I need new clutch linkage

[GAmes]

I just discovered that my South Bend master cylinder is leaking. The last one leaked also, that is why I replaced it. The new price for SB linkage is $373.75 with a TX sales tax of $32.70, total 406.45 On the other hand Luk linkage at RA is $202.79, with the discount, tax and shipping the cost comes to $220.54 When I installed the G56 the truck had stock linkage, which I believe was supplied by Luk. When it wore out I installed the first SB linkage. If you are still with me, my question is what makes SB's HD linkage any better than the stock Luk linkage? Is there a good reason to pay double for SB's linkage?

 

[GCroyle]

Gary,

Look at the master and slave cylinder for mfgr markings, like AP or FTE. I bet you'll find one or the other etc. Not sure what combo you're running but question is (to me anyway) what type clutch are you running OE type self adjusting clutch or the 13" NV5600 cover? The 13" needs a bit more travel at the bearing than the OE SAC. In the "std" parts the G56 used a 16mm MC dia and the NV5600 is 18mm dia and with the same stroke the 18mm pushes more fluid to the SC.

A pic of the MC might help too.

Gary

 

[petersonj]

Is there a good reason to pay double for SB's linkage?

I don't think so. Not really comparing apples to apples, but I am still using my OEM clutch master and slave cylinder on my '02. I think it is probably a LUK. At 297,000 miles I also replaced my clutch, pressure plate and flywheel with a stock LUK kit. No issues in 70,000 miles of driving with a mild tune towing up to 21,000 lbs (GCW).

- John

 

[GAmes]

I appreciate the replies.

What I have is a 13 inch single disc SB part G56-OR. I remembered that in the boonie box I had packed for my last trip to Alaska is a Mopar linkage, slightly used. It was only installed for a short time between finding the first SB linkage leak and installing the second. Then I reviewed the failures. The first occured in SLC and for all practical purposes stranded me. I still had the NV4500. I replaced it with an OEM unit from the local Dodge dealer. That linkage failed in Colorado a couple years later. It did strand me and I had to be flat bedded to the repair shop. Another OEM. Less than a year later it failed in TN. That is when I met Big Papa and had the first SBC unit installed. I received an new warranty OEM linkage from Dodge and put it on a shelf. That is the one I currently have. The thing is that the OEMs pretty much stranded me while the SBC linkages have merely leaked, but still operated just fine.

Today I compared the two sets of linkage. To my surprise both the master and the slaves are identical, made by the same company (AP). The only obvious difference is the tube that connects them. Tomorrow I plan to remove the SB linkage and compare part numbers. I'm thinking about using the linkage I have, but also am nervous about breaking down far from home.

 

[petersonj]

So, did the OEM linkages fail internally without leaks? Were the failures sudden? Just want to know for my own peace of mind. It is rather disappointing that the operational life of the OEM replacement clutch hydraulics is so short.

- John

 

[GAmes]

They failed internally, no leaks, with no warning. I was able, with the first and third, to "pump them up" sufficiently to drive to a place where I could replace them. I forgot to add previously that the current linkage has a little over 300k miles on it and was replaced about 7 years ago.

 

[petersonj]

I forgot to add previously that the current linkage has a little over 300k miles on it and was replaced about 7 years ago

Well, that's a little better. So, 300,000 miles on the SBC linkage and now leaking? Is it dripping, or just weeping? If it is just weeping and with the additional information you provided, I would probably stay with the SBC linkage because at least it is still functional and not letting you down and you are getting some miles out of it.

- John

 

[GAmes]

It's seeping into the cab at the firewall connection, just like the first one.

 

[petersonj]

I wonder if the system has a venting issue. It might be worth loosening the cap for a few days / weeks to see if the seeping stops. It is interesting in that on my truck I lost my cap to the clutch master cylinder well over fifteen years ago and over 250,000 miles ago. At the time I could not find a replacement cap. I have never had any signs of leakage nor any performance problems with the clutch. The only thing that separates the fluid from the air is the bladder-like thing that floats on top of the fluid. It makes me wonder if maybe the reason I have never had any leaks into the cab is because no pressure could ever build. Just a thought.

- John

 

[NIsaacs]

Over the years I lost three oems. Just quit with no warning. The last time I installed just the master from Napa. I just changed it again, with a complete unit from Auto Zone, they have lifetime warranty and the slave is aluminum, not plastic.

 

[GAmes]

Today I started to remove the slave cylinder to compare it to the OEM. Even though the part number was upside down it was visible so I snapped a picture and checked it out. The SB is the same as Mopar. So the only difference is the tube between the master an slave. Does the flexable steel braided hose have a different ID? What exactly makes it HD?

I then re-evalulated changing them out. The seep is barely noticeable, the clutch starts to engage with the pedal about 2 inches from the floor and there isn't any real problem. I decided to take the truck off the jack and get back to a high priority of my time, a newly repainted '54 Ford restoration.

 

[petersonj]

What exactly makes it HD?

Probably the steel braid around the line. From my experience in the hydraulic field, steel braids did not protect, but eventually caused leaks (from abrasion). Routing and protecting the line is more important. Kind of irrelevant in your case, since you never had a leak with any of your lines.

Nice project to go back to....

- John

 

[BigPapa]

Gary, I certainly don’t know for sure, but if the SBC and the Mopar MC us the same housing, I’m going to say there are mods that SBC has done to the inside. I’ve never known SBC to just rebrand a part. I can personally say that there was a definite difference in the operation between an OE with @ 75K miles on it and a SBC unit I put it in my ‘95 when the Luk hub had a come apart.

 

[GCroyle]

Scott,

W/O a pic hard to be detailed but AP or FTE hit on one critical detail a completely prefilled ZERO air assembly. Taking one apart to modify internals requires the same level of zero air prefilled system and w/o the OEM vacuum / fill system it's a bit challenging to achieve that level of precision.

There were a few odd ball systems made and one that I remember seeing was one for a gas motor that had a oops fire hazard (this is from dusty memory so FWIW) it had heat shielding (Cummins exhaust is on opposite side) but pics would help. They were proud of their adjustable pedal push rod. Selecting different bore sizes changes the effort required, stoke achieved etc and it's all tuned to the system. If I put an air bubble in my system the pedal effort, engagement point, perception of free play (which these do not have) release point and pedal feel signature would all change.

Off soon to my part time job, fixing chain caws etc for a nice saw shop.

How's the new knee?

Gary

 

[Timd32]

'54 coming along real nice.

 

[GAmes]

Scott, I don't think that using some of the same componants but changing another would be classified as re-branding. For all I know the inside diameter of the steel braid hose is different, the plastic tubing that Mopar uses might expand enough to cause failure, there are a few possibilities. I can't imagine them disassembling the master and slave to change o-rings or whatever. OTOH I can't explain the failure rate of the OEM replacements I did prior to meeting you.

 

[GAmes]

'54 coming along real nice.

Thanks. If only the classic car tire guys could get the casings I need for new tires. I've been waiting since Jan for a set of wide whitewalls. The delivery date has been pushed back three times.