mechanics re-use these bolts, believe it or not. I kind of agree because as I mentioned the wheel studs on any car last a looooong time.

So for the PN 31106769441 (bolt holding control arms), the dealer said I have to buy a minimum of 10 (yes 10 $2.96 each = $29.60 for 10), b/c bmw does not sell less than 10!!!
Anyone wants to share the rest I can send the other 8 to others in this board.....:)
 
#13 ·
So for the PN 31106769441 (bolt holding control arms), the dealer said I have to buy a minimum of 10 (yes 10 $2.96 each = $29.60 for 10), b/c bmw does not sell less than 10!!!
Anyone wants to share the rest I can send the other 8 to others in this board.....:)
:confused:

Weird, I bought some nuts and bolts for my E36, for the shocks and struts, and I only ordered two of each. They had to special order it too...

But, the total amount of nuts and bolts came to 10....hmmmm
 
#19 · (Edited)
I got a call from the BMW dealer, their mechanics re-use these bolts, believe it or not. I kind of agree because as I mentioned the wheel studs on any car last a looooong time.QUOTE]

The wheel studs are way over sized because the auto company knows that owners will not replace them each time a wheel comes off. Hell, you can drive with only two studs per wheel. Can you say ... way overbuilt?

Not so for the suspension bolts and nuts. Will the old ones fail upon reuse? Not likely but not unlikely.

Spend a bit more ,just a few dollars, and be safe. Or save a few dollars and buy more/better insurance.
 
#21 ·
CN90, if you want to get them from BMW and have the bolt and nut P/Ns Jared can get them for you even if he dosen't list them on his website. Just email him the P/N and quanity.

Takes a few days, but way cheaper than the dealer for the same parts...
 
#22 ·
CN90, if you want to get them from BMW and have the bolt and nut P/Ns Jared can get them for you even if he dosen't list them on his website. Just email him the P/N and quanity.

Takes a few days, but way cheaper than the dealer for the same parts...
Thanks!

Actually as it turns out, I checked realoem dot com again and there are 2 PNs listed for the same bolt.
So I use the alternate PN and it is OK. I can order only 2 bolts without problem.

For small orders and inexpensive parts (nuts and bolts), somehow I trust BMW dealer.
Plus BMW dealers typically ship thousands dollars of parts from their HQ everyday to the local dealership for their repair works, so I don't pay shipping charge because my stuff come with the daily shipment.

So for small items, I simply pay the amount that the dealer charges without shipping charge. It works out OK for minor small parts. Plus I develop a nice working relationship with the BMW parts counterman, He knows me pretty well now!
 
#25 ·
Let's digress a bit, philosophically for any cars out there, not just E39:

1. Wheel studs and Nuts, we keep them for life of the car even after changing the tires so many times. Once in a blue moon we change a bad nut or two. Also wheel torque is about 120Nm or so for most cars.

2. Control Arms Nuts and Bolts. When I did my 98 Volvo V70 control arms, I used all new nuts and bolts. Although the old bolts and nuts looked good, I can see why the repair manual stated to use new bolts/nuts.
The bolts are torqued to about 48 ft-lb, then tighten another 120 degrees.
Basically my arm hurts when doing this 120 degree thingy.
I can see that this high torque value can deform the nut.
So new nut is always a good idea, especially when your life rides on it.

The bolt is a different business, I think bolts can handle alot of stress, but being the only bolt holding the control arm ----> a new bolt is always better when doing suspension work. These bolts have seen 10 yrs of srevice and thousands of potholes and hard cornering....
(In contrast, the 5 studs holding the wheel: even if one stud is broken, 4 other studs hold the wheel).

My 2 cents....
 
#26 ·
Back to this old thread I started in 2009, it just occurs to me that we DIYers tend to be "an@l-paranoid" about nuts and bolts while the BMW mechanics at the dealer re-use them all the time.

Kind of funny because we don't do this for a living so we tend to worry more than the people who do it everyday LOL.
 
#29 ·
Lots of DIY info out there and what the usual sources say or do ....

BMW TIS: Replace nuts (if anything).
Bentley: Replace nuts (if anything).
Beisan: Replace nuts.
Most repair shops, in practice: Re-use everything.
Franka: Replace bolts & nuts.

Most of the time I'll probably just replace nuts (or bolts if wheel bearings) but now there'll be a little Franka angel floating over my shoulder whispering, 'Unh-unh-unh, think about your family..... Replaaaaaace the booooooooltsssssssss toooooooo....."
 
#33 ·
Cam, your car sees snow, slush and salt. Not so in Cali. I work in the oil & gas industrie and I have seen tons of failures due to microcracks produced by corrosion. The software and calculations almost every time showed those piece of equipment should last. In real world they did not - even they were beefed up. Those tiny corrsion cracks (we talk micrometer - less than 1 mm), induce fatigue acceleration. They are fatigue concentrators if you will. I've seen thick high grade chunks of steel that loked like they were sheerd off by a huge scissors. At very close inspection, most of the time the culprit is a tiny corrosion spot, or a tiny mark on the surface of the steel (imprints from some tools).
What I'm saying is, if a fastener has a tiny scrape or tiny corrsion point, and that fastener is submitted to effort in a cyclical way, chances are it can fail.
BMW does not change the bolts - it's economics for them maybe. If 1 bolt has a failure rate of 0.00001% that's good for them. They can always blame it on the age of the car, or that it was driven inappropriate - like it hit a big pothole that took also the wheel etc. If they were to change all the bolts at 2 bux a piece on all their work they might have to perform under warranty on all the cars that have some issues - that's quite a bit of change. And they have lawyers.
You will ned an undertaker.
0.02
 
#37 ·
I personally am in the 'replace the nuts and bolts' "camp", however my bigger concern is who is making all these new nuts and bolts, I would hazzard a guess that the vast majority of them are coming from a Chinese/Asian factory where, lets be realistic, sometimes quality control can certainly be in question.
It's a global economy and if a manufacturer can save even small percentages off their costs they readily do it.
So, you can get the peace of mind with the new hardware but I have serious doubts that the actual quality of that hardware is the same as it was 10-15 years ago.
Another rock and a hard place.
My 2 cents.
 
#38 · (Edited)
That could be said about anything, that its not like 15 yrs ago. Quality mfgrs have standards for such things, mfgrg and incoming standards they check themselves, and especially on fasteners and more especially on critical fasteners. Plus the mfgrs are super motivated to prevent liabilities.

So I personally would not be concerned with the quality of fasteners that originally come with a new BMW. Regardless of what China, France or Gaddafi is or is not doing. Its not like they run down to their local (German equivalent of )Home Depot to p/u a half million fasteners, where price is HD's main concern.
 
#43 ·
reuse bolts
some OEM nuts are better than new ( i guess original Germany > new China ) , also reuse them
That reminds me.... I think you pointed this out before in another thread. The new Lemfoerder control arms (rear wishbones) I installed came with new nuts but they are different than the old/original in that they don't have an integrated washer on them. I used the new ones but wondered...... so I still have the old just in case.
 
#46 · (Edited)
i think nuts yes - have you see them ?
original have better quality and as pleiades said they come with integrated washer
So if they are not rusted / broken i try to re-use them

BTW Lemförder has fabrics in China

The Lemförder Corporation in Brewer, Maine, established in 1980, is the first wholly-owned company. Further plants are set up in Hebron,
Duncan,Tuscaloosa, Lancaster, Lapeer, Williamstown, Chicago, and Hick-ory.In Brewer, a second plant is established as a joint venture.
The plants are product-oriented. In addition to the locations in the U.S., ZF Lemförder has production locations in Mexico,
Brazil, South Africa, India, Korea, and Thailand.
China starts becoming a focal issue in the mid-nineties. ZF Lemförder oper-ates plants and participations in Shanghai, Shenyang, and
Changchun. The latest addition to worldwide presence is a new plant in Australia. Following the integration of the subsidiary
ZF Lemförder International in Bremen as an aftermarket organi - zation worldwide spare parts activities are now handled by
ZF Trading.
 
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