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MG MGF Technical - MGTF Stiffening Bars
|Has anyone managed to get MG part numbers for the X-Brace fitted to the front subframe/body on the TF and the braces and brackets across the engine bay?|
I am thimking of modifying the X-Brace to go front subframe rear mount to front mount on my F but need part numbers.
The engine bay braces look like a relatively easy retro fit.
Similar X-Braces are used under the engine bay Jaguar XK and XJS series convertibles to good effect.
|Dave, getting parts full stop is a problem, getting parts for a TF would be even more a problem. I looked at a subframe stiffening kit some time ago this is relatively easy to make and fit,as I have 3 TF's in the shop to-day and ought to be working on them isstead of being here I guess, I'll look at the ones fitted and get the tape out see how much it would cost to make some as a retro fit for the F's.|
Mike , in stiff alu then please , NOT original blacksmith iron...
Regards , Carl.
|Ok Carl, one version as blacksmith/MG another version MS billet ali,LOL.|
PS anyone want the standard blacksmith version when I take it off;-)
|>PS anyone want the standard blacksmith version when I take it off|
Offer to 'official dealers'. Lack of spares currently !!! ;)
Seriously, I can't get what the front cross braces should improve at the old MGF ??
Main force is vertical to the subframe and not square from one corner to the opposite of the frame. The uprated old Cup-car subframe had strong pipes acting against this vertical forces instead the thin sheetmetal upper box profile.
Any thoughts ?
The rear is another case. The engine bay braces decrease for sure bendings of the body, cause they stiffen the upper area of the rear chassis.
Just my few bits.
|The X brace is designed to increase the torsional strength in the body. ie. reduce twisting in the front of the shell. As the front of the car, has to be an open space for fitment of the engine (only by cary over of design in the case of the F) it is weak in this area. The X brace acts as a tie bar taking forces in tension across the engine bay. |
Or at least that is my understanding. My idea is to take this across the body/subframe mount bolts, unlike the TF which takes it across the body to subframe as the subframe is solid mounted it can do this, unlike the F which is rubber mounted.
I do not intend to increase the stiffnes of the subframe.
I think steel tube would be a better material, as it would make it simple to make and cheaper. To connect to the bolts each side of the front mount will need a strong drop bracket possibly from ally.
If we have a look at the rear (engine) bracing I have a few questions.. Having an EE instead of the ME in my MSc I might be excused for not fully understand how the rear brace will function :) As seen it is NOT a true X-brace but more a V with connections at 3 ends. Knowing the strength of the wall between the engine and luggage compartment I see really no benefit from this bracing if this wall isnīt heavily re-inforced . If the bracing had been a true cross-bracing it would have been quite another story.... Help needed from mechanical engineers visiting this BBS !
Looking at the front bracing it is fully understood that this will give a lot more stabillity to the overhang that is created by the front bumper etc. This whole lot can (and will on the "F") get in resonance when riding over a railway crossing or bumpy roads.
Regards , Carl.
|I believe the point of attachment on the wall of the luggage bay is a box section so can potentially take quite a loading across into the shell. The attachment points behind the engine access hatch are also I believe part of a box section re-inforcement. The bracket used on the TF to the luggage bay wall is a fairly substantial item so must be (if they've done their sums, and they don't add cost to a vehicle for nothing) taking a substantial loading.|
my thoughts on both, the front and rear 'stiffening'. Convert the subframe in your mind into individual boxes and 'put' them together.
The rear. I'm with Dave. The upper V brace holds the rear engine panel stiffer to the security cabin.
Load gets transported in direction of the V arms. That's what I tried to say above.
Bounces to the far rear mounts of the suspension get routed through the far rear subframe mounts and inner wing panels (boot side walls to the engine bay panel).
Remember, all the force was transported to the centre of the subframe only at MGF. The TF hubs are mainly mounted to the inner front section now with the new long casting arms.
The front. Still not satisfied with explanations.
>The X brace is designed to increase the torsional strength in the body. ie. reduce twisting in the front of the shell.
A side mounted brace would, but IMO not a lower cross mounted.
The X works for shure in a front impact case, but less if bounces from below get to the subframe.
I have no CAD software, only tried to draw from memory about the front subframe look.
should show the differences between the
Standard, the Cup-car (green coloured brace), and the mgtf upgrade (red dot line)
Here the picture I took in 1999 at Spa from the cup-car brace. Welded to the SIDE of the subframe.
Though, maybe someone can explain my daubts due to the front X-brace better :)
Main ideas are based on the circumstance that the MGF and MGTF difference is a stiffer (bouncy) spring suspension with force from BELOW.
I hope this makes sense.
The material question between ally and steel, Mmmm, I would vote also for the cheapish blacksmith stuff cause it's less elastic than aluminum.
|I think that this is a very interesting project whose benefits cannot predicted without access to the CAD computers at Longbridge.|
If Mike could make up a 'prototype' MGF with these mods and finds a detectable benefit then terrific - but I wonder how much of the torsional strengthening is actually in these parts as opposed to the one-piece sills?
Mike, if you do replicate these strengthening members then I'd be very interested too (but will have to check with the scrutineers! LOL)
I'd also be very interested in this for my Trophy. A combination of this and adjustable shocks should make the car much better.
|Guys ,the extra stiffening I would incorporate would be based on feedback from the French series Trophy rally car we modified last year, this car as many of you will know is a standard production car ,modified for racing. We extensively modified subframes and mounts as Andrew Potts ,the driver , kept colliding with solid objects and bending bits!Without further study and on first observations the method of stiffening chosen by the factory would not be my first choice. |
This thread was discussed between 20/04/2002 and 22/04/2002
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