'65 Mustang - Pull Away Problems

[geordie]

Car:

Modified ’65 Mustang coupe. Engine is 302 cubic inch, .030-inch oversize, heads are high flow 351 Windsor 11:1 compression ratio and cam is Shelby hydraulic. Transmission is Tremec TR-3550 manual 5 speed and rear end is 9 inch Ford.
Car is used as a daily driver, traveling approx. 15 miles a day to and from work and some mileage at weekends. Car is not raced or driven hard, most mileage done at less than 50 mph, under 3000 rpm.

Problem:

1. Pulling away from a standing start in first gear is difficult without causing engine to vibrate or judder severely. It is only possible to pull away in first gear slowly and carefully, concentrating hard on clutch pedal release. Pulling away on an incline is very difficult. Moving slowly and smoothly a line of traffic, when coming up to a junction, for instance is difficult. It is currently believed that this vibration is clutch chatter however, I not sure.

2. Clutch chatter seems generally worse when engine is at temperature. Similarly, the car is easier to drive when the choke is out after cold start up.

3. When pulling away at a junction, particularly when turning right, there is often a ‘clunking’ sound from underneath the center of the car and sometimes it appears to come from the rear end. In addition there is a regular thumping sound from the front passenger wheel on pull away especially on a right hand bend. Sounds are always heard when engine is at temperature.

4. All other gears including reverse operate normally with no chatter, apparent clutch slippage or noise.

For the reasons described above there is little pleasure to be had driving the car at present and the inability to pull away smoothly at junctions makes the car potentially dangerous, increasing the likelihood of a rear end shunt.

Bottom line is that with the horsepower available from the engine, I should be being careful not to spin the rear tires at pull away, however, with the current problem there is no way that this is possible.

History of Problem:

Car was purchased from colleague at work with Ford Motorsport clutch fitted. Previous owner had the car for about 22 years and had restored it himself over the last 7 years or so. It was explained to me that the car did have some minor clutch chatter but that given time I would get used to the clutch and be able to minimize this. The previous owner gave me a new more ‘streetable’ clutch disc and pressure plate in the event that I wanted to replace the Motorsport clutch. I drove the car for about four months before deciding to have the Motorsport clutch replaced.

I took the car to a garage to have the clutch changed. The owner of the garage seemed very knowledgeable about Mustangs, indeed he owned a ’65 Coupe himself, however, I subsequently believe that most of the clutch work carried out on the car was done by someone else, one of his mechanics. The garage told me that the alternative clutch, which the previous owner had given me, did not fit. The garage bought another clutch to complete the work. When the Motorsport clutch was taken out the disc was shown to me. An area covering 180 degrees of the disc was blued (from heat build up) and abraded. The remaining area of the disc looked unmarked. This looked like an indication of misalignment to me. The garage informed me that the Motorsport clutch had been incorrectly fitted. In addition the pilot-bushing bore was lobed. The garage replaced the bushing with a rolling element bearing. In addition the garage removed the dowels, which located the Motorsport clutch to the flywheel. When the job was complete and I went to pick the car up it drove no better and had developed an exhaust rattle. The car was returned. I found out that the flywheel had not been skimmed, because it looked OK to the garage. The clutch was refitted with a skimmed flywheel. I don’t know what method the garage used to machine the flywheel. In addition the garage told me that they had lifted the transmission and shimmed it to re-align the drive shaft to the rear end, as this was part of the problem. The car appeared to drive better initially, however it developed a problem whereby the clutch pedal would go over a cam, or over center, and stick to the floor of the car. The car was returned to the shop, they spent time adjusting the linkage and welded a makeshift stop to the clutch pedal to prevent the possibility of it sticking to the floor pan. I argued that the work was unsatisfactory and to cut a long story short got most of my money back from the garage.

Has anyone encountered this type of probelm before? Any suggestions on how to cure the shuddering? Thanks.

[66StangGuy]

the shuttering only occurs in first gear? what happens if you start the car in second? also does is still shutter if you downshift from second to first? About what rpm does the shuttering go away? or does it not go untill you go into anohter gear (sorry i dont remember if you said or not)

Sounds like the people at the shop dont know what they are doing. i hate that, had my car alighned 3 weeks ago and got new tires the day after. I have almost lost all tread on the tires already because the guy set it wrong. well good luck and let me know if you learn anything new from that stuff above..

[geordie]

Thanks for your reply. Yes, the shuddering only occurs in first gear. If you pull away in second gear, no shuddering, if you downshift from second to first, no shuddering. When you pull away in first you have to virtually keep the revs below idle, say 900 rpm to achieve a 'smooth' pull away.
Anything above that and you risk the shudders. If I get the shudders on pull away they disappear if I shift into second. Strange eh!

I was warned about alignment difficulties when I bought my '65. The only advice I was given was try to find a shop with an older experienced wheel mechanic who is experienced in aligning older cars. Not much help I know. If you have any more thoughts...let me know. Good luck.

[missingpony]

Hi,
If you had the flywheel properly surfaced (not with a hand grinder like some shops) on surfacing machine and new disc, and you have no oil leaking from engine or tranny in to clutch that should eliminate that. ( If a hand tool was used you probably have a very uneven surface)
you mentioned thumping in front, how about checking for a loose or broken engine mount? Open the hood and have a helper watch the engine as you carefully try to engage clutch with car blocked or e-brake on if the engine tends to rock way up this could be the trouble. also physically inspect it and check by a bar trying to lift engine.
You also mentioned the pilot bushing wore funny, then how is the tranny input shaft bearing?
another thought because you say you have to run with the choke out some times, have you checked for vacuum leaks which can cause the engine to rough on take off? also is ignition timing properly set for that cam?
Just a few ideas for you, Scott T.

[PKRWUD]

geordie-
C'mon man, if you want help, you have to stop being so vague!

Seriously, geordie, that was perhaps the most thorough, detailed account I have seen in the 2.5 years I've been here. You must be a Brit.

I was also convinced it was a problem with the flywheel surface, until I read your reply to 66StangGuy. You mention not being able to exceed 900 rpms, or else the shuddering will occur. That is pretty much the opposite of what happens with a bad flywheel. When it's bad, the only way to pull away smoothly is to over-rev the engine.

Then, in the middle of missingpony's reply, a light came on. I think he is exactly right as far as the motor mount being your problem, but not just for the noise, but for the shuddering, too. It would explain why the pilot bearing was egg shaped, and why there is no shuddering while downshifting (the engine torque would be in the opposite direction during compression braking, which is what happens when you downshift, and the compression inside the engine is actually slowing the vehicle down). Also, when making a right hand turn, the g-force would be helping the engine to rock from passenger side to driver side, just enough to cause your "bumps", whereas the g-force applied during left hand turns would keep the engine planted. Lastly, if the engine and transmission are not completely secure, the clutch linkage, which mounts to the block, could become askew.

The thing that I don't understand is how the clutch disc was only worn on half of it's surface. The disc spins, so it should wear evenly.

This is starting to fall into place. I feel pretty good about the odds that you will find that your right (passenger) side motor mount is damaged. It really sounds like the transmission is mounted very securely, but the engine is not. This can and will lead to a broken bellhousing, or even engine block, where they bolt together.

Please keep me posted, as I am finding this one pretty exciting.

Take care,
-Chris

P.S.- When you say the car runs better with the choke out, do you mean with the choke applied, or with it off?

P.P.S.- Where are you from?

[geordie]

Hi Chris,

You guessed it. I'm a Brit, have been living and working in the States for four years. Geordie is a British term for a guy who comes from the North East of England. But don't let this put you off, despite my birthplace, I'm an o.k. guy, just trying to sort out my shuddering.

Thanks for your help. Am collating the responses I'm getting from various forums into a go forward plan. Would appreciate any additional advice you, or anybody else, may have.

Will summarize my go forward plan in a future message.

Anyway, mustn't waffle on........

p.s. ref your question the car drives better when the choke is applied....but is this because the car is cold.....I don't know...

Thanks again...

David

[PKRWUD]

Well David, I was kinda hoping you'd stick around and post some more questions. Maybe then these other newbies (and some of the old-timers!) would get a better understanding of what it means to give a detailed description!

Brits are fine. I lived in Perth for a while in the 80's, and the locals seemed to really have it out for you guys, but I never had any trouble with Brits. Very articulate (in my world, that's a good thing).

Good luck with your car! I'm sure the solution will be found.

For what it's worth, when any load is met with the engine torque, the engine will try to climb right out of the engine compartment, over the drivers side fender. It's the motor mounts, in particular the passenger side one, that prevents this from happening (okay, slight exaggeration, but go with it). If the drivers side mount is broken, as I suspect, the passenger side of the engine will jump when the torque meets the load. If you get the chance, and are curious, a quick test to see if the mount is suspect is to have an assistant try to accelerate while the wheels are blocked and the hood is open, and you can watch and see if the engine jumps at all.

Take care,
-Chris