MG Sports Cars

engine swaps and other performance upgrades, plus "factory" and Costello V8s

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coolmgcma
Mark Cooley

(15 posts)

Registered:
12/10/2010 04:44PM

Main British Car:


front suspension cross member
Posted by: coolmgcma
Date: February 06, 2012 09:43AM

Does anyone know if the front suspension cross member for a chrome bumper (1970) is the same as a rubber bumper car? If they are different how do you tell the difference?

Thanks Mark



Edited 1 time(s). Last edit at 02/06/2012 10:01AM by coolmgcma.


mowog1
Rick Ingram
Central Illinois
(1523 posts)

Registered:
10/17/2007 09:36PM

Main British Car:
1974.5 MGB/GT 3.9l Rover

authors avatar
Re: front suspension cross member
Posted by: mowog1
Date: February 06, 2012 10:34AM

No, it is not.

There are "risers" welded onto the rb x-member where it attaches to the car to give it the additional height that was required....sorry, no pictures to post.


coolmgcma
Mark Cooley

(15 posts)

Registered:
12/10/2010 04:44PM

Main British Car:


Re: front suspension cross member
Posted by: coolmgcma
Date: February 06, 2012 03:49PM

So if I grind off the risers then I have a chrome bumper cross member, correct?


mgbrv8
David Hetrick
McAllen Texas
(78 posts)

Registered:
03/09/2008 12:49PM

Main British Car:
MGBs- 1977,1969 Vettes-1965,1984,2003 ZO6 LS1s in MGs

authors avatar
Re: front suspension cross member
Posted by: mgbrv8
Date: February 06, 2012 08:13PM

I beleive the steering rack mounts not in the same location.

Dave


pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Re: front suspension cross member
Posted by: pspeaks
Date: February 06, 2012 11:52PM

I could be wrong about this but if you grind the risers you would probably induce more bump steering than desired and the amount of clearance between the rack and engine would be less causing the motor to be higher. Is that correct?


Paul


Moderator
Curtis Jacobson
Portland Oregon
(4526 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: front suspension cross member
Posted by: Moderator
Date: February 07, 2012 01:07AM

I wish I had more suitable photos at hand.

Here's a "chrome bumper" crossmember (viewed from the rear)... disregard all the extra holes that were cut in it to lighten it up for racing:

http://www.britishracecar.com/MikeAdams-MG-MGB/MikeAdams-MG-MGB-CY.jpg

Here's a picture of a rubber bumper crossmember (viewed from the front), courtesy of Pete Mantell... disregard the motor mounts Pete has added to suit a Ford V8 engine installation:

MGB 302 V8 KIT.JPG

As Rick mentioned, MG welded risers onto the crossmember to space the body higher relative to the suspension (to meet Federally mandated bumper height requirements).

Steering rack mounting pads are similarly spaced, but they're tilted at two different angles.


coolmgcma
Mark Cooley

(15 posts)

Registered:
12/10/2010 04:44PM

Main British Car:


Re: front suspension cross member
Posted by: coolmgcma
Date: February 07, 2012 09:00AM

Thanks guys guess I will go a different route. Mark



BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6218 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: front suspension cross member
Posted by: BlownMGB-V8
Date: February 07, 2012 12:36PM

Raising or lowering it will not affect bump steer since none of the wheel/steering angles changes. What will change is the steering rack angle, as Rick mentioned, in two aspects. It will change in rotation. This can be resolved with shims under the mount, as almost everyone who has moved the firewall cone downwards has done. The other aspect is the angle of the rack across the car. The later rack does not sit exactly horizontal. But this has a minimal effect and cannot be felt. Carl might have some valuable input here.

Also something to look for is any change in caster. I doubt you'll see that but you should check it. The use of caster wedges has been fairly common but I'm seeing less of it with the wider tires.

If it is desired to lower the rack on the crossmember, shaft collars, muffler clamps, and a 1/4" plate makes a simple and rigid mount which is adjustable for pinion angle. See the Roadmaster and 340 threads for full details.

Jim


J Man
jason adkins
NW OH
(202 posts)

Registered:
01/21/2009 08:49PM

Main British Car:
'61 Morris Minor panel, '70 MGB GT, '74 MGB GT MGB 1.8, unsure yet on the GTs

Re: front suspension cross member
Posted by: J Man
Date: February 07, 2012 07:06PM

Why not look for a earlier crossmember?


pspeaks
Paul Speaks
Dallas, Texas
(698 posts)

Registered:
07/20/2009 06:40PM

Main British Car:
1972 MGB-GT 1979 Ford 302

authors avatar
Re: front suspension cross member
Posted by: pspeaks
Date: February 08, 2012 01:17PM

Youre right Jim, If Id really put my brain in gear Id have noticed all that stuff is bolted to the cross member and changing the relationship to the frame wouldnt have an effect. I was wondering, as Ive never had my cross member off, are the bolts that attach the cross member to the frame tapered and are they different for rubber and metal bumper cars?


Paul


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6218 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: front suspension cross member
Posted by: BlownMGB-V8
Date: February 08, 2012 05:45PM

They are tapered so that they lock into the frame of the car. I'd think the RB ones would be an inch or so longer.

Jim


gstock
Gareth Stock
Hamilton, Ontario
(26 posts)

Registered:
10/12/2015 05:22PM

Main British Car:
1979 MGB Ford 5.0L

Re: front suspension cross member
Posted by: gstock
Date: July 14, 2022 03:58PM

Was it common for the bump stop mounts to be cut off the chrome bumper crossmember? I've got a used chrome bumper crossmember that I am trying to swap into a RB car and it looks like my mounting tabs are missing.
20220715_083144.jpg



Edited 1 time(s). Last edit at 07/15/2022 09:04AM by gstock.


MGBV8
Carl Floyd
Kingsport, TN
(4284 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: front suspension cross member
Posted by: MGBV8
Date: July 15, 2022 09:28AM

Never seen that. Looks like they removed both the upper & lower parts where the bump stops would fasten. Would love to know what was being done to the front suspension that required that.


gstock
Gareth Stock
Hamilton, Ontario
(26 posts)

Registered:
10/12/2015 05:22PM

Main British Car:
1979 MGB Ford 5.0L

Re: front suspension cross member
Posted by: gstock
Date: July 15, 2022 11:04AM

Thanks Carl. Looks like I've got a welding task this weekend.


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