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MG MGB Technical - 73bgt and clutch
|clutch is engaging as soon as the pedal leaves the floor. is this a hydraulic issue? possible solutions?|
Yes, it probably is. Consult the archives on clutch bleeding problems before you start to work.
|Newell. Maybe. The most common cause of this problem is a clutch master cylinder and/or a clutch slave cylinder with failing seals. The only way to check them out is by a tear down inspection. At that point, it makes sense to rebuild them and replace the flex line from the hard line coming off the master cylinder to the slave cylinder. Take a very good look at the break down illustration of the system. There are some copper washers used, to make a good, tight seal, where the MC connects to the banjo bolt and where the flex hose connects to the slave cylinder. |
There is, however, another area of the system which can also cause this symptom--the pushrod for the master cylinder and the clevis pin that links it to the clutch pedal. The clevis pin can have grooves worn in it which will affect the proper operation of the cylinder. The pushrod can have its holes wear oval. When the two problems are combined, you can have the same problem you are experiencing.
However, replacing the pushrod requires that you remove the master cylinder, at least for most of us. There is a snap ring holding the pushrod into the cylinder and limiting its outwards travel. It might be possible, for someone who has small hands and excellent eye sight, to replace the pushrod in place. If so, I should like to meet such a talented individual and share a beer with him/her.
So, the bottom line is that you will probably have to pull the MC from the car and, unless you know it has been rebuilt recently, you should rebuild it at that time, including new copper washers, a new clevis pin, and a new pushrod. If you are going through that much trouble, it would be wise to replace the flex line, rebuild the slave cylinder, replace the slave cylinder pushrod (it also has its hole wear oval over time), and replace the clevis pin.
The standard method of securing the clevis pin in location is a cotter pin (which the Brits call a split pin). I am using "hair-pin" clips for this application. Easier to insert and easier to get out. They have held up well in use for a number of years.
|Check to ensure that the clutch fork where it connects to the slave cyl is travelling about 5/8" otherwise you are not didengaging the clutch far enough to give the necessary pedal clearance.|
If it were me I started with the easiest problem first and worked backwards. When I had a similar problem I had a look under the car and saw I was not getting the required travel. I was also able to see small bubbles at the slave cylinder. Further to that I took the push rod and clevis pin out (takes two minutes to remove) and they have loads of wear. So I replaced them and the slave cylinder. Bled the system and all was well. A slave cylinder is cheap and a new one is less likely to fail than using a repair kit on the old one (indeed mine had previously been repaired by the previous owner but did not last long). The total bill for me was less than $100. A master cylinder is far more expensive. Personally I'd only fiddle with it if you have already eliminated the slave as a problem. Keep it simple!
PS Bleeding the clutch can be problematic. Do a search in the archives for a hundred different ways! I used an Eezi Bleed system which was fairly successful (2 attempts to get a good pedal!).
|I D Cameron|
This thread was discussed between 07/04/2007 and 11/04/2007
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