Serious clutch problems.

[Cheeserdoofle]

Been working on a 1988 K1500 for a few months now. It's got a 6.0 LQ4 from an 01 Silverado. NV4500 5 speed. I used the Sachs NFW1050 flywheel, SC70318 pressure plate, SD80323 clutch disk and SN1716SA throwout bearing. Everything installed fine, I used an alignment tool. First issue I had is the face of the throwout bearing never even made contact with the clutch fingers at full pedal. I could reach my fingers in where the slave cylinder is supposed to push the clutch fork and I could physically move the clutch fork full travel in both directions without the bearing ever making contact with the clutch. I ditched the clutch fork setup and bought an 82876 throwout bearing. During this process I measured and shimmed the bearing until I had roughly 0.115" gap from the bearing to clutch. I cleaned the clutch master cylinder, installed a new clutch line as well. The new problem now is when we bleed the clutch, the pedal goes down about 90% without doing anything and then will not travel the final 10%, it's like the pedal is bottomed out. If I open the bleeder, we can get full travel out of the pedal again but as soon as the bleeder is shut, the pedal is limited. We ran into a similar problem with a previous S10 build, I can't figure this out.

 

[Sean Buick 76]

What year of vehicle is the 4500 from and which application flywheel are you using?

 

[Sean Buick 76]

Look into the longer throw out bearing discussed here:

Mating a SBC/BBC Trans (T10, Muncie, Richmond, TKO) with an LS motor - LS1TECH - Camaro and Firebird Forum Discussion

Conversions & Swaps - Mating a SBC/BBC Trans (T10, Muncie, Richmond, TKO) with an LS motor - I've seen and answered a lot of questions on putting a earlier Gen trans behind an LS motor here and in emails. I've done a Richmond 6 speed, Muncie, and T10 (in progress) behind LS motors. So I thought...

ls1tech.com

 

[Cheeserdoofle]

What year of vehicle is the 4500 from and which application flywheel are you using?

The truck is originally a 5 speed, 1988. Everything worked prior to motor-swapping. I included the part number for the flywheel in the original post.

 

[Cheeserdoofle]

Look into the longer throw out bearing discussed here:

Mating a SBC/BBC Trans (T10, Muncie, Richmond, TKO) with an LS motor - LS1TECH - Camaro and Firebird Forum Discussion

Conversions & Swaps - Mating a SBC/BBC Trans (T10, Muncie, Richmond, TKO) with an LS motor - I've seen and answered a lot of questions on putting a earlier Gen trans behind an LS motor here and in emails. I've done a Richmond 6 speed, Muncie, and T10 (in progress) behind LS motors. So I thought...

ls1tech.com

Yeah that information is no good. I used the 1050 flywheel , matching clutch and pressure plate. He states you can reuse the clutch fork and throwout bearing. Mine had full travel in any direction and never made contact with the clutch. Yes, the clutch fork and bearing was installed correctly. I checked and measured. I had to go with a hydraulic throwout bearing to get anything that came close, I had to use basically every shim that came with it to engage the clutch. Except when I bleed the new throwout bearing, the pedal doesn't do anything and then stops or "bottoms out" before even touching the clutch safety switch.

 

[someotherguy]

The truck is originally a 5 speed, 1988. Everything worked prior to motor-swapping. I included the part number for the flywheel in the original post.

Won't be a 1988 NV4500 though. They didn't exist yet.

Richard

 

[Cheeserdoofle]

Won't be a 1988 NV4500 though. They didn't exist yet.

Richard

I wasn't aware that GM put in anything other than a NV4500 in the K1500. What are the other possibilities? Even if it's a different transmission, how does this relate to the clutch pedal issues?

 

[someotherguy]

I wasn't aware that GM put in anything other than a NV4500 in the K1500. What are the other possibilities? Even if it's a different transmission, how does this relate to the clutch pedal issues?

It would actually be exceedingly rare to find an NV4500 in any 1500 series truck. They're out there, but it's an uncommon option.

Richard

 

[Cheeserdoofle]

It would actually be exceedingly rare to find an NV4500 in any 1500 series truck. They're out there, but it's an uncommon option.

Richard

I appreciate the prompt response but I still don't understand how it relates to my issue.

 

[AuroraGirl]

Been working on a 1988 K1500 for a few months now. It's got a 6.0 LQ4 from an 01 Silverado. NV4500 5 speed. I used the Sachs NFW1050 flywheel, SC70318 pressure plate, SD80323 clutch disk and SN1716SA throwout bearing. Everything installed fine, I used an alignment tool. First issue I had is the face of the throwout bearing never even made contact with the clutch fingers at full pedal. I could reach my fingers in where the slave cylinder is supposed to push the clutch fork and I could physically move the clutch fork full travel in both directions without the bearing ever making contact with the clutch. I ditched the clutch fork setup and bought an 82876 throwout bearing. During this process I measured and shimmed the bearing until I had roughly 0.115" gap from the bearing to clutch. I cleaned the clutch master cylinder, installed a new clutch line as well. The new problem now is when we bleed the clutch, the pedal goes down about 90% without doing anything and then will not travel the final 10%, it's like the pedal is bottomed out. If I open the bleeder, we can get full travel out of the pedal again but as soon as the bleeder is shut, the pedal is limited. We ran into a similar problem with a previous S10 build, I can't figure this out.

sounds like maybe a slave cylinder bore is problematic or maybe the final connection is being limited mechanically by something