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MG MGB Technical - Oh the joy of a rebiuild.

Well after 5 years rebuilding my Heritage shelled 69 GT finally fired up. Ran her for 15 minutes to bed cam in, etc. Everything is new or recond every nut bolt and washer renewed & looking great.
But, next time I tried to start her, QH fuel pump failed, solid state voltage regulator u/s bypassed that as a check and fuel gauge doesn't work (traced to new sender in new tank courtesy of Paul Hunts notes). Overdrive doesn't function and brake bleeding is really trying my patience.
Hey ho we'll get there, however, only goes to reinforce the basic lack of quality of some replacement parts.
Just thought I would share that with you. Now just waiting for all the rubber bits and bobs to start falling apart.
Cheers
Mark
Mark Dollimore

QH fuel pump? I would have thought that you would have gone with an original points or solid state SU fuel pump. I installed one of the latter, in my '67 B that I've owned for forty three years, and it's worked flawlessly. I'm still using the original mechanical points style voltage stabilizer. Never missed a beat. I had a failure with my OD and it turned out to be an intermittent short circuit in the solenoid. Hope that your luck improves. Having owned my car for so long, it seems that I've replaced everything at least twice. I've kept a complete record, on my computer, of everything that's been done to the B since '83. It comes in very handy when it comes to troubleshooting. I, too, have been amazed at the lack of quality in a lot of today's replacement parts. It never used to be like that. RAY
rjm RAY

Love to see pictures and kudos on you determination and patience.

RE bleeding the brakes. Really the best I've found that pressurizes the system and bleeds it quite nicely is a kit sold here that honestly looks like a plant sprayer with a gauge on it. Works very well at getting micro bubbles out and a solid peddle feel. Made by motive products.Best of all you can do it yourself and no bug anyone else to sit in the cockpit.

I've had point fuel sender and recently the solid state version which has lasted many years. Recently, I've read people are concerned about the SS version. I'm sure I could have saved a fair amount of money over the years by just replacing points in a sender had I known it had points.

Agree with RJM on the OD. Might recheck your connections as well.
Max71

Mark,
All the niggles of troubleshooting odd systems was nothing compared to the really poor quality of the Heritage shells I have worked on (a Gt and a Roadster).
Get a good fuel pump, SU or Facet, check the O/D switch, a dose of contact cleaner sorted mine out after it had been idle for too long. The lock out switch on the gearbox might be faulty, try by-passing BUT DON"T ENGAGE O/D IN 1st or 2nd while trying it!!!
Never had a bleeding problem but use an Easybleed modified to run off my compressor. I also have a bleed nipple on the end of the Servo slave which seems to solve the usual problem of successfully bleeding that!! (picture upside down......don't ask me why!!!***)


Allan Reeling

Would you b... well believe it - centre exhaust hanger - rubber parted company, this morning, tempted fate a bit too much me thinks.
Allan, couldn't agree more about the shell looks OK now but was an absolute b.....ard to get looking anywhere near plus all the holes in wrong place, rad mount different side to side, rear quarter light apertures, door shuts, tailgate fitting, I could go on and on.
Roll on when I've got to a reasonable finish and I can get back to work on my MGA at least I know them reasonably well (Nr 5) having rebuilt my first one back in 75/6.

Cheers

M
Mark Dollimore

"I've had point fuel sender ... I'm sure I could have saved a fair amount of money over the years by just replacing points in a sender had I known it had points."

Tank sender or fuel pump?

The tank sender doesn't contain points like a fuel pump, but a variable resistance. You would be very unlikely to be able to fix that other than by replacement. So-called 'solid state' senders still contain the same variable resistance but it's more like a set of contacts embedded in a solid substrate rather than turns of wire wrapped round a former. They eventually wear through, or get snagged by the wiper (that's happened to me twice). At least that can't happen on current stock, although the wiper could still fall off.

If an OD goes short-circuit it will burn the wiring - unless you have fused it which I strongly recommend, as well as the fuel pump. If the OD doesn't work when it should then it is very unlikely to work in 1st and 2nd. Some people have bypassed the lockout switch precisely to get OD in 1st and 2nd. Whilst it may well damage the OD eventually if you tromp on and off the accelerator enthusistically, the capitalised dire warning is more applicable to not engaging reverse with the OD manual switch left on, if you find it is engaging in 1st and 2nd as well as 3rd and 4th.
Paul Hunt

Mark,
Just interested, you mention "door shuts", did you have a problem with the passenger door opening? Both shells I worked on needed the opening "spreading, once the lock plates were fitted.
Allan Reeling

Paul

I want to fuse OD on 1975 gt, which wire do I use? I recall reading that the yellow wire should be fused; is that correct.
R E Merrall

The feed for the O/D is taken off the ignition live circuit (WHITE un fused) to the O/D switch so easy to put a line fuse on the yellow side of the switch.
Allan Reeling

R E, it depends on the year of your car and whether you have the dash manual switch, the later column switch, or the latest gear-lever switch.

For the dash switch fit an in-line fuse with a male spade one side and a female the other where the white wire connects to the switch.

However if you have the 3-synch gearbox it's slightly more complicated as there are two 12v feeds - one for the manual switch relay as above and another for the relay contacts direct from the fusebox. To fuse both as well as an in-line with spades for the manual switch you would need another where the white connects to the relay contact C2.

For the column switch unless you are willing to cut wires behind the dash it's easier to fit it where the yellow wire from the gearbox harness joins to the yellow wire in the main harness, in the mass of connectors by the master cylinders. In that case the in-line fuse has bullets on the ends.

For the gear-lever switch it's much the same but goes where the white from the gearbox harness joins the white/browns from the main harness.
Paul Hunt

'69 Paul!
Allan Reeling

Others might want to know (that's my excuse ...)
Paul Hunt

I suppose year isn't always definitive, there are lots of "bitzas"!!
Allan Reeling

Thanks for the advice. Fused the white wire from the switch.
R E Merrall

Come on Mark, am interested in your Heritage stories, particularly the real bad inaccuracies. i.e.., passenger door opening,(too narrow) tailgate hinges, rad grill opening, (too narrow), steering column bottom location, front chassis rails (too narrow), corrugated panels, particularly front wings and doors, boot floor Zeus holes, rear light openings, rear exhaust mounting plate, and/or valance cut out. captive nuts in front valance. As well as your rad diaphragm, I have had all of these, plus more I can't remember off hand.
Allan Reeling

Paul - the points referred to the fuel pump. I wrote an article on How to calibrate the fuel sender and gas gauge correctly for another site. If there's interest I can also upload it here with suggestions on where to upload.
Max71

Allan - sounds like your experience with Heritage shells has been worse than mine. I do not apparently have any issues with the front chassis rails , the front cross member attached reasonably easily & rear axle sits fairly central. Rear light areas are bowed so I'll have to wait and see how much they leak. The lower rear window aperture dipped towards the rear by a good 6mm each side about 2/3ds towards the rear and the location of the captive nuts for the rear quarter lights are too close to the seal flanges so the windows are under tension all the time when clipped closed -I even used the old seals to try and gain a better less stressed closure. The doors are the best fit I could get with a wider shut width at the B post. compromised so that the striker plate would actually miss the end of the door. This was fairly consistent each side. The quality of the welds generally and the 'flame' cut apertures to the rear 3/4 panels are very amateurish. I ended up cutting the mounting brackets off each side of the rad and bolting back on so the rad could sit between the diaphragm and the horizontal duct panel (out by about 7mm across width) and the grill had to be gently bent at each top edge to sit back into the grille aperture. Every captive nut had to be tapped clean and I'm still not convinced the gearbox cross member is quite right. I cannot get the tailgate to sit squarely in the hole and had to resort to placing the seal on the body rather than around the tailgate to get it to close at all. The interface between the top of each door and the front edge of the quarter light is a very poor fit.
I have used up a lot of seam sealer to prevent moisture ingress into the welds on the underside. But, that could just be me being a somewhat pernickety. I am realistic enough not to expect perfection when the original cars were way short of todays computerised robot precise builds. But, the amount of effort has added considerably to the build time and tainted the pleasure one should get from undertaking such a project. I'll post a couple of images of the 'finished' article when I have finalised sorting the rack and column alignment!
Mark
Mark Dollimore

Mark, the rack and column alignment was a big issue on the GT V8 shell, involving cutting out the bulkhead "cone" panel and welding a new panel in to get the two to line up. As for the tailgate, you will probably find that the fit will be improved if you use your original hinges. Comparison of the new and original will reveal the problem.
The V8 shell took something like 150 hours just to get it on 4 wheels ready for painting!!
Allan Reeling

These shells are now very expensive and if they are that bad, how come no-one has asked Trading Standards if these goods are actually "Fit for Purpose", which is what the law requires of anything sold to the public. I can't think of anything else where the purchaser has to make radical and specialised adjustments to the product just to make it usable.
Mike Howlett

Mike, it's a case of what alternatives do you have, and Heritage know that. It's either their fresh metal or nothing!! I'm not even sure they have the expertise, or desire for that matter, to improve the product.
Allan Reeling

This thread was discussed between 17/10/2015 and 21/10/2015

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