Silverado clutch/trans info?

[Jim Ross]

Hi All,
I recently bought a well used '05 Silverado 1/2 ton reg cab short bed 4WD w/ 4.3 V6 and the 5 speed Getrag transmission. After spending hours researching on a site dedicated to these trucks, I have come "home" to the TDR hoping for better info/guuidance.
This Silverado needs to have the clutch pedal pushed HARD against the floor in order to get a grind-free shift and it bucks like crazy when in reverse backing uphill. I'm figuring at 148K miles that it needs a clutch and new flywheel, but what I have learned is that the hydraulic clutch system on these trucks is plastic and even with brand new systems, some owners still have to have the clutch pedal hard against the floor to get a decent shift.....and several owners have had un-ending issues with the clutches on these trucks. Knowing what I know now, I don't think I would have bought this truck, at least not in manual trans configuration. I have heard that some of these trucks came with automatics and a floor shifted T-case (like on the manual trans).
I am in the process of putting in a new flywheel, clutch, clutch hydraulics, up-dating the T-case, and adding a limited slip unit in the rear axle (including u-joints, bearings, seals, etc) plus getting custom skid plates built.
No one seem to know if any other transmission will interchange with the Getrag and whether there are different clutch systems or parts to make this truck better. Rumor has it that the NV3500 was offered in these trucks, but no one seems to know for sure.....and even if it was, did it still have the plastic clutch parts?
In the worst case scenario, I could see trying to swap an automatic into this truck if I can marry the automatic to my T-case.
Before I go that far tho, I am going to put everything back to oem and see if things work well, but.......I would like to be prepared with good info in case the oem set-up is not satisfactory.
I like this little truck and plan to use it for some off-roading in NV, ID, and MT as well as a general errand runner.
Anyone have any good info or ideas?
Thanks in advance.

 

[GCroyle]

Jim,

My 1st impression solely (your limited vehicle history and info) based on having the push hard on the pedal comment is that you have an air bubble in the hydro's. We assist calls from all over the US and assist folks on TESTING and TROUBLESHOOTING hydraulic clutch release systems. Its real hard to quantify how big or small the bubble is but bubbles that amount to the size of a couple of garden peas are enough to mess one up.

Most all techniques that work on brakes are the last ones that work on clutch hydros.

Does your clutch pedal feel a bit mushy at the top of the down stroke? Use your hand, not foot to really assess. These systems start creating PSI in about 1/8" master cylinder pushrod travel.

This video might show you the bubble perspective. https://www.youtube.com/watch?v=bngJkM_vkUE&list=UUSufPrfq8lm0rYJ0cM03jXg

If you want to discuss, give me a PM or post and I'll walk you thru it.

Gary

 

[Jim Ross]

Gary,
This is an excellent video, thanks for sending it!
When I first got this truck and experienced the "hard against the floor" clutch pedal, my first thought was that the system needed to be bled. On this truck the cap on the master cylinder is a soft rubber-like material and it just pushes onto the body of the master cylinder. When I removed the cap, the first thing I observed was that the rubber "bulb" (for lack of a better term) was compressed and flattened up into the cap. I knew that this was not right and I also observed that the master cylinder was full to the point of over-flowing. What I did was this: I pulled the rubber bulb out of the cap and straightened it out to what I thought was close to its full size, then I put a clean rag under the master cylinder and pushed the cap (with bulb) back onto the master cylinder. Of course, the expanded bulb pushed fluid out of the mc and onto the rag.
After doing this, the clutch seemed to work better, but not for long. After it was depressed a few times, the pedal still had to be pushed hard to the floor to get a clean shift. My guess, after watching the video, is that there was still air in the system.
The truck is my trusted shop in Reno as we speak and I have given the "go ahead" for them to put in a new flywheel, new clutch and new clutch hydraulic system (along with the other work that I mentioned in my first post).
As I mentioned, I like this little short bed reg cab 4x4 and truly hope the clutch issues can be resolved.
Your thoughts, please?
And, again, thanks for your input. This TDR group is so much superior to other web sites....the only other one that even compares is the VRCC web site.

 

[GCroyle]

Jim,

This can be proven if you do or do not have an air bubble in the system. I'm going to direct you to our Ford Ranger Part 2 video. I know, its a Ranger and you have a Chevy. Similar but cosmetically and dimensionaly different concentric slave cylinders but basically the same design family. Your master cylinder mounts differently and has an integral reservoir, Ranger external but the technique and concept of bench burping and gravity bleeding techniques will be basically the same.

https://www.youtube.com/watch?v=91IYY_YENRw

Want to see where I predict the air bubble might be hiding? Take a water bottle, unopened and hold it horizontal next to the master cylinder. Your master cylinder reservoir supplies fluid to the CENTER of the MC bore thru a pretty small hole and then discharges the pressurized fluid at the bottom of the housing. So holding the water bottle horizontal, see the air bubble at the top of the reservoir? How do you get it to go down and out the BOTTOM of the cylinder? Short answer, good luck.

Test by disconnecting the line where it connects to the slave cylinder at the quick connect. Push with your hand on the clutch pedal, carefully feel the resistance and note where it starts to convince you that it is making PSI. Now do it again, but measure how far the MC pushrod moves before your get the hard pedal feel.

1/8" MC pushrod travel = correct response and indicates no air in the master cylinder and the line you just connected and deadheaded. I bet it will be more than that.

If you test in chassis and it IS only 1/8" proceede to gravity bleeding as noted below.

Greater than 1/8", remove MC, pushrod and line as one piece, go to bench and position MC pushrod down from horizontal 30-45 degrees. Politely if necessary stretch the line down to create an uphill flow path for any air bubbles.

Now short stroke the pushrod, maybe 1/4" strokes or so. Air bubbles will start to pop in reservoir. Continue short stroking until 1/8" to WOW I can't push it anymore. It will be bled and air free.

Install in truck.

Gravity bleed, requires 2 people.

One guy monitors fluid level and refill as req'd, DOT 3 or 4 only.

Other guy connects line, then open bleed screw allowing 1 reservoir of fluid to flow thru system. Top guy cannot wander off during this process. Close and tighten bleed screw. NOTE a short section of tubing connected to bleed screw draining into waste container makes the job a whole lot neater.

Test release.

Did you notice, nowhere in the above did I say pump pedal? Correct, NO NEED TO PUMP PEDAL!

The Ranger setup looks different but the design elements compared to your Chevy, you got the GM version, Ford used their version.

PS, you already have all the fluid you will need in that last small bottle to do this job, sorry no shortcuts, just follow procedure and those plastic parts will be just fine. Assuming you do not have any hidden issues, leaking parts or other undisclosed issues.

Gary

 

[Jim Ross]

Thanks again, Gary.
I copied your info to my trusted shop in Reno as I will not be back there until around 9/8 (I'm in Idaho now and getting ready to go antelope hunting tomorrow and after that I'm taking the Ram to Oregon to get a custom turbo and new exh manifold put on it).
I will keep your info and will get in touch with you after 9/8 if we can't get the new clutch to work well in the Silverado. Thanks a million for your input!
Jim

 

[GCroyle]

Jim,

Good luck. I'm afraid a lot of shops feel they know how to bleed stuff but they are using brake bleeding techniques that rarely transfer to clutch hydraulic systems. I think our presentation on YouTube says what our message is and it varies from system type to system type with no one single technique being the one size fits all.

Gary

 

[Jim Ross]

Gary,
I just got my truck back and the new clutch works great! My shop replaced the orig clutch (it had 148K mi on it), installed new clutch master cyl and slave cyl and "lightly" surfaced the orig flywheel. My clutch is now "like new"....apparently my shop guy did the bleed correctly.
Thanks a million for your assistance.
Jim