MGB & GT Forum

Please Sign In or Register to Search

Wheel alignment ?

Posted by Fusion 
Fusion Avatar
Luke Ogier
Auckland City, North Island, New Zealand   nzl
1970 Vespa PX 200
1976 MG MGB GT "Jock"
1997 Lotus Super Seven "SUB"

How many degrees is one full rotation of the rod end on the rack ?(RB) if that makes a difference.

dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

"How many degrees is one full rotation of the rod end on the rack?"

It is not degrees, it is inches. Adjusting the rod end (tie rod end) in or out changes the "toe" setting. The toe is measured in inches, and is the difference between front-to-front and rear-to-rear of the front tires.

The MGB front tires were pointed inward (Toe-in) 1/16" to 3/32" when static/motionless. When rolling the friction of the tires against the road compresses the suspension bushings slightly rearward and the tires become parallel.

Measure the distance between two adjacent threads and that dimension will be the increase/decrease of the toe.



Be safe out there.
Kenny

mark21742 Avatar
mark melton
mercersburg, Pennsylvania, USA   usa

I started tie straping a 4 foot straight edge to each gront tire from the back edge of the tire pointing forward padt tje front end to do my measuring and it really makes a lot easier job to get it right quick. Measure the difference of right in front of the tires to the leading edge of the strait edge.

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info
rrmgb Avatar
robert schau
Reston, VA., USA   usa
1973 MG MGB
1973 MG MGB

Yeah, the toe can be measured in degrees. I believe the norm is measured at 10' of scuff/mi for 1/16".
My head spins thinking about doing it that way. confused smiley
That being said, if you were to turn one side one full turn, your steering wheel would be about 12 degrees (2 minutes of arc) off depending on whether you turn it CW or CCW.
As others said, for DIY, measuring toe in inches is easier. I'll estimate one full turn to be 1/8". You could also count the threads traveled on the rod, do the math vs. threads per inch.
I'm getting dizzy.



"It is a mistake to try to look too far ahead. The chain of destiny can only be grasped one link at a time."
Sir Winston Churchill
---------------------------------------------------------------
"It all starts in your mind's eye, then it goes to your heart
and finally to your very soul."
G.S.George PHD



Edited 1 time(s). Last edit at 2013-10-28 12:13 PM by rrmgb.

Fusion Avatar
Luke Ogier
Auckland City, North Island, New Zealand   nzl
1970 Vespa PX 200
1976 MG MGB GT "Jock"
1997 Lotus Super Seven "SUB"

Thanks to those who tried to answer the question.

All wheel alignment is measured in "Degrees" because "toe" and "camber" and "caster" are all angles.


I crawled under the car with a ruler and TP gauge to get a rough starting point.

The steering arm is approximately 150 mm between centers. The rod end thread is approximately 1.5mm TP ( thread pitch)
Using the online calculator (cant find my SINE tables)

1 full rotation of 1 rod end = .57 degrees. So 1 turn in on each end will add approximately 1 degree of toe in.

Once I get it up off the ground I will check the steering arm length and TP more accurately unless some one has one on the bench?



Edited 1 time(s). Last edit at 2013-10-28 07:54 PM by Fusion.

ohlord Avatar
Rob C
North of Seattle, N.W., USA   usa
1971 MG MGB "Bedouin 2"

Without the aid of adjustable bushes or refigured arms Caster and camber are fixed and non adjustable.
Toe is measured in inches. The specs are in the manual for CB models and the RBB modelseye popping smiley



"You take off the roof and the top is the height of the nearest Star"

joron Avatar
Michel Joron
Roxboro, Quebec, Canada   can
1977 MG MGB "Victoria"

About 1/16 of inch to 3/32 of inch toe-in, measure at the wheel rim. According to section J.1 page 227.

1 turn is 1/24" 24 threads per inch on the tie-rod.

Personally I inflate both tires at exactly at 28.5 psi in front
normally I have 26.5 in front and 25.0 in the back.
I use the position about 8 o'clock for the rear versus 4 o'clock for the font. (More or less just slightly lower then exhaust pipe.)
I measure the distance on the rear I mark that position with a chalk on the tire
than I roll the car to measure the front around that point when it gets to about 4 o'clock.



1977 MGB Red 'Victoria'
All Classics:
Married, 2 children, 1 dog, MG MGB Summer, Jeep TJ Winter

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info
dipstick Avatar
Kenny Snyder
La Center, Washington, USA   usa

Luke, "All wheel alignment is measured in "Degrees" because "toe" and "camber" and "caster" are all angles."

No/wrong. Toe is measured in inches as referenced above in the factory manuals; read them. The pic is from the MGB F/P race car initial wheel alignment evaluation on the 4-wheel laser alignment rack at Warren Secord Tires in Kent, WA. Please note that the toe is measured in inches, not degrees.

It is easy to lay a calibrated bubble level device vertically across the rim and measure the camber in degrees. Please explain what sort of device will measure toe in degrees, the result has to be measurable on an alignment rack corresponding the unit measurements provided by the factory.



Be safe out there.
Kenny


Attachments:
Toe measurement.png    101.6 KB
Toe measurement.png

barry s Avatar
barry stoll
alexandria, VA, USA   usa
1972 MG MGB GT
1974 MG MGB
1980 MG MGB

Math aside, 'toe' can be measured easily and accurately using a cheap 'spring' curtain rod. (a couple of bucks at WalMart or Kmart). Unscrew the rod to a distance slightly larger than the width between the tire sidewall or rim. (I prefer sidewall) Compress the rod and insert between the wheels parallel to the floor. Roll the car to bring the rod to about 3 oclock, at the front. Make a mark on the rod where the inner and outer rods meet. Now roll the car forward until the rod is just below the oil pan, around 8 oclock. Again mark at the slip joint. The space between the 2 marks is the toe (in or out). Adjust to achieve 1/16" to 3/32".

Rod H. Avatar
Amity, Oregon, USA   usa
1964 MG MGB
1968 MG MGB GT

In reply to # 2507710 by barry s Math aside, 'toe' can be measured easily and accurately using a cheap 'spring' curtain rod. (a couple of bucks at WalMart or Kmart). Unscrew the rod to a distance slightly larger than the width between the tire sidewall or rim. (I prefer sidewall) Compress the rod and insert between the wheels parallel to the floor. Roll the car to bring the rod to about 3 oclock, at the front. Make a mark on the rod where the inner and outer rods meet. Now roll the car forward until the rod is just below the oil pan, around 8 oclock. Again mark at the slip joint. The space between the 2 marks is the toe (in or out). Adjust to achieve 1/16" to 3/32".

The alignment tool I have had for almost 40 years operates on this same principle, except it has some refinements, like a gauge, offset ends (so the tires can be moved 180 degrees), points where the ends contact the sidewalls, and a few other features. It's served me well, and saved me perhaps $1000 on alignments. I think it cost about $12 in the mid 70s!



I can't understand why people are frightened of new ideas. I'm frightened of the old ones. John Cage

'63 MGB
'68 MGBGT
'80 VW Vanagon Kombi
'09 Mazda 3 with 5 speed manual

Dave Braun Avatar
Minnesota, USA   usa
1952 MG TD "Tommy"
1970 MG MGB "Maggie"
1974 Triumph Spitfire 1500 "Sammy"

Interesting ways to set toe!

I place a piece of masking tape on each tread and make a thin mark with a pen on each. I roll the car a couple of revolutions forward and measure the distance just below the oil pan. Then, I roll the car forward and measure in front of the tires at the same height as the rear measurement. And then adjust. Since the tie rods are at a different radius than the treads, counting threads doesn't work, as there is a lever ratio involved.

A couple of things I keep in mind, since I'm measuring at the tire, as compared to the inside rim, and slightly lower, it is ok to measure a slightly higher value than book for toe-in. Also, helping out with an MGC last summer showed a need for greater toe-in on that model as opposed to an MGB.


Member Services:
dbraun99 LLC provides complete bench services on SU Carburetors. We also provide advice, repairs and restorations of both systems and complete cars.
riley1489 Avatar
Bruce Hopgood
Great White North, -, Canada   can
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB

Like Robert
I am getting dizzy.
So easy with toe plates ............

http://www.mgexp.com/phorum/read.php?1,1555441,1555441#msg-1555441

Math is for high school students winking smiley

Bruce

joron Avatar
Michel Joron
Roxboro, Quebec, Canada   can
1977 MG MGB "Victoria"

Currently mine is set to just slightly less than 1/8". Anyway it is more significant than 1/16" I don't think I could set to that value even if I want.

Roughly around 7/64", just slightly less than 1/8". I never any problem with the stability of the car neither with premature wear of any tires. But I admit my steering is not perfectly at zero anymore it is more or less at 5 to 7 degrees CW.
The first thing to do next spring to put back straight, otherwise my wife (she want to try it) will complain.
It was starting to rain I rushed a bit the last time.



1977 MGB Red 'Victoria'
All Classics:
Married, 2 children, 1 dog, MG MGB Summer, Jeep TJ Winter

mark21742 Avatar
mark melton
mercersburg, Pennsylvania, USA   usa

I'll admit mine still has a bunch of static toe out...I hope to get it back in the garage this weekend to fix it, but I have to get another car out first sad smiley

Fusion Avatar
Luke Ogier
Auckland City, North Island, New Zealand   nzl
1970 Vespa PX 200
1976 MG MGB GT "Jock"
1997 Lotus Super Seven "SUB"

In reply to # 2507584 by dipstick Luke, "All wheel alignment is measured in "Degrees" because "toe" and "camber" and "caster" are all angles."

No/wrong. Toe is measured in inches as referenced above in the factory manuals; read them. The pic is from the MGB F/P race car initial wheel alignment evaluation on the 4-wheel laser alignment rack at Warren Secord Tires in Kent, WA. Please note that the toe is measured in inches, not degrees.

It is easy to lay a calibrated bubble level device vertically across the rim and measure the camber in degrees. Please explain what sort of device will measure toe in degrees, the result has to be measurable on an alignment rack corresponding the unit measurements provided by the factory.

Hi Kenny, In 30 years of racing cars in several countries, wheel alignment has always been in degrees. Your image is in degrees.

Every alignment machine I have used is in Degrees. The current one an old Dunlop optical in degrees an minuets. Im at the beach an I feel the car needs 1 - 2 degrees more toe through the hill section (Tirua Whitianga Rd) I have new 205/60 x 15

. You can hide this ad & support the site by upgrading to a Gold Membership ~ click here for more info

To add your reply, or post your own questions

Members Sign In   or   Create an Account

Registration is FREE and takes less than a minute!

Having trouble posting or changing forum settings?
Check the Forum Help File (FAQ) or contact the webmaster.


Join The Club

Sign in to ask questions, share photos, and access all website features

MGExp Menu

What's New

Membership

Forums ->

MGB & GT

MG Midget

Buy, Sell & Trade

Vendor Market

MG Engine Swaps

Original MG

MGA

MGC

MG Magnette

1100 & 1300

T-Series & Prewar

Modern MGs

MG Motorsports

Member Meetup

MG 2015 Event

Other Vehicles

Off Topic

Clubs

Forum Search

Random Topic

Latest Posts

Live Chat

Calendar

Journals

Tech Library

Car Registry

Cars For Sale

Model Info

Motorsport

Directory

Member Map

MGExp Store

Search Site

Advertising Info

Smartphone quick link
mgexp.mobi

Adjust Text Size

Larger Smaller
Reset Save