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MG MGB Technical - underside of mgb
| can anyone help please, i was wondering if there was anyone or website producing a diagram of the underside of a mgb showing all mechanical parts, ie sills ,castle rails, jacking points, etc, with arrows showing the different parts, ive been advised what to look for by description , but i find it easier to find by photo......regards |
| c jeffries |
| Hi C Jeffries In the photo you will see the outer cill, castle rail with a line of holes down the raised section and the jacking point at each end of the centre cross member. hope this helps Regards Pete  |
| PJ Thompson |
| i cant blow that up to full size for some reason |
| c jeffries |
| Depends what you mean by 'full size', it's only 600x450 pixels as posted here, despite being 375KB. http://www.mgb-stuff.org.uk/wn_bodyframe.htm and clicking on 'Sill Contruction and Drainage' might help. Doesn't show the outrigger under the floorpan very well but you can see the jacking tube and that is attached to the end of the outrigger. |
| P Hunt |
Here's a picture of the underside of mine with labels after I had replaced all the panels. The jacking points are missing but are round tubes that are welded onto the ends of the cross member. I have left them off as I would never use them anyway. |
| Mike Howlett |
The sill is a complex structure. There is the strong inner sill which forms the vertical part you can see on the inside of the car and the horizontal top. Then welded to that, and to the castle rail underneath, there is a vertical membrane shown here in this picture. This is completely invisible once the outer sill is put on. You can see that the sill is much more than the bit under the door. It runs from front wheel arch to rear wheel arch behind the front and rear wings. |
| Mike Howlett |
And in this picture you can see the complete outer sill which is then welded through the inner membrane to the other component parts. |
| Mike Howlett |
| Great pics, thanks guys! Splendid job PJ. What is the colour and can you give us a pic or three of the thing right side up? FRM |
| FR Millmore |
Just to make everything clear I've sketched a cross-section of the sill. |
| Mike Howlett |
| Ok FRM here's one pic took about 3 months ago, the colour is Mineral blue. Regards Pete  |
| PJ Thompson |
| Here's another almost ready!!! Pete  |
| PJ Thompson |
| One of the latest pics, Can't get the bloody thing started ( see my thread "starting problem" ) Regards Pete  |
| PJ Thompson |
| Pete,can you shoot a pic of the whole side? Would like to see how the "GAP" is where the front wing and outer rocker meet,Thanks,Rich O |
| rich osterhout |
| Pete, I don't think that I would go with that vent filter for the crankcase. It should be under a small amount of vacuum. I fear that it will coat your clean new engine and bay with a fine mist of oil. RAY |
| rjm RAY |
| Rich Whats the outer rocker??? im confused! Regards Pete |
| PJ Thompson |
| Pete,I'm refering to the section under your door(the rocker panel)Follow the door margin(hinge side of door) all the way down.I'm wanting to see the groove(seam) where the wing meets your "outer" rocker panel. It would be below the "A" Post.Hope this helps,Rich |
| rich osterhout |
| Rich Is this the area you mean? but looking square on Pete  |
| PJ Thompson |
| Pete, what we call the sills, our American friends call the rocker panels. What Rich wants to see is how the gap down the front edge of the door blends into the gap where the front wing overlaps the sill. |
| Mike Howlett |
| Shouldn't all three panels be flush where they meet, with three equal gaps? The step back in the outer sill to allow the wing to go over the top but still be flush with the area of the sill that is under the door should be under the leading edge of the door. In a perfect world. |
| P Hunt |
| A 68 should have a PCV valve. It changed to the much better carb suction for the 69 models, but your carbs don't look to have those ports. A PCV valve would be much better than your arrangement, which won't allow for any positive venting of the crankcase and scavenging of condensation and the like, which can lead to internal corrosion. You are unlikely to get any ventilation at all with that filter and the restricted and filtered oil filler cap, only pressure equalisation, and you would get that just with the oil filler cap and sealing off the port in the front tappet chest. I agree with Ray, you are likely to get oil mist coming out of that filter, that port is prone to it. |
| P Hunt |
| Pete,That is what i was speaking off......ans YES straight on.Paul,yes they are all flush(just replaced the Rocker(sill)inner,and outer(sill),however the gap(margin) seems to be a tad bit wider than i remembered.(i'm orginial owner)Mike(above)has explained what i'am after as far as the picture goes.Regards,Rich O |
| rich osterhout |
| PJ - Thanks for the pics, excellent! The colour looked different under lamps, the daylight one shows it accurately. Long time since I saw Mineral Blue & shiny - I am so tired of red cars! FRM |
| FR Millmore |
| Fletcher,How about "Bronze Yellow" :) :) |
| rich osterhout |
| RE-visit for Pete |
| rich osterhout |
| I'm looking for some comment on the strength requirements for the inner frame rail that runs from the heavy cast structure that supports the engine mounts and runs back alongside the gearbox tunnel to join the gearbox cross-member. Specifically the hollow box sheet steel structure sections that run under the floor panels about six inches outboard of the transmission tunnel. On the RH side of my '76, there is a lot of through and through corrosion of this piece, but the inner sills (rockers) are all solid. The replaced floor panel (PO) seems to be the only solid element of structure on my car. It doesn't look like this is a purchasable piece according to the catalogues, so would a home made box of sheet steel covering the affected part be an acceptable cosmetic repair or is there more to the structural integrity of the car provided by this piece than it appears? Trevor |
| TJ Whitehouse |
| Trevor,Look on page #130,part #HZA 439,and HZA 438(side member assembly) in THE ROADSTER FACTORY catalog. You can call it up online www.the-roadster-factory.com i have purchased many body structures from them,great quality. Hope this helps,Regards,Rich O |
| rich osterhout |
| Rich, That's the item except for the '76 they are HZA4966 and 4967 and they run about $360/per side and there aren't any sub-assemblies (it's the whole rail or nothing). The forward part of that rail is the heavy cast member that the engine is mounted on but when it bends down and aft of the bell housing it turns into a grafted-on sheet steel open-top channel structure. The forward parts of the rails on my car (and I would imagine almost any other car) are fine and they would probably only need replacement in the event of a front-end collision. I can't see them rusting out. And, replacing them would be a major job. The tail end of the rail, the sheet steel open top channel part doesn't seem to do a heck of a lot other than support the inner side of the floor if I understand correctly that the car's body strength comes from the sills and the castle rail. To my way of thinking it would be a very expensive repair, in way of part price and shipping that piece, when compared to the cost and effort in fabricating a steel U channel which could just be welded over top of the existing rusted area. If I'm wrong here and the piece is an essential component to the overall strength of the body then I guess I'm looking for someone who has some knowledge of the construction to tell me that and I should get on with it and replace the whole rail. For what it's worth, on my car there is no body flex, everything opens and closes as it should with no gaps or sags and the passenger side floor is solid. But every time I'm underneath I note the holes in the frame rail channel and wonder if I'm just running on the overbuilt strength of the body. Trevor |
| TJ Whitehouse |
| Trevor,Do a seperate post(thread)on here and i'm sure that Les,or Fletcher,Paul(been around MG a long time)will offer you great advice. I just dont have that kind of knowledge,Rich O |
| rich osterhout |
| Trevor - First, nothing in the frame is cast, it's all sheet metal fabrications. Secondly, the function of the frame rail extensions is to feed the suspension loads along the floor and into the sills and gearbox tunnel at the crossmember behind the gearbox. No reason at all you can't fabricate a similar piece to replace rusted bits, however: DO NOT weld it on over existing bad parts! Doing so is an invitation to disaster, since there may be serious damage (mainly to the actual joints between pieces) that you cannot see, and the sandwich that results will be not correctly attached to the surrounding structure, and it will allow additional rapid deterioration as it traps more water to eat your car. Typically, panels are mostly fine, but the welded joints between them are rusted away, necessitating repair of all panels intersecting at a joint. Cut the bad part out, as little as possible to get to sound metal, fabricate suitable bits, and weld them in so it looks just like the OE sections. FRM |
| FR Millmore |
| Trevor, To add to and second what FRM said, yes of course that part is structural, and no, none of it is cast. It is all just bent sheet metal. You can buy the entire part and cut from it what you need, or you can fabricate your own; your choice. The decision depends upon your skill, and available tools, and how much of yours is rotten. As FRM said, you need to get the rusty crap out before you weld in the new stuff. I did luck out once and had the opportunity to cut most of those parts out of a parts car so that I could weld them into mine. That may be a possibility for you, but I suspect it doesn't become available very often. PJ, I do like that mineral blue. Charley |
| C R Huff |
| Pete Your car looks great. Mineral Blue attracts much of the attention at the shows I exhibit at with my mgc roadster. It's a real credit to you, you have done a wonderful job. I see that you have had your car on a Rotisserie (Frost or CJ Autos? Both the same, only the Price is different!). Is it as easy to use as they quote, assuming that you have the correct fitting rail for your particular vehicle? Can you literally spin the bodyshell 360 degrees in the car's width? I think that my garage is a little narrower than yours, looking at the photograph. What is the width of your garage? Robert |
| Robert Lynex |
| Hi Robert Thanks for your kind comments, I love the colour and its the cars origonal colour. The chassis tilter was from CJ Auto's and is invaluable as it make's working on the car so easy, the bumper irons i made to attatch the car to the tilter was ok to spin the car easy with one hand its only when you start building the car the weight below centres starts to build and the car gets harder to turn. The car does spin in its own width but its nice to have a bit more space, my garage is 3.6 metres wide internally and 10 metres long. Regards Pete |
| PJ Thompson |
| Pete Thanks for the information on the Tilter/Rotisserie. Garage length is not a problem for me, but thanks to an intransigent neighbour, I wasn't able to build my garage to the width I would have liked. Subsequently, I ended up with a garage only 2.5 metres wide! I'm coming up to the West Midlands on Saturday (Solihull was my home town) to pick up my next project - a 79 R/B MGB GT. This will be a total restoration and, having previously restored a 67 mgb roadster and a 55 MG TF1500, I thought that a Rotisserie would save a lot of aches and pain! Thanks again for your help. Robert |
| Robert Lynex |
| Robert The tilter is well worth the money, You won't be to far away from me on Sat, if you have time your welcome to call in for a cuppa and a chat, im in Wolverhampton. Regards Pete |
| PJ Thompson |
| Pete Thanks for your kind offer of a cuppa and a chat, I might take you up on that one day, sadly, not on this occasion. Cornwall to Solihull, even without a trailer as you know, is a long enough journey (4hrs 49mins and 258 miles), but then I've got to 'rescue' an MGB GT that has been sitting on a driveway for seven years and not started for three years! The tyres are flat as pancakes (surprisingly) and rodents have eaten all the interior. Always were portly rats in Solihull!! Then it's another 258 miles back down the M5/A30 and home to bed. Thanks again for your comments on the Tilter. I might just have to invest in one, if it's as good as you say. I could always hire it out afterwards. I always say that I'm never going to do another restoration - and then do! BTW, that's my car on the front of November 2007 Issue of Classic Cars Magazine. I wasn't allowed to drive it for the photographs, though! Regards Robert  |
| Robert Lynex |
| Robert Beautiful looking car, always wanted a C and maybe ill have one in the future. Have you restored this one? I keep saying this is the last resto its the 3rd MG, dont think ill stop though its a really satisfying hobby, ive always wanted to do a moggy pickup and might be my next project. Anyway good luck with your journey. Regards Pete |
| PJ Thompson |
| Pete,how would feel about cutting out sills(rockers) when on a tilter?,thanks,Rich O |
| rich osterhout |
| Pete I bottled out of restoring an MGC. I bought this one from its second owner who had only had it for eighteen months. The First owner restored it from ground up in 1991 and it had only done 4,200 miles in fourteen years when I bought it. I just retrimmed the interior and replaced the chrome wire wheels, that had rusted by being stored in a damp garage, with replica minilites. Email me off BBS, Pete, and I will send you other photos from the Classic Cars Magazine photo shoot. Robert |
| Robert Lynex |
| Rich I think its possible with the door appertures braced, the car upside down and the transmission tunnel supported with timber on a trlley jack, this would make welding easier. having said that i hav'nt attempted this but i have done them with the car sitting on builders trestles the correct way up. Its not such a bad job to do even welding upside down. I think this is the better way as the car is better supported on the chassis legs and easier to open and close doors while alighning panels. On the tilter its supported on the bumper mounts a bit to far out for my liking. Regards Pete |
| PJ Thompson |
| Hi Robert Ive E-Mailed you Pete |
| PJ Thompson |
| Thanks Pete,I do have it on the floor,and i do have it braced.Just wondering,Thanks again,Rich O |
| rich osterhout |
This thread was discussed between 03/01/2010 and 22/01/2010
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