Clutch Problem

[Batman1458]

66 Musang Coupe (sig has specs)

Car runs good and shifts pretty well. The problem I have is starting out in first gear from a dead stop. I am still in the experimental stage and am trying to figure out why it is so difficult to start from a dead stop without the engine bucking like crazy. So far, I have found that starting out with the least amount of throttle or even no throttle at all, has worked the best.

At this point, there is no making a left turn with anyone coming. I cannot be sure that I will get out of the way in time. I have to start very slow and then accelerate after first gear engages. If I have a little bit of roll going, then it is a lot easier to get into first.

Any ideas? The engine is original, but the transmission was swapped out in the mid 80's, by a previous owner. It is a RAD-4 out of a 76 mustang. It is a 4 speed, with no OD. The drive shaft on this trans is longer than the original, so there is a 1" spacer between the bell housing and the trans.

Any help is appreciated. I would like to swap out for a T5, but right now, do not have the funds, so I need to find a fix that is not going to cost a lot.

Thanks for the help!
Ed

 

[mustang6]

This really sounds like a broken or failing motor mount to me. It's often hard to see without a load on the engine, so have someone stand next to the car with the engine running and the hood up while you let out the clutch. I'll bet they will see the motor will practically lift off the broken mount.

 

[Batman1458]

That was one of the initial problems. Replaced both motor mounts first. Although, you really couldn't see it jump with a load, but the way it was acting, it had to be a motor mount. Even with the new ones, it is 100% better than it was, but still having trouble in 1st gear.

One thing I forgot to mention, I never have any trouble at all in reverse. It engages and backs up fine with no hesitation or bucking. One person thinks it might be a carburator issue, but the engine runs and idles fine.

Thanks for the reply.
Ed

 

[CobraSix]

Ed,

Would you get the same reaction from the engine if you were going 20MPH and shifted into 4th?

Have you tried starting in 2nd gear?

My initial thought is a carb issue of some sort, have you tried reving to like 2000RPM and then slowly releasing the clutch?

 

[Stubby]

There is another problem with the old three finger pressure plate that causes it to jerk or pulse rather violently. I don't know how familiar you are with clutches. When it happens it is usualy obvious that it's not in the engine but the clutch grabbing.

If you need a second opinion, find the oldest mechanic in the area and ask him to test drive it. I don't know about your area, but around here the old timers are always willing to help steer you in the right direction.

 

[Batman1458]

CobraSix, I tried starting out in Second gear and I have no problem. As far as starting out with a higher RPM, I don't have a tach and don't have a good reference, but the couple of times I tried it with more gas, one time it was fine and another it spilled the coffee all over my friends hands.

What does this mean?

 

[Stubby]

It means your friend shouldn't drink coffee while riding with you.

 

[Batman1458]

Ok, higher RPM with a steady increase as I let out the clutch seems to be working pretty well. Also, going from second to fourth at about 20 miles per hour is fine.

Any ideas, other than give up coffee?

 

[Frankenstang]

Hi Ed,
It's funny you titled this post 'clutch problem', because that was one of my first thoughts as well. Since you've eliminated engine mounts it would seem to leave only fuel as Slade/CobraSix suggested or drivetrain. If it is fuel related I would think it would most likely be caused by a float/needle sticking, or incorrect setting on the float. I would also think that would show up in other situations. You might want to check the condition of the plugs to see if you're running too rich or lean.

Edit: Don't forget tranny mount too
Edit 2: I'd probably check the BH/tranny mounting bolts as well or anything else that would allow the driveline to shift about

I'm more inclined to think driveline related. I'd inspect the u-joints/drive shaft throroughly for any excessive play/slop. Normally when a clutch fails/wears out you have a lot of slippage almost as if the tranny is dropping out of gear or similar to how an automatic acts when it's really low on fluid. Sound more like you're having intermittent engagement issues with the clutch. Doubt it's a fouled clutch(soaked with oil from a leak at tranny or rear of engine), but guess that's still possible. My guess would be a clutch disc or pressure plate failing, possibly broken or breaking/coming apart.

I had a pp lose a fulcrum pin on one of the three fingers several years ago, but it's been so long I can't remember the exact symptoms. I want to say it was slipping as well, but not sure it wasn't doing that rodeo thing you're describing. I would also think a disintegrating clutch component would cause you other problems shifting in and out of gears at some point. As you probably know, there's only one way to assess the condition of the clutch assembly

Although if the clutch is wearing out or falling apart, it'll probably prove itself sooner rather than later.
Good luck!

 

[Batman1458]

I know this is an old topic, but I thought I would post my final findings on this problem. I know I like it when others tell how they fixed things.

The problem with the bucking, starting if 1st gear was caused by my carburator. I finally got the time to rebuild it and apparently the accelerator pump was bad. It is a Holley 1940 and I suspect it was never rebuilt. Since the rebuild, the car runs like new. I still have to fine tune it, but he bucking and hesitation in 1st gear is gone.

Thanks to everyone for your help and suggestions!

Ed