Steering column upper to lower joint (CSR)

[BenF]

Whilst on an early morning blat this morning, I had to do a three point turn and heard a clunk from the steering when on full lock.  I then found the steering wheel was off centre, although the car itself was behaving itself fine - inspection of all bolts relevant to the steering system showed the reference marks still lining up.

On inspection in the garage, I found the joint between upper and lower parts of the column was switching between two positions when a decent amount of torque is applied.  Disassembling the joint, I can feel witness marks in the flat on the lower column where the grub screw had engaged, but there is no obvious damage as such.  The clamping bolts were in their original position, at least based on the reference marks on the heads.  I assume that over time, there has just been a bit of plastic deformation and the grub screw just needs readjusting and tightening.

My plan was just to adjust the grub screw to have more contact force on the flat and then reassemble everything with some loctite on the bolts.  I was a bit bemused to find such an agricultural connection between the parts of the column, but there you go.

Has anyone had this problem before?

[ECR]

It's not uncommon. The joint is designed to collapse under impact...

[BenF]

Ah right - so that the lower part would just slide up inside the upper part on impact.

 

[Wrightpayne]

Yes, and the clamp will contact the outer column tube thus stopping the steering wheel moving too far before the dash takes the impact forces!

[Wrightpayne]

Recent post on the same....

https://www.caterhamlotus7.club/forum/techtalk/steering-column-design-safe

[Jonathan Kay]

Ian's post links to the correct sequence for adjusting and tightening the assembly.

Jonathan

[BenF]

Thanks Jonathan!  I had not noticed that this topic had been covered so recently.

[BenF]

So on this topic, it was not possible to loosen the grub screw (at least not without a vice and breaker bar, neither of which I have at home), so I had to make do with mating the grub screw on a fresh part of the flat on the lower column.

Does anyone know from the build manual what the tightening torque for the two bolts should be?

[Jonathan Kay]

From the Assembly Guide:

"The two parts of the steering column are clamped together using the locking clamp, make sure the cut out faces the column, refer to Fig 29. Insert the grub screw loosely into the clamp. Secure the two halves of the clamp using two bolts , plain washers and spring washers. Torque to 14 Nm. Tighten the grub screw with an Allen key to eliminate any free play in the steering. Lock the grub screw into place using locknut."

Jonathan

[BenF]

Thanks Jonathan

[Wrightpayne]

Is there a locknut present (on the grub screw)?

[John Vine]

#11:  Good question.  From my Assembly Guide:

 

JV

[BenF]

Yes, there is a 17mm locknut on the grub screw. It's hidden in the photo above, it's on the other side of the clamp.  Try as I might, I can't get the grub screw to move.  I could try doing this in situ but it would mean putting lots of load into the column, which I don't want to do.

Later this next week I will try to get hold of someone with the right tools, to get it moving again and then reassemble it as per Stu's instructions in the other post.

[Wrightpayne]

If its had loctite applied I wonder if a bit of heat might help? Of if just siezed then a soak in something.

[SamC]

Ben, just to paranoia check, you are trying to undo the 17mm nut first aren't you? The grub screw won't move until you've loosened that.

[John Vine]

#13:   ...it's on the other side of the clamp.

I'm not sure I understand that.  Can you turn the steering wheel until the locknut and grub screw are on top?  Or are CSR's different to the S3/SV?   Agree about #15.

JV

 

[Wrightpayne]

John,

I think he was referring to the picture posted..

Ian

[John Vine]

Ah, silly me.  The photo in #1.  Of course.

JV

[BenF]

Yes exactly, but when it's off the car, it's difficult to get enough of a grip on the part to loosen the 17mm nut.  I do need to get a proper workbench and a vice!

Obviously, the locknut will have to be tightened again when back on the car, but I can do that in a controlled way, whereas loosening it on the car by putting a lot of torque into it until it shifts, is something I would rather avoid, i.e. I don't want to be putting a lot of bending moment into the column unnecessarily when trying to undo it.

[John Vine]

Do you have a garage or machine shop nearby with a big vice plus a bit of heat?

The alternative may simply be to renew the entire clamp assembly.

JV

[BenF]

John, yes I have access to a workshop, not on this bank holiday weekend, but later this week.

However it's a wake up call for me to get a proper workbench and vice.  I've got loads of tools but the usual blocker for me when doing maintenance is whenever I have to loosen something which is tight or seized, it ends up being a right PITA.

[SLR No.77]

Ben, maybe try reassembling the clamp around a suitably strong rod (long socket extension) to imitate the steering column then try again? The 17mm nut can be extremely tight even without Loctite due to being tightened to FT lbs through fear of it coming loose.

Stu.

[BenF]

Very good idea Stu.

I've left it as it is, as the car is being MoTd on Weds and I don't want to start fiddling around with it now.  Afterwards I'll disassemble and have another look.  Also ordered myself a workbench today as the next step in getting my garage better prepared for this kind of thing.

 

[21jigsaw]

The clamp was modified a few years ago by increasing the width of the top plate. This was due to over tightening and bending the top plate.I  check  the plate for flatness.( I bent one of the thin ones)

[BenF]

Thanks 21jigsaw

The plate looks good, I cannot imagine how it could be bent, it must be the uprated one.

So my friendly technician loosened off the lock nut, I bought new bolts from Trident Racing Supplies just for peace of mind and the assembly is back on the car and tightened up correctly.