MG Sports Cars

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

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BOOTLEG
Gary Rosema
Wisconsin
(47 posts)

Registered:
11/18/2013 07:26PM

Main British Car:
1978 MGB Rover 3.5L

CB Cross member help
Posted by: BOOTLEG
Date: September 17, 2014 06:16AM

I too must lower my 78 B. Currently ~17" wheel center to chrome. Got a donor CB Xmember and cut the steering rack brackets off and bolted them to a steering rack. Installed and leveled the Xmember and car on jacks laterally. Positioned the rack w/steering rod through the motor mount and in the U-joint. Squared them using the distance from the center tube on the steering rack to the front edge of the Xmember. Made paper templates and cut 3" wide 1/8" thick flat steel into 4 bracket connectors and welded the rack mount brackets to the Xmember in the "new" position. Had fun making it and the steering rotates nicely but not sure I want it on my car because the brackets are not centered.
Comments please.
CB Xmember.jpg


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5657 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: CB Cross member help
Posted by: BlownMGB-V8
Date: September 17, 2014 06:45AM

Gary, have you considered bump steer? As you move the rack forward the steering arms should normally be lengthened by an equal amount. That's not practical for most so the rack pinion is usually shortened instead. If you have done that please disregard the above.

Jim


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1032 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: CB Cross member help
Posted by: ex-tyke
Date: September 17, 2014 09:42AM

Quote:
...because the brackets are not centered.

You'll find that if you look at the steering rack alignment on an original RB xmbr, the body is not parallel to the xmbr - the right hand mount bracket is longer than the left, leaving the rack askew - all done to allow correct shaft routing through the engine mount and up to the U-joint.


MGBV8
Carl Floyd
Kingsport, TN
(3509 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: CB Cross member help
Posted by: MGBV8
Date: September 17, 2014 10:33AM

Bolt 'er up! Let us know how it worked out. I have one laying in the garage waiting to go under my '79 B.


Moderator
Curtis Jacobson
Portland Oregon
(4404 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: CB Cross member help
Posted by: Moderator
Date: September 17, 2014 10:38AM

Why didn't you use the chrome bumper crossmember (unmodified), along with a chrome bumper rack?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5657 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: CB Cross member help
Posted by: BlownMGB-V8
Date: September 18, 2014 01:00PM

The RB has a deeper firewall cone and shorter u-joint, but still I don't think it works with the CB rack (if he has one). I think you have to lengthen it.

The RB rack has to be shortened 1-7/16", we just did this with the Chump car:
[forum.britishv8.org]

The CB rack does have a quicker steering ratio though.

Jim


MGBV8
Carl Floyd
Kingsport, TN
(3509 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: CB Cross member help
Posted by: MGBV8
Date: September 18, 2014 05:51PM

Mike Moor said he didn't shorten his. I haven't tried it yet. If the rack moves forward, though, it will be into my harmonic balancer.



BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5657 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: CB Cross member help
Posted by: BlownMGB-V8
Date: September 19, 2014 02:25AM

Might want to ask him how he did his, I've see it done a bunch of different ways. It's pretty easy to change the length, especially if you have access to a lathe. But it can be done using a snug fitting piece of tubing and a welder too. Plus it's a good opportunity to assess the condition of the rack and service it.

Jim


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1032 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: CB Cross member help
Posted by: ex-tyke
Date: September 19, 2014 09:00AM

I have another original, unmodified rack in my garage with the CB ratio (2.92:1). I ran it for a couple of years before switching back to my RB rack (3.57:1) - both racks have identical length steering shafts, so no modification required to switch racks.
I can't tell you what year it is from, but clearly the quick ratio rack is available as a direct replacement for the RB rack.


MGBV8
Carl Floyd
Kingsport, TN
(3509 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: CB Cross member help
Posted by: MGBV8
Date: September 19, 2014 10:04AM

That's interesting Graham. Wonder if it was just another transition piece?

Jim,

Mike slightly relocated the rack mounts, then it all bolted up. I may have to give it try this winter. Problem is my harmonic balance is only thousandths away from the rack now.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5657 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: CB Cross member help
Posted by: BlownMGB-V8
Date: September 19, 2014 11:30AM

Any time you have to mess with the rack mounts, the split coupler/exhaust clamp mount really is the way to go. Simple and easy to make, easy to position, adjustable side to side and in rotation. Makes aligning the rack a snap, just hook it up and clamp it down.

Jim


MGBV8
Carl Floyd
Kingsport, TN
(3509 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: CB Cross member help
Posted by: MGBV8
Date: September 19, 2014 03:59PM

Yes, I agree. That was a very slick method on the Roadmaster. In my case, though, the mount has already been modded cause I have Mike's old CB crossmember.


Capt'n Moorgone
Mike Moor
Angola,IN
(111 posts)

Registered:
11/20/2008 07:05PM

Main British Car:
1973 MGB 300 Buick

authors avatar
Re: CB Cross member help
Posted by: Capt'n Moorgone
Date: September 19, 2014 08:57PM

Gary,
There are many ways to skin a cat. As Carl said, I didn't shorten the shaft. The easy way is to leave the RB rack hooked to the steering shaft and cut the mounts off the cross member. Leave the rack hang on the car. Remove the cross member. Cut the mounts off the CB cross member leaving about half the bracket in place. Now bolt the CB cross member up. Where ever the rack and brackets land against the CB brackets, weld it together. I'm not sure, but I may have heated the steering arms on the spindle and bent them down to correct bump steer measurement. This set-up worked very well for several years before converting to Fastcars' cross member. I remember Bob Senecar, ASA champ, driving my car and saying how well it handled before I switched to Fastcars' unit. I almost backed out of the purchase. Don't regret the change. Fastcars' unit took #80 off the front end. Take your time, and you'll be happy with the results.


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