1958 MGA Coupe

[bobs77vet]

well unluckily the clutch side isn't producing enough pressure for a good anything....


heres the bottom line.....the clutch side of the MC is not developing pressure. when I power bleed the system I get the best pedal movement but only temporarily.....when I regularly bleed it the first 1/4 of pedal travel produces no fluid. when I map the slave pushrod travel to the pedal movement the first 1/4 of pedal movement produces nothing the middle half gets the most movement and the last 1/4 get a small amount. I was so hung up on the clutch slave being finicky to bleed and since I spent the extra $$$ on an AP MC I just missed the obvious. I will rebuild my old MC and use that as a test unit. I have all the parts to rebuild it and I took it and the clutch slave apart this am.


here it is



slot the bottom to expose the hole and grind off the bleed nipple





drill and tap





and fill with oil and then use grease from a grease gun

 

[bobs77vet]

almost there....heres the scoop...the clutch slave cylinder lip seal was allowing air into the salve cylinder every time the clutch pedal would return to normal height. Why you ask....look at this horrible design its almost begging for this to happen

doesn't look so bad here...rebuild kit one is the shorter one



looks like same width



can you see the 6 half radius indentations in the lip seal, the original spring and spreader is on the left in the back ground and the new one is on the right







no shit it allowed air in...so I replaced the original seal and spring with one from a rebuild kit I had purchased when I first got the car.


so lets do this one final time heres the set up





plastic bottle NEVER USE GLASS



that hose clip is on the bleeder nipple and stops the bleed hose from coming off and also holds he combination wrench in place



the end result was the car will go in gear with no grinding, which is a first. But will still almost stall with the clutch fully depressed in gear with brake on. there is no bubbles in the slave cylinder and even after pumping it there was no bubbles. I have 11mm of slave push rod travel and I believe its more firmly pushing against the pushrod then it was before. I had to reuse my silicone fluid and I strained it each time but I believe its pretty well agitated and probably has some micro bubbles in it. tomorrow I will get another qt of fluid and then in a day or two will rebleed it. I will look for bubble again in slave cylinder but I think once I get the micro suspended bubbles out we will be ok.

lessons relearned.....1. just cause its a new part doesn't mean it will work properly
2. just cause something has a horrible reputation for being finicky doesn't mean that's the problem
3. don't ignore the obvious symptoms....air that keeps showing up in the slave cylinder has to come from some where

 

[bobs77vet]

tuesday:
still chasing the beast or maybe its chasing me

well swapping the slave cylinder guts has gotten rid of all the air slipping by the lip seal, so I reliably have no air in the clutch slave and I also have 11mm of travel but that's it, but this is uniform and predictable now which I didn't have before. When we map the clutch pushrod travel to the clutch pedal movement its pretty uniform with 2-3mm in first 1/4, 5-6mm in second and third qtrs and 2-3mm in last 1/4 totaling about 11mm and clutch pedal is to the floor. this also happens to be when there is a lot of resistance on the throwout lever. I tried levering the throwout lever back and I couldn't move it with one hand and a 6" lever. How much pressure should it take to move the throwout lever arm? I am not sure if this is an issue or not but the bottom line is the pedal hits the floor at the same time we get maximum movement of 11mm so theres no room for further movement of the clutch slave pushrod

Now up top on the new AP 7/8" MC the clutch side is not predictable on where the piston will stop when it returns to full clutch pedal height. there is as much as 8mm of free play irregularity. by this I mean we start off with 1/8" free play measured at clutch pedal (barely about 1mm of travel of MC pushrod) and then pump away for several times and then take a measurement when the pedal feels and sounds different and you now have up to 8mm more of MC pushrod travel before it hits the piston. pump away some more and it will move back to where you started or any where in between. there doesn't seem to be any pattern to when it decides to stop prematurely. on one time i could actually unscrew the MC pushrod all the way in order to touch the piston. i don't think the MC clutch side is developing full pressure. any thoughts on anything i am missing or the next logical troubling shooting step? I wonder whats going on with that MC clutch piston???? thks bob


Weds: so as part of the trouble shooting process at lunch time i was able to verify that mechanically the clutch, throwout bearing and clutch disk all worked correctly

i even did it single handedly

i used a 1" piece of square stock slipped over the throw out lever fork ( the slave pushrod removed) used a strap and put it over the front hub....so when you turn the wheel the distance shortens and pulls the lever towards the front and the frame cross member acts as a fulcrum (i will need to do some paint touch up)





i used a screw driver as a lever in the universal joint and i could turn the steering wheel to engage.disengage the clutch and i was able to turn the drive shaft while the car was in gear and the fan did not turn....turn the steering wheel to the right and the disk would engage and the fan would start to turn....so mechanically the clutch assembly is working fine and it engages and disengages with predicatability




there was 5/8" of movement in the lever arm this is an approximate measurement it was 1 1/8 to 1 3/4

heres a picture as i was trying to figure out the measuring technique.

 

[bobs77vet]

rebuilt the old MC tonight to use as test/temporary unit




doesnt look like much



if you ever wondered how big those fluid return holes are this is with a flash light shining in the bore



not very pretty but its just for a temporary use.





i am cycling the pistons to make sure that they will return freely under spring pressure and just for fun some of the cycling has been done with fluid in it like doing a bench bleeding.....

 

[bobs77vet]

well last night I swapped the rebuilt old MC with the new one and you could feel an immediate increase in pedal pressure, i filled it up from the bottom and for some reason i could not get a good seal on the motive pressure bleeder up top for a final pressure bleeding. i think this is because the screw heads are taller then the flatter bolts so i have a partially bled rebuilt MC that is giving me more pedal pressure and marginally more pedal travel 1-2 mm on a partially bled system. i will take that as a positive step forward.

heres the old nice looking unit ....



and the rebuilt one since i was working solo all of my measurements were done with a clamp up top which also lost me some small amount of pedal travel since it didn't fit very well, this after noon when my helper gets out of school we will nail this down

 

[bobs77vet]

I am so close.......the rebuilt MC with out bleeding has me within 2-3mm of where I know the clutch pressure plate disengages from previous measurements taken with the lever and strap, but the 56 yr old springs that that were in the MC which I reused are just not up to the challenge of returning the piston forward with fluid in the system after I push the pedal down to bleed the system the manual way. add to that the top plate screws are too high for my motive pressure bleeder early Ford adapter to work. so I need to either rethink a bleeding strategy or just wait for the new MC to arrive.

the defective MC will get shipped back tomorrow to the vendor for replacement , but the vendor for the clutch slave will not take a return if silicone fluid was used so I am getting some prices from a different source.

on the positive side I have incredible pressure at the clutch pedal I just need to get rid of some residual air....so close

 

[bobs77vet]

this is the old lock heed unit with holes at 12 and 3




heres the new unit with holes more like 1:30 and 3....now rotate this clock wise some when it gets mounted and you can see where you have trapped air.





so lets pretend the last 2 wks never happened.....everything is back to where it was...



cleaned up the pressure bleeder and i will order the correct bleeding cap



all lines capped

 

[bobs77vet]

I'm not good at doing nothing....


I made this and used a nut and big washer on my old slave cylinder to make a mechanical clutch release




heres proof I am not nuts its a video just click on it, the clutch disengages


http://smg.photobucket.com/user/bob...s/VID00030-20140223-1132_zpsb1c6dfda.mp4.html

 

[bobs77vet]

about 2 hrs of work....I have a leaking water pump which needs to be replaced and I want to switch over to the MGB PCV so I need to take lots of stuff off any way.....and my clutch still just doesn't seem right. Using my mechanical pressure plate release I can release the clutch and move the drive shaft by hand yet when I turn the engine over and its running the clutch seems to be engaged? really strange.....it almost seemed like something is off center and acting like a cam picking up interfence as it rotates....

up up and away



hows that for a nice smooth throw out bearing...that sure doesn't look right




end of the shaft isn't scored



disk is mounted right



this isn't right ...........look at the shoulder that has been dug/grinded into the pressure plate



so as we looked at this we realized that the splined center of the pressure plate must not be centered, these are the distances to the edge of the clutch disk that sits in the pressure plate from the center opening



heres the old clutch disk sitting in the pressure plate showing the free play from side to side, the measurement shows the amount of the pressure plate I could measure from side to side





the new clutch disk has NO movement or free play



heres the shoulder that has been dug into the pressure plate



heres the undamaged side



so heres the bottom line the clutch disk Spline was off center and there was not enough free movement in the pressure plate opening that it sits in to accommodate the off centerness and the clutch disk would then be shoved into the side of the pressure plate opening causing the shoulder and since the pressure plate is mounted to the fly wheel it would drive the input shaft...

what a complete waste or time.....a MC with a defective cylinder.....a slave cylinder that sucks in air.....a clutch disk manufactured incorrectly and now a defective throw out bearing...

 

[bobs77vet]

SNOW DAY.....



you know where that's going...



55 minutes from putting the old components back on to having it installed... 15 mins to get it aligned and close and then 35 mins of wiggling and massaging the angles and then it slipped right in place with no effort.



cleaned paint over spray off of the oil filter mounting plate



2 hrs from start to finish





and heres the MGB valve cover and front tappet cover having the cork gaskets mated to the stamped steel with permatex




total time 2.5 hrs and the best part the clutch works perfectly, I can disengage with it a lever and I can turn the drive shaft by hand and it feels right .....I am a happy camper!!!

 

[bobs77vet]

we are iced in so heres a quick hour

I found the leak on the water pump and its at the bottom weep hole



definitely not a leaking gasket



time for a new water pump.



I was looking at the rear side tappet cover and the MBG is indented where the 1500 one is protruded and it is much thicker, the PCV front cover plate actually has a tubing collar where the bolt goes through almost like they are trying to keep oil off of the center bolt. I will leave these as they are but when I remove the intake manifold again to put the body on if the rear is leaking I will swap it with the MGB one

 

[SuperBuickGuy]

it's fighting you....

Perhaps you should post a picture of it when you bought it in front of it as a warning to remind it where it will end up if it fights too much.

 

[bobs77vet]

either that or push it out side over night.....

lets play around with cleaning up the PCV and see what I can do with the broken exhaust studs

so this is the hand I was dealt, I had used nuts and bolts before for the test runs of the engines but lets see if I can get some studs in there




while tapping the threads you know the hole is in the right space when you get this





now to move on to the next one



looks like they burned the old studs out but I need the holes to be straight so I am using a file to clean it up




this will get a helicoil if this were a stressed part this repair is awfully close to the out side






I am using 3/8x 16 GM style exhaust studs, I really like the double long brass nuts




finished repair



next one .....now this will be a challenge but at least I can straighten up the hole for the nut and bolt





a broken file chucked in the drill


cleaned up but too big for a heli coil so I am just using a nut and bolt I could plug it and drill it but its just not that critical to me.



finished


cleaned up the PCV from the MGB



and the cap gets some stainless steel paint to cover the rust stains

 

[bobs77vet]

in with the new water pump..... I use some RTV sealent on both sides of the gasket



I don't know why we could expect the holes to line up



I sprayed the water pump with some clear



cleaned up the good radiator and painted it, I used black lacquer since it is so thin I thought it would look more like radiator paint





todays work

 

[bobs77vet]

PCV valve set up installed



this little handy bracket actually keeps everything together pretty nicely



I figured out I could make the choke work in the MGA over the filter style by reversing the abutment and changing the cable stop style on the HS4



the good radiator does not leak, we back flushed it extensively this morning



and we figured out how to drive the tublar rivets to mount the valve cover labels using punches, not very pretty but effective



the engine runs great and the PCV set up works as it should

 

[bobs77vet]

lets try this again...

clear coated the MC



let the MC sit on top of the bolts and install the fittings



I could tighten the brake line before it was installed but the clutch banjo got tightened after it was installed



filled up the clutch slave circuit from the bottom so there are no air pockets



the brake circuit got bled from the top



I only did one wheel tonight just enough to get the air out of the MC.


done




so I dont have any bone headed moments




AND IT WORKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[bobs77vet]

well I finished bleeding the brakes with the Motive power bleeder and then cleaned up a little and put a wheel back on and then took her off the jack stands and looked at the car and said what the hell......I opened the garage door in the 22* weather at 11:15 pm and I drove it in and out of the garage under its own power......the first time the car has moved under its own power in over 40 yrs. I cant wait until the 60* days coming up. the car has so little weight in the back I have tire spin marks from backing it in the garage.....its first burn out in 4 decades. it felt pretty good!!!!
any body need 2 qts of clean, strained and recycled silicone brake fluid that was used only on all new parts. I just don't see a need to hold on to this until the next build. it would be perfect for any one who wants to switch from regular fluid to silicone and wants to use a sacrificial fluid as a first flush. pm me if you are interested

 

[bobs77vet]

mid 50* I guess and she is drivable, these are both a clickable link and a video that you can click on

http://smg.photobucket.com/user/bob...s/VID00031-20140314-1639_zps35e9d65c.mp4.html





second run

http://smg.photobucket.com/user/bob...s/VID00032-20140314-1657_zpse62e13eb.mp4.html



I think early tomorrow am we may go a little bit further down the street.

 

[MYBAD79]

Awesome videos!!! I bet this was a lot of fun, the kids seem to like it ...lol

 

[Sam Cogley]

I'm probably forgetting something from an old post...but after all of that work you did on it, where is the body?