EVO component swap--Done!!!

[Galaxie500XL]

I've got a '95 LQ1 Cutlass, which has the NV7 variable effort steering. The pump is whining like crazy. A friend is giving me a pump, but his doesn't have the EVO component on it, which means I'll have to pull the variable orfice off of my pump, and place on the new one. I see there's a snap ring on the top of the EVO, but have no idea past that how to safely pull it off of my old pump, and install on the new one.

 

Anyone know the right way to do this?

Edited August 26, 2011 by Galaxie500XL

[95 vert]

That piece unscrews from the pump. No need to touch the snap ring. You gotta put a wrench on the nut on that.

[Galaxie500XL]

I'll do a more specific write up later, but it's done. Learned a few things about doing this swap---

 

1. There is insufficient room with the fluid tank installed to get a socket wrench on the nut to remove the EVO component, the tank must be removed.

 

2. You MUST have a 30mm 6-point socket wrench. The nut will round if you try to use anything else, and will nearly round even with the proper wrench.

 

3. The only way to get the socket wrench on that nut is to disassemble the EVO, which isn't that big a deal.

 

4. If those of you with NV7 pumps attempt this, MAKE SURE to hold on to your old pump. The fluid tank for an NV7 is NOT the same as a standard 3.4 power steering tank. There's a lip on a standard tank that isn't present on an NV7 tank..that lip gets in the way of the EVO component, so you'll have to swap tanks.

 

The beauty is, as long as your EVO component is still working, a standard power steering pump can be used on your NV7 car. GM no longer offers the NV7 power steering pump, used on '95 LQ1 Cutlass and Grand Prix GTP, and rebuilt pumps with the EVO are VERY difficult to find....AND expensive, once you do find them. Total cost of this swap was $28.00. Best cost I could find on a rebuild with an EVO component was $120.00.

Edited August 26, 2011 by Galaxie500XL

[94 olds vert]

What does the EVO component do?

 

I haven't had the best luck with Power steering pumps. Went though about 5 in a couple months. Then found an original one off a low mileage GTP and that one has worked better than any of the reman pumps.

[Galaxie500XL]

Basically, it's simply a coil, and a pin that sits in an orfice to vary the output of the pump. It varies the output pressure of the pump, so you have full assist at low speeds, and reduced assist, and greater steering effort at higher speeds. Oddly enough, the ABS computer controls the EVO. Also, there's a sensor in the steering column that detects steering wheel position, and this input also allows the system to vary the output pressure of the pump based on speed, and steering wheel position. I assume the ABS computer was used to control the system, because the ABS unit is reading wheel speed from the tone wheels at each wheel.

 

Intererestingly enough, the pump I got came from a friend's car. He had a GTP, which also originally had EVO, but he put a standard pump in it's place. I had heard the pump running on his car--very quiet. However, on my car, once the EVO component was put in place, the pump does whine somewhat when turning, which it didn't do before on his car...I'm assuming it's due to the restriction on output the EVO unit places on the pump, or I've got an issue with either a restriction in the return line, or a rack issue. At least it's not making the horrible grinding noise the old pump made, and assist is noticeably improved over my old pump.

[94 olds vert]

My pump whines constanly, but I have full assits all of the time.

[Galaxie500XL]

I don't feel much difference between full assist, and partial assist at speed. There IS a difference, but it's rather subtle. I can tell you if it isn't working at all, you'll probably see the ABS light lit.

[92GrandPrixSE]

I'll do a more specific write up later, but it's done. Learned a few things about doing this swap---

 

1. There is insufficient room with the fluid tank installed to get a socket wrench on the nut to remove the EVO component, the tank must be removed.

 

2. You MUST have a 30mm 6-point socket wrench. The nut will round if you try to use anything else, and will nearly round even with the proper wrench.

 

3. The only way to get the socket wrench on that nut is to disassemble the EVO, which isn't that big a deal.

 

4. If those of you with NV7 pumps attempt this, MAKE SURE to hold on to your old pump. The fluid tank for an NV7 is NOT the same as a standard 3.4 power steering tank. There's a lip on a standard tank that isn't present on an NV7 tank..that lip gets in the way of the EVO component, so you'll have to swap tanks.

 

The beauty is, as long as your EVO component is still working, a standard power steering pump can be used on your NV7 car. GM no longer offers the NV7 power steering pump, used on '95 LQ1 Cutlass and Grand Prix GTP, and rebuilt pumps with the EVO are VERY difficult to find....AND expensive, once you do find them. Total cost of this swap was $28.00. Best cost I could find on a rebuild with an EVO component was $120.00.

 

Whats a socket wrench?

[94 olds vert]

Whats a socket wrench?