450C Jerky starts in forward and reverse

Goober · Post by **Goober** » Fri Jan 16, 2015 11:37 am

Finally got the undercarriage repaired on my (new to me) 450C (new rollers, welded up idlers, repaired both yokes, new hydraulic hoses all round) and did a full fluid and filter service. Machine runs great, pushes dirt and rocks strongly but is rough engaging forward and reverse when I'm using the HLR (I always wait for machine to come to a full stop before engaging forward or reverse). It engages very suddenly and jumps harshly each time it engages in either direction, and I worry this is stressing the final drives (this is in 1st, 2nd through 4th feel too hard starting on the machine so I don't use them). I'm not supposed to need to use the inching clutch to engage the HLR, but that's what I've been doing. What should I be looking at to adjust/fix this or is it normal?

TIA,
Niall

DrLoch · Post by **DrLoch** » Fri Jan 16, 2015 12:22 pm

Sounds like you need to do a clutch control valve adjustment and/or the needle valve adjustment. Look at this post for the write up I did, http://www.jdcrawlers.com/messageboard/ ... php?t=9734
end of the 1st page.

After adjusting my clutch control valve mine shifts harshly also. I just use the "inching clutch" when going from forward to reverse. I've been told that you can crack the case with it shifting abruptly and I can believe it. Going forward to reverse with out using the clutch will bring you out of the seat on mine.
I'm to lazy to try and adjust the needle valve to slow down the shifting not to mention it's a real pita to get at.

Goober · Post by **Goober** » Fri Jan 16, 2015 1:35 pm

For doing a clutch adjustment I see that a 250psi gauge is ideal - where would one find a 250psi hydraulic/oil pressure gauge?

DrLoch · Post by **DrLoch** » Sat Jan 17, 2015 7:44 am

Do you have a Northern Tool near you? They offer a 0- 300. Also you can try http://www.surpluscenter.com/Hydraulics/. They have any number of gauges, they will also have fittings and hoses

Goober · Post by **Goober** » Sat Jan 17, 2015 12:13 pm

Is there any reason I couldn't use a 250PSI gauge off an old air compressor? I have a few of these gauges lying around.

jtrichard · Post by **jtrichard** » Sat Jan 17, 2015 1:19 pm

PSI is psi YES you can

DrLoch · Post by **DrLoch** » Sat Jan 17, 2015 5:07 pm

jtrichard wrote:PSI is psi YES you can

I thought air PSI was different than hydraulic oil PSI....

jsal · Post by **jsal** » Sat Jan 17, 2015 5:55 pm

better off with a liquid filled hydraulic pressure gauge more accurate !!!

JIM

Stan Disbrow · Post by **Stan Disbrow** » Sat Jan 17, 2015 6:19 pm

Hi,

Modern pressure is measured in kPa. Only the old stuff uses PSI....

Stan

DrLoch · Post by **DrLoch** » Sun Jan 18, 2015 7:52 am

This is an older machine so PSI should still apply, kPa is used on the "G series machines and newer isn't it?

Goober · Post by **Goober** » Sun Jan 18, 2015 11:31 am

I'm glad my pressure gauge question could be a source of such amusement here.

I still haven't been able to get used to pressure in kPa or bar, I guess I am stuck somewhere back in the 70s along with my dozer. But seriously, do most pressure gauges have a sealed mechanism such that as long as the fluid in question doesn't dissolve or break the seal they are good to go?

Stan Disbrow · Post by **Stan Disbrow** » Sun Jan 18, 2015 12:21 pm

Hi,

The standard pressure gauge has a curved tube inside, attached to the gauge frame on one end. The other end is left loose and has a connecting rod to a tiny crank and some gears which rotate the pointer. As the working fluid (liquid or gas) pressurizes the tube, it tries to straighten out. Moving the pointer.

Obviously, the pressure scale used is meaningless to the operation of the gauge. We just have fun converting from ine to the other when the gauge reads differently than our brains...

Stan

Edit: the tube is usually copper or brass so most things we want to read won't hurt the tube.

jtrichard · Post by **jtrichard** » Sun Jan 18, 2015 12:28 pm

Here is a pic of a simple gauge ..... the BOURDON tube is generally made of copper and soldered in place so other than very corrosive things like acids YES your "air" gauge can be used.....liquid filled gauges are mainly used in HIGH vibration applications https://images.search.yahoo.com/images/ ... rt=mozilla

DrLoch · Post by **DrLoch** » Mon Jan 19, 2015 7:41 am

Goober wrote:I'm glad my pressure gauge question could be a source of such amusement here. I still haven't been able to get used to pressure in kPa or bar, I guess I am stuck somewhere back in the 70s along with my dozer. But seriously, do most pressure gauges have a sealed mechanism such that as long as the fluid in question doesn't dissolve or break the seal they are good to go?

We have to have some fun from time to time.....

If you haven't noticed most of us are stuck in the somewhere past. These are older machine we are playing with. The newer generation wouldn't be working on this old stuff, or junk as they would call it. They want the shiny new stuff.

Stan Disbrow · Post by **Stan Disbrow** » Mon Jan 19, 2015 7:59 am

Hi,

Yup. We all have piles of self-propelled scrap iron. When they become stationary piles of scrap iron, we show up here!

Stan

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450C Jerky starts in forward and reverse

450C Jerky starts in forward and reverse

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