Front torsion bar removal, without special tools

[Richard Williams]

Always one to defer to some of the experienced on this list, I have been planning the fabrication of the special tool needed to remove front torsion bars...apparently Planning was a far as I had got when I thought I could see a way of removing them without the tool.
Please note the lower front suspension arm is free with lower ball joint dissembled. Note too that this car is 1970 R4 not a GTL
1. Slacken both bolts witch fix the torsion bar cam extension to the cross member.
2 Slacken the adjusting cam bolt
3 Rotate the adjusting cam to push the torsion bar cam back
4 retighten the torsion bar clamp bolts
5 Now slacken the adjusting cam bolt ,move the cam away from the torsion bar cam ,and then undo the bolt and remove
6 from under the car lever the adjusting cam forward to leave room for the torsion bar cam to swing across it's position in the next stage.
7 now undo both clamping bolts , the cam swings across to the limit of it's adjustment... take lower one out
8 remove upper bolt... the cam swings across and unloads the torsion bar.
9 lever forwards the torsion bar cam(marked position first)
10 The torsion bar can now be removed backwards through the aperture in the chassis extension. I found it with drew from the lower suspension arm easily.

I have not yet worked out how to load the torsion in the bar during reassembly but I thought it may interest a few. In the photo the two bolts on the left are on the tension bar cam. The other is the one which fixes the adjusting cam.

 

[angel]

I always thought that disassembling the lower ball joint and unbolting the shock absorber lets the lower wishbone swing down further therefore unloading the torsion bar (the wishbone pin must also be loosened). Is this the case? Never remembered to try it on the car.
I have used your method when I didn't have to re-tension the bar (when breaking a car for spares). Som tension remains on the adjusting lever and you should be careful because the lever springs back when the last bolt is removed.
I have found no practical way to reposition the bar. There is enough space for a large adjustable wrench to be used, but the problem is that the octagon is tapered and the wrench will slip when force is applied.

 

[Richard Williams]

Reassembly or the torsion bars

I've just purchased a 33-mm spanner to try on these torsion bar nuts. If I grind it down carefully to fit this really annoying tapering nut ; does anyone think I stand a chance of getting enough purchase in it to take up the required tension in the bar?
I know I will have to increase the length of the spanner I have a length of tubing that will do the trick.

 

[angel]

If it has sufficient thickness, then maybe as your torsion bars don't have too much tension when the cams are zeroed. But remember the correct tool is 20mm thick and is also shaped like a pipe union wrench, gripping 7 sides of the octagon. Even this has a tendency to slip under load.
When adjusting/ removing torsion bars on Japanese pick-ups (just a long bolt) I feel that Renault engineers intended to make mechanic's life harder when designing the R4...

 

[malcolm]

Tension on the torsion bar is reduced quite a lot when the lower suspension arm balljoint is removed. I've done them with a big adjustable spanner, though the process felt very dangerous.

Becomes a one man job with a little tool. I copied angel's one (think it was angel that posted the photos). Mine is a low budget one and will only work with the lower arm balljoint removed. http://www.renault4.co.uk/torsion-bar-tool.htm

 

[malcolm]

Found a pic of the GTL front torsion bar mountings BTW. (Sent a mail a while back but there's been trouble with my outgoing mail going missing so it might not have made it through).

Mountings do look different. I wonder if the splines at the end of the torsion bar where they connect to the chassis are the same as the GTL splines. Wouldn't be surprised.

 

[angel]

All front torsion bars from '69 onwards are interchangeable. Although there were two (or three?) different thicknesses the splines were always standard. Renault changed the mounting only in 1978. Pre-1978 ones (like Richard's) have the cam adjustment, later ones like Malcolm's are not adjustable and you must reposition the bar to adjust ride height (arrrgh!!).
Of course with the later mountings there is more tension compared to a "zeroed out" cam mounting. With my tool I managed to remove and retension the bars on a R4 having such mountings, that was raised by about 30mm at the front. But I made the tool over-dimensioned as I had such instances in mind, and as a precaution I clamped the special spanner with a pair of welder's grip pliers, so that it could not slip from the octagon.

 

[Richard Williams]

Spline type nad further thoughts

I will post some photos of the splines , but really no luck with my large spanner. Why did Renault make this nut cast and tapering? Has any one thought of mechining the nut to take a conventional spanner? I guess this would have to be done professionally but with both cams off with the method I stated it would be tempting just to take them off to be adjusted.

 

[angel]

These levers are forged rather than cast, as they should withstand heavy loads. Such parts must have a taper in order to help them separate easier from the die during the forging process. It's the manufacturer's choice to machine the piece after it has been forged. I guess Renault didn't want to do so because machining creates sharp edges that act as stress risers (note that the whole lever has nice rounded edges for this very good reason). If you milled the octagon sides parallel, you would have weakened the lever by removing material at a critical point, and also create stress risers at the point where the octagon meets the flat part of the lever.
I think that a machine shop will charge more for machining both levers than making the special tool!

 

[Richard Williams]

Splines on Early R4s

Here is the fixed end of the front torsion bars on a 1970 R4 discussed above. Do we agree that the torsion bars are the same compared to later GTL ones?

 

[angel]

Yes, all torsion bars from '69 onwards are the same.

 

[SIM]

hi torsion bar replacment front drivers side no cam ajustment fixed position how to u tension torqe bar as its fixed cannot move and torque what is the way to fit please