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MG MGB Technical - Continued cutch/gearbox problems

I love working on my 77 MGB but it sure would be nice to drive it for extended periods every now and then.

About two weeks ago I posted a problem with the clutch which resulted in the replacement of the clutch slave cylinder. Job went beautifully and system was bleed with no problems and no air left in the system.

Prior to the problems with the clutch I began to experience what I perceived to be a front end vibration at 60 MPH. I tightened down all front end connections as a first step to investigating the problem. Today while driving the vibration seemed worse and I heard what I thought was a noise of some sort coming from the center console of the car near or at the gearshift lever. I placed my hand near the lever on the console and could feel a grinding/vibration on the console which seemingly would be coming from on top of the gearbox.

Upon looking underneath the car after arriving home I could see a tream of oil coming from the rubber boot surrounding the clutch lever. See enclosed image. I'm not sure if I'm dealing with two seperate problems here or one. Can someone please identify the oil leaking from the rubber boot problem and advise on how to proceed? As always your help is greatly appreciated.

JCH Hibbard

did you fit clutch,was the spigot bearing ok,if not this could be your two problems ,
da wright

Not sure how to answer that DA. What do you mean by did I fit clutch? And honestly I would not know a spigot bearing if it bit me on the butt. I've done a lot of work on this car myself and fitting the clutch slave was pretty simple. I have not yet had much experience with the clutch and gearbox, so I'm afraid at the risk of looking dumb I'm not sure what you are referring to.
JCH Hibbard

JCH, the first thing I would check is what sort of oil it is. Engine oil is generally dirty, gearbox oil is generally clean and they both smell very different to hydraulic fluid. Is the oil also coming out of the drain hole at the bottom of the bell housing?

There are oil seals on the engine and the gearbox, they do wear over the years. I changed both of mine about 3 months ago, mainly because it seemed prudent to change both whilst the engine was out of the car.

The spigot bearing (bush)is where the 1st motion shaft from the g/box sits in the engine crankshaft by the way.

I'm sorry but this doesn't help your vibration problem. It could be any number of things.

Cheers

Tony
Tony Oliver

There is no oil comining from the drain plug on the bell housing. Both the gearbox and the engine are running Castrol 20/50, appears to be a little dirty but hard to tell if it's from the engine or gearbox, definitely not hydraulic fluid. How do I check the spigot bearing?

I can't help wondering if the grinding/vibration I can feel coming from the console is somehow not related to the failure of the clutch slave. If perhaps the problem didn't damage something in the gearbox. And as I said not sure if this is what is causing the vibration I feel in the front or if that is a seperate problem.
JCH Hibbard

JCH

I would expect the front end vibration issue you mention to be separate from the gear lever/console noise issue and from the oil leak as well.

On the front end. Good that you have checked everything for tightness. Often a front vibration at a specific speed of confined to a specific speed range can have its origins in wheel alighnment/wheel balance/wheel or tyre trueness running out.

As a first step I would exchange rear wheels to the front and see what happens. If there is no change I would next have the wheel alighnment checked. If the vibration goes away with the wheel swap I would have a check done on wheel balance for those currently on the front.

The gear lever/console vibration sound and feel is something many have commented on here in the past. We need to remember that the lever is a mechanical connection to the gear change rods. Add to this the fact that the release bearing must sometimes be rubbing (however slightly)against the clutch face and its little wonder that there is some noise evident. In my car it sometimes sounds like a mob of bees in a tin (no, there is no pinging going on here). If I grasp the gear lever I can "feel" the sound as well, if that makes sense.

Unless the sound in yours is worsening or has suddenly appeared, I would be inclined to wait and see if it changes in any way (possibly indicating a developing cause) or whether it settles down to appear as just one of the quirks of your particular car. Having just replaced your slave cylinder I would, however, take the precaution of checking that you do have appropriate slave rod travel - just to make sure that the throwout bearing is not being held against the clutch by a declining efficiency in the slave system by, for example, air entering the system.

The oil leak is not excessive and, although I would expect to see that at the drainage hole at the front lip of the bottom of the bellhousing (should have a split pin in the hole), it is possible that a leak at the front gearbox seal could be working its way across the face and down the clutch fork arm to appear as is in your case. Most of these cars would be showing some leakage at that point, or the rear engine oil seal (or both), certainly if its been years since either has been replaced (if replaced at all).

Short of such a leak making it onto the clutch or bearing face most people live with it until the engine and gearbox come out for a clutch change - or the leak becomes so bad that oil is spreading at a rate requiring too regular a top-up for the engine or the gearbox.

I'd encourage you to separate the issues and take them one at a time. I'd do the front end vibration first.

Regards
Roger
Roger T

As well as everything else, it looks to me like you have the clutch slave flex hose and bleed nipple in the wrong places. For some reason the bleed nipple comes in the flex hose hole on new slaves, possibly for packaging reasons, or possibly because in its original (non-MGB) application it *should* be in that location. This usually causes bleeding (language, Timothy!) problems, but if yours bled OK then I'd leave it alone.

Oil coming out of the release arm hole is probably coming from the gearbox first-motion shaft oil seal. If there has been a rapid increase in noise and vibration from the lever, then it's possible this bearing (or something else in the gearbox) is breaking up and that is causing excessive shaft movement which is causing the seal to leak. If you have a *stream* of oil coming from that place, i.e. continually dripping or running off the bottom of the bell-housing (may only happen when the engine and gearbox are turning), then checking the level of oil in engine and gearbox should show which one is dropping.

Paul Hunt

JCH. If you have had the wheels balanced lately I bet that the shop did not use a spider mounted to the wheels but just stuck the wheels on the balance machine. The holes in the center of MG steel wheels is not concentric with the rim.This leads to severe vibrations that seem to start around 50-55 MPH.
Good shops use a unit that has arms that bolt to the wheel and then in turn is mounted on the balance unit.
Sandy
conrad sanders

Roger already switched back wheels to front and still have vibration at 60 MPH. I can definitely feel the sound as I grasp the gear lever and the sound has appeared since the clutch slave cylinder change. There is oil at the bottom of the bell housing at the split pin but not able to be seen in the image. I was indeed hoping this could go until a clutch change and rear seal replacement as you have said. I think your right in regard of seperating the issues and I will look at it from that perspective.

Paul as I understand it the bleed nipple on the clutch slave is put in the position of the feed line for shipping purposes but is in the correct position as seen in the image.I will check both the engine and gearbox oil levels to see what has dropped. Upon my last check the engine was fine. I believe I will also try bleeding the slave one more time to insure the proper travel of the slave rod, however I did check it upon installation and all seemed fine.

I'm wondering Conrad that even though I have swapped tires front to back and still feel the vibration if the tires which have not been on that long were all machine balanced and even swapping out front to back would not make a differencein the vibration.

You have all been very helpful, I really appreciate your input.
JCH Hibbard

JCH,
One other thing, are the universal joints and yokes in good condition. If not the drive shaft could be off balance and really start a whole lot of shakin'

Ralph
Ralph

Thanks Ralph, a few weeks back I took a look at the u joints and everything there seems to be up to specs.
JCH Hibbard

I've been anxiously reading this thread waiting for somebody to make Ralph's point: U-joints! JCH, this is still high on my list, and of course it has nothing to do with the clutch slave - it would be purely coincidental. But U-joints can sometimes go out rather suddenly. You say you "took a look" at them. With the car in gear and the emergency brake set tight, can you rotate the driveshaft at all? If so, can you observe any slop in the U-joints when you do so? In doing this test, grab the driveshaft right next to the front and then rear yokes so slop in the U-joints isn't confused with slop in the internal splines.

Regarding the leakage problem, while you're routinely checking engine and transmission oil levels, also be checking fluid level in the clutch master. It doesn't look like very much leaking to me. There is a hole in the bottom of the bell housing just behind the mating surface to the engine that has a cotter pin hanging in it. If there is leaking from the engine rear main seal or first motion shaft seal on the transmission, you will definitely see signs of oil leakage at that hole. In fact, if there are no such signs there, I would say the leak is not coming from engine or transmission.

FWIW,
Allen
Allen Bachelder

JCH

Is there a connection between the tyre fitting and the appearance of the front end vibration? ie did it start only after the tyres were fitted - not having been an issue with the former set of tyres.

Don't overlook the wheel alignment aspect. Was this done when you fitted new tyres? It should have been. The points above about tyre mounting techniques might be worth confirming with the shop that did the installation. They should not have a problem with re-checking the alignment as well.

The fact that the vibration is in the front still makes me think wheels/tyres, although the mentions above to prop shaft (all 8 bolts and nuts there and snug?) have me thinking also about rear axle attachment to the springs. Check the soundness of the u bolt nuts - but don't overtighten these. When you see the rubber pad just starting to deform is about the maximum tighten point - put a second nut on each thread if not already there as a precaution against loosening. Also check the rear spring bush condition and attachment.

Regards
Roger
Roger T

Since you have suspicions of it being clutch or transmission, why not take it to a respected transmission shop near you for an expert opinion? I'm having a hard time finding any reason for your vibration from the words, but the feel and sound will probably be unmistakable to someone who deals with this stuff day in and day out.

The best explanation from something related to the slave replacement would be adjustment or air in the line, as already mentioned. But vibration, no (squealing slipping grinding) really doesn't lead me to that. A positive check of both bleeding and adjustment should eliminate your suspicion of a commonality of the problem and the previous repair.

I still say take it to the best tranny guy in town and tell us what he says. The best Brit car guy would be even better.
Tom

JCH - of course the bleed nipple is in the correct location, my mistake.

There is no adjustment available on the clutch, and air in the hydraulics simply leads to a low biting point, or baulking/grinding when *selecting* gears if bad enough.
Paul Hunt

Drop the drive shaft to check the U joints. It can be impossible to feel a worn U joint when the shaft is bolted in place. You can feel roughness in the joints when flexing them with your fingers that can't be felt when they are in the car. My experiance has been that if you can feel they are bad when in the car, they are really gone.
John H

Hi JCH
Check your rubber engine and gearbox mounts for the vibration. Johnny C.
JG Cook

This thread was discussed between 01/09/2008 and 03/09/2008

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