Renault 4 Torsion Bar Adjustment

All work on the ‘Turkey B’ has been put on hold, there has been some work to do on the Renault 4, I say work to do but really it’s been more learning that work. 

I have become more aware that the suspension on the front end of the Renault 4 is not what it should be. I have changed the upper wishbones and all shock absorbers but the front driver side has been low and often reaches the lower extent of its travel all too often.

How to Fix it – Reset the front suspension, measure and adjust, that involves removing the two front torsion bars.

It must be said that removing the front torsion bars is not difficult, dangerous or anywhere near as much of a specialist job that everyone on the internet makes out, no special tools are really required and even the most ardent couch mechanic should be able to do this work with only a basic tool kit, a basin wrench and a trolley jack.

I have read a lot about doing this work and I was sure there was some black magic to it and approached it with a sense that it might all go very wrong. Over the last few weeks, working one day at weekends, we have found that all of the ‘How to’s’ online are one kind of bodge or another, some are just wrong.

The torsion bars on my car had been off before, badly adjusted and the rear boss adjusters damaged.

This is not a ‘How to’, this is the way I approached it and found it to work.

It’s my opinion that the only way to adjust the torsion bars on the front is to first totally disassemble the entire front suspension, that means releasing the lower ball joint, track rod end, tie rod, brake calliper, loosen the bolt at the front of the lower wishbone (it’s easier to do this when the bolt is under some load, it’s a French bolt, with only one end) and drive shaft, this will enable the hub assembly with the brake disk to be removed from the car. 

At this point the wishbone is only lightly loaded.

I decided after looking at the torsion bar adjusting boss tapered nut that it needed a tool, a normal basin wrench ground down lightly to fit the taper is more than strong enough to unload and load the torsion bar.

After reading that this could be done on a ramp with all manner of complex nonsense tools and hocus pocus I wasn’t sure if this could be done even with the wheels on or not, but here is the big question… How do you know how much to adjust?

There are some bits written about how much to adjust, splines here and there but everything I have read fails to mention that you actually need to know a kind of ‘day one’ or ‘zero level’ of the torsion bars before you start, well in my case I did as they had been poorly adjusted and I would suggest that if you are going to do this work you make a point of ‘zeroing’ the torsion bars before adjustment if you don’t know how they are set to start with.

How did Renault do it? Maybe nobody knows, this is what I did….

First of all, if there was a French Heath Robinson, he surely would have done it this way.

First of all, soak each end of the torsion bars in penetrating oil, WD-40, GT85 or something, but soak each end, did I say soak each end, make sure you soak each end, plenty of lubrication.

Leave it for 30 minutes and soak them again, the more you can soak them the easier this is.

While you are waiting for the soaking to ‘happen’ it’s time to position the car. No need for a ramp or anything magic, I just jacked the car up so it was about 40-50cm off the ground, small ramps to the rear and wooden blocks under the floor at the front. Soak the torsion bar ends while you think about how to position the car.

With the car positioned simply strip down the front suspension, so the lower wishbone can be lowered to its lowest point against the chassis, the torsion bar are all but unloaded now. Use you new basin spanner on the torsion bar boss, one end on the boss and the other on the cup of a trolley jack, looking from the rear of the car, add a little pressure on the spanner with the jack by jacking it upwards in an anti clockwise direction for the left side and clockwise for the right.

Next, I slid the front seat forwards and loosened all of the bolts. First problem we ran into was that the bolts had been cross threaded so they resisted the ratchet a little but an impact wrench worked well. I just took all of the bolts out as the basin wrench had the tension under control. Release the jack under the car and the torsion bar relaxes.

At the front end, hit the lower wishbone beside where the torsion bar enters, soak some more and keep hitting, I found a metal club hammer was the tool of choice here. Occasionally, as the torsion bar drifts backwards we had to tap it back into the wishbone and start again, this allowed for more soaking and more drifting until it all came out.

I didn’t mark anything at all, no need, it was all filthy and needed a good clean on the wire wheel.

After a bit of paint and a few new parts, ball joint and plenty of grease it was time to put it all back together. The torsion bar goes into the lower wishbone first, I added copper grease, plenty of it, just in case.

The bit I decided was important was to know how the car sat on the ground if I extended the lower wishbone as far as it would go then fitting the boss on the rear of the torsion bar and fitting it into its correct location within the car, vertically aligned, as if adjusted up. I did this and of course reassembly is quite simple, just a trolley jack under the lower wishbone to work again the tension of the torsion bar. We did this on both sides.

Once everything is back together and the car lowered it’s quite easy to tell how low the car is and how much adjustment is required, the car looked ok really but I wanted it a little higher.

Remember, my car had been damaged somehow so things needed a little care. The drivers side I decided need the rear boss rotating three splines and the passenger side one spline.

It’s even more important to remember here that everything you read, perhaps including this is wrong. You don’t rotate the torsion bar, you first need to understand its ‘zeroed’ position and the increase its torsion by repositioning the boss at the rear and adding tension, don’t take it out of the lower wishbone any more.

So, back on the small ramps and blocks, strip down the front suspension again, everything comes apart easily as there is plenty of grease on everything. Release the torsion bar tension then ONLY remove the boss from the rear, this can be done with a centre punch under the car. I turned the boss three splines in the clockwise direction (anti-clockwise for the right side boss) when viewed from the rear and then fitted the boss back on the torsion bar and into its retainer.

Now it’s time to add some tension to it. We used the basin wrench again and making sure the lower wishbone is fully extended a little pressure added to the basin wrench with the trolley jack soon added the right amount of rotation to line top the bolt holes (our job would have been easier of we had good bolts and good bolt holes.).

It’s worth remembering here that even a little rotation adds significant tension to the torsion bar, adjusting three splines needs a rotation of about one eighth of a turn, nothing more than that and certainly not a scary amount of pressure.

Again, reassemble the front end and lower from the health and safety proof ramps and blocks, stand back and admire the work, the car is level.

This turned out to be more about learning what was happening rather than difficult, quite simple really and only a few basic tools, I seem to remember there are only about ten nuts to remove at the front end and four at the rear, so hardly a lot of work.

If this was once your car and you know that you tried to adjust the suspension I have to tell you you didn’t know what you where doing and you made a terrible job, we have addressed that and it’s back to how it should be.

Enjoy the little video…