Suspension bolts

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M0T

M0T

M0T

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Are suspension bolts different in terms of strength to normal bolts?

I have to drive to leicester first thing tomorrow and today set about changing my lower wishbone, unfortunatly the nuts that were welded onto the wishbone were made of cheap alloy and wouldn't torque up fully (pattern parts :(). I went to 3 different spares places and none of them stocked a suitable nut as the bolts have an odd thread pitch.

In the end I bought some standard threaded m10 bolts and matching nylock nuts and replaced 2 of the existing bolts. However I recalled previously trying to buy a nut to go with one of these bolts and being told that they were high tensile, will the bolts I have bought be suitable replacements (off the shelf from Halfords)?
 
You need proper bolts, they have a plain shank and wont shear.

Threads on bolts are stress concentration points and because the forces are acting on the bolts in single shear it makes them pretty easy to snap.
 
Look on the head of the bolt and it should have an indication of strength on it. For suspension, i'd be looking at 8.8 at least...
:)
 
You're probably better going to a local engineering factors than a motor factors if you're after specific nuts and bolts, motor factors will have limited stock of this sort of thing, and will probably just try and order you in the proper stuff from a manufacturer or other supplier.

go straight to the source, my local engineering factors were very helpful when i was rebuilding my mini (lots of imperial, odd pitch stuff on that) and often gave me the odd nut and bolt for free.
 
plain shank is where only the end where the nut is going is threaded, not the entire length of the bolt.
 
RiPz said:
plain shank is where only the end where the nut is going is threaded, not the entire length of the bolt.
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In that case the existing bolts are not plain shank, 2 of the four have threads the whole way down.
 
M0T said:
No what I mean is the official bolts are not plain shank, I have 2 complete sets with their silly pitches and 50% have threads the whole length.
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I dont even know what bolts they are to be honest. Depends where on the suspension they are
 
Simon said:
I dont even know what bolts they are to be honest. Depends where on the suspension they are
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4 bolts that hold the lower wishbone to the subframe, 2 clamps have bushes in to the wisbone and are then bolted to the subframe. The bolts at the front of each clamp are m10 40mm with a fine pitch, marked 10.9 and are completely threaded the whole way down. The back on the rearmost clamp is an m10 70mm 10.9 with the end threaded and the back on the foremost clamp is an m10 50mm 10.9 with thread only at the end.

I replaced the 50mm bolt on the foremost clamp with a 'normal' pitched m10 8.8 bolt threaded all the way down and the front bolt on the same clamp with an 8.8 40mm bolt threaded the whole way down.

Now if this is not safe I don't want to drive the car, I can put off leaving until 10am so I should have enough time to source and fit either the correct pitch nut for the factory fit bolts or a set of decent standard m10 bolts. Problem is that dealers don't sell nuts for these bolts because the nuts come as part of the wishbone so its not much use trying them. My problem is that I do not know where else I can try to get either the bolts or the nuts, so if anyone knows of a place near Croydon I would be much obliged.
 
If they meet the same specs are the OEM ones they shoudl be fine. Surprised they are fully threaded though.
 
Simon said:
If they meet the same specs are the OEM ones they shoudl be fine. Surprised they are fully threaded though.
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Only the short ones are and since you've scared me I'm going to be calling up motor factors and engineering suppliers from the yellow pages tomorrow until I can find some 'proper' ones.
 
Bolts for key load bearing areas are one thing I will always go to the dealer for. They might charge silly money for them but at least i know there's no way I'll kill myself by accidently getting the wrong spec. For the sake of a couple of quid it's not worth taking the risk.
 
kaiowas said:
Bolts for key load bearing areas are one thing I will always go to the dealer for. They might charge silly money for them but at least i know there's no way I'll kill myself by accidently getting the wrong spec. For the sake of a couple of quid it's not worth taking the risk.
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Thats the problem though, I have the dealer bolts but they don't sell nuts for them because the nuts come welded to the wishbone. In this case the thread in the nuts became completely wrecked before reaching the proper torque, and I couldn't find anyone selling nuts with the same pitch as the bolts so ended up buying different bolts.
 
If the original bolts are marked 10.9, then you have replaced them with bolts that have about 70% of the tensile yield strength.

The manufacturer will have specified high tensile bolts for a reason, and whilst your 8.8 bolts are unlikely to fail in the short term, the stresses imparted on the suspension when you hit bumps and potholes is very high. The fine thread on the OEM bolts is also stronger, and means the clamping load will be higher for a given torque.

http://www.namrick.co.uk/ are usualy good for nuts and bolts.
 
Dogbreath said:
If the original bolts are marked 10.9, then you have replaced them with bolts that have about 70% of the tensile yield strength.

The manufacturer will have specified high tensile bolts for a reason, and whilst your 8.8 bolts are unlikely to fail in the short term, the stresses imparted on the suspension when you hit bumps and potholes is very high. The fine thread on the OEM bolts is also stronger, and means the clamping load will be higher for a given torque.

http://www.namrick.co.uk/ are usualy good for nuts and bolts.
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Does the plain shank issue matter or not? I am going to be calling round local places tomorrow morning so I ideally need to know exactly what I'm looking for.
 
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