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*** HELP*** MGTF Rear Subframe Fitting 
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Part built GTM

Joined: Sun Oct 15, 2017 7:44 am
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Location: Glasgow
GTM: K3
Post *** HELP*** MGTF Rear Subframe Fitting
Having changed over the front subframe to MGTF, to allow me to use campers and coils springs, I have turned my attention to the rear and one issue I am having is that I want to fit the whole TF set up but cannot get under the K3 to see if the compliance mounts for the trailing arms clear the tub when the subframe is mounted; therefore, has anyone done this mod without cutting the tub, or give me pointers how to get it all in without fibreglass surgery?

Looking at others build photos, it looks tight but I live in hope that I can be done, as I don’t want to have a hybrid of TF/F/Metro parts for ease of maintenance and most importantly, I have a decent handbrake from the TF. :lol:

One other potential problems I face is fixing the 2 torque tubes to the TF subframe and again, if anyone has done this previously, pointers and tips would be appreciated.


J.


Sat Mar 31, 2018 8:47 am
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Part built GTM

Joined: Sun Oct 15, 2017 7:44 am
Posts: 86
Location: Glasgow
GTM: K3
Post Re: *** HELP*** MGTF Rear Subframe Fitting
Well, things are not looking good.

After a few hours of thinking, looking and prodding, I have came to the conclusion that the TF frame with the standard MG suspension with trailing arms WILL NOT fit a K3 for one simple fact that I overlooked..............

To fit the TF frame, you have to cut the front end body mount bracket off, to utilise the holes equivalent to the Metro set up and when you fit the 2 hole front mounts into the ‘new’ holes, the bracket fouls the trailing arm compliance bush :oops: :evil: :twisted:

How the feck did I miss that when stripping it?

Image

Soooooooo, I don’t need to worry about tub clearance, because it just won’t work!!!!


Back to the drawing board, as the options now are;

* Use the existing, manky Metro frame with individualised hydragas spheres and keep the sh!tty GTM handbrake
* as above, but use PEEPS, fantastic coil over mount brackets
* Use the MGF front subframe that I have with individualised hydragas spheres and keep the sh!tty GTM handbrake
* as above, but use PEEPS, fantastic coil over mount brackets
* Use the TF frame, but with MGF front hubs, arms etc and keep the sh!tty GTM handbrake
* Buy a MGF rear subframe and use with individualised hydragas spheres, keeping hubs, etc as I really want a proper handbrake
* as above, but use PEEPS, fantastic coil over mount brackets

My brain hurts, I’m pi$$ed off royally and fell like scrapping the bloody thing :cry:



J.


Sat Mar 31, 2018 4:52 pm
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Part built GTM

Joined: Sun Oct 15, 2017 7:44 am
Posts: 86
Location: Glasgow
GTM: K3
Post Re: *** HELP*** MGTF Rear Subframe Fitting
Well, after weeks and weeks of trying, I cannot get the TF frame to fit due to the torque tube location requirement, as there is either fouling of the spring/damper assembly, or if relocated up slightly the stress on the subframe completely changes and would be liable to crush/collapse; therefore, I have decided to go back to the MGF set up, which I have and use PEEPS fantastic brackets with GAZ shocks.

Unless major surgery is done to the tub, then fitting the TF set up is not possible :(


Tue Jun 05, 2018 3:23 pm
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Post Re: *** HELP*** MGTF Rear Subframe Fitting
From the previous post where you showed the basic subframe in place it looked like you were so close.
Its a shame it wont fit. Looking at the torque tubes and how they are placed I would be interested to see how much they are actually doing to stiffen the assembly.
I can see they are sitting in what looks to be a triangulation back to the body, however at the dimentions of the tube and the body thickness where they attach I think they may have been designed to look right rather than designed with real data.

So here is my radical sugestion before you completely ditch the idea.
Measure the body mount to frame dimention
Put the car down on its wheels without the torque tubes fitted. Measure again. I would imagine that there should be some flex. Add some weight to the car and measure again. Once more I would expect flex.
You will now have an idea of how much extra support is really needed. It may not be as much as you imagine.
Now put the car back off its wheels and fit a brace between the bulkhead and the subfame suspension turrets. I would use a lump of wood for quickness.
Repeat the proccess of measurements. I suspect that as long as the brace has a little bit of a slope to the back of the car it will be plenty to stop the flex.


Wed Jun 06, 2018 9:22 pm
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Part built GTM

Joined: Sun Oct 15, 2017 7:44 am
Posts: 86
Location: Glasgow
GTM: K3
Post Re: *** HELP*** MGTF Rear Subframe Fitting
techead wrote:
From the previous post where you showed the basic subframe in place it looked like you were so close.
Its a shame it wont fit. Looking at the torque tubes and how they are placed I would be interested to see how much they are actually doing to stiffen the assembly.
I can see they are sitting in what looks to be a triangulation back to the body, however at the dimentions of the tube and the body thickness where they attach I think they may have been designed to look right rather than designed with real data.

So here is my radical sugestion before you completely ditch the idea.
Measure the body mount to frame dimention
Put the car down on its wheels without the torque tubes fitted. Measure again. I would imagine that there should be some flex. Add some weight to the car and measure again. Once more I would expect flex.
You will now have an idea of how much extra support is really needed. It may not be as much as you imagine.
Now put the car back off its wheels and fit a brace between the bulkhead and the subfame suspension turrets. I would use a lump of wood for quickness.
Repeat the proccess of measurements. I suspect that as long as the brace has a little bit of a slope to the back of the car it will be plenty to stop the flex.


I had shown the photos and a sketch with measurements to a friend who is a structural engineer and he advised that the angles set by GTM were taking the load to the bulkhead correctly and any slight deviation may result in collapse under driving load - I did remove the torque tubes when the Metro frame and engine were fitted and stood inside the tub and there was noticeable flex, with strain on the front subframe mounts that could potentially burst the GRP areas around them.

The torque tubes could have been fitted 100mm higher up, welded to the strut towers but the deflection loading was the risk, again as advised by my friend and the only other option was to make a strengthened strut tower with a lower skirt but the loadings would be on a point and not spread across the structure, so I discounted that too.

The other option was to make an offset torque tube and bolt it to the subframe where the rear engine/gearbox mounts are, but there was fouling on both when I made a template using flexi pipe, so that was discounted too.

There is a member on here that has fitted a TF frame, but it is tied into a custom internal roll cage for racing, and I don’t want a cage for road use.


On a more positive note, my low mileage subframe with engine etc finally arrived today and hopefully I can get on with fitting that over the next few weekends, work commitments permitting.


J


Wed Jun 06, 2018 10:21 pm
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Post Re: *** HELP*** MGTF Rear Subframe Fitting
jaybee wrote:
....... and keep the sh!tty GTM handbrake



J.


It's a long while ago, the club magazine had an article on fitting Rover 620/820 (can't remember which) calipers which stopped My MOT station moaning (alternated with "You are joking"). GTM (Peter & Paddy era) also did a kit that allowed Rover 420 calipers

If you are forced to keep the existing sub frame the hand brake is fixable

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Malcolm
GTM O/C Member 754.


Sun Jun 17, 2018 6:45 pm
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Part built GTM

Joined: Sun Oct 15, 2017 7:44 am
Posts: 86
Location: Glasgow
GTM: K3
Post Re: *** HELP*** MGTF Rear Subframe Fitting
Malcolm_Ball wrote:
jaybee wrote:
....... and keep the sh!tty GTM handbrake



J.


It's a long while ago, the club magazine had an article on fitting Rover 620/820 (can't remember which) calipers which stopped My MOT station moaning (alternated with "You are joking"). GTM (Peter & Paddy era) also did a kit that allowed Rover 420 calipers

If you are forced to keep the existing sub frame the hand brake is fixable



Malcolm.

Due to the condition of the Metro subframe, which was totally rusted and every bolt corroded or siezed solid, I decided to go the TF route, due to wanting to get rid of the hydragas system and have a proper handbrake; therefore, due to the issues in trying to install the aforementioned, I will now fit a full MGF subframe, engine, PG1 gearbox and all ancillaries, allied to PEEPS coils over brackets all round with GAZ shocks and Faulkner 8" 375lbs springs on the rear.

The front will still be TF for the time-being, given how much I have spend on it and will fit a pair of Faulkner 6" or 7" 250lbs springs onto the standard TF soft ride dampers - I still have a full MGF front set up that I can fit. using PEEPS coils over brackets all round with GAZ shocks again and 8" Faulkner 8" 250lbs springs if I decide that that is better for balance and handling.


J


Mon Jun 18, 2018 11:18 am
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