Lots of folks have trouble with the TOB leaking etc and there is often talk of Prebleeding, which is impossible.

But it is possible to precharge the TOB once its assembled on the transmission, and before you install it on the car.

Here is a test I did that shows what can be done.

I spent some time with the assembly. In it I found that one of the processes I follow is to depress the TOB to expose the spigot it travels on and litely grease it. VDub actually sell a special grease for that purpose, I just use decent synthetic grease.

By doing that I have pushed the internal seal back. So when the fluid does get put in through stroking the pedal, I get immediate fluid fill/little or no air. Thats an aside to explain why I never found the need to do what what folks are suggesting, to pre-bleed the TOB, which is impossible.

Now I set up the parts on the kitchen counter as I am making supper.

asseembled the parts.

Please note that there is a fairly large spring on the TOB It stays out by itself with no problem and will only depress with some effort.


Clearly the easiest way to pre fill ( not bleed that is the wrong term) the TOB , is this:
Simply depress ( pushes the seal back internally) and hold depressed the TOB, then put a head of fluid in the fill pipe to the distribution block, with the bleed nipple closed. Release the TOB slowly, and it will draw the fluid in. Done.


This is the set up, with a new pipe, TOB and distribution block. I have a spare Redline hose that connects to the master cylinder reservoir so it was easy for the test.

Note that with the distribution block in place and the nipple closed, it is possible to hold vacuum on the fill pipe ( that goes to the reservoir.)

So assemble, depress TOB hold depressed while dipping reservoir hose in a bottle of brake fluid and release TOB done. Now remove the reservoir hose and plug that with a cap ( thats going to be hard to find, but they do come with new distribution blocks to keep dirt out.


Conclusion:

Remote bleeding is impossible. Pre Charging the TOB with fluid is. Once installed on trans with clutch pipe and distribution block in place, and a spare fill pipe and available brake fluid. No need to pressurize fluid, just let the Depressed TOB do the work.

 

http://www.crateenginedepot.com/pdfs...ctio_Sheet.pdf

http://www.crateenginedepot.com/pdfs...gProcedure.pdf

and if you have low engagement concerns with Spec southbend etc try this
LNF TOB Spacer CED2673-30

 

Awesome info!

 

One last thing. If you decide to go this route, you may want to consider switching around or replacing the bolt that goes through the bell housing to the block by the distribution block. That bolt has a threaded stud on the end to hold the wiring harness and it makes it difficult to install that studded bolt with the disto block in place. SO. change the bolt. That works. Wiring harness will be okay without the support.

 

Subd, great info thanks john

 

****, wish i saw this before the trans is up and together already.

 

great info. thanks for sharing

 

For what its worth, I finally convninced our front line techs to do it this way.Precharge the TOB . Make sure the bleed nipple is closed. cap the distribution block line port and install the trans.

Guess what? Not only is it easy but in our experience its not necessary to bleed the system. Just stroke the cluitch pedal twice or so and be happy.

Drive on , James.

 

Excellent, I bled mine and didnt have any issues this time around but as you may have seen, I had a LNF TOB fail at 7000 miles (3 months as I commute) with a KY Stage 3 clutch. I had a mechanic at my toyota dealership do the swap, our machine shop redid the flywheel and it looked perfect. KY clutch/TTR racing blame the fact that I cannot confirm the depth milled off the flywheel, as to the reason it failed saying that it over extended. (did so on a launch, so happened to crack the T case as well and create a acid rain storm of bad luck)


Also about 2600 miles into the new setup i hit the track. After passes I noticed a bleed off in pressure, in fact the clutch pedal would get mushy. I waited a few hours and it seemed to go back to normal, and note I already had the Dezod (or whatever the brand) Stainless clutch line.

So hope I have better luck, never liked the 6 puck on a hydrolic system anyways, chose GMPP this time.

 

LOL, i made a thread asking if anyone has pre-filled the tob with fluid before installation and everyone recommended against it. Ive done it a few times now with success. thanks for clearing this up for everyone John

 

i guess people say they are pre bleeding the tob. thats impossible and if actually attempted under pressure would ruin the TOB.

I would still bleed it once installed, though. Personally I use a harbor freight vacuum bleeder its really good with new hose and some small mods and cheap. bleeding becomes a one man deal

leaving the disto block on the trans is a major step forward imho

 

Sub'd for potential later usage.

 

this is now SOP here. SO works!!! lol

 

subd for future use