overtorqued front sway bar securing nuts

[H3nrY]

Hey all

I removed and reinstalled my front sway bar, and i over tightened the left securing nuts for the sway bar. Didn´t really notice the frame rail going as well...stupid me..

Anyway, the damage is not that bad. There is a small dip in the rail itself along with some deforming. Will this affect structural rigidity, or should I leave it as is ? Been thinking about welding a plate alongside it for extra strength.Or am I being to hasty.

 

[zbloke]

Personally, I think that sort of modification to the sway bar mountings should always incorporate an anti crush tube of some sort within the chassis rail

IMO of course

 

[H3nrY]

Personally, I think that sort of modification to the sway bar mountings should always incorporate an anti crush tube of some sort within the chassis rail

IMO of course

Wel, tbh the brackets came from the PO, didn´t really think things through

 

[rallymanDP]

Hendrik

No quick fix available here, I'm afraid.
I hate to tell you that the whole Chassis rail will need replacement in the long-term. You can see from the photos that it has had substantial repairs in the past and now the twisting moment of the anti-rollbar mounts are trying to tear it apart.
Zbloke is right - it would help to have some tubing inside the Chassis Rails to spread the load, but as you will have to cut away some metal to do so, the only solution is to have new sections ( i.e. the whole 'box' section in profile ) replacing the old weakened metal. And at the same time, you can let in some tubing to spread the load through the top and lower faces.

Any short term solution is going to go the same way pretty quickly as the force bearing on the Chassis rails at that point will soon have the same effect.

Sorry to have to bring you the bad news ! Not terribly expensive, but a bit complicated to do.

 

[H3nrY]

Hey duncan

Yea, i thought about replacing the front rail entirely as well, it must be full with repairs and patches from the po. as wintertime is coming, this should be an ideal moment for such a project.,guess ill keep my welding arm ready

 

[morbias]

I had 3mm thick lengths of angle welded inside my replacement chassis rail sections, then drilled holes for the ARB bolts to drop through which were then welded in place. It seems a bad idea to me to have the bolts for the ARB going through both the bottom and top of the chassis rails as there is that massive void in between.

 

[H3nrY]

I had 3mm thick lengths of angle welded inside my replacement chassis rail sections, then drilled holes for the ARB bolts to drop through which were then welded in place. It seems a bad idea to me to have the bolts for the ARB going through both the bottom and top of the chassis rails as there is that massive void in between.

Morbias

Indeed, it´s a bit strange why such huge bolts are needed to keep the ARB on the chassis. anyway, when I redo the rails, I´ll keep your idea in mind !

 

[SKiddell]

Duncan and Tim are absolutely right of course, to do it properly then some anti crush mechanism is needed but I “through bolted” mine in 2005 after pulling one out at Castle Combe, since then I have done a good number of track days and many thousands of miles of spirited driving, with big thick anti roll bars, stiff bushes, 250 lbs springs and sticky tyres and they have held up very well….maybe one day I will get around to adding the anti crush tubes.

Note, the plates I used are much bigger than the ones you have Henry, they are the width of the rail and about 100mm long (above and below the rail), I never tighten the bolts up to the point where the rail begins to deform, just enough to ensure that any movement of the ARB is eliminated, after all where is it going to go ???
nylock nuts prevent any "backing off"

 

[H3nrY]

Duncan and Tim are absolutely right of course, to do it properly then some anti crush mechanism is needed but I “through bolted” mine in 2005 after pulling one out at Castle Combe, since then I have done a good number of track days and many thousands of miles of spirited driving, with big thick anti roll bars, stiff bushes, 250 lbs springs and sticky tyres and they have held up very well….maybe one day I will get around to adding the anti crush tubes.

Note, the plates I used are much bigger than the ones you have Henry, they are the width of the rail and about 100mm long (above and below the rail), I never tighten the bolts up to the point where the rail begins to deform, just enough to ensure that any movement of the ARB is eliminated, after all where is it going to go ???
nylock nuts prevent any "backing off"

Skiddell,

Thats a good call there. Ill make some plates in the mean time in the size you describe, and hopefully that will balance the load a bit.

 

[Throttleton]

You can't really tighten a bolt across a 2 inch void and hope it wont deform.
A plate top and bottom isn't ideal either.
Steel tube welded into the chassis rail before the rails are welded on would stop any compression when tightening the bolts up. I would still be worried if you can distort the chassis rails with a spanner doing up a bolt mind.
Can you clean all the paint and crud off a much larger area around the problem and have a good look at the steel??

 

[Rob Gaskin]

I used plates to stop the captive nuts and inner-plate pulling through when I fitted my MSA bars. A combination of the two approaches would be strong, perhaps a U shaped piece welded over the leg (sideways if you know what I mean) would be a stop-gap?

However your chassis legs are probably still stronger than those on 50% of old S30s. Don't panic but it all will need to be checked for corrosion, it's an important area of the shell. Those US shells are tempting aren't they?

 

[SKiddell]

You can't really tighten a bolt across a 2 inch void and hope it wont deform.
A plate top and bottom isn't ideal either.
Steel tube welded into the chassis rail before the rails are welded on would stop any compression when tightening the bolts up. I would still be worried if you can distort the chassis rails with a spanner doing up a bolt mind.
Can you clean all the paint and crud off a much larger area around the problem and have a good look at the steel??

That's the whole point though, you DON'T tighten to the point of deformation, you tighten to the point of clamping......you could of course just fill the whole thing with concrete to be sure
But I'm just looking at it from an engineers perspective

 

[zbloke]

You could always be really outrageous and use a torque wrench, its only an M8 bolt, max. of 18>>20 ft/lbs with the clicking stick and ur done

 

[MaximG]

You could always be really outrageous and use a torque wrench, its only an M8 bolt, max. of 18>>20 ft/lbs with the clicking stick and ur done

Finally some common sence. Acording to the book 1.9 to 2.8 kg-m or in old money 13.7 to 18.1 ft-lb. I usually go for some where in the middle.

Mike B

 

[vpulsar]

Finally some common sence. Acording to the book 1.9 to 2.8 kg-m or in old money 13.7 to 18.1 ft-lb. I usually go for some where in the middle.

Mike B

I'm guilty of over tightening mine as well, At the moment my Z is away having some work done and one of the jobs is to replace one of the captive nuts that I broke off with my over enthusiastic efforts . My problem is that being a big lump I'm quite strong and should use my torque wrench to be sure .



Rob

 

[H3nrY]

You could always be really outrageous and use a torque wrench, its only an M8 bolt, max. of 18>>20 ft/lbs with the clicking stick and ur done

Jep I know. I immediately got a torque wrench afterwards. Should have done it beforehand.
However, illd do as Pullsar says, clean up the paint, and see what is going on corrosion-wise.

Thanks for the replies all !

 

[Throttleton]

Good idea from vpulsar about cleaning up the paint and having a look at the steel
Steve I had an idea you would say that an rightly so, but as an engineer you will see the drawback to the mounting idea of the the sway bar in that way.? All well and good with new strong steel but even using the correct torque levels on an old and weaker chassis rail will cause problems will it not??

 

[vpulsar]

Good idea from vpulsar about cleaning up the paint and having a look at the steel

That was the best idea I never had :lol:.




Rob

 

[SKiddell]

Good idea from vpulsar about cleaning up the paint and having a look at the steel
Steve I had an idea you would say that an rightly so, but as an engineer you will see the drawback to the mounting idea of the the sway bar in that way.? All well and good with new strong steel but even using the correct torque levels on an old and weaker chassis rail will cause problems will it not??

You are right Craig, new metal is one thing 40 year old tin is another, I always work from the position that the metal in question needs to be sound and in good condition to start with, if not it needs attention prior to any modification, my post was based on this prerequisite.

I would not dream of doing anything on a frame rail that is like a bean tin, most certainly not trusting my life with it

One of my great failings is that I often forget that most people dont have experiance of engineering practices so may not have the same thought proceses