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Discussion Starter #1
Hi everyone,

I have almost completed my conversion but have hit one last hurdle that's proving to be very difficult to solve.

Conversion summary:
Two wheel drive Hilux
HPEVS AC51 motor bolted to gearbox. Still have flywheel, clutch, gears
Salvaged Nissan Leaf battery modules (60)
160V system
Everything drives fine, works fine, I'm going through the certification process here to get it road legal.
I appreciate the help I got last year on this forum when I was grappling with how to set up the battery pack.

The challenge in front of me now is my braking performance. In a nutshell, the standard I have to meet is to stop from 100km/hr to zero in 4.4 seconds or less, 3 times within 2 minutes. I can pass this test in the dry, but not in the wet.

I'm running completely stock braking system components, but have replaced the following with new OEM; calipers, pads, rotors, drums, fluid, new Hankook Kinergy ST tyres. Bosch electric vacuum pump provides 24 inches of vacuum to the servo.

The battery box sits inside the load tray and weighs approx 200kg. The front end is lighter by around 150kg (ICE I think weighed 200kg, AC51 weighs 50kg)

I've lifted the rear by way of shackle extenders 50mm to improve how the vehicle sits.
The load sensing valve has been adjusted to compensate for this lift using brake rollers test equipment so that I have 51% front and 49% rear bias.

Brake feel is fine, but under heavy braking the front wheels will lock up.

My next step is to trial the use of ballast in the front end to get the vehicle back to stock weight distribution.

I would greatly appreciate any feedback on how to solve this issue, or how any other project grappled with a similar problem.
 

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Hi
You simply need to adjust your load sensing valve - bit less on the front, bit more on the rear
The 51/49 will be for the standard weight distribution
 

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Discussion Starter #3
Thanks,

So what would be the best way to determine the extent of adjustment?

Small adjustment followed by a road brake test to ensure the back wheels don't lock up, repeat as necessary to get to the sweet spot,

Or work out my weight distribution as a % and adjust using brake rollers?

Any thoughts?
 

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You will need to do the road test anyway!

There are two situations
Dry road good conditions
Wet road slippery conditions

You always want to lock up the fronts first

In the dry you get more weight transfer to the front so you want to ensure that the fronts lock up first in the dry - which should mean the same happens in the wet

The fact that you have a LIGHTER vehicle should mean that you ace the certification brake test

There is a presupposition from the old lead acid days that an EV will be heavy
 

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I would guess the height sensing proportioning valve is not a good combo with lifted rear. I would try temporarily disconnecting the rod that goes from prop valve to frame and tie it in one position. Normally this compensates for the huge difference in heavy vs light loaded truck braking needs. With the long shackles this system could be malfunctioning, changing braking characteristics too much during every stop.
 
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