Torsion Bar
The lowdown on suspension torsion bars.
The Basics:
What is a Torsion Bar?
The torsion bar is basically a spring but with a slightly different shape to the spring you’d normally see. The idea of a torsion bar is one end is fastened to the rear axel frame of the car and the other is attached to the control arm of the vehicle.
As the control arm moves with the road surface the torsion bar tries to move wit it but it cant due to being fastened at one end. When this happens it causes the torsion bar to twist and distort creating movement. Once the pressure on the torsion bar is release it then tries to twist back into place creating the movement process.
It sounds very technical and advanced compared to the usual spring setup but that’s because it is. Torsion bars are usually used on heavier duty vehicles, this is unless your car is French of course. The French tend to use torsion bars on most of their vehicles no matter how big or small it is!
So by modifying my Torsion Bar what am I doing?
If you have a vehicle with a torsion bar and you are thinking of lowering your ride then its worth knowing what it is exactly what you are about to do. The torsion bar needs adjusting (or “reseting”) to a new level.
To adjust the ride height you need to wind the adjuster bolt at the fixed end of the torsion bar so this does not add any more force to the pivoted control arm end of the torsion bar, meaning the ride quality is unaffected. Winding the torsion bar adjuster bolt is the same as installing blocks between the axle and leaf springs or a set of coil spacers, it simply moves the spring to a different position.
So how do I lower my Torsion Bar then?
Now then, lowering a torsion bar is not impossible nor is it impossible for you to do at home on your driveway however there are a few things you do need to know.
- You need a slide hammer. These are not the easiest tools to get hold of, nor are they cheap.
- You need to know how to use a slide hammer. Yet again not easy first time round, slide hammers are crazy tools that don’t take to long to get over excited with them and end up breaking something so please, please do not use it first time round on your brand new cars suspension.
- You need to know how a torsion bar works. Fair enough we’ve just told you this but its not a simple as the abc. Torsion bars are tricky, you need to measure how much you are twisting and how far you are twisting it on each end as otherwise you’ll end up with wonky suspension.
- You need to e aware that Torsion bars seize quite easily.
It doesn’t take that long at all for a torsion bar to seize up and unless you are aware of the symptoms of a seized torsion bar you could end up in trouble! Things have a tendancy to snap or break if your torsion bar has seized up and you apply to much pressure, then your stuck with a broken car with a seized up torsion bar stuck inside. Not Good.
What advantages and disadvantages does lowering my Torison bar have then?
Advantages: if your lowering your torsion bars hen the chances are that you want to lower your car a bit. The handy thing with torsion bars is one you’ve released the bar you can adjust them as far as you want, and that means to the floor if you want to. This is normally where the term slammed comes into play but do remember that speed bumps don’t go down to well with slammed rides!
Disadvantages: By lowering your torsion bar you are decreasing the amount of play in your suspension, this now means the ride is less comfortable and a heck of a lot tighter than it used to be. Going full hog and slamming could also get you into trouble too if you haven’t thought it out, it will only take you on attempt at a hard speed bump to ruin you whole suspension if you do it worng!
What to remember about Torsion Bars:
Torsion bars are deceiving objects. They leave you in control of your own ride height so play carefully. If you are in any doubt then please leave it and take it to the professionals. The average cost is £100 to lower your torsion bar evenly on both sides so its not as expensive as a new car. The professionals use high tech equipment and generally have experience of setup similar to yours on a day to day basis so for the £100 odd it costs, its worth every penny!
The Law on Torsion Bars:
There is no law to state that Modifying your torsion bars is illegal however a ride that is to low that it either A, allows the wheels to foul the bodywork or B, disallows an MOT tester to drive it onto a ramp will find itself with a failed MOT ticket, so be careful!