Shudder While Engaging 1st Gear

[CriticalMass]

I get a pretty severe shudder when engaging 1st gear from a stop and I have to give the engine more throttle than I otherwise should in order to get moving (427/Toploader). It seemed a pretty clear case of clutch slippage to me at first, but to confirm that, I stood on the gas in 4th gear and didn't experience any issues. The shudder/'slippage' is severe enough in 1st that I would expect it to show itself in 4th if that was indeed the problem.

Coupled with the fact that the car only has 20,000 miles on it makes me question the cause. I thought it unlikely that the clutch disc would already be worn out (although they're aggressive miles I suppose).

I checked the motor mounts and there's no sign of any damage (everything is tight as well). I checked/adjusted slave cylinder play and travel. It looks good and clutch fork actuation appears normal.

So my question is does anybody have any other 'easy' suggestions on what to check before I start tearing the transmission off?

Also, assuming I end up replacing the clutch, are there any good references/books out there for a step-by-step guide through the process? I inherited this car and so I'm no expert with it. It'll be my first time dealing with the toploader/bellhousing/clutch.

The car is ~28yrs old. Is there any maintenance that is prudent to take care of while I have the transmission off the engine if I go in to replace the clutch?

Assuming that there is no comprehensive guide out there on the process (I've looked a bit and not found anything) and I just have to start pulling bolts, can the Toploader be removed from below the car, or do I need to remove the trans tunnel and do it from above?

Any help is appreciated,
Thanks.

[patrickt]

With that engine, and a 2500 lb. car, you should be able to pull away in second, or even third, gear without a whole lot of trouble. Do you experience the same shudder/shake/rock 'n roll in second or third?

[Tommy]

Critical Mass,
Is this a new problem that only recently came up, or is this car new to you? I ask because some clutches (like the one in my car) are very sensitive and tend to shudder until you have a lot of practice with them.

[jhv48]

Definitely sounds like clutch chatter/shudder.
Can be caused by a warped flywheel, disc or pressure plate, weak pressure plate springs, or oil or some other contaminant on the disc/pressure plate/flywheel.

Does it get worse when hot? How about when you slip the clutch while revving the engine. If yes to either of these, a new clutch is in your future.

[CriticalMass]

I've been driving the car off and on for over a decade, so this is definitely an emergent issue and not just a matter of getting used to the car. It was in the care of a third party for the last two years while I was overseas and the issue developed during that time. I've only driven it once with the issue to get it from their place to mine when I took possession of it again after returning home. It then went up on blocks for winter storage. I'm in the process of trying to get it ready for summer driving now.

I recall starting from a stop in 2nd gear and having the same symptoms and particularly remember getting shudder in reverse as well when backing it up my driveway into the garage, so it's not specific to a particular gear. I didn't notice any change with heat (over the duration of one drive) and can't recall deliberately slipping the clutch, so I don't know about that. It did not have any adverse symptoms at speed while changing gears, and again, I couldn't get any RPM spike in 4th while standing on the throttle.

Regardless, I figure it is most probably a clutch issue as well. Just wanted to make sure I wasn't overlooking something stupid before I crack into this thing.

So on that note, any good references for the process? Can I do it from below the car, or do I need to remove the transmission tunnel? Should I take the opportunity to refurbish the transmission while I'm at it even though it's operating normally, or not worth it?

Thanks for the help, guys.

[eschaider]

My bet would be the damping springs in the clutch disc hub. I suspect one or more are either broken or have fallen out. Without the springs to dampen the engagement process the disc winds up on the hub and slams into the remaining springs/stops producing the jerky shuddering you experience when attempting to start up from a stop smoothly.


Ed

[DanEC]

Basically if you have replaced the motor mounts and inspected/replaced the transmission mount - your best approach is to plan on pulling the transmission and clutch. It could be any number of things internally to the clutch - glazed disc/flywheel from excessive slippage, contaminated disc from oil, warped, heat checked flywheel, worn pilot bushing, and on and on. I would tear it down and then don't just throw a new pressure plate and disc in it and button it up. Have the flywheel surfaced or if showing heat cracks then replace it. Replace the pilot bushing/bearing. Inspect the transmission front bearing retainer and replace if worn. Inspect the throw out fork for wear and replace as needed. Inspect the back of the block for oil leaks. Inspect the transmission input shaft tip for abnormal wear. Make sure the front bearing still turns freely without coarseness. Trying to chase a chattering clutch one part at a time is very frustrating and time consuming (I know). Best to tackle everything in one effort and replace or machine everything.

[DAVID GAGNARD]

Sounds exactly like the pilot bushing/bearing in the rear of the crankshaft that the trans. shaft rides on...........have seen it a number of times.........will shudder when you take off from a stop in first gear and not do it shifting thru the rest of the gears....

either way, the trans/bellhousing/clutch/flywheel all have to come out to be checked out........

David

[PeteF]

Put car on jack stands. You will need under car access for some things. Remove seats, parking brake cover and shifter. Remove tunnel. Support rear of engine, then remove driveshaft, trans, bellhousing, clutch from inside car. It helps to use two makeshift studs in two trans mount holes so the trans slides straight aft. Make them by cutting the heads off two long bolts. There is room to put a rolling jack under the trans to aid in sliding it out and in again. Take your time and it's not too bad.

[LG57]

So, yes the trans has to be taken out from the top. Be prepared, it's HEAVY.

[Anthony]

I'm guessing you heat damaged the clutch, flywheel and pressure plate, and you may have to replace the clutch and pressure plate. The flywheel can be reground, but it may not fix the problem, as the heat damage may be deep to the surface.

[PeteF]

I forgot to mention, before you remove the tunnel, you must remove the small access plate at the rear of the tunnel. If you have inboard brakes, this is a good opportunity to bleed them if needed.

[DanEC]

I didn't notice this was on an ERA - yes, the trans comes out from the top and it is heavy (90+ lbs I believe). The dowels to slide the transmission on are an excellent suggestion as they will help prevent the weight of the transmission from hanging on the clutch disc hub and bending it (causing more chatter and shudder). I used an engine hoist to install my transmission but that was kind of a chore to as it goes in well under the dash cowl lip. I had to rig up a lift beam to hang off the engine hoist with the transmission strapped to the forward end of it so I could slide it under the dash cowl and into the clutch.

Using the dowels, it is probably easier to fit a good piece of plywood across the frame and carpet under the transmission - after raising it slightly with a jack and removing the transmission mount - and slide it back on to the plywood with the dowels. They lug it over to the door sill so you can lift it out.

If you're a 250 lb gym rat lifting lots of weight every week - forget all that and just reach over and pluck it out.

[CriticalMass]

Thanks for the help, guys. I got everything uncovered and the drive shaft out today. I expected to run into seized bolts or other complications but it's gone pretty smoothly so far. I was out of time for the day so I just broke all the bolts free on the trans and bellhousing and I think I'll wait until I can have a friend help me lift the transmission out of the vehicle to go any further.

I did hit one snag with a single bolt on the bellhousing that's too tight/close to the bellhousing to get a thin walled socket around. It also happens to be in that 'sweet' spot where if I rotate it with a wrench until I hit the frame, I still can't get around the next side of the bolt to continue loosening it up. So I'll have to figure that one out, but otherwise I'm just happy that I'm not already curled up in the fetal position on the floor of my garage. Of course I know that I've only dealt with the easy part so far...

I'm sure I'll have more questions once I get this thing cracked open and these forums are a great resource, so thanks again.

[patrickt]

Originally Posted by CriticalMass

I did hit one snag with a single bolt on the bellhousing that's too tight/close to the bellhousing to get a thin walled socket around. It also happens to be in that 'sweet' spot where if I rotate it with a wrench until I hit the frame, I still can't get around the next side of the bolt to continue loosening it up. So I'll have to figure that one out, but otherwise I'm just happy that I'm not already curled up in the fetal position...

Loosen the motor mounts and put a jack under the back of the engine. You can move everything up a little bit to give you the room you need to get to the bolt.

[CriticalMass]

No mystery what the problem was anymore. The clutch disk was completely shot. The entire disc was nearing end of life, but there was also a section of friction material that had come loose which I found at the bottom of the bellhousing...so that could certainly cause a vibration.

Now I'm looking for replacement kits. The pressure plate/disc were 11.5" 10-spline long-style.

From reading a bunch of toploader posts on the forums I see fairly unanimous praise for David Kee, so I've been looking at his website. It seems he recommends McLeod clutches (in that they're the only brand on his site), however there are no 11.5" models (Super Street Pro Clutch Kits). I do see 12" diaphragm style kits that mention they have the same bolt pattern as 11.5" long-style models.

Anyway, in the end I don't know what I'm looking for, so I'm open to suggestions on how to go about choosing a suitable/compatible replacement. I don't mind the 'heavy' clutch pedal, so I don't have an active desire to switch to a diaphragm style, but is there any reason not to?

If not, are the two 12" kits at the bottom of the page in the link above good replacement options? The difference between the two is in the 1-1/16" vs 1-3/8" measurement. Is that clutch disc hub thickness?

For reference the car puts out a little under 500 bhp.

[Detroit Bill]

Originally Posted by CriticalMass

No mystery what the problem was anymore. The clutch disk was completely shot. The entire disc was nearing end of life, but there was also a section of friction material that had come loose which I found at the bottom of the bellhousing...so that could certainly cause a vibration.

Now I'm looking for replacement kits. The pressure plate/disc were 11.5" 10-spline long-style.

From reading a bunch of toploader posts on the forums I see fairly unanimous praise for David Kee, so I've been looking at his website. It seems he recommends McLeod clutches (in that they're the only brand on his site), however there are no 11.5" models (Super Street Pro Clutch Kits). I do see 12" diaphragm style kits that mention they have the same bolt pattern as 11.5" long-style models.

Anyway, in the end I don't know what I'm looking for, so I'm open to suggestions on how to go about choosing a suitable/compatible replacement. I don't mind the 'heavy' clutch pedal, so I don't have an active desire to switch to a diaphragm style, but is there any reason not to?

If not, are the two 12" kits at the bottom of the page in the link above good replacement options? The difference between the two is in the 1-1/16" vs 1-3/8" measurement. Is that clutch disc hub thickness?

For reference the car puts out a little under 500 bhp.

I would ask David Kee and buy the clutch from him. Brent also could suggest a clutch and sell it to you.

[Anthony]

You can call McLeod and ask for their recommendation as well.

I've bought toploader parts, as well as a tranny from Kee, met and spoke to him several times. A quality guy, businessman. Kind of rare today.

Check the surface of the pressure plate and flywheel to see if the metal looks uniform in color(should be), to check for heat damage. You can measure the metal diameters on the pressure plate to see if it goes 12", if it fits.

Check the release bearing for wear as well. Make sure you know the difference between a 1 1/16" input vs 1 3/8" input shaft.

With the hydraulic release bearing , generally the effort for the clutch is not bad.

[DanEC]

I think Brent would be a very good and accessible source for a new clutch. I have McLeod clutches in two cars including my ERA and have no problems with them. I prefer diaphragm clutches. That's what most people run. I believe the disc on a 12 inch clutch measures 11.5 inches. Those 12 inch McLeod clutches on the posted link, depending on the transmission input you're using, are probably what you need. Again Brent would be a good source for advice.

Since you are this far into it the smart thing would be to have the flywheel surfaced. At minimum, clean up the surface with emery cloth to remove any glaze and check it with a straightedge and even a dial indicator mounted to the block. It's not easy to find information of what acceptable run out is on a mounted flywheel because a portion of it could be in the crank flange and even if there is a bit of run out in the surface, with the pressure plate mounted to it some say it doesn't really matter except in severe cases. I did find a MOPAR spec once of .005 in max run out for the flywheel.

[CriticalMass]

All good stuff. I called David Kee and he was very helpful. I'll end up ordering the 1-1/16 12" McLeod in the link I posted.

The flywheel is already at the machine shop...it definitely had some heat damage but it didn't look like anything a resurface couldn't fix.

I'll probably be back with more questions when I start to put everything back together.

Thanks, again.