NBS master cylinder Swap

[Pinger]

Noticing brake designations are mainly JB. My (Hydroboost) is JD 7. Is JB for vacuum servo systems and JD for Hydroboost?

Re 'twitchy EVO. What I've noticed with mine at highway speeds is strong self-centring in the straight ahead position which requires more of a tug at the wheel to deviate from and then it feels like the appropriate amount of assistance is there. There are times when a slight course correction is required the initial effort required feels to be a bit more than might be expected - a slight criticism. If that's what others regard as 'twitchy', I can see where the complaint comes from.

But the effect, that initial resistance, I like. Suits my way of driving which is to go decisively to the corner's apex in one clean sweep. EVO rewards decisive inputs. Everyone has their own 'style' of driving and preferences as to how a vehicle responds so can see why EVO could be controversial. Especially if a preference for very light steering has taken root from earlier experience - which contrasts with my experience of starting off with un-assisted systems.

 

[Supercharged111]

The twitchy feeling is a distinct and sudden change in steering effort as the system switches from low to high boost when it should stay on low boost. It'll make the truck jump.

 

[thegawd]

I bought my sierra from a buddy why had "a vibration that made the truck scary as hell to drive as it would randomly feel like sliding on ice." he had no idea about this evo sensor. he had extensive work done to the truck and could never figure it out. he got fed up and sold it to me for $150. I unplugged the evo sensor and drove the truck home with him following me without any problems whatsoever, my buddy was in disbelief but he bought a new truck and so he didnt really care. this was 3 years ago and the evo has been unplugged since. I wanna delete it but my PS pump n lines and all that **** seems fine.

can one of you post up a link to the delete kits. my sierra is a 98.

thanks

Al

 

[Pinger]

The twitchy feeling is a distinct and sudden change in steering effort as the system switches from low to high boost when it should stay on low boost. It'll make the truck jump.

Mine doesn't do that. I don't even know at what speed the transition occurs.
From shunting it off the driveway (high assistance) the next I really notice is that it's weighted up by the time I encounter a corner and on the way back down I only notice the full assistance back when I've slowed to junction speed.

 

[Supercharged111]

Mine doesn't do that. I don't even know at what speed the transition occurs.
From shunting it off the driveway (high assistance) the next I really notice is that it's weighted up by the time I encounter a corner and on the way back down I only notice the full assistance back when I've slowed to junction speed.

Sounds like yours is working correctly.

 

[L31MaxExpress]

Noticing brake designations are mainly JB. My (Hydroboost) is JD 7. Is JB for vacuum servo systems and JD for Hydroboost?

Re 'twitchy EVO. What I've noticed with mine at highway speeds is strong self-centring in the straight ahead position which requires more of a tug at the wheel to deviate from and then it feels like the appropriate amount of assistance is there. There are times when a slight course correction is required the initial effort required feels to be a bit more than might be expected - a slight criticism. If that's what others regard as 'twitchy', I can see where the complaint comes from.

But the effect, that initial resistance, I like. Suits my way of driving which is to go decisively to the corner's apex in one clean sweep. EVO rewards decisive inputs. Everyone has their own 'style' of driving and preferences as to how a vehicle responds so can see why EVO could be controversial. Especially if a preference for very light steering has taken root from earlier experience - which contrasts with my experience of starting off with un-assisted systems.

That stiff around the center feeling is exactly why I do not like it. When you suddenly get broadsided by a 40-50 mph cross wind gust things get a bit interesting. To compensate you need to be able to quickly adjust the steering angle and the wind itself fights that steering angle change. With EVO there is little to no assist.

 

[kennythewelder]

I bought my sierra from a buddy why had "a vibration that made the truck scary as hell to drive as it would randomly feel like sliding on ice." he had no idea about this evo sensor. he had extensive work done to the truck and could never figure it out. he got fed up and sold it to me for $150. I unplugged the evo sensor and drove the truck home with him following me without any problems whatsoever, my buddy was in disbelief but he bought a new truck and so he didnt really care. this was 3 years ago and the evo has been unplugged since. I wanna delete it but my PS pump n lines and all that **** seems fine.

can one of you post up a link to the delete kits. my sierra is a 98.

thanks

Al

So, if your pump is good, then you remove the EVO valve from the back of the pump, ( your best bet, is to remove the pump to do this) and replace it with the adaptor, then the U shaped pipe. In my case, the pump was bad anyway, so I just got one with the kit all ready installed.

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[Pinger]

That stiff around the center feeling is exactly why I do not like it. When you suddenly get broadsided by a 40-50 mph cross wind gust things get a bit interesting. To compensate you need to be able to quickly adjust the steering angle and the wind itself fights that steering angle change. With EVO there is little to no assist.

Agreed, it's less than perfect in that situation (but still not as twitchy as typing this - EVO needs 'text manager') and I tend to just give it a sharp nudge. Less like steering, more like guiding a ball with a stick.
I forgive it though because it is so precise and well weighted (IMO) once off-centre and aiming at an apex.

On-centre steering feel though is governed by more than just levels of steering assistance. Steering geometry and the stiffness of the front anti-roll bar have a big influence. Might people's opinions on EVO be coloured by different steering geometry and anti-roll bar stiffness depending on GVW, 2/4WD? (Is there any topic this thread hasn't touched on yet?).

Anyone got an answer on the JB vs JD designations?

 

[Gary Cookc]

Not to drag the conversation back to EVO but I'd like some clarification here if anyone can provide it. How does a truck actually behave after deleting EVO compared to when the EVO system is intact and functional?

The reason I ask is what you two stated about unplugging things to "test the feel without EVO." I've never unplugged the solenoid on the pump, but I have unplugged the column sensor which puts the system in full boost all the time. Simply put, that sucks. I can't understand why anyone would be advocating the EVO delete if that's what it makes the system feel like. Steering that over boosted feels unsafe to me at high speed.

I've seen other people say that deleting the EVO results in a constant boost level but less than full, which would be much more reasonable.

On another note I swear I've seen someone mention fine tuning the boost level by restricting fluid flow at some point in the system...

TL;DR Deleting the EVO properly doesn't really provide the same result as unplugging the column sensor does it?

I deleted my evo with the evo delete kit found online. About $40. My 98 c1500 2wd now drives great like earlier trucks before evo. The orifice that screws into the pump has a 1/8th port to restrict flow to the gear box. Works great. No wander ot twichy feel.

 

[HotWheelsBurban]

Noticing brake designations are mainly JB. My (Hydroboost) is JD 7. Is JB for vacuum servo systems and JD for Hydroboost?

Re 'twitchy EVO. What I've noticed with mine at highway speeds is strong self-centring in the straight ahead position which requires more of a tug at the wheel to deviate from and then it feels like the appropriate amount of assistance is there. There are times when a slight course correction is required the initial effort required feels to be a bit more than might be expected - a slight criticism. If that's what others regard as 'twitchy', I can see where the complaint comes from.

But the effect, that initial resistance, I like. Suits my way of driving which is to go decisively to the corner's apex in one clean sweep. EVO rewards decisive inputs. Everyone has their own 'style' of driving and preferences as to how a vehicle responds so can see why EVO could be controversial. Especially if a preference for very light steering has taken root from earlier experience - which contrasts with my experience of starting off with un-assisted systems.

Yes as far as I know, the hydroboost is designated by JD# and the vacuum booster system is designated by JB#.
I think the EVO system is working okay on our Burb. Easier to park, and power assistance proportioned as you need it. Admittedly sometimes on Houston area crappy roads it's hard to tell.
Did you get the master cylinder sorted out on your Burb? It sucks to get bad parts when the store is only across a small town; can't imagine how it feels when you have to wait for it to swim across the Atlantic....