TexRiv_63

Clutch Adjustment Question

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This pertains to my 34 Chevy but may be universal for prewar cars with through-the-floor pedals. My clutch currently engages (roughly) very near the top of the pedal travel arc and I want to adjust it so that it engages more in the middle of the travel. The book says there is supposed to be 1" of freeplay in the pedal before it touches the throwout, I currently have about 1 1/2" to 2". If I adjust the freeplay to the desired 1" will that move the engagement point the way I want it to be?

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14 hours ago, Rusty_OToole said:

No, you would have to go the other way.

That doesn't sound good...is that an indicator that my clutch disc is worn out?

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 The high engagement point is probably due to wear in the linkage, the pedal pivot and the crosshaft. Adjusting the clutch pedal freeplay, will probably not affect the engagement point, very much. If your car is shifting OK and the clutch is not slipping, you can probably continue driving the car until you have problems. Then you should be ready to rebuild the linkage and replace the pedal and crosshaft bushings while you have the transmission out.

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You say the manual calls for 1" free play and you have 1 1/2" to 2". This is perfect. As the clutch wears down the pedal will get closer to the floor. When it gets too close it is time to adjust it back up to 1".

 

Now you say you want the clutch pedal closer to the floor. That would call for adjusting the opposite way. Down instead of up. Hope this is clear.

 

PS your clutch is not worn out and adjusting it the way you want will not make it wear faster. It will just mean you need to adjust it more often.

Edited by Rusty_OToole (see edit history)
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Thanks Rusty...I know it's not my question, but I literally am dealing with this exact same issue on my '65 Dart after I fixed some linkage issues Saturday.  I was doing the preliminary picturing parts in my head when I came upon this discussion.  

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20 hours ago, Rusty_OToole said:

You say the manual calls for 1" free play and you have 1 1/2" to 2". This is perfect. As the clutch wears down the pedal will get closer to the floor. When it gets too close it is time to adjust it back up to 1".

 

Now you say you want the clutch pedal closer to the floor. That would call for adjusting the opposite way. Down instead of up. Hope this is clear.

 

PS your clutch is not worn out and adjusting it the way you want will not make it wear faster. It will just mean you need to adjust it more often.

Not sure it is clear...when you say the pedal will get closer to the floor are you referring to the clutch engagement point?

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On ‎11‎/‎17‎/‎2019 at 11:07 AM, 19tom40 said:

 The high engagement point is probably due to wear in the linkage, the pedal pivot and the crosshaft. Adjusting the clutch pedal freeplay, will probably not affect the engagement point, very much. If your car is shifting OK and the clutch is not slipping, you can probably continue driving the car until you have problems. Then you should be ready to rebuild the linkage and replace the pedal and crosshaft bushings while you have the transmission out.

The clutch is not slipping and it shifts fine but the clutch engagement is rough and it chatters, hard to slip the clutch. All the linkage was cleaned and lubricated by the PO and seems tight but I am definitely not an expert.

20191107_130715.jpg

20191107_130728.jpg

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Chattering clutch often means oil on the clutch plates. Essentially, disassemble and replace.

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True enough, but even more often it is motor mounts and/or linkage trouble, which don't require taking the whole drivetrain apart.

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 Bloo is correct. Check the trans and engine mounts. If they are loose or too soft your clutch  will chatter.

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4 hours ago, Bloo said:

True enough, but even more often it is motor mounts and/or linkage trouble, which don't require taking the whole drivetrain apart.

The motor and trans mounts are new but the linkage may be an option.

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I guess it rules that out. Good that they're new.

 

What I don't know is how advanced (or not) the clutch disc was in 34. I don't know whether it has belleville springs in it, or whether it has a sprung hub. Since the car is so original, it is probably the original one. I do know that my Pontiac, a 36, has a clutch disc that has both and is more like a modern clutch. On the other hand, I think I have heard Buick people complaining about a "waffle clutch" disc that may lack one or both of those features as late as 1938.

 

The sprung hub (visible coil springs) in a clutch are not about chatter reduction, they are about keeping the firing pulses from banging against any driveline slop or gear lash while underway at part throttle.

 

The belleville springs are flat spring steel inbetween the layers of the clutch lining. If it doesn't have those (and it might really not), the engagement will be extremely harsh. It will feel like one of those race clutches with the little pucks. Engagement would be so harsh that it might be tough to take off without chatter. It might take a LOT of practice to get used to it.

 

Anything that causes the clutch to not engage evenly around the disc will cause chatter. A bad pilot bearing will do it (because the clutch won't stay centered, and may try to engage a little "off". Any misadjustment of the pressure plate fingers or throwout disc can also do it. The type of pressure plate used in my Pontiac took special tools back in the 30s to set up, and would take some real fiddling of the pressure plate and flywheel, off the car, by a machinist (or someone with precision tools), to get right. The slightest error causes uneven engagement and chatter. I wouldn't be surprised if you have the same type. As Spinneyhill mentioned, oil on the disc will cause chatter too.

 

If you take the clutch apart (I still wouldn't be in a hurry to do that), look into using a more modern disc if one is available that fits properly, and if your original lacks belleville springs. Be sure to check and lubricate the pilot bearing while things are apart. There's no way to do it with the transmission and the clutch installed in the car, so it may have been done last in 1934....

 

BTW there appears to be a bunch of slop in the clutch linkage:

 

PPUasRH.jpg

 

 

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10 hours ago, TexRiv_63 said:

Not sure it is clear...when you say the pedal will get closer to the floor are you referring to the clutch engagement point?

That too. The clutch pedal when at rest will be closer to the floor and the engagement point will be closer to the floor. That is what you want isn't it?

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On ‎11‎/‎18‎/‎2019 at 11:37 PM, Bloo said:

I guess it rules that out. Good that they're new.

 

What I don't know is how advanced (or not) the clutch disc was in 34. I don't know whether it has belleville springs in it, or whether it has a sprung hub. Since the car is so original, it is probably the original one. I do know that my Pontiac, a 36, has a clutch disc that has both and is more like a modern clutch. On the other hand, I think I have heard Buick people complaining about a "waffle clutch" disc that may lack one or both of those features as late as 1938.

 

The sprung hub (visible coil springs) in a clutch are not about chatter reduction, they are about keeping the firing pulses from banging against any driveline slop or gear lash while underway at part throttle.

 

The belleville springs are flat spring steel inbetween the layers of the clutch lining. If it doesn't have those (and it might really not), the engagement will be extremely harsh. It will feel like one of those race clutches with the little pucks. Engagement would be so harsh that it might be tough to take off without chatter. It might take a LOT of practice to get used to it.

 

Anything that causes the clutch to not engage evenly around the disc will cause chatter. A bad pilot bearing will do it (because the clutch won't stay centered, and may try to engage a little "off". Any misadjustment of the pressure plate fingers or throwout disc can also do it. The type of pressure plate used in my Pontiac took special tools back in the 30s to set up, and would take some real fiddling of the pressure plate and flywheel, off the car, by a machinist (or someone with precision tools), to get right. The slightest error causes uneven engagement and chatter. I wouldn't be surprised if you have the same type. As Spinneyhill mentioned, oil on the disc will cause chatter too.

 

If you take the clutch apart (I still wouldn't be in a hurry to do that), look into using a more modern disc if one is available that fits properly, and if your original lacks belleville springs. Be sure to check and lubricate the pilot bearing while things are apart. There's no way to do it with the transmission and the clutch installed in the car, so it may have been done last in 1934....

 

 

 

The PO told me he did not replace the clutch but did replace the throwout bearing 6000 miles ago. I pulled the inspection cover and it looked good, there were no signs of oil or grease but due to the design of the flywheel I could not see the clutch disc. Per the manual the stock clutch did come with an 8-spring cushioned hub but there is no mention of Belleville springs. The car has 38,000 original miles so it may very well be the original clutch. I am getting used to it as I drive it more but still would not want to try starting on a grade with a car behind me...

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On ‎11‎/‎18‎/‎2019 at 11:37 PM, Bloo said:

 

 

BTW there appears to be a bunch of slop in the clutch linkage:

 

PPUasRH.jpg

 

 

By the way thanks for dual responding here and on the VCCA forum.

I did notice that link connection you circled and need to look at it. Anyone have any spare Chevy clutch linkage parts?

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Usual cure for worn linkage like that is to take it off and weld or braze up the hole then redrill to the proper size, and replace the pin with a new one.

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On ‎11‎/‎18‎/‎2019 at 11:37 PM, Bloo said:

 

 

BTW there appears to be a bunch of slop in the clutch linkage:

 

PPUasRH.jpg

 

 

I have determined that I most likely have 1933 clutch linkage on this car since it was a very early 34 build. Does anyone know a source for a photo or illustration showing detail for the metal link between the throwout fork and linkage shown with the red circle above? Perhaps a parts catalog page? It would be a big help to know what that part SHOULD look like before I remove it and attempt to modify it. Thanks!

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