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Rear Near side chassis rail

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edthebad Edward Applewhite
Princes Risborough, Bucks, UK   GBR
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Unfortunately I have to have a rear chassis rail repair done (rear spring hanger) for my 1977 BGT to pass the MOT and it's been suggested that the most cost effective means of doing this is to take out the spot welds from the wheel arch and boot floor so that it can be accessed from the boot area. The rear quarter ring is not rotten. My question is, is that advice correct and would a day and half's labour seem appropriate (I have been quoted £720 at least, barring other problems which may appear). My budget is tight and I have a friend who can weld and I'd love to tackle it myself but it would be on my drive and I'm a little apprehensive. Is the repair section straight forward to 'cut in' as it were. There are some mobile welders on the net (some of whom talk of working on classics) but I wondered if any UK forum members had used them. I'm in Buckinghamshire.

Thanks



Edited 1 time(s). Last edit at 2014-09-01 06:16 AM by edthebad.

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twigworker Avatar
twigworker Jack Austin
Blowing Rock, NC, USA   USA
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Ed, I believe that "we" over here will have little experience with that level of repair. Even under the pressures of coastal or gulf shore living our MGs rarely get so dogged.

I am writing this and making the entry just so that you don't begin to thnk that "yanks" are not very friendly.

Best of luck with your repair.

Jack



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j-blueridge user35940 (Disabled)
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Please post a photo if you can.

I did some work on mine in this area; the chassis leg had water lying in it and the bottom was rusting.
I bought an entire leg section and cut out a section to fit the area of rot I had cut away. I am a little worried about my welds and in fact I went over the area twice.

Not a good place to start as a beginner probably, but perhaps your friend could tack it in place and a pro could finish the job.

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NOHOME P P
O, ON, Canada   CAN
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1967 MG MGB GT "Maggie (GT From Hell)"
In reply to # 2785304 by twigworker Ed, I believe that "we" over here will have little experience with that level of repair. Even under the pressures of coastal or gulf shore living our MGs rarely get so dogged.

I am writing this and making the entry just so that you don't begin to thnk that "yanks" are not very friendly.

Best of luck with your repair.

Jack

Jack, You are back! Made my day.

To the OP...Fender does not need to be touched. The filler piece between the frame and the quarter does and the trunk floor does also. As with any job on these cars, a bit of internet research, mental preparation and patience will get the job done. To be fair, if you were paying me, I would charge about what the shop quoted. It does take time.

If you enter "MGB rear spring hanger repair" into the Google search window, you will get a bunch of hits. Hitting the imges option and going to the site will also lead you to relevant information.

Pete



Edited 1 time(s). Last edit at 2014-09-01 01:45 PM by NOHOME.

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edthebad Edward Applewhite
Princes Risborough, Bucks, UK   GBR
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In reply to # 2785304 by twigworker Ed, I believe that "we" over here will have little experience with that level of repair. Even under the pressures of coastal or gulf shore living our MGs rarely get so dogged.

I am writing this and making the entry just so that you don't begin to thnk that "yanks" are not very friendly.

Best of luck with your repair.

Jack

Thanks Jack. I'd love to know what that's like - living in a climate where rust isn't usually so much of an issue.

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edthebad Edward Applewhite
Princes Risborough, Bucks, UK   GBR
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Thanks Pete that's very helpful. My friend is insistent that we can do this and he has welded professionally - I need to take the plunge and have a "what's the worst that's going to happen" attitude. I've attached the photo to just ask whether the yellow lines are where I should be cutting in order to 'drop' the old rail. I'm a bit confused because there seem to be some spot welds on the top of the rail (show with the red crosses) is that the actual top of the repair panel or is there another fascia panel on top of that. I don't have the new panel in my possession yet because those questions might answer themselves, but in the meantime I'm trying to get as much info as possible in order to do any possible prep work.


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Chassis Rail Cutting.jpg    44.4 KB
Chassis Rail Cutting.jpg

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
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You don't need to cut the boot floor or the closing panel that attaches to the rear wing. Just drill out all the spot welds and cut the section out. It is tricky to remove the section without wrecking the surrounding panels but it can be done. I did one side on my car and the repair is invisible even without filler.

Adrian



Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


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NOHOME P P
O, ON, Canada   CAN
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1967 MG MGB GT "Maggie (GT From Hell)"
In reply to # 2787203 by pinkyponk You don't need to cut the boot floor or the closing panel that attaches to the rear wing. Just drill out all the spot welds and cut the section out. It is tricky to remove the section without wrecking the surrounding panels but it can be done. I did one side on my car and the repair is invisible even without filler.

Adrian

Adrian:

Are you saying that you did this with the trunk panel and closing panel left in place?

or are you saying:

Rather than cut the metal drill out the spotwelds to remove the closing panel and boot floor?

In my world, both the trunk and the side panel need to come out. You do so by picking spotwelds. I have marked in red dots where spotelds might be on the closing panel (Note RH side panel) The panel is NOT welded to the quarter panel.

Site that does this work http://www.mgb-rebuild.co.uk/mgb_floors-a.htm


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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
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Yes. I did this with the trunk panel and closing panel left in place. I replaced the spring hanger/chassis rail/spring mount with new Heritage pieces from Brown and Gammons. It took lots of careful drilling and grinding.

Adrian



Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


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NOHOME P P
O, ON, Canada   CAN
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1967 MG MGB GT "Maggie (GT From Hell)"
In reply to # 2787349 by pinkyponk Yes. I did this with the trunk panel and closing panel left in place. I replaced the spring hanger/chassis rail/spring mount with new Heritage pieces from Brown and Gammons. It took lots of careful drilling and grinding.

Adrian

I cant begin to picture how you would do that.

The way I do it is the two panels come off.

Start from the outside of the chassis leg: The inside closing panel comes off from the arch, the rear valence and the old box section. Drilling these spot welds is no fun. The new closing section fits in where the old came off and is located with sheet metal screws to fit over the upper hanger cross tubes. Once the new closing panel is secured, it becomes the locating piece for the new channel section

The rotted channel is marked and cut as far forward as required to get rid of the rotted bit. Use as little of the new part as you can. The joint will be stronger if the weld line for the channel is staggered from that of the closing panel. The alignment of the channel section so that your spring hanger ends up in the right position is now dictated by the closing panel that is held in place with sheet metal screws.


When you weld the new channel section on, do a but-weld bead from the outside with the heat cranked way up, then on the inside weld some flat bar across the seam to re-enforce the but weld. Replace the closing panel and spotweld in place.

Replace the trunk with old or new part. Replace closing panel with new part since I would most likely sawzall the old one out.

Drink beer.

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
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I am far too lazy (and cheap) to remove perfectly good panels to repair a rotted section. It wasn't any great feat. I'm sure it's a lot less effort than removing the entire boot floor(?!).

Adrian



Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


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edthebad Edward Applewhite
Princes Risborough, Bucks, UK   GBR
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I feel like you've laid down the gauntlet Adrian - a challenge to see how many panels we can keep intact. . I'm going to tackle this in the next couple of weeks. Can I just ask how you deal with the rear valence . I'm assuming that stays in place too and then acts as a guide for the hanger?

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
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The valance stayed in place too. The only thing I removed was the chassis rail. It was completely filled with Hemlock seeds which probably caused the need for its replacement in the first place. Pesky squirrels.

Adrian



Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


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edthebad Edward Applewhite
Princes Risborough, Bucks, UK   GBR
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Well having mulled over all the good advice I've received and feeling confident about proceeding I thought I'd just check the other side chassis rail just in case - two weeks ago my optimistic prodding made me think all was fine. Being a bit more ruthless today makes me think I'd be silly not to do the pair now. Especially as I've got to refurb all the rear suspension anyway. So my question is this. Whilst Adrian has said it's possible to do this in situ as it were, surely to do both would be so much easier if I removed the boot floor or would you guys still do one side at a time? It seems there have been repairs in a previous life because for the life of me I can't find spot welds on some panels only seams meaning I'd have to do some cutting anyway.

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trewjohn2001 John Trew
Dorset, Poole, UK   GBR
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I have a small hole in the rear of the same section - mine seems to have rusted from the rear of the valence - it hasn't reached the spring hanger. I have cut and ground out the hole and I'm just going to weld a plate over it for the moment.

It spent a few hours fighting the bumper bracket bolts - in the end I cut the whole bumper bracket off in pieces. They were seized solid - it's a big chunk of cast to try and heat.

The cause I think was my hatch and tail light fittings leaking.

What would be the best way to mark datum points for the spring hanger in the case of a complete replacement?



Edited 1 time(s). Last edit at 2014-09-08 10:44 AM by trewjohn2001.

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