4 Speed Swap Clutch Issues - PeachParts Mercedes-Benz Forum

w123love · #1 02-24-2012, 02:05 AM

I am at a dead end in my current project, a 4 speed swap into a 300TDT. I am using a 300GD flywheel, brand new pressure plate and clutch, with OEM crankshaft for a 300D.

Problem is I am not getting a clutch pressure. After pumping and pumping, reverse bleeding, gravity bleeding, and playing the waiting game, I still had nothing. I could get fluid to squirt out of the slave, quite a lot actually, but still no pressure in the pedal. When I loosened the bolts on the slave, I could see it piston actuate and make slave move back slightly.

I ordered a new slave and clutch M/C, but I am starting to think it could be the release bearing and pressure plate. Is it possible to order the wrong one? I know there are two types of pressure plates and release bearings. The release bearing I am using fits very nicely in the clutch fork. But could I have messed this part up?

Help?

Thank you

t walgamuth · #2 02-24-2012, 03:09 AM

The question is whether the other to bearing will work either. Using the G fw may be part of the problem.....

Were you able to find anyone who had done the conversion using the g fw?

JB3 · #3 02-24-2012, 07:46 AM

Are the slave and master cylinder new or used? The hydraulic system is notoriously difficult to bleed. Did you try the factory method of connecting the slave bleeder to the right front caliper bleeder and using the brake pedal to prime the system? This should take about 15-20 pumps of the brake pedal to prime the clutch, and you will see air bubbling up in the brake reservoir from tghe clutch system.

the master could potentially be leaking internally with the force of the pressure plate applied, and still move the slave push rod a little. Do you have a hard pedal, or is it on the floor? If you have no pedal, there is air in the clutch system still

IMO, its much more likely an issue with hydraulics than anything to do with the flywheel

Stevo · #4 02-24-2012, 10:02 AM

Hummm, There are two different slaves, with different length push rods also there are two throw out bearings with slightly different "shoulder" height (where the fork rides). Either one of those wrong parts could be causing the problem.

junqueyardjim · #5 02-24-2012, 10:09 AM

Yes, and you can install it with the throw out bearing in backwards. Then it won't work either.

w123love · #6 02-25-2012, 10:13 PM

Quote:

Originally Posted by dropnosky

Are the slave and master cylinder new or used?

Used. I just bought got new ones in today I will install tomorrow.

Did you try the factory method of connecting the slave bleeder to the right front caliper bleeder and using the brake pedal to prime the system?

Yes I tried this method, but what was strange is the line I used from the caliper to the slave started bulging under the pressure. I know both the nipples were open. Am I supposed to compress the clutch pedal while pumping the brake?

This should take about 15-20 pumps of the brake pedal to prime the clutch, and you will see air bubbling up in the brake reservoir from tghe clutch system.

Never happened.

the master could potentially be leaking internally with the force of the pressure plate applied, and still move the slave push rod a little. Do you have a hard pedal, or is it on the floor?

To the floor. No pressure at all. Only returns because of the spring.

..

Fulcrum525 · #7 02-25-2012, 11:08 PM

Umm. Not sure if this will help but on my 300GD the clutch master cylinder is a separate unit from the brake master cylinder (As opposed to my brothers 240D which is one unit)

There is a clutch master cylinder and a slave cylinder as well as the separate brake master cylinder.

http://www.eurotruck-importers.com/index.php?main_page=product_info&products_id=367
http://www.eurotruck-importers.com/index.php?main_page=product_info&products_id=371

I supposed this was done for a survivability/durability stand point. If you lose the brakes the truck can still be driven and shifted.

JB3 · #8 02-25-2012, 11:59 PM

Quote:

Originally Posted by Fulcrum525

Umm. Not sure if this will help but on my 300GD the clutch master cylinder is a separate unit from the brake master cylinder (As opposed to my brothers 240D which is one unit)

There is a clutch master cylinder and a slave cylinder as well as the separate brake master cylinder.

Clutch Master Cylinder - FTE [0012958006] - $229.75 : Eurotruck Importers, Your source for Mercedes-Benz off-road vehicles and spare parts!
Clutch Slave Cylinder - 4-Speed - FTE [0012956807] - $42.50 : Eurotruck Importers, Your source for Mercedes-Benz off-road vehicles and spare parts!

I supposed this was done for a survivability/durability stand point. If you lose the brakes the truck can still be driven and shifted.

240D has a separate clutch master as well, they only share the reservoir. His master is inside the cabin bolted to the pedal assembly

JB3 · #9 02-26-2012, 12:05 AM

Quote:

Originally Posted by w123love

..

The clutch pedal can be left in the up position whil you prime it with the brake pedal. Strange the connecting line was bulging, sounds like it was completely blocked. I had a problem once where a used slave cylinder was jammed up with rust, sealed completely so that even with the bleeder completely removed, it was still sealed. Maybe you are just not getting any flow through the older components

New parts will probably kill the issue

t walgamuth · #10 02-26-2012, 07:43 AM

He said he could see the slave pushing the rod in and out I believe so a siezed slave is unlikely.

JB3 · #11 02-26-2012, 08:09 AM

Quote:

Originally Posted by t walgamuth

He said he could see the slave pushing the rod in and out I believe so a siezed slave is unlikely.

That's what was weird about it. The slave was fully functional, just the bleeder was blocked off with grit. Worked fine in the donor car until I had cause to take apart the hydraulics. (300D 4-speed swap)

Stevo · #12 02-26-2012, 11:23 AM

I think the clutch slave and the bleed nipple in particular, are the lowest point of the system so it stands to reason that thats where the crud would collect.
The bleed nipple of my 79's clutch slave was plugged when I went to flush the system.

w123love · #13 02-26-2012, 07:40 PM

Today I replaced the master first. After letting it sit and gravity sipping brake fluid, I felt a LITTLE bit more pressure. I had another person feel it who knew what it felt like before, and they felt the same pressure I did. So I know it wasn’t just a mental thing.

I pumped a hundred times or so but I still didn’t feel any difference. Next step was to bleed it from the slave. I opened the slave nipple and fluid started coming right out. So I pumped again, but still no change.

Moving on to the next variable, I went ahead with the slave. Though I knew that the slave I had ordered did not look right. Ends up it doesn’t fit at all. Apparently it is not for this transmission, though it was listed on blahblah AZ as a replacement slave. There were two options and I guess wrong. (In my defense what I received was not the same slave in the picture). So time to wait for parts again.

One thought to ponder: When I unbolted the slave from the bellhousing, I left it connected to the line. I pushed on the clutch pedal a couple times, and managed to shoot the pressure actuated piston out of the slave completely. So I assume I am all good hydraulically down to the slave?

charmalu · #14 03-02-2012, 10:36 AM

Did you finally get this resolved? you up and running yet?

Charlie