Shearing spacer & wheel studs
Discussion
Hi guys,
This has happened to me twice now. After driving on track for a while all of a sudden something it will feel odd and not under control at the rear…………the nearside rear spacer's spigot(?) shears, and a stud or two will snap off, leaving the remaining ones loose.
When I first bought the car it had wheel studs and 10mm hubcentric spacers on, they sheared so I bought some Eibach spacers & extended Drifworks bolts to replace the studs, thinking they may both be better/stronger than the originals.Nope! They both sheared off in just the same way.
I’ve been lucky not to have a massive accident. I don’t want it to happen again.
In each case the wheels had been put on by different garages, the last was motorsport alignment company.
Does anyone know what could be causing this? Any help much appreciated.
Rob
This has happened to me twice now. After driving on track for a while all of a sudden something it will feel odd and not under control at the rear…………the nearside rear spacer's spigot(?) shears, and a stud or two will snap off, leaving the remaining ones loose.
When I first bought the car it had wheel studs and 10mm hubcentric spacers on, they sheared so I bought some Eibach spacers & extended Drifworks bolts to replace the studs, thinking they may both be better/stronger than the originals.Nope! They both sheared off in just the same way.
I’ve been lucky not to have a massive accident. I don’t want it to happen again.
In each case the wheels had been put on by different garages, the last was motorsport alignment company.
Does anyone know what could be causing this? Any help much appreciated.
Rob
Guessing that these are for the E36 track car and you have the driftworks + 20mm longer wheel bolts made from 10.9 high tensile steel which although in theory should be stronger than the more common 8.9 steel bolts used by OEM what you might be finding is the bolts are so long with not much flex that you are snapping them when the (relatively) weaked 8.9 bolts may simply bend instead of shearing.
Might be an obvious question OP but worth asking, are you using OE wheels and if not have you made sure the bore centres are correct? If the bore centre is even slightly slack then it will put a lot of load through the studs.
If the wheels are non standard then you also need to make sure that the taper is correct so the nuts are seating on the wheels properly as that will also load the studs. Also worth checking that the wheel mounting face is flat and undamaged which isn't a given with cheap replica or aftermarket wheels.
Final potentially obvious question is what torque you are using for both spacer to hub and wheel to spacer? In the absence of a specified torque from the spacer supplier then you should be using OE wheel nut torque.
If the wheels are non standard then you also need to make sure that the taper is correct so the nuts are seating on the wheels properly as that will also load the studs. Also worth checking that the wheel mounting face is flat and undamaged which isn't a given with cheap replica or aftermarket wheels.
Final potentially obvious question is what torque you are using for both spacer to hub and wheel to spacer? In the absence of a specified torque from the spacer supplier then you should be using OE wheel nut torque.
Its an E30 3 series with the standard BBS wheels, the bolts are BMW specific from Driftworks.
I see what you mean with the bolts snapping with being longer and possibly less flexible, Kerrly, but wouldn't the spacer have to break first before shear forces are put on the bolts?
I've no pics I'm afraid xRIEx, my car is not kept at my house unfortunately.
Thanks for the replies so far.
Rob
I see what you mean with the bolts snapping with being longer and possibly less flexible, Kerrly, but wouldn't the spacer have to break first before shear forces are put on the bolts?
I've no pics I'm afraid xRIEx, my car is not kept at my house unfortunately.
Thanks for the replies so far.
Rob
The Wookie said:
Might be an obvious question OP but worth asking, are you using OE wheels and if not have you made sure the bore centres are correct? If the bore centre is even slightly slack then it will put a lot of load through the studs.
If the wheels are non standard then you also need to make sure that the taper is correct so the nuts are seating on the wheels properly as that will also load the studs. Also worth checking that the wheel mounting face is flat and undamaged which isn't a given with cheap replica or aftermarket wheels.
Final potentially obvious question is what torque you are using for both spacer to hub and wheel to spacer? In the absence of a specified torque from the spacer supplier then you should be using OE wheel nut torque.
Fully agree but it is very forum to argue that the centre bore size isn't relevant and that the studs/bolts are not only to hold the wheel on and that they should bear the weight of the car too...If the wheels are non standard then you also need to make sure that the taper is correct so the nuts are seating on the wheels properly as that will also load the studs. Also worth checking that the wheel mounting face is flat and undamaged which isn't a given with cheap replica or aftermarket wheels.
Final potentially obvious question is what torque you are using for both spacer to hub and wheel to spacer? In the absence of a specified torque from the spacer supplier then you should be using OE wheel nut torque.
doogz said:
aka_kerrly said:
Guessing that these are for the E36 track car and you have the driftworks + 20mm longer wheel bolts made from 10.9 high tensile steel which although in theory should be stronger than the more common 8.9 steel bolts used by OEM what you might be finding is the bolts are so long with not much flex that you are snapping them when the (relatively) weaked 8.9 bolts may simply bend instead of shearing.
In this case, stronger bolts are stronger bolts. They have a higher shear capacity. Are you suggesting the bolts are yielding radially? If the bolts are torqued up properly, there should be no possible way for them to bend, if all the surfaces are clamped together properly.jamieduff1981 said:
doogz said:
aka_kerrly said:
Guessing that these are for the E36 track car and you have the driftworks + 20mm longer wheel bolts made from 10.9 high tensile steel which although in theory should be stronger than the more common 8.9 steel bolts used by OEM what you might be finding is the bolts are so long with not much flex that you are snapping them when the (relatively) weaked 8.9 bolts may simply bend instead of shearing.
In this case, stronger bolts are stronger bolts. They have a higher shear capacity. Are you suggesting the bolts are yielding radially? If the bolts are torqued up properly, there should be no possible way for them to bend, if all the surfaces are clamped together properly.I have also seen wheels in the past where the wrong type of bolt heads have been used and the hole for the wheel nuts have become oval shaped which might account for the bolts having slack around them which is putting more force on them.
GC8 said:
The Wookie said:
Might be an obvious question OP but worth asking, are you using OE wheels and if not have you made sure the bore centres are correct? If the bore centre is even slightly slack then it will put a lot of load through the studs.
If the wheels are non standard then you also need to make sure that the taper is correct so the nuts are seating on the wheels properly as that will also load the studs. Also worth checking that the wheel mounting face is flat and undamaged which isn't a given with cheap replica or aftermarket wheels.
Final potentially obvious question is what torque you are using for both spacer to hub and wheel to spacer? In the absence of a specified torque from the spacer supplier then you should be using OE wheel nut torque.
Fully agree but it is very forum to argue that the centre bore size isn't relevant and that the studs/bolts are not only to hold the wheel on and that they should bear the weight of the car too...If the wheels are non standard then you also need to make sure that the taper is correct so the nuts are seating on the wheels properly as that will also load the studs. Also worth checking that the wheel mounting face is flat and undamaged which isn't a given with cheap replica or aftermarket wheels.
Final potentially obvious question is what torque you are using for both spacer to hub and wheel to spacer? In the absence of a specified torque from the spacer supplier then you should be using OE wheel nut torque.
Some vehicles don't need the correct centre, but they tend to have very beefy studs/bolts.
Rob175kks said:
Its an E30 3 series with the standard BBS wheels, the bolts are BMW specific from Driftworks.
I see what you mean with the bolts snapping with being longer and possibly less flexible, Kerrly, but wouldn't the spacer have to break first before shear forces are put on the bolts?
I've no pics I'm afraid xRIEx, my car is not kept at my house unfortunately.
Thanks for the replies so far.
Rob
Sorry, just to clarify, does the car have studs or bolts? I see what you mean with the bolts snapping with being longer and possibly less flexible, Kerrly, but wouldn't the spacer have to break first before shear forces are put on the bolts?
I've no pics I'm afraid xRIEx, my car is not kept at my house unfortunately.
Thanks for the replies so far.
Rob
If you've fitted longer studs to the hubs then you may need open ended nuts. There has been many a crashed Caterham race car from using slightly shorter Metric nuts on an Imperial Car which means that the nut backs out at a point where the wheel is seated but isn't clamped fully.
Thanks for all the replies guys, i'll try to answer everything here.
The wheels are standard/original BBS and undamaged as far as I can tell.
When I first bought the car it had wheel studs all round, they nearside rear sheared off so i had them removed and wheel bolts used instead.....which then also failed.
The centerbore of the spacer is correct and the hub, spacer and alloy fit together snuggly with no play.
The bolts/nuts were a tapered fit, which is correct for the wheels.
Although I'm usually fairly hands on with my cars I haven't been so far with this one and until yesterday hadn't at any point taken off/replaced any wheels.
The one thing that I haven't (ever) done is check the bolts part way through a track day. If working their way loose under heat and stress is something that happens then that could well be the problem. But that doesn't explain the studs (on the original setup) snapping as they can't work their way out.
Thanks again for the replies.
Rob
The wheels are standard/original BBS and undamaged as far as I can tell.
When I first bought the car it had wheel studs all round, they nearside rear sheared off so i had them removed and wheel bolts used instead.....which then also failed.
The centerbore of the spacer is correct and the hub, spacer and alloy fit together snuggly with no play.
The bolts/nuts were a tapered fit, which is correct for the wheels.
Although I'm usually fairly hands on with my cars I haven't been so far with this one and until yesterday hadn't at any point taken off/replaced any wheels.
The one thing that I haven't (ever) done is check the bolts part way through a track day. If working their way loose under heat and stress is something that happens then that could well be the problem. But that doesn't explain the studs (on the original setup) snapping as they can't work their way out.
Thanks again for the replies.
Rob
Rob175kks said:
The one thing that I haven't (ever) done is check the bolts part way through a track day. If working their way loose under heat and stress is something that happens then that could well be the problem. But that doesn't explain the studs (on the original setup) snapping as they can't work their way out.
Rob
Its the same failure mechanism - clamp load reduces, so loads between hub and wheel are taken through the bolts or studs rather than through friction across the hub / wheel faces.Rob
Rob175kks said:
The spacers are there to add stability.
I find it hard to believe 10mm spacers - so 20mm extra track - will add much to "stability". They'll shorten wheel bearing life, but otherwise they'll just be cosmetic, unless you need the extra space on the inside to clear brakes or suspension.GC8 said:
Fully agree but it is very forum to argue that the centre bore size isn't relevant and that the studs/bolts are not only to hold the wheel on and that they should bear the weight of the car too...
What does "hold the wheel on" mean if not carrying some of the duty loads? How do you think torque is transferred between the wheel and hub?TooMany2cvs said:
I find it hard to believe 10mm spacers - so 20mm extra track - will add much to "stability". They'll shorten wheel bearing life, but otherwise they'll just be cosmetic, unless you need the extra space on the inside to clear brakes or suspension.
You are most likely correct to be honest. Even if they did have an effect, I'm not a good enough driver to notice a 20mm difference in rear track width.Gassing Station | General Gassing | Top of Page | What's New | My Stuff