Steering, Suspension, & Brakes

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MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: August 29, 2023 04:25PM

A post over on that other forum has sent me down the rabbit hole today.

Using coil springs in the rear of an MGB is something I have pondered over the years. I vaguely recall the MGB designers tried coil springs, but they did not like the handling. What did they use to retain the rearend laterally? Maybe that was the reason.

Anyway, I believe it to be do-able.

MGB Body Shell Botton Rear.jpg
Coil Spring Location 2.jpg
Coil Spring Trailing Arm Panhard Rod.jpeg
Coil Spring Rear Suspension.jpg



Edited 1 time(s). Last edit at 08/29/2023 04:26PM by MGBV8.


mgb260
Jim Nichols
Sequim,WA
(2463 posts)

Registered:
02/29/2008 08:29PM

Main British Car:
1973 MGB roadster 260 Ford V8

Re: Rear Suspension - Coil Spring not Coilover
Posted by: mgb260
Date: August 29, 2023 05:42PM

Fox Mustang is similar but 2 upper links for triangulated 4 bar. A lot of Cobra kit cars use it. some have done away with the coil springs and went with coilovers where the shocks are. Only with stronger mounts. Probably for the cool look.



Edited 1 time(s). Last edit at 08/29/2023 05:42PM by mgb260.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

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Re: Rear Suspension - Coil Spring not Coilover
Posted by: BlownMGB-V8
Date: August 29, 2023 06:06PM

The rate of the springs will need to be calculated based on the position on the LCA. MGB front springs are rated for about 200% of the corner load due to the 50% lever arm reduction. So travel is also about 50% of spindle travel. Exact numbers would require exact measurements.

So, there is no reason why you couldn't use full size coil over springs. I think it might be better than using the 2" ones we've been seeing and there should be plenty of room for them.

Ideally the spring seat would be in line with the two pivots, at the body and at the axle for even loading. That would determine the top spring seat location. I think that puts it in line with the frame rail though and I'm not sure there is enough vertical space there. The spring could also be angled forwards but that raises the spring rate.

Jim


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: August 29, 2023 06:20PM

In the past, I have read about the Mustang triangulated uppers causing bind. May not be an issue when not very much travel.


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: August 29, 2023 06:29PM

Yeah, no room for the spring on top of the axle. Plenty for full size coil spring forward of it. I have seen that on production cars and NASCAR.


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: August 29, 2023 06:30PM

Trailing Arms.jpg


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: BlownMGB-V8
Date: August 30, 2023 07:46AM

Might use a lower link similar to some of the traction links being used, if needed a drop section for the spring seat, then either triangulated upper links like in the CCE 4 link kit or a single top link and a whatchacallit for sideways. Shock might have to be behind the axle.

Jim



MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: August 30, 2023 10:30AM

Track bars are not ideal for an MGB, but offset coil springs (adjustable, even) in conjunction with a 3-link & panhard rod, just may be.

Adjustable Coil Spring.jpg


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: BlownMGB-V8
Date: August 30, 2023 04:14PM

I really like the adjuster idea. Looking forward to seeing someone take off and run with the concept. It's too good not to get done.

Jim


ag1234
Arthur Gertz

(66 posts)

Registered:
03/29/2023 08:26PM

Main British Car:


Re: Rear Suspension - Coil Spring not Coilover
Posted by: ag1234
Date: September 03, 2023 12:10PM

Coil-overs, proportunately are pretty high. Personally, I don't like the lateral arch of a panhard bar, especially with tight tire clearance.. A watts link has better properties but is more complicated. "What if", the outer ends drove a torsion bar ? No coils needed. Might fit better in tight constraints.
Art.


ag1234
Arthur Gertz

(66 posts)

Registered:
03/29/2023 08:26PM

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Re: Rear Suspension - Coil Spring not Coilover
Posted by: ag1234
Date: September 03, 2023 12:14PM

Wait ! What if torsion bard was splined or hex, you could tune the springrate.


88v8
Ivor Duarte
Gloucestershire UK
(1041 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: Rear Suspension - Coil Spring not Coilover
Posted by: 88v8
Date: September 04, 2023 05:26AM

Mmm, doesn't the bar itself define the rate, the hex just raises or lowers the susp?


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: September 04, 2023 09:42AM

Yes.


waterbucket
Philip Waterman
England
(112 posts)

Registered:
07/30/2011 01:08PM

Main British Car:
1972 MGB GT

Re: Rear Suspension - Coil Spring not Coilover
Posted by: waterbucket
Date: October 15, 2023 05:10AM

Carl
"MG was aware of the ride issue long before the first MGB was even built. According to an interview of MGB designer Don Hayter (which I found in Ken Smith's excellent little book "Aspects of Abingdon" as published by MG World, copyright 2006), the very first MGB prototype was fitted with a trailing arm and coil spring rear suspension that included a Panhard rod for side-to-side axle location. A similar suspension had been installed on MGA developmental vehicles. The factory engineers preferred coil spring suspension over leaf springs to achieve a smoother ride. Ultimately though, MG engineers were unable to overcome a slight steering effect caused by fitting a too-short Panhard rod".

This is copied from [www.britishv8.org]


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6470 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: BlownMGB-V8
Date: October 15, 2023 11:28AM

Seems they could have used a Watts linkage...

Jim



MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: October 16, 2023 10:15AM

I read an article about that long ago, Philip. That is a good part of what had me pondering this approach. It is also why my panhard rod is 35-36 inches long. :)


MGBV8
Carl Floyd
Kingsport, TN
(4512 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: Rear Suspension - Coil Spring not Coilover
Posted by: MGBV8
Date: October 16, 2023 10:59AM

The Watts was part of the plan, Jim. They went with the cheaper panhard rod that doomed the 4 link.

"Enever and chassis engineer Terry Mitchell explored a variety of alternative suspension layouts in hopes of smoothing out the ADO23ís ride without sacrificing handling. The ideal solution would have been to reduce the rear unsprung weight with either independent rear suspension or a De Dion axle like that of the EX181, but cost considerations precluded either. As a compromise, Roy Brocklehurst, who had designed the original MGA chassis, came up with a four-link design that traded semi-elliptical leaf springs for coils, locating the axle with four trailing arms and a Wattís linkage, later exchanged for a cheaper Panhard rod. The new suspension provided a much better ride, but the Panhard rod mounting caused structural problems and erratic handling.

Given time, those problems could undoubtedly have been resolved, but with the project already running well behind schedule, Brocklehurst and Mitchell decided to retain Hotchkiss drive. The production carís sole concessions to improved ride quality were redesigned spring shackles and longer (and thus softer) leaf springs, the addition of which required the tail to be stretched about an inch (25 mm)."


[ateupwithmotor.com]


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