Grinding noise on engaging clutch

[620Bob]

I am new to the forum. Just put a dogleg into my 1973 620 and got it working yesterday. It makes a rumbling/grinding noise when the clutch is engaging, but is quiet when the clutch is fully out or fully in. I replaced the throwout bearing and moved the clutch fork and throwout arbor over during the swap, so the dogleg has the same fork/throwout combination as the previous 4-speed. Anyone have any ideas what might be causing the grinding noise?

[datzenmike]

Are you saying you used the clutch arm/fork from the 4 speed on the dogleg? I just checked the clutch arm part numbers and they appear to be the same so you were very lucky. I would have used the dogleg arm but it appear that the 620 F4W63 4 speed arm can be used with the FS5W63A dogleg.

 

Just a guess here... is the release bearing pressed on to the housing facing the right direction?

 

http://i138.photobucket.com/albums/q251/datzenmike/Tranny/transreleasebearings2Large.jpg[/img]"]

[620Bob]

It looked to me on close examination that the release bearing assembly and clutch fork were the same on both transmissions. I believe I put the new bearing on with the correct engaging surface towards the pressure plate. Really, the only time it makes the noise is when I'm slipping the clutch to get going (usually in first gear). The replacement clutch disc had four springs instead of six, and they were somewhat larger in diameter than the previous disc. Perhaps I should have installed a complete bearing/disc/pp package. The noise really puzzles and alarms me.

[datto510]

Did you use a clutch alignment tool? Is it vibrating?

[620Bob]

I have an input shaft from another 4-speed trans that I use as a clutch alignment tool. That part of the job went smoothly and the transmission fit snugly with the block with minimal wiggling. I also checked to ensure that I was fitting a 200 mm disc.

[datto510]

I'm stumped then. What Datzenmike already said about the bearing being pressed on the wrong way makes the most sense to me. Looks like your going to have to pull it out for a look.:mad:

[datzenmike]

I use a spare input shaft as well. Is the disc facing the right way (grasping here) how about the pilot bushing in the crank, new one?

 

Does this make noise if in neutral or is this when driving?

[620Bob]

Forgot to answer this question on last post. The clutch doesn't seem to chatter or vibrate while it's making all the racket while slip engaging. Likewise, it is quiet while I'm only shifting between higher gears. The clutch briefly makes the noise while stopped and letting the clutch out in neutral.

[datto510]

Try turning up the radio.:lol:

[620Bob]

I've thought of this solution but I don't like the looks on the neighbor's faces as they watch me back out of my driveway. Ditto for other spectators at 4-way stops. It's the clutch noise that's attracting the attention and not my loud radio. It seem that something soooooooooo loud needs fixing. Guess I'll need to pull the tranny and look at the clutch.

[datto510]

Post pictures of what you find. Good luck.

 

Oh, and Welcome to Ratsun! Post some pictures of your truck!

[datzenmike]

Forgot to answer this question on last post. The clutch doesn't seem to chatter or vibrate while it's making all the racket while slip engaging. Likewise, it is quiet while I'm only shifting between higher gears. The clutch briefly makes the noise while stopped and letting the clutch out in neutral.

 

 

First thing CHECK THE OIL LEVEL! It's easily overlooked and will sometimes cure tranny noise.

 

 

The clutch can't decide to be quiet in the higher gears and noisy the rest of the time, doesn't work this way. When you release the clutch (in neutral) it transmits turning force to the input shaft and spins it. The input or main shaft is directly coupled to the counter shaft and it spins too. I would suspect a possible bad front counter bearing. It's located just below the main input shaft bearing and rides in the front case behind the cover plate.

 

Here is a picture of the main and counter front bearings. This isn't a dogleg but it's very similar:

 

http://i138.photobucket.com/albums/q251/datzenmike/Tranny/620CAFS5W71B85turbo200sx010Large.jpg[/img]"]

 

You would have to remove the front cover and take the front case off and inspect them. This is easily done with a 12mm wrench and snap ring pliers. This will give you access to the two front bearings. They should turn smoothly with no excess slop or roughness. You could probably remove the bottom one with a simple gear puller the main will require a special puller to get at it, maybe a tranny shop could replace them for you.

[620Bob]

I pulled the transmission last weekend and inspected the clutch components. I purchased a Sachs clutch kit and replaced the pilot bushing, release bearing, clutch disc and pressure plate. The culprit was that the clutch disc anti-chatter springs that were rubbing on the top of the flywheel bolts. There wasn't any real damage; just the springs on the forward side of the plate have a polished/rubbed area. The Sachs clutch disc is a little less high and now everything is running smoothly. I took some pictures and when I can upload, I'll post a picture of what the disc looked like. Now I can turn up the radio when I hear a good song......

[datto510]

Glad to hear you got it fixed. Now hurry with the pics!:D

[slam_dat_sun]

Yeah wheres the pics :lol:

[620Bob]

Here's a pic of the clutch disc that rubbed the flywheel....