What to expect upgrading to a 5.5gpm machine?

So gear drive pulls water in also?

Yep. Arguably more reliable and definitely more compact.

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OK. I have two Simpson 4200/4gpm machines now. Can i take one and swap the pump with a gear drive then?

Yep. There’s at least a couple of options. I think @patriotspwashing bought an Allison pump with gear box a couple weeks ago? There’s also a couple threads on doing so with a GP or Udor pump I believe?

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Great im checking them out now.

I went with a GP HP5535 with an Udor gearbox. I’ve had it for about a year and love it. I soft-wash with 6.6 gpm all day long. Driveways are easy as long as you pre and post treat. Part of me wishes I would have put an 8gpm pump on the gx390 but then I’d be getting 1600 psi which doesn’t wash concrete but I do 90% house washing and 10% driveways so it may have even worth it.

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That pump is almost as much as a brand new machine.

I got it from Russ at Southside for about $800 shipped

Yeah. New 4200/4 is only 900. That’s crazy.

It depends on your perspective. I used to have a 4200/4…I could barely clean 3 houses a day…about 1.5 hours each. I can clean 6 houses now by myself at 40-50 min each. I can run circles around someone running 4gpm…I can make up the cost of a pump in one days work…so it just depends on your perspective.

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So that pump just swaps on to the GX 390 after removing the cat pump that comes with it?

4 bolts…do a search on upgrading to 5.5 on a gx390. There’s a few threads on here from a few years ago. You’ll definitely need a buffer tank though.

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Nice. Yeah i have a 100 gallon tank now. Searching now.

I believe a cat pump has a fixed screw you’ll need to remove to get the pump off.

Gear driven or direct drive? I think the gearbox alone is around $400?

Definitely a direct drive if new for $900. I don’t know if I’ve ever seen a new gx390 with a gear drive pump. Most people build them. I’ve seen a gx690 Water Dragon with 8gpm gear drive Udor pump for $3800.

The machine I bought is direct. It’s a great machine but I have two now. Sip why not swap a pump on one.

You can always spend a little more and get a 8gpm gear drive pump and just use it for house washing. If this GP pump ever gives me trouble that my next move. Most people on here would discourage doing that though but there’s a few posts on here of people doing it.

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Do you all find 3000psi to clean concrete effectively or is 3500 necessary? I’m using 200’ of continuous hose.

At some point I’d like to get an 8gpm but not sure if I need 3500psi.

yes, spend the money for the 3500 if you’re ever going to do much concrete and/or commercial

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