VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1916-1922 - Model 490 490 Clutch

1. What makes the 490 clutch so grabbing?
2. What can be done to reduce this grabbing?

The leather cone clutch can be oiled with neatsfoot oil, go slowly if you add too much you will then need to dry with fine ground earth to remove some of the oil.

Too dry , and it grabs , too oily and it will slip.

Thanks Jack, I keep a stick to hold clutch depressed when not in use . I have fitted a small copper pipe in floor panel which can deposit some neats footoil directly on to depressed clutch every time I go motoring !This works fine for one trip only. I never have to use fullers earth to dry. So I manage OK but it is not the way it should be!! I have relined the clutch twice with leather. There must be something in the design wrong...other cone clutches work very well without grabbing.. It seems to be a Chevy difficulty. No other 490#s in Ireland !!

The old question is: "What is the fastest vehicle for the first three feet?" Ans: A 490 Chevy! I personally think it as measured at a 30 degree angle to horizontal.

When I looked at the flywheel and clutch on my 490 engines I noticed that the clutch assembly that has the cone clutch fitted can wear at the area it is fitted Into the flywheel,the flywheel internal surface can also wear, if these two areas are worn excessively, the cone clutch can be cockeyed when it is engaging . The flywheel “may” need to be checked, and the corresponding surfaces on the cone clutch carrier. Bushing and rework may be needed to bring the two back into alignment. Been a while though, and I am sure that the carrier fits and moves in an out of the flywheel centre bore.

I guess that you have full control on the six expanders. I relined with new leather, 15 years ago. After driving say 100 kilometers I had to change the play on several of the expanders by turning the adjustment nut just a half turn, and that made big difference. After say 100-200 kilometers I checked the play once more, and as I remember I adjusted on or two of them another half turn. After that I have been driving 17 000 kilometers, the clutch has been very smoth - no grabbing, no slipping. No additions of neats foot oil, no fullers earth.

I noticed no wear on the flywheel or else. I agree with Jack that wear could cause problems with grabbing.

Another thing: When I fill the clutch yoke with heavy oil I also squirt two or three drops on the ingoing axle to the transmission, while holding the clutch pedal down with my left hand. (My 490 is LHD).

Thank you Jack and Per-Ake. Very informative. I will check the expanders again!. In honesty I do not feel like removing clutch to check surfaces and alignment. We rebuilt the back axle 4 years ago with new half shafts, main drive shaft and CW and Pinion. All good. Engine rebuilt new pistons. MY car is LHD 1918 and was a true barn find in Conneticut. No paint left and up holstry hanging together.. Stored in a tobacco barn for 70 years.
How sweet the roar of a chevy four.
Anyone know where I can find a 3 exhaust port chevy 490 cylinder head? I am rebuilding another engine.!

I remember one thing that maybe can help. When I removed the transmission from the combined engine and transmission supports there were two thin shims between the transmission front end and the supports. I guess that they were there to get the ingoing axle to the transmission ,"Main drive gear", part 41532, get in line with the clutch hub. The shims are U-shaped, so if you can find out if the main drive gear and the clutch hub are not correctly in line, without removing any parts, then I guess it is possible to fit in such shims . Thickness? I did'nt measure, so I have no notice. If I had to guess I would say 0.10mm, or between 0.005 and 0.015mm.

Thanks all for advice. Re checked the adjusters for 5 thou clearance all round and things are improved Keep safe

Gentlemen,
I have a 1922 490. My Dad (passed at 88 last year) and I rebuilt the motor two years ago, but we have a ”˜shimmy’ in the transmission-clutch. This is the Summer to get it on the road for Dad, may I run a few questions by you?
Bill, Saratoga Springs, NY

Yes, lots of helpful people on this site, welcome Bill.

There was an article in the G & D magazine years ago, written by Harold Gilbert, addressing this problem with a grabby clutch. He goes on to write that he learned of this fix from an old time mechanic many years prior. You would use sheet metal strips instead of the adjustments on the clutch disc.

On the disc, turn the adjustments down to where they are flush with the disc surface. You will not use the adjustment, the sheet metal strips will provide the adjustment needed. Now, from a piece of sheet metal, approximately .020 inch thick, cut six strips about 3/8 inch wide. The length should be cut to same as the width of the leather lining, about 1 1/2 inches. Ensure the six metal strips are flat and smooth. Ready to install, press down on the clutch pedal and insert the metal strips under the leather lining about equal spacing. This should provide you a smooth clutch.

Harold used this fix for years on his car and I use it on my car as well. If at some time the clutch should show signs of becoming grabby, simply move the metal strips to a different location under the leather.