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MG MGB Technical - Removing the Clutch Master Cylinder Bottom Bolt

Alright, I know we've all seen this topic before. But I've been looking through the archives and I still can't seem to find a good way to remove that darn bottom bolt. Actually, there's probably no "good" way--but there must be a better way than me trying to fit a wrench into a small space and get it to turn ever-so-slightly and then straining to repeat the process a hundred times.

The top bolt came out easily--as it does for everyone. But I've already spent a couple hours trying to remove the lower one and I think I've perhaps turned it half a turn (and the nut may have moved with it--thus no actual improvement). Any suggestions?

Jeremy
1974.5 MGB
J. Palgon

Jeremy - There is a rubber access cover under the dash just above the pedals. Pop the cover out and reach in with a socket on an extension to get to the bolt head. A half inch open end wrench can be inserted through a hole in the side of the pedal box to hold the nut while the bolt is unscrewed. Once you have the M/C out, do yourself a favor, before reinstalling it or a new one, have a machine shop install 5/16 helicoils in the bolt holes. Doing this will eliminate the need of trying to start a nut on the bolt in an inaccessible place. Good luck - Dave
David DuBois

Dave,
Good advice as always. I read about this method of removal (and adding the threads) in the archive. In fact, I first tried to remove the bolt in precisely this manner. Clearly, this method requires two people--becuase I can't possibly reach the bolt from the front with the wrench while using the socket under the dash at the same time. Actually, I'm having a heck of a time just getting the socket near the screw from under the dash. I certainly can't see the screw from under there. I guess I'll just try it again in the morning.

Jeremy
J. Palgon

Success! I didn't manage to do it the way Dave described, though I tried for a couple hours. Eventually I managed to work the socket onto the bolt with a little room to maneuver. Since I already bought a new master cylinder, I was less concerned about hurting my old one. So, I just pushed hard against the MC with my right hand while turning the bolt with my right. I managed to create just enough pressure to hold the screw in place while turning the bolt. Hopefully installing the new one will prove easier.

Jeremy
J. Palgon

I,ve covered this before but take a new bolt and nut and clean with solvent. Then clean the back of the M/C flanges in the same way and after putting a little super glue un the back of the nut put the bolt in just nop it up. After a few minutes you can remove the bolt and the nut will stay firmly in place. Refitting the cylinder is now easy but puit a little grease on the bolts before you do.
Iain MacKintosh

Ian,
Your method is pretty novel. Sounds like a good idea. What solvent do you like to use to clean the nuts and bolts up? This method should work to reattach the bolt; but will the super glue really hold up long term? Or is the super glue there just so that you can get the bolt reattached easily?

Jeremy
J. Palgon

Cellulose thinners is fine for cleaning. I don't know how the super glue will hold up long term and I hope I don't have to take it off again, but for fitting it works a treat. The idea of cleaning and oiling the bolt is so that in future you can hold the nut with a finger if worst comes to worst.
Iain MacKIntosh

Helicoil the master. You can do it at home and buy the helicoil kit on eBay.

Sure it's easy for the factory to assemble the masters when the box is out of the car but insitu it's almost impossible to do.
Mike MaGee

I did mine in 30 mins Mike. It was a non event
Iain MacKintosh

Either way, I hope it's a non-event. Getting the master cylinder out certainly was an event. What a pain.

Jeremy
J. Palgon

Alright gang, I've got the helicoil kit. It cost me about $30 but I think it'll be worth it for the hassle saved the next time I have to remove the MC. The new problem is that the slave cylinder bolts will not budge. They're accessible, but I simple cannot move them. I've tried penetrating oil, with no luck so far. Any suggestions?

Jeremy
J. Palgon

Right, they will be tight but should come out OK using a ring key. I cannot see how they would seized and am reluctant to use heat at the moment but the differential expansion between the housing and the steel bolts would loosen them. In the meantime go into thwe house have a beer and then with a good ring key or single hex socket and ratchet remove the bolts. You can do it.
Iain MacKIntosh

Iain,
Thanks for your help. Unfortunately I don't have a ring key...and it seems that the hardware stores around here don't either. I, too, am loate to use heat to remove the bolts. I've been trying to remove them with both a typical wrench and a socket and ratchet. Maybe they're not siezed; but they are certainly on so tight that I can't create enough leverage to move them at all.

Jeremy
J. Palgon

Jeremy - Due to the position that one has to work on the slave cylinder, it is difficult to get a lot of force on the wrench to break the bolts loose. It is doubtful that they are seized or in need of heat to break them loose. I use a 12 inch breaker bar to get them started. You might consider a rubber hammer on the end of the wrench you are using to break them loose. Good luck - Dave
David DuBois

Iain, I have to admit I don't know what a ring key is. It's good we have a common language or we would have serious communication problems. Maybe it will turn out I'm the only one who doesn't know. I typed in "ring key" on Google and found lots of jewelry links but no tool information.

On the clutch slave cylinder removal, I use a 1/2 drive 16" breaker bar with a 6 point socket.

Clifton
Clifton Gordon

Sorry Clifton for not being more explicit. Try Ring Spanner and you will know what I mean. Now I can relate just fine to a 16" bar, 6 point 1/2" sq drive socket and that will do the job just fine !!
Iain MacKintosh

Iain, Thanks, no problem, Ring Spanner=box end wrench here. I usually understand the UK/US differences in tool descriptions.

Clifton
Clifton Gordon

Well guys, I have tried the rink key and the drive socket. Still no luck. Unfortunately, I'm going out of town for a while, so I guess it will have to wait. Thanks for all your help.

Jeremy
J. Palgon

Apply heat?
Dan Robinson

I can't believe this. I know it is a bit awkward to get at but if you can get a breaker bar on it it WILL come off. Heat the bell housing a little if you wish but you will need to apply heat from a fairly powerful frame as the casying is aluminium and will transfer the heat away fairly quickly. I still don't think you need heat here.
Iain MacKintosh

Did this a few years ago, as I recall there
is a rubber insert under the dash on the
driver's side that is easily removed.

Then used a 1/4" ratchet with
6" extension to get at the clutch master lower bolt
from inside the car through the opening.
Ronald

No rubber insert and you will need more than a 1/4 ratchet to remove these bolts
Iain MacKintosh

Iain,
It don't think it's the tools that are the problem. The bolts are just awefully stuck and I just can't seem to muster up enough force in the limited space beneath the car. When I get back I'm going to put it up on jackstands in the hope that with greater freedom of movement I'll be bale to exert more force.

Thanks for the input Dan, but I'm going to stay away from heating it for a while.

Ronald, you are correct about the rubber insert with regard to removing the master cylinder bolt. I acutally got that out already (with some pain). the bolts we've been discussing at the bottom of the thread are the easily accesible ones holing the slave cylinder in place.

Jeremy
J. Palgon

Jeremy, you really do have to lift the car a bit to get proper access to these bolts. One of the difficulties will be that without sufficient space you are actually trying to turn the wrenches whereas if you can get height you can actually pull on it if you see what I mean. The breaker bar will fix it as from memory they are only 3/8" bolts and something has to give with a bar on the end !!
Iain MacKintosh

This thread was discussed between 08/12/2005 and 16/12/2005

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.