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B GT Suspension

Posted by TomBrooksuk 
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Tom Brooks
Leicester, Leicestershire, United Kingdom   gbr
As promised (quite awhile ago!) here are some pics of the coil over suspension for the BGT. We are working on fitting the rear suspension today, the front is all but complete.

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Tom Brooks
Leicester, Leicestershire, United Kingdom   gbr
A few more....
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TomBrooksuk Avatar
Tom Brooks
Leicester, Leicestershire, United Kingdom   gbr
Right back to work re-fitting the gearbox and prop shaft!

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Andrew Metford
Perth, Australia   aus
1966 MG MGB
1973 MG MGB GT
1974 MG MGB GT
Where did you get all that from?? Never seen anything like it. You running a 3 link rear, with leaf springs as well?
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Fred McConnell
Hollidaysburg, Pennsylvania, USA   usa
1992 Mazda Miata NA "MAC"
I recognize that blue and satin black. Beautiful stuff!



2012 SCCA FP MARRS Champion

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Joe Phillips
Bristol, United Kingdom   gbr
Looking good Tom.

Where does the top of the coilover unit on the rear suspension fix on the chassis?
Joe Phillips
Bristol, United Kingdom   gbr
The rear suspension design looks very similar to the Colin Chapman Lotus 7/Lotus Cortina design but with more bracing on the rear axle to prevent the diff casing from flexing under load.

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Hap Waldrop
Greenville, SC, USA   usa
1967 MG MGB "The Biscuit"
Tom, I'd be interested to seeing the rear supsension photos when you get all the links hooked up. I worked on a couple of cars with the wishbones, both Spridgets, both use the original drain plug area of the rear housing for the rear attachment point of the wishbone, one of the Spridgets I worked on the person who did the fab work, made no alternate diff drain, so that was huge PITA, I see Dave had added a alternate diff drain plug thumbs up



Hap Waldrop
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Dave Headley
Cortez, 4 corners, Colorado, USA   usa
Hap, I learned the hard way that attaching the rear of the A-frame through the banjo drain plug will quickly lead to housing cracks. The way this is done is to bridge the side loads out to the tubes via the structure you see here.smileys with beer
Fast-MG.com Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
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Paul Gaylo
Corning, NY, USA   usa
Fascinating. What is the prevailing wisdom on wishbone, triangulated type rear suspension? I thought there were issues with this. However, looking at this it seems like a super simple good idea. Lightweight, simple with the benefit of having the roll center really low.

The suspension is like a 3-link minus a lateral control device. Instead the middle link serves as the lateral control. Articulation should be fine without bind. I would like to know where the upper links attach to the chassis.
bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can
In reply to # 1966834 by JP12 The rear suspension design looks very similar to the Colin Chapman Lotus 7/Lotus Cortina design but with more bracing on the rear axle to prevent the diff casing from flexing under load.

That was exactly my reaction. Lotus found that the A frame tended to fail. The switched to semi-elliptics and traction arms in the Mk 2 Lotus to fix it. Hope this application on the MG does better.

When I designed my MGA rear suspension, I purposely avoided an A arm for location and opted for lower traction arms, one upper locating arm and sliding spring plates a la Huffaker.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC


TomBrooksuk Avatar
Tom Brooks
Leicester, Leicestershire, United Kingdom   gbr
Two final pics of the day,

I will post some pics of the upper links when they are finally attached, we need to set the axle in the car at its final height relative to the body prior to deciding exactly where the upper arm slots will go to ensure we have a reasonable amount of adjustment on the angle of the upper arms.

The body of the car is set on blocks in the final two pics at its approximate final ride height (dictated by the front suspension)

As for the rear coil overs they will be mounted as part of the rear roll cage within tower structures, these will allow vertical adjustment. pics to follow.

Tom
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Dave Headley
Cortez, 4 corners, Colorado, USA   usa
Paul and Bill, the lower A-frame has proven it's mettle in several other race cars that I've done. One key is that it is triangulated for stiffness and made with 1 1/4" OD, .125" wall tubes. The rear Heim joint is 3/4" shank, 5/8" eye attached to the axle in double shear.

Low roll center and simplicity are the big advantages. Upper links are angled(side view) to control roll steer.
Fast-MG.com Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can
Yeah - IIRC the weak point on the Lotus was the attachement at the diff. The pictures above show a damned skookum attachment point on the MGB, so it should hold up pretty well.



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC


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Dave Headley
Cortez, 4 corners, Colorado, USA   usa
Skookum???confused smiley
Fast-MG.com Dave Headley, dba FAB-TEK offers full service race car parts and preperation for MGB & MGA race cars, SCCA and Vintage. Dave is a mechanical engineer and has raced MGBs since 1963.
bills Avatar
Bill Spohn
W. Vancouver, BC, Canada   can
In reply to # 1967173 by fast-MG.com Skookum???confused smiley

Sorry, used local term without thinking.

SKOOKUM



Bill Spohn www.rhodo.citymax.com/carstuff.html
1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe
1969 MGC roadster, 1957 Jamaican MGA
1965 Jensen CV8, 1971 Jensen Interceptor
1969 Lamborghini Islero S, 1988 Fiero GT turbo
2009 Pontiac Solstice GXP Coupe
West Vancouver BC
chormy Avatar
Shaun Holmes
Norwich, Norfolk, United Kingdom   gbr
1963 MG MGB MkI "3330 PE"
1968 MG MGC "Crosby"
1969 MG MGC GTS "Yippee"
2005 Land Rover Range Rover
Maaybe I should go buy another shell, LS3 and join the thunder sports guys.

Awesome job Tom, hurry up Snetterton 26h feb has a few places left !!
Holmes Racing   – Norwich United Kingdom MGC & B racing, incorporating MGCspares from a good used or rare part to remanufactured items to keep your C as you would like it. See you at MGLive 2013.
Speedracer Avatar
Hap Waldrop
Greenville, SC, USA   usa
1967 MG MGB "The Biscuit"
In reply to # 1966916 by fast-MG.com Hap, I learned the hard way that attaching the rear of the A-frame through the banjo drain plug will quickly lead to housing cracks. The way this is done is to bridge the side loads out to the tubes via the structure you see here.smileys with beer

Yep, thats probably a good idea, both the wishbone Spridget I worked with, actually now that I think of it, one of the Spridgets was not wishbone, the Huffaker Bugeye used a horitzontal watts link and that was it pivot attachment point, both had large, thick steel bungs welded into the diff housing in that location, and the Huffaker car had some bracing added to the rear housing as well.



Hap Waldrop
MGexperience Supporting Vendor
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TomBrooksuk Avatar
Tom Brooks
Leicester, Leicestershire, United Kingdom   gbr
Thanks everyone for the positive comments

Without the help an advice from so many people on this forum the car would be nothing like it is today so thanks again

Speedracer Avatar
Hap Waldrop
Greenville, SC, USA   usa
1967 MG MGB "The Biscuit"
In reply to # 1967785 by TomBrooksuk Thanks everyone for the positive comments

Without the help an advice from so many people on this forum the car would be nothing like it is today so thanks again

Thanks for sharing your progress with us, keep it coming Tom thumbs up



Hap Waldrop
MGexperience Supporting Vendor
Make Sure to check our promotions/product offerings in the Vendor Deals Forum here.
Acme Speed Shop   – Greenville, SC USA VTO Wheels 866-855-3473 Acme Speed Shop (864) 370-3000

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