This thread is about the physical fitment of the 2nd gen electric brake booster common on most modern hybrid/electric cars. This is a honda CRV unit, but basically all of them are the same process

These are both compact, readily available and push VERY hard. Bear in mind they draw about 40A of juice in use, so make sure the batt/alt are up to the task. Big cams, boost etc are no sweat

Buy one with the master and electrical connectors. Masters have minor differences even though they look the same. Most reservoirs do swap though
I recommend getting the connectors because replacements are very expensive for what they are




Mock-up of the old booster and pedals. The booster doesn't need to work



Grind the 4 rivets off the backside of the booster to remove the firewall bracket. The bracket bolts to the backside of the iBooster. This model is steel, but some are cast aluminum. It's a flat plate, so don't fret if you need to make a new one from 3/16"-1/4" plate
I hammered the mounting studs out of the flange and sandblasted both



Mock-up. Drilling two more holes can allow the booster to be clocked in 90* increments

 

Welded and mounted back to the pedals




The pushrod is pretty simple. I've had a tesla, chevy bolt and honda CRV version and ALL have had a M10x1.5 coupler nut going to the respective pedal. You can weld to this adapter or source your own coupler nut and eyelet. I put a washer on booster studs to simulate the firewall thickness. Pull the brake pedal back slightly from the stop to account for the switch plungers




Mounted. Strut tower clearance is excellent, exhaust clearance is excellent. Different donors clock the booster but it doesnt seem to matter. LH exit master cyls barely clear the strut tower, but do clear. It looks like the chevy bolt reservoir is the best fit for 3rd gens






Electrical is surprisingly simple. These units are inherently complex, but without the full CANBUS system or ECU control, they default to 100% manual function which is a swappers dream
The small 4 wire connector is a travel sensor. These loop strait to the big connector. Required
The big connector has the 4 wires for the travel sensor, 10ga batt, 10ga grd, 20ga IGN and a bunch of CANBUS/ECU stuff. The power, grd, IGN, and travel sensor are all that are needed. CANBUS and ECU wires can be ignored. Be sure to put a 40A fuse in the main power cable

This link explains in more detail
https://www.evcreate.com/wiring-the-ibooster/

Reservoir
This CRV unit is designed to run a remote reservoir. You can, or swap the base to something more traditional. Reservoirs attach via roll pin or thin bolt. I know for a fact CRV and Bolt resevoirs directly interchange. I've seen custom adapters to run older reservoirs, but these are case by case

Master fittings
Most use common M10/12 metric bubble flare which is readily available. Some like the Bolt, use metric M12x1 inverted flare which is super rare
M12x1 inverted flare to 3/8" 24 adapter
https://www.ebay.com/itm/39456840458...evt=1&mkcid=28
Tube nuts, these only recently hit the market. Be sure to get inverted flare, not bubble. 4mm is 3/16" line, 6mm is 1/4" line
https://belmetric.com/m12x1-0-brake-...RoCNB4QAvD_BwE

 

Here's one I previously installed
Chevy bolt booster with a CRV remote reservoir remote mounted under a 1953 Pickup. These boosters are awesome

 

Great information! I think these iBoosters are a great alternative these days, and massively overlooked. Getting a few of them out in the wild should get the projects flowing!

 

By default mode, does that mean no abs?
How does it work with the eng/ign power off?
Is the prop valve still needed?
Are the flare nuts larger size? If so, Is a reducer needed to splice into the older brake lines?
Any lighter/heavier?

Great work btw.

 

These units have a complex computer attached to them to determine the required level of braking assist under a variety of conditions. Since they were primarily used on EV/hybrids, regenerative braking is preferred to mechanical. Sometimes user inputs way more braking than necessary and the ABS will reduce assist to maintain traction

These are not useful to hotrodders, so the system defaulting to 100% assist without CANBUS input makes the unit appealing

Engine off, yes it functions normally until the battery is completely drained
IGN off, I haven't personally tested, but I can't imagine this scenario. They may have a capacitor built in for a final pump or two like vacuum/hydro boosters. I'm not certain
If it's completely off without IGN, then connecting a stoplight wire with diodes to prevent a back-feed may be useful, possibly a timer relay to an IGN source. In those cases, the only fail state would be the battery/alt being disconnected entirely

Prop valve is still needed. The master attached to the unit is just a re-packaged traditional design. Most modern cars have a motorized ABS pump which has bias valves internally. Without that, a traditional prop valve is needed

I put the section about the nut adapter because is an uncommon metric inverted flare. Not all of the iBooster masters use it. Several like the honda versions use a more standard metric bubble. It was a problem that took several hours to solve my first time, so I added it to help someone else who may encounter it

Weight is similar to the vacuum booster/master. While aluminum, it does have alot going on inside, so that adds mass. It's much lighter than the cast iron hydroboost units

Thanks

 

Great info, thank you.

 

A friend of mine did this on his Mazda RX-8 autocross car. He did it mainly for clearance issues with a new intake manifold (he has an unusual swap to a Ford 2.5) but said it was still an improvement on pedal feel. He used a Tesla Model Y reservoir.

Pat