Dianose the cause(s) for rear wheels hops during hard braking on my Ariel Atom3 300

[GTED]

Hi all

With all the technical gurus we have here on our Forum, I'm hopeful I can get better educated on this than other forums.

What would be the likely causes for the rear wheels to hop, and a few sparks from left front wheel during hard braking? I was out testing my in-cockpit remote brake bias adjustment on my Atom yeterday, so I purposely induced locking the wheels to set up the bias. During the first several attempts, I experienced these occurrences, not necessary with sparks in front and rears hop at the same time/same attempt. By the end of the testing session, about45 mins, I now have the fronts to lock just b4 the rears, which is how it should be, and I don't see sparks in the front anymore, but the rears still hop occasionally. I might further adjust the bias a couple more more forward next time, as it was getting dark yesterday. I have not done any launches with the Atom (and I don't intend to), so I don't know if a power-hop would occur or not. The Atom has Wilwood brakes all 4 corners and weighs ~1348lbs wet.

Any thoughts on common causes for the sparks and hops, so I can watch for it or test it?

Thx

GTED

 

[PL510*Jeff]

Metallic impregnated pads?

Suggest you contact Wilwood Tech series. They"ll know.

 

[the Wizard]

I would think the rear wheel hop could be reduced by dialing down the rebound setting on your rear shocks, if they are adjustable, if not you might need them......at least this is a topic you could study up on...

 

[Mullet]

I got sparks when my pads were worn out.

 

[nota4re]

I think sparks are pretty normal for metallic track pads which you likely have. The more work the brakes are doing, the more they will sand off fine bits of pad/rotor which is the source of the sparks. My Laguna Seca front brakes with the track pads could double as the Space Shuttle booster rocket ingniters when you jump on them.

Rear wheel hop is the harder one to diagnose and remedy. Most likely the shocks are in good shape - as a bad shock or loose suspension joint could cause this. You might be able to experiment with different pads and find a formulation that mitigates or eliminates the issue. (Also, make sure that the rotors aren't glazed.)

 

[GTED]

Thank you for the replies, thus far! The pads I have are Hawk DTC30. I'll do a search to see if it contains metallic material in them. Kendall, your explanation makes sense, thx!
As for the rear wheel hops, I also wonder if it was caused by the rear tires to be transitioning between slipping (lost of traction from the induced lock up) and re-establishing traction as the car slows down during my threshold braking exercise to induce lock up. I'll definitely do another fine tuning this coming weekend by dialing a little bit more bias to the front, and will also experiment softening the rear damper a click or two to see if these additional adjustments would dial out the hops.

If anyone has more thoughts on this, please keep them coming.

thx

 

[RALPHIE]

Scott Sahlman, Mark McGowan, Roketman (Ron)...any ideas?

I'm trying to think about the forward weight transfer under the extreme braking taking so much weight off the rears that firm suspension will allow the wheels to lift, and that a softer rear setting would keep the tires on the surface, however without much traction. Or perhaps, a higher front setting?