why does my 720 grind going in reverse?

[justaguywitha720]

I have a 720 and every time i want to go into reverse it wants to grind a little bit. But i have heard that is normal in 720s. Can i get some more understanding please.

[Stoffregen Motorsports]

Reverse has no synchro. So when putting into reverse, go into another gear first. All the other gears have synchros and by putting it into another gear, you will stop the transmission from spinning allowing reverse engagement without grinding.

 

If you're trying to put it into reverse while moving, you can't do that.

[datzenmike]

Hold the clutch down and very slowly engage reverse with the engine running. If you hear a constant light grinding of the gears your clutch (for several and unknown reasons) is not disengaging the transmission from the engine. This could be a damaged pressure plate or clutch disc but more likely low clutch master cylinder fluid. The clutch master is beside the brake booster.

 

As stated if the truck is rolling or you are too fast jamming it into reverse from neutral slow down and let the vehicle stop first.

[banzai510(hainz)]

always bleed the Clutch first .

[justaguywitha720]

Thank you for the help guys I have a new master cylinder but I have not installed it yet. So it sounds like that might be the problem because it is the OEM one still

[datzenmike]

There several causes mentioned. Throwing parts at it, hoping it will work is expensive and time consuming. Trust me the original master is 10X better than the thing you replace it with. Figure out what's wrong first.

 

You didn't answer my question about a slow shift into reverse. Does it grind continuously?????

and...

Is it low on fluid????? take a look.

[justaguywitha720]

Sorry I didn't mean to get off on the wrong foot. I did slow and it does in fact grind the whole time until I push hard enough. I looked at the fluid and it seems fine. I do have problems with my clutch pedal feeling loose after I drive for a little bit but I just pump it and it becomes solid again. I have tried bleeding the clutch.

[datzenmike]

OK sounds like air trapped in the hydraulics. Have you checked the fluid level????

 

Top it up and have someone watch and top it up as needed while you bleed the slave.......

 

1/ Pump several times and hold pedal down.

2/ Open the bleeder on the slave... fluid and bubbles will come out.

3/ Close the bleeder.

4/ Let pedal up

 

Repeat 1 through 4 until only clear fluid comes out.

 

This should fix things but if the pedal goes soft in a few days air is getting in.

 

 

[Stoffregen Motorsports]

Yep, try bleeding the clutch again.

 

What method are you using to bleed? If you're using a pressure bleeder or vacuum bleeder, or any other fancy gadget, those are only really good at getting fluid in the system. A two person "pump, crack, close, again" method is going to be your best bet.

 

Clutch hydraulics are so simple that it is possible to gravity bleed them. Fill the reservoir, pump the pedal a couple times, open the bleeder and walk away. Let it drip for a few minutes and close it up before it runs out of fluid. Easy peasy. And usually works well enough.

 

If your hoses or hard lines have been changed. and there are any loops or hard turns in them, and if they go up above the height of the reservoir, that will make it harder to bleed the system.