Trying to find out why braking hard at high speed causes wheel wobble.

 

Clocked all the discs and they are good. 0.2mm was the worst one. But thats not a lot.

Checked bushes and didnt find any that are worn. Think I checked them all. Dunno if theres any little ones hiding anywhere.

 

Not really sure what else it could be?

 

Sorted my brake pedal though, found some air hiding in the inner nipple on the front drivers side caliper :nono: Now shes nice and solid!

Could ba a problem with your shocks? I had this problem a few years back with a 735 BMW it also kept locking on braking in the wet. well scary. Had everything looked at until someone told me to check the shocks. Low and behold they were fooked.

Worn front tension rod bushes will cause that.

 

Vijay

Which ones are those mate?

Thought id checked them all.

number 5 in this pic :) http://www.zcentre.co.uk/shop/product_info.php?cPath=21_28_58&products_id=124

Hmmmm, they look fine. Ill double check em though.

 

Thanks!

Deffo tension rod bushes!

Check steering uj rack end could be worn or track rod ends or front lower ball joints.

Clocked all the discs and they are good. 0.2mm was the worst one. But thats not a lot.

 

What was 0.2mm ? When it comes to brakes 0.2 mm can be huge. What were you measuring ?

Check out this site - very interesting

 

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

 

In there you will see

The driver can feel a 0.0004" deposit or TV on the disc. 0.001" is annoying. More than that becomes a real pain

 

Also note that any machining of the front discs must be done on the car

 

Good luck and I hope this info helps

Brilliant article that. Wish I could find more stuff like this.

calipers sticking can make it feel wobbly when braking from speed....you can get them overhauled with a kit

HTH

I don't think its the tension rods, I bought some when I had the car but didn't fit them because the existing ones looked fine. The whole brake setup is also brand new (gtr calipers,dba golds, porterfield pads), and its not this as the wobble is intermittant and you don't feel it as you slow down. I thought it was either the shocks or the steering rack bush. The shocks felt like they needed replacing to me, they were getting a little bouncy.

Sent you a pm Mark, you can have the ones I've got here if you really want to try, but I don't think there's anything wrong with the ones that are on there.

This is well known for the tension rods to cause it - Change them first if you've already bought them and take it from there.

Mine looked fine when I replaced them but there was nothing left inside them so had obviously leaked for a while. The new bushes will be solid or speak to Smithy about adjustable ones :)

 

Vijay

I get the same thing and when i put my car on stands the other day i noticed sticky clear fluid coming from one of those bushes, it dripped down a fair amount. It happened when the car was off the wheels so it was in a abnormal position.

I've looked for fluid leaking as i've read that before. But like Royal said, they look good!

What was 0.2mm ? When it comes to brakes 0.2 mm can be huge. What were you measuring ?

 

Zeroed a DTI in a fixed point and rotated the disc. 0.2 was the largest deflection.

what does it mean if fluid IS leaking tho?

 

Its like vasaline but sticky - dont laugh!

IIRC the original Nissan bushes are filled with a grease like substance, aftermarket ones are solid.

 

Vijay

what does it mean if fluid IS leaking tho?

 

Its like vasaline but sticky - dont laugh!

 

Well it means there will be play in the bushes under pressure and I'm not sure but think it might be an MOT fail?

If they're leaking then I'd replace with some poly ones or get rose jointed tension rods.

mmm its clear tho, not like normal grease. I know that drive shaft boots have loads of grease on them etc but are these bushes not solid? I think the garage my have put some thin lube on them to stop a sweak or something?

The nissan bushes are silicone filled - it's that thats leaking - you need to replace them. You can get Nissan ones from MJP at about £40 each. I've used poly bushes before and they make the ride and steering harsher. I imagine the rose jointed ones are worse. Also there's storys about the poly bushes tearing the rear of the tie rod ends from the lower control arm - so, choice is yours.

 

Good luck

 

...I've the same problem, and I'm not convinced it's the tie rod bushes, but, it's the cheapest place to start tracing the fault.

mmm its clear tho, not like normal grease. I know that drive shaft boots have loads of grease on them etc but are these bushes not solid? I think the garage my have put some thin lube on them to stop a sweak or something?

 

some people put grease on them to protect them from heat and age, bit like an old woman puts on oil of ulay lol

 

but if its thick and sticky its normally the silicone leaking, a sign the bushes are worn, check steering gators are not damaged as any dirt getting in to or on to the rack can mean big bills down the line.