Running Board and Tire Tread Gap Distance from Rear Wing

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timberstone
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Running Board and Tire Tread Gap Distance from Rear Wing

Post by timberstone » Wed Jan 01, 2020 2:51 pm

Need consensus on whether there is a TC "Factory Original" value for, and if so how much, gap there is between tire tread and rear wing (fender) front opening. Stated another way, but with same result, what is the "set out" measurement of the rear wing from the running board?

Taking some measurements "in the field", found values from 1 to 2+ inches lateral differences for the gap between the tire tread and the rear wing front opening. These were random, just started sampling this year.
Has anybody else taken actual measurements of these values "in the field"?
Some owners say they are original coachworks; others are professional rebuilds. For original coachworks, it does not matter the side of the car or the year of build -- there is still a range of values of sufficient variety, even from side to side, that some of the tires are hard to dismount and remount on sides of the car with the lesser of the gaps between wings and tires.

For a professional rebuild, the definitive reference might be Mike Sherrell's book "TC'S Forever" which states a value of about 1/2" for the rear wings to be set out from the running boards (page 217), making no mention of lateral variations. This would provide approximately 1-1/2 inches gap between tire tread and rear wing front opening. There are other sources for a statement of these values, but are not at hand.
However, encountering this range of values in the field frequently enough, even in the same car with lateral differences, makes me wonder whether the assembly procedures at the factory were so variable because either:
-- because it was all done by hand,
-- that one side of the line worked differently from the other side,
-- or the assembly lines were engineered differently.

This phase of the assembly took place in Abingdon, not at some distant coachbuilder's location.

Note is taken that the rear wings changed in section from semi-circular form to a "Squaring Up" form (Sherrell, p189) and this could be the source of some of the variations even in professional rebuilds. However, should any variation be found in "Factory Original" samples, and if so, how much?
Octagonally yours,
Boxley (Robert and MGTC0820)
Attachments
Right Rear Fender Clearance from Tire.jpg
Right Rear Fender Clearance from Tire.jpg (106.23 KiB) Viewed 286 times
Left Rear Fender Clearance from Tire.jpg
Left Rear Fender Clearance from Tire.jpg (117.23 KiB) Viewed 286 times

frenchblatter
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Re: Running Board and Tire Tread Gap Distance from Rear Wing

Post by frenchblatter » Wed Jan 01, 2020 10:23 pm

Robert, about time you replaced those aging tyres, Of course, this may alter the gap :)

The wheel can normally only be removed when the axle is on stands, in other words the axle isn't hanging. Even then the wheel has to wiggled out from the rear first then the front will pass the wing lip.
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timberstone
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Re: Running Board and Tire Tread Gap Distance from Rear Wing

Post by timberstone » Thu Jan 02, 2020 2:41 pm

These tires are the "Poster Children" for weather checked and dry rotted examples of the original Dunlop tire species of prehistory.
Yes, it would be easier to get these off and on if at least one of the wings were a bit more outboard, but I wanted to be sure of the amount of set out for, or how much more outboard to make, the fenders -- and In order to change the tires easily.
Now, we raise the whole car instead of just raising the axle. That way is hoped to help give more clearance for the tire to be removed and replaced.
Octagonally yours,
Boxley (Robert and MGTC0820)

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Duncan M
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Re: Running Board and Tire Tread Gap Distance from Rear Wing

Post by Duncan M » Thu Jan 02, 2020 3:50 pm

It does make it easier to get the rear wheels off by jacking up the axle. Good reminder, Norman. I had some Dunlops on my wheels that were so old and hard that I had to use a sawzall to help get them off.

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Steve Simmons
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Re: Running Board and Tire Tread Gap Distance from Rear Wing

Post by Steve Simmons » Thu Jan 02, 2020 7:17 pm

So you're looking for the measurement from the side of the tire tread to the outer face of the rear wing? My car was restored before I owned it, and the shop didn't do a very good job in a lot of areas. Mine measures quite different between left and right. From tire tread to the inner edge of the rolled lip is 1/2" on one side and 1-1/8" on the other.So if you average those out, and add about 1/4" to the outside of the fender, it's right around 1".

Unless you were after the distance from the tire tread to the front of the wing, which on mine is 1".
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Duncan M
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Re: Running Board and Tire Tread Gap Distance from Rear Wing

Post by Duncan M » Fri Jan 03, 2020 7:13 pm

"Tread gap" measured as above pictures, 1 1/4" on one side and 1 1/2" on the other.

timberstone
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Re: Running Board and Tire Tread Gap Distance from Rear Wing

Post by timberstone » Sat Jan 11, 2020 2:56 pm

With new tires, of larger circumference, the tread gaps between the rubber and rear fender opening seem not to have changed much, but the larger circle of the tire seemed to make the wheel well more cramped and increases the difficulty with removing and replacing the wheel.
Rear Fender Left Side Gap with New Tire.JPG
Rear Fender Left Side Gap with New Tire.JPG (86.11 KiB) Viewed 108 times

The Right side, which already had its fender too far outboard, was no problem with removing and replacing the wheel
Rear Fender Right Side Gap with New Tire.JPG
Rear Fender Right Side Gap with New Tire.JPG (91.62 KiB) Viewed 108 times

The next project is to go back to the Rear fender placements, within the tub arches for both sides, and to adjust the attaching screws so that the outboard distances of the fender front opening gaps on both sides are to be approximately equal at about 1" to 1-1/4" distances from the tire treads.

At the outset the question was: should this gap equalizing even be done if the inequality came that way from the factory?
Octagonally yours,
Boxley (Robert and MGTC0820)

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