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Senior Contributor
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I was also busy through the weekend. I used old central support bracket, cut-off its support legs and made temporary legs to determine their exact location for proper lift of the bracket. It turned that they should be relocated approx. 0.5” lower than original legs. That lifted the bracket to the top of the tunnel. I also welded nut at the bottom which allowed me to adjust the height of the polyurethane bumper that arrived from McMaster.

The result was good. Just by lifting the central support bracket, I got 3 degrees angle of the torque tube (it was 0 before). There was actually no need to further lift t/t with the adjustable bumper, so I set it to just support the t/t. That gave me very satisfactory U-joints angle of 1 degree front (it was 4.5 before modification) and 2 degrees rear (it was 6.5). I will now proceed with the final modification of central bracket, similar to RB’s modification shown few posts earlier.

This modification should be beneficial to any lowered GT and it is really not that much of a work.
So on the installed one you cut off the support tabs and welded them back on 1/2" lower to push the whole bracket up into the tunnel? I also assume there is a lock nut somewhere to keep the new poly bumper up in place.
 

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Opeler
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I experimented with discarded bracket, so I made legs of 1/8 flat steel and bolted them on the bracket as I had to reposition them few times to find the right height.
I will now use good bracket and reposition (weld) its legs 0.5" lower. I am considering to possibly weld them even 3/4" lower and use washers to regulate its position.
Busy this week but will post when done.
 

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Opeler
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Here is the final version of modified central support. It was more difficult to modify it than Manta/Ascona support but this is nature of the GT. It involved a lot of welding and reinforcing.
Legs have been lowered almost 1" which is more than the support can go up before hitting the top of the tunnel but it leaves an option to insert washers between central support and the car floor. By using different thickness of washers, the tube angle can be fine tuned. I replaced M10 bolts with studs as it makes installation way easier. I also trimmed the protruding part of top bumper to create more space for lifting the central support.
 

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Pedal Smasher
1973 Opel GT
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How is the (stock) carrier attached to the (stock) support beam? Is it welded together in a few spots? A continuous weld? Awesome looking end result.
 

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GT Owner
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Attached legs

Here is the final version of modified central support. It was more difficult to modify it than Manta/Ascona support but this is nature of the GT. It involved a lot of welding and reinforcing.
Legs have been lowered almost 1" which is more than the support can go up before hitting the top of the tunnel but it leaves an option to insert washers between central support and the car floor. By using different thickness of washers, the tube angle can be fine tuned. I replaced M10 bolts with studs as it makes installation way easier. I also trimmed the protruding part of top bumper to create more space for lifting the central support.

Wonder if using washers to shim the angle to floorboard might also assist in tuning the degrees. Do they even sale washers thicker on one side or would they have to be made ?
I am going to copy this someday :)
 

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Pedal Smasher
1973 Opel GT
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2,613 Posts
While it would take a lot of work initially, I think it would be better to create temporary pieces to mock up the desired end product. Then, once you know the exactly dimensions of everything, modify the rear axle support. That is why I asked how the carrier is connected to the support beam, spot welds or continuous? If you could grind away the welds and separate the two parts, you could easily modify it. Maybe even just weld in a strip of steel between the carrier and the support beam. In the attached photo, can you separate the part where the green line is?
 

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Discussion Starter · #69 ·
It is continuos weld. I also added some gussets on both sides.
My MIG welds are not nearly as pretty as RBs but they will hold well.
PJ, have you had a chance to road test this yet? Just wondering how it drives…
 

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Opeler
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PJ, have you had a chance to road test this yet? Just wondering how it drives…
Yes, I drove the car last Saturday to Orangeville ON, some 200 miles round trip. While I did not have major vibration before, the car was noticeably smoother after modification.
I am pleased with the outcome, thank you for the guide to Spicer Driveline Angle Calculator. It is great tool.
 

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Discussion Starter · #71 ·
Great to know! I might make that a project of my own once I finish up the current one of putting an AW4 transmission into my Javelin.
 
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