Clutch fluid


Matt77

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I know that's not the technical name. There was another thread where we were talking about Redline mt90. Is that transmission fluid? What is the AT-4 for then? Should it be synthetic or not?

Now I think they said clutch fluid should be AT-4? Synthetic? Anyways as I looked at the clutch fluid resivor it said to use dot 3 brake fluid for the clutch fluid right on the cap. Yes I'm sure bc the brake fluid resivor also said to use dot 3 brake fluid.
 

ohiopatriot

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Dot 3 goes in the clutch reservoir.

The Mt90 is good for a manual transmission

ATF+4 is good for auto trans and transfer case. 2003 and up power steering also.
 
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Matt77

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Dot 3 goes in the clutch reservoir.

The Mt90 is good for a manual transmission

ATF+4 is good for auto trans and transfer case. 2003 and up power steering also.
So if I empty and refilled my clutch fluid is there a chance that it will shift better? Hard going into 1st and 2nd gear and reverse grinds.

Also I should check my transmission fluid?
Since I have not kept up with changing the transmission fluid I would change less than 1/3 bc I don't want to wreck the transmission. I have wrecked the transmission before on an old van by changing 100% of the fluid after never keeping up with it. :(

The clutch does seem to work better after pumping it. What does that mean?

@Chris, @Jerry Bransford , @jjvw , @mots
 

mots

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So if I empty and refilled my clutch fluid is there a chance that it will shift better? Hard going into 1st and 2nd gear and reverse grinds.

Also I should check my transmission fluid?
Since I have not kept up with changing the transmission fluid I would change less than 1/3 bc I don't want to wreck the transmission. I have wrecked the transmission before on an old van by changing 100% of the fluid after never keeping up with it. :(

The clutch does seem to work better after pumping it. What does that mean?

@Chris, @Jerry Bransford , @jjvw , @mots
I have a lot of automotive experience with other cars, but I’m new to TJ’s since just this year. I’ll yield to the experts on this one for the details ;)

If it hasn’t been changed in a while, I would change it out using OEM fluid recommendations and not stress it. In general, in my experience with other cars, it might make a slight difference in shifting performance, and more so likely if it hasn’t been changed in a while. The best matched fluid might be able to make it a bit smoother in some cars under some conditions, cold, heat etc (i.e. performance grade synthetics etc.), but it won’t be a magic bullet and I’d stick with OEM unless someone else recommends otherwise. If there are truly mechanical issues due to wear and abuse, the fluid won’t be a magic bullet of course.

For the clutch, you might have a slow leak if the effect is very pronounced, repeatable, and not just perceived. The likely culprits could be the master or slave cylinder going south, or a clutch hydraulic system that wan’t properly bled during it’s last service.
 
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ac_

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So if I empty and refilled my clutch fluid is there a chance that it will shift better? Hard going into 1st and 2nd gear and reverse grinds.

Also I should check my transmission fluid?
Since I have not kept up with changing the transmission fluid I would change less than 1/3 bc I don't want to wreck the transmission. I have wrecked the transmission before on an old van by changing 100% of the fluid after never keeping up with it. :(

The clutch does seem to work better after pumping it. What does that mean?

@Chris, @Jerry Bransford , @jjvw , @mots

So if you have a leak in your hydraulics (clutch fluid(Brake Fluid)) then you can introduce air into the system. If you get air in the system it stops you from putting the clutch in all of the way which could cause a hard shift.

If you you had a clutch put in recently and they put gear oil in the transmission it can also make it shift hard. (Not necessarily reverse as it doesn't have a synchro.)

How to check the clutch system for leaks you ask?

First with a flashlight under your dash follow the rod from the clutch pedal through the firewall and look for paint discoloration or fluid? Then under the car follow the line leaving the master to the slave. There is a boot on the end of the slave. Pull the boot back, and if fluid comes out it leaks.

If you have a leak at all replace them both.

Also if you have gear oil in your transmission change it with this.

https://www.amazon.com/gp/product/B002INX20C/?tag=wranglerorg-20
This will make it shift better and is better for your synchros also.

Let us know if you have any questions.
 
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mots

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@ac_ Red Line’s MT 90 was king for the 300zx community I recall. Everyone used that stuff, including me! They claimed it shifted better at low temps. Probably not @Matt77 ‘s problem in FL though, haha! Still good stuff from my experience for any temp.

Curious to see what others use for fluid (I have the 6 spd). Per my carfax service records, mine was supposedly changed at a dealer, but who knows what was used, or even if it was changed. Nothing is certain, so I usually do it over myself so I know what was done and exactly when.
 
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ac_

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@ac_ Red Line’s MT 90 was king for the 300zx community I recall. Everyone used that stuff, including me! They claimed it shifted better at low temps. Probably not @Matt77 ‘s problem in FL though, haha! Still good stuff from my experience for any temp.

Curious to see what others use for fluid (I have the 6 spd). Per my carfax service records, mine was supposedly changed at a dealer, but who knows what was used, or even if it was changed. Nothing is certain, so I usually do it over myself so I know what was done and exactly when.

i live in Arizona and I grinded in 2nd and 5th. I replaced gear oil with that, and it definitely fixed my shifting. And we haven't been under 100 degrees for 3 months now. The 90w gear oil is way to thick for the synchro in the ax15. I definitely noticed a difference. I won't use anything else. Seriously no 5th gear scratches anymore.
 
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Matt77

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How much brake fluid does the hydraulic clutch system hold so I know how much to get? Before I bleed out all the old fluid and replace with new?
 

ac_

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You should be fine just getting any name brand dot 3 fluid. I usually get valvoline or napa myself. You can do fine with just a pint. You will bleed the fluid through the bleeder of which I hope you are actually calling the zirk fitting. A zirk is where you would normally grease something through, but the bleeder looks similar.

Generally you will want two people. You want the person in the cab to pump it 6 to 7 times slowly as not to cause bubbles, and hold it to the floor while you loosen and retighten the bleeder, then repeat till there are no more bubbles taking breaks, and checking the fluid making sure you don't run out in the reservoir.

But all of that aside. It wont, make much difference if you have a leak, so make sure nothing is leaking first.
 
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Matt77

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You should be fine just getting any name brand dot 3 fluid. I usually get valvoline or napa myself. You can do fine with just a pint. You will bleed the fluid through the bleeder of which I hope you are actually calling the zirk fitting. A zirk is where you would normally grease something through, but the bleeder looks similar.

Generally you will want two people. You want the person in the cab to pump it 6 to 7 times slowly as not to cause bubbles, and hold it to the floor while you loosen and retighten the bleeder, then repeat till there are no more bubbles taking breaks, and checking the fluid making sure you don't run out in the reservoir.

But all of that aside. It wont, make much difference if you have a leak, so make sure nothing is leaking first.
I checked my resivor and it's full so I'm not sure if there's a leak? Can air get in there without it leaking?
 
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ac_

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I checked my resivor and it's full so I'm not sure if there's a leak? Can air get in there without it leaking?
Most likely not, but moisture can. If the Tj has over 100K and the fluid has never been changed there is a good chance the fluid is not as good as it once was. Although I haven't had my Jeep that long yet I usually replace all of my clutch fluid every 30K. I haven't actually done mine yet, but do plan to on my next oil change, so I have a point of reference since I bought my TJ used.
 
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Matt77

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Most likely not, but moisture can. If the Tj has over 100K and the fluid has never been changed there is a good chance the fluid is not as good as it once was. Although I haven't had my Jeep that long yet I usually replace all of my clutch fluid every 30K. I haven't actually done mine yet, but do plan to on my next oil change, so I have a point of reference since I bought my TJ used.
I was at O'Reilly auto parts today. For my chevy express van which I wrote about in another thread but had them quote me the master and slave clutch hydraulics parts. And they were about $50.00 each. So I might get around to swapping them out if the bleed and refill doesn't work. My jeep is 20 years old but only has 128k miles on it and a whole list of problems. Lol
 

ac_

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Another test you can do to your hydraulics. This is not the only thing that happens if they are bad, but if this does happen then they are bad.

Start your Jeep and put it in gear either 1st or reverse doesn't matter. Do it on flat ground so you don't have your foot on the brake, but are stopped.

Hold your clutch to the floor with no brake and no gas in gear for a minute and see if it starts to move on its own. If it does, that means that your fluid is not holding pressure against a piston and I would definitely replace both. I have seen this quite a bit. Usually it also has a leak, but I have seen it where they have leaked passed a piston but not out of a seal.

Now saying that, if it doesn't happen, that doesn't mean that they are not bad, that just means they could be a different kind of bad.
 
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