T-Series Does this sound like clutch problems?

[William]

Okay, so Dad's been mentioning a weird thing happening with his 1971 MGB roadster. Says that the clutch feels like it's slipping at high rpm's, usually when accelerating. I've only driven the car a few times this season, and hadn't experienced anything. He and I went for a drive today (just got back a minute ago), and it happened. We were driving along, probably about 40 or so, and he nailed the gas. We were at about 2500 RPMs, but around 3000 or 3500 the revs seemed to flare up to 4000 or a bit more before he lifted. They dropped right back to somewhere int the mid 20's. This happened twice, the first time he was actually passing a car and it certainly felt like we were accelerating. The second time it did not feel like we gained any speed at all.
A whole bunch of work has been done on this car this spring. Engine and trans mounts were all replaced due to oil leaks ruining them. and all sorts of engine and trans seals were replaced because of leaks, plus a new clutch cylinder (I think it's the master, but I could be wrong). At all other times-like driving in town and working your way up to speed rather than nailing it to pass-the clutch feels fantastic, really good bite and it certainly doesn't feel like it slips when you decelerate. I do not believe that the clutch itself was replaced, and I'm hoping that it just got contaminated by oil or something during the rebuild that needs to wear off, or that maybe the new clutch hydraulics are wonky. Any other ideas? I'm stumped.
-William

PS- all the work was carried out by a very highly respected foreign old car specialist that's been in business for years and years and so far (in both my Midget ownership/repairship and with Dad's B), never done something incorrectly or on the cheap.

 

[aerog]

Does it have overdrive?

 

[William]

No overdrive. So far, this has only happened when cruising in fourth.
-Wm

 

[Steve]

Sounds to me like the clutch is on its way out. I believe that it first starts to show symptoms when in fourth.

 

[aerog]

Ditto what Steve said... without the OD it narrows it down a bit. It may not be a worn clutch, but just as bad (sort of) an oil leak dropping oil onto the clutch. Either way it's going to take pulling it apart to fix.

 

[William]

Yeah-can't get the symptoms to occur on a regular basis. We tried again tonite to no avail. Everything feels fine in first and second, this has only happened in third and fourth, and not consistently. There's one new wrinkle, though-when we got back, Dad decided to check the oil, and we had a look around the engine room. The nice shiny new clutch master cylinder (for it was the master that was replaced) seemed to have something on top of it-you know how those metal master cyls have the screw on top and a big shoulder on top. Turns out the cap was loose-Dad was able to tighten it right up, and the liquid was hydraulic fluid by the yellowish looks of it. Makes me wonder if we were lacking a little extra clutch pressure because of this.
-William (keep 'em coming!)

 

[aerog]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by William:
Makes me wonder if we were lacking a little extra clutch pressure because of this.
<hr></blockquote>

Unfortunately it doesn't work that way. The hydraulics simply provide a way to overcome the springs that hold the clutch in position. Lack of fluid, and thus pressure would result in the inability to shift gears (or at least a quite difficult time of shifting).

My guess is in third and fourth gears you're able to get enough torque on the engine side to spin the engine against the clutch - again, a symptom you can probably recreate by holding the brake while trying to move the car in third or fourth gear.

 

[coldplugs]

Ditto and ditto. I don't think there's any adjustments to play with. Most likely some oil got in there & is causing the slippage. Chances are you'll really notice it going up a long hill in third or fourth, and possibly smell it, too. Unfortunately slipping clutches usually don't get better by themselves. You said that the fellow who worked on it knows his business, so it's probably not in backwards or anything like that.

John C