Steering, Suspension, & Brakes

tips, technology, tools and techniques related to non-driveline mechanical components

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RobertE
Robert Edgeworth

(77 posts)

Registered:
02/19/2008 08:27AM

Main British Car:


DIY aligment / squaring rig?
Posted by: RobertE
Date: June 18, 2012 09:44PM

Not sure if this is the right section to post - if not please move it!

I have a '79 MGB - I finally got to drive it toward the end of school. Besides scaring the living hell out of me
I also realized I do not have the four corners completely square.

Early in the project I had the car at a repuatable frame shop and it was squared off. However later down the line
while lowering/installing some new parts in the rear I cut down the existing front spring perches. I believe
even though I measured a dozen times I have something slightly off - It was able to feel it accelerating and especially under hard braking(back end kicked out).

Does anyone have a DIY alignment/squaring rig they can suggest for all four wheels? I've tried measuring front wheel center
to rear wheel center on both sides - one side is dead on to spec - other isn't. Also tried just using a measuring tape but usually requires a friend and isn't dead on accurate. If anyone can recommend something or even has pictures of their rig I'd greatly appreciate it. Due to college loans trying to avoid taking it back to a shop.

Thanks for the help.


rficalora
Rob Ficalora
Willis, TX
(2675 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: DIY aligment / squaring rig?
Posted by: rficalora
Date: June 18, 2012 09:56PM

Are you sure your brake bias is set right? Sounds like the rears are locking up before the fronts. Did you change front or rear brakes?


RobertE
Robert Edgeworth

(77 posts)

Registered:
02/19/2008 08:27AM

Main British Car:


Re: DIY aligment / squaring rig?
Posted by: RobertE
Date: June 18, 2012 10:09PM

Rebuilt both ends - Thats what I thought originally after the first test drive. However I remembered that it felt slightly off taking off/under moderate acceleration(didn't get on the fun pedal much). The only other reason besides that I have to believe its the frame alignment is measurents I took(one side 'longer') - and the limited slip is always locked , leading me to believe its caused by the rear end not being sqaured up.


roverman
Art Gertz
Winchester, CA.
(3035 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: DIY aligment / squaring rig?
Posted by: roverman
Date: June 18, 2012 11:03PM

Robert, I suggest veiwing Jim Stabe's MGB build. He used a creative and easy to build alignment jig. Of course someone can follow behind your car, attempting to go straight, while checking for "crab" effect. As a crude check, you might center the front wheels, and pull a string front to rear, on both sides. Good Luck, roverman.


Moderator
Curtis Jacobson
Portland Oregon
(4465 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: DIY aligment / squaring rig?
Posted by: Moderator
Date: June 18, 2012 11:59PM

In principle, basic four wheel alignment is entirely "do-able" with four jackstands, two pieces of string, and a tape measure. Perhaps this photo (from BritishV8 2009) will help:

http://www.britishv8.org/Articles/Images-V17-2/BV8-2009-Apex-Vintage-AE.jpg
(In this case, the car's front track is narrower than its rear track, so the string is just wrapped around the rear tires... only two jackstands were needed in this case.)

For best accuracy, it's important to get the car level first. (If your floor isn't level, use shims under your tires.) Since I usually work alone, and since I can't hook a tape measure over a string without causing deflection, I find it helpful to put masking tape on the floor in a few strategic spots and then use a plumb-bob and a pen... basically getting from a 3-dimensional world to a 2-dimensional one that's easier to measure.

Actually, I don't use actual use string at all anymore. I have a nice, stiff, straight aluminum extrusion that's far handier. I have a mark on it at mid-point that I align with the holes in the MGB hub bearing covers. A longitudinal groove in the extrusion is a convenient feature - my plumb-bob's string fits neatly in it. Once I have two marks on the floor for each tire, I can measure side-to-side to get toe-in. The extrusions extend out to twice the diameter of my tires. (So by my method, a measurement of 1/8" of toe-in on the floor equates to 1/16" of toe-in on the car. Comprehend?) I can also snap a chalk line to extrapolate from one end of the car to the other, to verify that the front and rear are in alignment with each other.


Dan B
Dan Blackwood
South Charleston, WV
(973 posts)

Registered:
11/06/2007 01:55PM

Main British Car:
1966 TR4A, 1980 TR7 Multiport EFI MegaSquirt on the TR4A. Lexus V8 pl

authors avatar
Re: DIY aligment / squaring rig?
Posted by: Dan B
Date: June 19, 2012 08:55AM

If you have a chalkline you can strike a line on the floor.


Bill Young
Bill Young
Kansas City, MO
(1337 posts)

Registered:
10/23/2007 09:23AM

Main British Car:
'73 MG Midget V6 , '59 MGA I6 2.8 GM, 4.0 Jeep

authors avatar
Re: DIY aligment / squaring rig?
Posted by: Bill Young
Date: June 19, 2012 07:01PM

First thing I'd recommend is to tighten the U bolts holding the rear axle to the springs. Loose U bolts can cause the rear axle to move forwards and backwards under brakeing and acceleration resulting in some pretty dramatic torque steer. Crank them down as tight as you can with a standard 1/2 inch drive ratchet and see what it feels like then.



RobertE
Robert Edgeworth

(77 posts)

Registered:
02/19/2008 08:27AM

Main British Car:


Re: DIY aligment / squaring rig?
Posted by: RobertE
Date: June 19, 2012 08:54PM

Thank you for your replies - I greatly appreciate it.

The U-bolts are the last thing I checked and the only culprit I can think of causing the situation with
everything else considered. My procedure thus far as been to measure both sides front center line to
rear center line - One side is spot on at 91" which is what my fathers MBG measures at and also
what I've read is the correct length. One side is side is at 91" ; The other side was about 1"+ off when
I measured after the test drive. I removed the traction bars and realized bar had been "pushing" the incorrect
side back. After I removed both I was still 3/4" off. I've tried matching both rear shackle angles and boring
out the front mount to slide the spring foward - its still off. After fighting with it I took a break from it.

Hopefully its something very minor(possibly the u-bolts) I'm missing and I'll have it corrected soon.
Otherwise its back to the frame shop. Thanks again guys.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5919 posts)

Registered:
10/23/2007 12:59PM

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

authors avatar
Re: DIY aligment / squaring rig?
Posted by: BlownMGB-V8
Date: June 20, 2012 12:51AM

You can fit heavier u bolts for better clamping force. Just drill out the plates a little. Makes a big difference.

Jim


roverman
Art Gertz
Winchester, CA.
(3035 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: DIY aligment / squaring rig?
Posted by: roverman
Date: June 20, 2012 12:07PM

Robert, Both springs have same arch, length and no broken leaves ? Good Luck, roverman.


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