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First gear "judder"

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trotti

trotti

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I finally got all the brake issues resolved in my car and I'm on to tackling the next issue - an unfortunate "judder" or vibration when pulling away in first gear. It's much more pronounced when starting from a hill. As I begin to lift off the clutch, a slight judder begins that intensifies and gets quite dramatic. This happens both when the car is cold and after it has warmed up. Feeding it more gas doesn't help. It will start off fine in second gear without the vibration, but starting from second every time is not a good fix.

I've read everything from bad motor mounts (mine look to be in great shape), fouled plugs (just put in new Champions gapped at .025), low tire pressure (I'm 32 all around), bad carb setup and even bad pedal linkages causing this in other vehicles; seems like there are a variety of causes. I've bled the clutch slave cylinder and it appears to engage/disengage correctly. Shifting throughout the other gears is fine. There is an overdrive attached and it seems to work without a hitch.

Thoughts on what might be causing this?
 
trotti said:
I finally got all the brake issues resolved in my car and I'm on to tackling the next issue - an unfortunate "judder" or vibration when pulling away in first gear. It's much more pronounced when starting from a hill. As I begin to lift off the clutch, a slight judder begins that intensifies and gets quite dramatic. This happens both when the car is cold and after it has warmed up. Feeding it more gas doesn't help. It will start off fine in second gear without the vibration, but starting from second every time is not a good fix.

I've read everything from bad motor mounts (mine look to be in great shape), fouled plugs (just put in new Champions gapped at .025), low tire pressure (I'm 32 all around), bad carb setup and even bad pedal linkages causing this in other vehicles; seems like there are a variety of causes. I've bled the clutch slave cylinder and it appears to engage/disengage correctly. Shifting throughout the other gears is fine. There is an overdrive attached and it seems to work without a hitch.

Thoughts on what might be causing this?
Click to expand...
Have you checked the transmission mount bushings?
 
How old is the clutch ?
 
trotti said:
Have not - will put that on the list for this evening. I assume I just want to check to ensure they're intact and not cracked?
Click to expand...
They will most likely have been oil soaked and deteriorated to the point of being soft or missing.
 
Healey Nut said:
How old is the clutch ?
Click to expand...

I bought the car from the wife of a gentlemen who unfortunately suffers from Alzheimer's so the details I have are spotty. All I know is that it sat for about 7-8 years shortly after it was restored from the ground up. During that restoration, he replaced nearly everything so I imagine the clutch has only a few thousand miles on it at most, but is about 10 - 15 years old.
 
Patrick67BJ8 said:
They will most likely have been oil soaked and deteriorated to the point of being soft or missing.
Click to expand...

Got stuck on other projects last night - rewired the control head, re-installed and did general tidy up from that project. I'm hoping to get the car up on jack stands and check this evening.
 
Gearbox off centre... check and tighten each bolt or clutch pate misaligned.. again check bolts that retain the clutch plate.. faulty slave cylinder cheapest and simplest thing to change..
 
andrewss said:
Gearbox off centre... check and tighten each bolt
Click to expand...
Pardon my ignorance - are you referring to the gearbox screws which attach to the engine where they mate or the gearbox mounting screws? Any idea what each of these should be torqued to?

andrewss said:
faulty slave cylinder cheapest and simplest thing to change..
Click to expand...
I did check the slave for operation and it does appear to be working - it's got a decent throw and appears to be engaging/disengaging the clutch as expected. Any way to test function? Although not expensive, I'd prefer not to replace unless I can verify there's an issue with the piece.

Thanks for the help and ideas--greatly appreciated.
 
Might just be a bit of ROT on the flywheel which may clean off over a bit of time.????
 
Keoke said:
Might just be a bit of ROT on the flywheel which may clean off over a bit of time.????
Click to expand...

I was thinking this or a patch of oil/grease/dirt on the friction plate or flywheel which after a few clutch dumping starts would clean up .
Or you could try riding the clutch a little in top gear to get some heat into the friction plate etc and burn off any residue .
 
I experience a bit of judder from time to time, which occurred more often after I installed a Lempert 3.54 rear end. Counter-intuitively, perhaps, the judder is best avoided by 'popping' the clutch somewhat quickly, as opposed to slipping it a bit on engagement; fortunately the torquey Healey engine allows it. When I experienced severe judder as you describe I had to replace the clutch--it was shot. As others mentioned, motor and gearbox mounts need to be in good nick, and technique has a bit to do with it.

WRT "... he replaced nearly everything so I imagine the clutch has only a few thousand miles on it at most..." That's an assumption (wishful thinking?); some 'restorers' are known to skimp when they think they can get away with it (clutches aren't visible). Also, I believe that as the traditional clutch lining material--asbestos--became unwise/illegal to use some substitutes were tried that proved less than satisfactory.
 
If you are sure that the clutch cylinder is fine then go back to basics... drain the system of fluid and refill with new DOT4 and bleed the system. If it still judders you know its not the the clutch cylinder. At this stage you will need to drop the gearbox from the engine and drive shaft. Check the drive shaft bolts (both ends) and check the rubber mounting blocks of the gearbox. Check the clutch plate for wear.. I would recommend that you change it at this point regardless of what it may look like. Make sure that it is centered when you replace it.. If after having done all that you still have a judder then have a look at the engine mounting rubber blocks to see if they are deformed from the oblong shape they should be.. If they are deformed then your problems may be greater than you think.. I am currently restoring a 100 Le Mans that had a front left impact prior to the last restoration. The restorer did not check for engine alignment and left the LHS engine mount out by 4 degrees.. This put stress on the engine/gearbox shaft causing the clutch plate, gearbox box bolts, etc creating the judder you talk about.. anyway good luck..
 
Thanks everyone for the replies - they've been extremely helpful. I have drained the hydraulic system and flushed and replenished the fluid with DOT 4 (see my separate thread on my trials/tribulations relating to my brakes). I was able to jack it up last night and all the rubber mounts are intact and solid - looked quite good.

However, I did take it on a spin yesterday for about 5 or 6 miles. The characteristics of the problem have changed. It now does not judder at all while cool, and does slightly when warm, but I can work my way out of it by being a little more aggressive with my starts and letting the clutch out quicker. Does this mean the likely culprit is what Keoke and others suggest . . . crud that will eventually work its way off?
 
If you do pull the gearbox, consider installing urethane bushings for the mounts and tie rod. Rubber will get oil-soaked and turn to goo after just a few years; I installed urethane bushings many years ago and haven't had any problem with them. Also, it's my experience that reproduction rubber parts are some of the worst WRT quality.
 
My gearbox rubber bushings had turned to goo given the oil soaking they got from years of transmission seepage. I replaced them with urethane, which are essentially solid. This led to some additional vibration transmitted to the car. But they will never deteriorate.
 
I know the tie rod can use the same urethane bushings as the anti-sway bar, but are there urethane transmission mounts? I replaced mine recently, and put a sheet of plastic between the transmission and the mounts to hopefully send the oil around the mounts. I did use urethane for the tie rod.
 
John Turney said:
I know the tie rod can use the same urethane bushings as the anti-sway bar, but are there urethane transmission mounts? I replaced mine recently, and put a sheet of plastic between the transmission and the mounts to hopefully send the oil around the mounts. I did use urethane for the tie rod.
Click to expand...

I THOUGHT I'd replaced the mounts--it was years ago--but I don't see them available anywhere; looks like only the tie rod bushings are available:

https://tomsimport.com/new/parts/parts.asp?sect=2&new=1


Tim, where did you get your urethane transmission mounts?
 
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