Lower front suspension bushes XK120. Can I replace them without taking off the torsion bar ?
No, the tension on the torsion bars have to be relieved.
Best to disconnect the upper ball joints first and let the lower A-arms down, then go from there.
Be aware that the torsion bars are pre-stressed for installation on the left and right; be absolutely certain you don’t put them on the wrong sides.
Hi Mike…as per Robs post above…just a word of warning…the front suspension is under a lot of tension all held in the torsion bars…they are very easy to work on but you need to release the tension…make sure you fully understand how to this safely befor you start…Steve
Thanks Rob, I guess the unscrewing the adjustment nut relives the tension. One thing that confuses me is the process of supporting the chassis and supporting the suspension under the brake drum, then disconnecting the lower wishbone lever from the bottom ball joint. Seems to me this would be rather insecure. Perhaps I’m miss understanding the service manual. Page J.11 ? I’ll read it though again.
Thanks MGCJAG, I’ve replied to Rob.
You should first support the car securely with jack stands under the chassis frame, not any suspension parts.
Then use the jack to lift up the brake drum so you can start removing parts. Shocks and upper ball joints are first. You can’t undo the lower ball joints until you can tilt the stub axle support outwards.
Then when the stub axle carrier is out of the way you can lower the lower wishbone lever.
This way you don’t have to disturb the torsion bar adjustment nuts at the rear.
Rob, do you mean that the stub axle is now leaning outward, like at a 45 degree angle to the ground? Thanks.
Yes, otherwise you can’t get a wrench on the lower ball joint nut.
OK Rob, I understand that. Does lowering the lower wishbone completely release the pressure on the torsion bar and, if so, will I then be able to unbolt the muff and get at, and replace, the bush that is under it ? Your help is greatly appreciated as I have never seen what lies inside the muff. Exploded diagrams and service manuals are all well and good but they don’t always give you all the knowledge you need.
Also, Rob, is the lower wishbone lever tie rod under any stress or can I just undo it to replace the bush at the front ?
Yes, when the lower wishbone is lowered completely, there is no tension on the torsion bar. It will rotate down to nearly 90 degrees.
I forgot to mention that you will want to disconnect the anti-roll bar at both ends.
Also the steering tie rod, which can be disconnected at either of the ball joints, or the bolts through the brake backing plate.
You can hang the brake backing plate from a wire so you don’t have to strain the hose and risk damage and losing brake fluid.
Inside the muff is another big nut just like the one on the front end of the lower wishbone. Try to loosen those big nuts while you have the wishbone shafts still on the chassis.
You will find the bushing job easier if you remove the lower wishbone shafts and continue your struggle with the rubber bushings on the workbench. You may need a hammer and chisel. Some of the bolts holding them on are special shoulder bolts, which are for precise alignment of the shafts on the chassis. Be aware that you have to put them and the shafts back on in the same locations and orientation they came off.
That’s brilliant Rob, just remember to turn your chassis over, otherwise the body won’t fit !!
I’m setting it up for driving in the antipodes.
Ok seriously, I was doing some welding on the bottom of the cross member.
I am following this thread with interest as I will be doing these things in reverse. I am a couple months away from assembling my front suspension, but I have been rehearsing it in my head. Is this the right order of assembly?
- Assemble the lower wishbone on the bench then attach to the chassis.
- Connect the torsion bar to the lower wishbone and the chassis.
- Assemble the upper wishbone on the bench then attach to the chassis.
- Assemble the back plate/stub axle on the bench, then connect it to the lower wishbone.
- Raise the lower wishbone with a jack (assuming the chassis is weighed down with the motor).
- Connect the upper wishbone to the stub axle.
As Rob mentioned above…but just to reinforce…pay attention to the lower wishbone shaft …you must fit them the correct way around…if you lay them on a flat surface and view them from the side you will see they are tapered…so when bolted to the chassis they lay at an incline…it must be a downward incline towards the front…shown in Viarts book…but weve been told by moderators that we cant post photos shown on the books…Steve
Also guys remember to mark the position of the muff and the torsion bar…or you wont know where to refit them and then have to reset your ride height…Steve
Hi John you are missing a step…you will need to use a setting like to position the torsion bar to the lower wishbone to set your ride height…and set position of the rear torsion bar adjuster…then No7 attach shock and lower jack…Steve
Marking the position of the muff and torsion bar assumes that they were good before you took it apart.
The idea of this contraption is to set the rubber bushings with the control arms in their normal riding height position, then tighten the nuts.
Then you can crank up the torsion bars to normal riding height before letting the weight down on the suspension.
I made up these 7-1/8" height test blocks. I did the fronts with the rear wheels off and the chassis sitting on these rear blocks.
Thank you gents for your advice. Aside from being left/right specific, are the torsion bars marked for the initial setting? I removed mine over 30 years ago and I don’t think I indexed anything. How would someone in my predicament go about installing the torsion bars so the ride height will be in the right ballpark from the start, so that it can be further adjusted only with the “big nuts”? Thank you.
Hi John…the torsion bars are only marked with the part number for left/right…to install and set your ride height you need to use the setting lenght tool or make something to simulate it as pictured in Robs photo above…the process is detailed in the service manual…Steve