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MG MGB GT V8 Factory Originals Technical - tubular cross members

Hello all.

I have been toying with this idea myself and thought I would open it to the group at large. As many of you know I hang with the mustang crowd heavily here in the Pacific NW. One of the big things in the mustang crowd is replacing the stock crossmember with a modern, Tubular one. This is done for a few reasons.

1. Weight Savings
2. Improved clearances for engine add-ons and modifications
3. More regidity

#1 is usually the big factor, as lightening the nose of a car helps cornering and even straight line accel by letting the nose rise a touch more and transferring more weight to the rear wheels under hard acceleration..

Enough on the theory, I have started thinking more and more about getting one made for myself, as a test unit, with hopes of arranging to have them more "mass" produced and sold to the MG public at large.

My ideas are multifaceted, I would want the finished units to arrive to owners powdercoated and ready to install, no tinkering or modifying required.

Basic concept to start.

1. Single crossmember to work for Stock 4cyl, Buick V8's and Ford V8's. Being tubular it would basically be "pre notched" due to it's basic design and nature. Then it would be predrilled for the options below.

2. Removable/swappable steering rack mounts. Basically There would be 2-3 premade Rack mount brackets that are swappable. one in stock location, one droped say 1/4" and one dropped say 1/2. These would be BOLT ON brackets.

3. Removable/swappable engine mounts. None for the 4cyl as it is chassis mounted. One bracket for 215's, another for 302's. These would be made to utilize a stock motor mount for given engine if at all possible. I have found the cross memeber pads alone dampen vibration a bunch, which is why I would go for crossmemebr mounting of even the 215.

So basically, if you ordered you would pick which package you wanted, 4cyl, MGB, Rover/buick V8 or 302 V8. By doing it this way I think it will also allow quite a bit of flexibility to the purchaser. THey could later upgrade to a V8, or change motor, or change steering locations..

ANYWAY, I have no idea on pricing, but since new cross members are not available, it would probably be better than nothing.

Please get back to me, I am contacting a local professional welder about this, and would like to able to give him some ##'s to maybe get the $$ figure down..
Larry Embrey

larry would this crossmember work in the V6?
Steve

I will be honest I have no idea about he V6 installs. From what I have heard they do not require modification to the cross member, SO then yes this should fit with no issues..

This would be low slung much like a notched cross member. Again this is all prelim, but I can't think of a reason it would not fit.
Larry Embrey

I remember reading a thread on a bulletin board a few months ago about torrsional stress ripping apart a crossmember in Mustang II's. I forget where I read it, but I think I got the link from this BBS. I'm interested in the idea of a tubular crossmember that we could essentially bolt our mounts to for our motors, but I'd want to make sure it's not going to come apart at the seams. 375hp isn't unreasonable from a 302, and I'd be afraid that kind of power would rip those four bolts out of the crossmember holding it in place.

Is my fear unfounded?
Justin
Justin

Here is an example from one of the mustang sites..

http://www.lmperformance.com/images/parts/km001_1.gif

Guys, these are what the pro's use in thier road course and drag car because they are stiffer. YEs I will be asking about strength also, but rememeber our stock units are just thin (18ga) stamped steel.

From what I have been told by the mustang guys they are stiffer torsionally. and they are all using the 302, many of them 500+RWHP..

Mine should be in the 350-360 range this summer, so we will see how the stock unit handles it..
Larry Embrey

I, too, have thought about using the Mustang II front end. The question I have is whether the track of the front wheels will be widened? It won't be a problem for me as I have 2" flares, but, it could for some. I've driven an MGB with a Mustang II front end adapted to it and was very pleased with the way it handled. The guy had to use front wheel drive wheels though to get the wheel under the front wheel well even with 2" flared fenders.
Using the Mustang II set up opens the door to a wide variety of wheels, shock/spring combos and brake systems (11 to 13 in. vented), as advertised in the hot rod mags.
Bob Fish

I am not talking abotu using mustang parts. I am talking about a purpose made tubular cross member made to replace a stock MGB cross member.. These will stiffen the front end of the car and drop weight..

Larry Embrey

Larry,

It sounds like a good idea, something purpose built. I think for most people on a budget it comes down to a cost per benefit ratio. If the benefits you are talking about can be gained for a reasonable price then I think you are on a winner.

From the investigation I have done most if not all "mass produced/generally available" front and rear modified suspension systems come out of the UK. For most everyone outside the UK, due to the exchange rate, it makes the cost unreasonable.

I look forward to hearing more about it.

G
Graeme Weston

Yes outside the UK shipping makes it difficult at times. I have already had one person from the UK respond and wish to help with regulations and importing to the UK.

I have started a poll thread on the mgbconversions website.. link to the forums is here;
http://www.mgbconversions.com/forums
Larry Embrey

Larry, a very big, big project. The Mustang crossmember has rear bracing, and the front suspension is made out of struts thus directing the energy to the upper mount. The MGB has the suspension bolted to the crossmember, etc... There are several factors involved in making a tubular crossmember.
I have some drawings that I have been working on for some time now. I need to test them in the computer for flexing etc. This is not an easy task.

r/Bill
Bill Guzman

No, not an easy task at all. The stock unit is actually extremely stiff so additional stiffness really isn't needed, however a decrease in stiffness would be undesireable. I do not believe you will be able to retain equal stiffness *and* decrease weight without going to a different type of suspension, but give it a try. You may surprise me. Now getting equal stiffness and clearance for the pan of the 302 while keeping the weight *nearly* equal seems like a lot easier task.

Jim
Jim Blackwood

This thread was discussed between 25/02/2003 and 27/02/2003

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