front wheel hop while braking

I did search, and couldn't find the discussion that I've seen here before about compromised braking while driving over washboard or uneven road surfaces.

I'm at 31k miles, really love the simplicity of my LeafS. I don't know if this issue has gotten worse, or I've just been driving in areas with rough roads.

While driving on broken/uneven road surfaces, and braking, there seems to be some FE wheel hop, which creates a rather alarming loss of braking efficiency. The brake pedal seems to momentarily be unresponsive, and it takes a split second to re-engage.

I'm assuming the braking regen system and the hydraulic braking systems are in a split-second discussion, working out their priorities. It can be rather unsettling.

Thoughts? Or, a link to a previous thread? Thanks.

I have noticed same thing going over a pothole.

Any of these what you are looking for?

http://mynissanleaf.com/viewtopic.php?f=27&t=25800&p=526809&hilit=Loss+of+braking#p526793

http://mynissanleaf.com/viewtopic.php?f=30&t=15594&hilit=Loss+of+braking

http://mynissanleaf.com/viewtopic.php?f=8&t=6086&hilit=Loss+of+braking

http://www.mynissanleaf.com/viewtopic.php?f=30&t=18977&hilit=Lost+regen+after+bump

It isn't wheel hop. It's the ABS kicking in, and making the car seem to lose braking power briefly. Priuses do it as well. I assume that the above links are to topics on that.

LeftieBiker said:

It isn't wheel hop. It's the ABS kicking in, and making the car seem to lose braking power briefly. Priuses do it as well. I assume that the above links are to topics on that.

Click to expand...

Agree, our Prius also does it but I'm not so sold it's strictly a ABS phenomenon as I've never seen it on a vehicle with ABS that also didn't have regenerative braking. Now maybe it's as the OP said it's some sort of split-second timing issue between the ABS and regen but I personally believe it's more to do with regen than ABS. Of course since you'd probably never see a vehicle with regen that also didn't have ABS it's hard to say but you do see plenty of vehicles with ABS and no regen and I'm sure open to correction but I've personally never experienced the temporary feeling of loss of braking like I do on our Prius or Leaf. I know one thing, I really don't like it and to help reduce it, if I know a particular stretch of road is bumpy and regularly requires braking(such as a stop sign at the end of a downward freeway off-ramp) I tend to brake harder before the bumps so I can slightly let up on the braking when over the actual bumps, this seems to help greatly and gives a piece of mind.

I agree that it seems to be something specific to vehicles that have both ABS and regenerative braking. I suspect that the ABS is programmed differently for cars with regen.

It is actually a combination of ABS sensitivity and suspension tuning. I had a 2000 SUV that never did it and traded it for a 2004 of the same model. The 2004 would sometimes engage ABS when hitting a bump while stopping (happened consistently at a certain traffic light on my way to work). I thought it was due to the ABS being more sensitive on the 2004, but the problem went away completely when I replaced the OEM shock absorbers with high-quality aftermarket units which have special valving to allow the wheels to step over bumps, but still provide a firm ride. I concluded that the original shocks were not keeping the tires in firm contact with the road over those bumps. I forgot about the bump at that intersection until I bought the 2011 LEAF. The 2011 was and the 2015 is consistent with a momentary loss of braking at that intersection where there is a transition from pavement to concrete. I have also noted the issue on my motorcycles that have ABS.

I would try new shocks and struts for the LEAF if I could find some with similar valving design to what I have on the SUV.

I would not recommend spending ANY MONEY on shocks or struts based on a SYMPTOM. No Nissan needs new suspension parts at 30K miles, especially struts. If he has the car suspension checked, he will ne fine.

All cars with ABS will "skate across" rough roads, and it will feel like jolts, especially in the wet, cobble stone-like roads, and if the car is moving at over 20-30 miles per hour.

Thanks for the lively discussion.
I've had ABS for 2 decades, and this isn't the same feeling as ABS being momentarily confused. My bet is on the ABS/regen combination.
I figured it's just an annoying characteristic, and I've learned to live with it. I don't think it has gotten worse, probably just the notoriously rough pavement throughout the DFW region.

I never suggested replacing struts or shocks, just that the cause could be a combination of things. I currently have over 76,000 miles on the original shocks and struts on the 2015 LEAF and the 2011 was still on its original suspension when it met its demise at 50,422 miles. I will try to find better struts and shocks when the originals get weak to minimize the momentary traction loss/ABS/Regeneration action over sharp bumps.

Variable valve units, with a tuning more towards performance, would probably reduce the conflict with the ABS over smaller bumps, but would also likely result in a somewhat more harsh ride in many conditions..

OH... Another idea.. I would also check the car with Leafspy to see if there are any OBDII error codes. On my car I had a bad antilock wheel sensor. The car would jolt for no reason, and it finally gave error lights on the dash....

Leafspy can tell you if your abs has errors...