- My model of MX-5 is: NC 3.75
- I’m based near: Bath
- I’m looking for technical help or recommendations on: See below
My MX has developed an unusual issue where I can occasionally hear knocking under braking and when steering. It’s difficult to identify exactly where it’s coming from because it can be felt through the pedals, wheel and passengers can feel it through the floor.
Nothing appears to be loose or missing. I can’t feel any play through the drop links etc. It had a fast road alignment and full coilover change in the winter but the knocking has only become an issue recently.
Any suggestions or known components you think I should give another once over?
Bushes, rod ends, inner tie roads, steering rack… so many things it could be.
My first suggestion would be to check the slider pins on the front calipers. One of them has a rubber sleeve, which deteriorates with age, which in turn makes the pin stiff.
This can cause brake judder.
Would you expect to hear the brakes rubbing if the slider pins were stuck?
I’ve tried to move the calipers and they don’t move at all so even if this isn’t the cause of the knocking issue, I definitely need to get them off to regrease them.
I’d check for broken front road springs and then bushes.
When you do re-grease them, and I take it you mean the slider pins, it’s worth running a drill by hand down the caliper holes to clear out any hardened grease. Never use copperslip or the like as it’s a killer for rubber and will cause the bellows to swell and perish.
I’m gonna regrease the pins tonight. Can’t find any silicon based grease anywhere near me but it looks as though Lithium is a suitable alternative.
Will let you know how I get on
The bottom pin has a rubber sleeve, the rubber sleeve on mine had swollen with age causing the pin to bind.
As a test I took the rubber sleeve off and took it for a short run.
I think if I were to replace the pins again, i wouldn’t bother with the bottom rubber one and just use solid ones.
I’ve been looking at your Youtube channel and noticed you had issues with your steering rack a few months ago.
Were there any other issues you were having, other than the self centering issues, that caused you to look into this?
Sounds daft, but have you checked the wheel nuts are tight ?
If you have coilovers and it’s come about since fitting them check the top nut is tight and all nuts/bolts and locking collars are secure.
I had been on a track day and attacking kerbs quite hard. I then started getting a knocking noise at the front. The tie rods and rod ends were new along with the drop links, so I looked else where.
I removed the inner tie rod gaiter from the end of the steering rack and I could move the shaft. There is adjustment so tried that first but it just made the steering too stiff. I ordered a low mileage rack from email and the movement has gone and no knocking.
Yeh it’s not the wheel nuts and I’ve just regreased the caliper pins. It’s not them either.
I’m now of the opinion it’s either the bushes or the steering rack. I might swap out the drop links too just to be sure.
Did the pins move freely before greasing and the wheels rotated freely before stripping down the brakes.
Yes no issues at all. One of the lower bolts that secure the pins was loose on one of the calipers but it’s made no difference either.
I’ve experienced a similar situation following wheel alignment and it was one of the alignment bolts not nipping one of the front lower arms properly. The bolt was tight but I think rust build up prevented the bolt fully securing the arm allowing it a tiny amount of movement.
Ok good to know. The car does have a bit of corriosion build up. Will take a look at that next.
Car is booked into Performance Link for a once over next week. I’m hoping they can solve this for me. I don’t to hand it over for a full underbody restoration earlier than planned!