Spring install: non-reusable bolts?

[f22bub]

Hi Everyone,

I was going through the service manual to find out the torque specs of the bolts that need to be loosened to install some new springs and saw that all bolts (based on the videos I have seen so far) are not re-usable. I never heard or read anyone mentioning that and am wondering, if you all still re-use the same bolts or get new ones?

All bolts with a black dot on them are not reusable bolts according to the Service Manual. I highlighted the ones that need to be loosened for a spring install in yellow.

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[f22bub]

Anyone?

 

[Msoupe]

I re-used all of my bolts. From my experience, these should be fine to re-use if torqued properly.

 

[Wetherman]

F22bub - can you tell me where I can pick up the shop/service manual for the 2021? Definitely need the part numbers, torque settings and drawings. And I presume if I had the manual you screenshot above, I could decipher the numbers associated with the parts?

 

[f22bub]

@Wetherman Sure, here you go: https://www.supramkv.com/threads/workshop-service-manual.2415/post-138348

 

[Msoupe]

This post has a more spam free link.
https://www.supramkv.com/threads/workshop-service-manual.2415/post-138375

 

[Okvilln]

My mechanic re-used the same bolts torqued to spec. Maybe another member can explain, but I dont see the logic using new ones.

 

[Deighvid]

Interesting. I wonder if this is the BMW level of service where they prefer this practice. Just speculating based on how expensive it is for the dealership to do literally anything on a BMW lol

Thanks for the manual! Did anyone find a 2021 specific or just that 2020 version?

 

[gr_supra_lt]

Hi Everyone,

I was going through the service manual to find out the torque specs of the bolts that need to be loosened to install some new springs and saw that all bolts (based on the videos I have seen so far) are not re-usable. I never heard or read anyone mentioning that and am wondering, if you all still re-use the same bolts or get new ones?

All bolts with a black dot on them are not reusable bolts according to the Service Manual. I highlighted the ones that need to be loosened for a spring install in yellow.

hey did you find highlighted part numbers? Thanks!

 

[tracer bullet]

It would seem if they aren't stretched (i.e. super high torques or some torque + 90 degrees turn for example) they can be reused. Regarding bolt integrity anyhow. However -

I would only caution to check the type of bolt and the top perch for the spring itself - BMW loves to make those things from aluminum and without any threads in them, so that when you are reassembling it you are actually cutting new threads during the installation. In that case you might want a pristine bolt with a sharp edge, nothing in its threads, and so on if you are also replacing that top mount piece. I know this is how it is for other BMW's I've owned but I am not certain if the Supra / Z4 are this way.

For the nut at the top of the strut, they are often nylock nuts, and so you might want a new one for the new nylon inside and be sure it doesn't come loose. You could argue that after one's been used it's going to be less grippy having gone on and back off once before. Not sure I'd argue it but you could.

The bolts at the bottom might be torque dependent, if they're cranked on (very well might be) then it could be best practice to replace them. Some of that lower end stuff with the arms is really tight.

I'm sure you won't run off the road by reusing bolts but maybe consider some of this when deciding for or against.

 

[Thraxbert]

hey did you find highlighted part numbers? Thanks!

Part numbers for everything.

 

[lucky phil]

It would seem if they aren't stretched (i.e. super high torques or some torque + 90 degrees turn for example) they can be reused. Regarding bolt integrity anyhow. However -

I would only caution to check the type of bolt and the top perch for the spring itself - BMW loves to make those things from aluminum and without any threads in them, so that when you are reassembling it you are actually cutting new threads during the installation. In that case you might want a pristine bolt with a sharp edge, nothing in its threads, and so on if you are also replacing that top mount piece. I know this is how it is for other BMW's I've owned but I am not certain if the Supra / Z4 are this way.

For the nut at the top of the strut, they are often nylock nuts, and so you might want a new one for the new nylon inside and be sure it doesn't come loose. You could argue that after one's been used it's going to be less grippy having gone on and back off once before. Not sure I'd argue it but you could.

The bolts at the bottom might be torque dependent, if they're cranked on (very well might be) then it could be best practice to replace them. Some of that lower end stuff with the arms is really tight.

I'm sure you won't run off the road by reusing bolts but maybe consider some of this when deciding for or against.

There's generally two reasons manufacturers specify one use only fasteners these days. One is the fastener is a TTY bolt and the other is the bolt requires a locking medium such as Loctite to be applied which the new OEM bolt will come with pre applied. Manufacturers don't trust dealer techs to apply Loctite these days so they sell you new bolts with it already applied.
Phil

 

[tracer bullet]

Loctite

That's a good point, some certainly do come this way.

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