Milwaukee Midget

[ggl205]

I have tried welded diff, open diff and now, a torque sensing diff. Have not tried the torsen diff yet but have high hopes. Just trying to obtain the most control I can get on an ever changing track surface.

John

[fordboy628]

I am not an LSR authority, but I can't envision any circumstance where a welded diff will be detrimental on a low traction surface with very low power at the drive wheels.   I'm thinking that it will be an advantage to have both rear wheels engaged with the surface, since you are going in a straight line.

Also an advantage on a poor (uneven) surface where a 1 tire loss of traction would result in loss of "thrust", and therefore acceleration.    You never had CG Vs center of pressure issues that you are aware of, have you?  At the low rates the MM is going to achieve, I just can't see how some extra traction could be bad.    But, WTH do I know . . . . .     Your call buddy.

And, YES, it will be a PITA to push by hand while turning . . . . .

[fordboy628]

Here's a thought:

Compare pounds of car weight per engine hp.    For your MG Vs the higher powered V8 vehicles.

Your MG is more like Jacksoni's ride, hence: less sensitive to traction lateral bias, more sensitive to longitudinal traction loss.   Working theory on my part.   Discuss . . . . .

 

Thinkyboy

[Milwaukee Midget]

Been doing some searches on the forum.

It's doubtful I'll have issues.

Those who have had problems had a LOT more power and were going a lot faster than the Midget is capable of.

[PorkPie]

if Chris has something to fear......

it's head wind....

as the air resistance  from that brick (means the MG)....will increase progressive......

[manta22]

...also, don't let your brake pads drag on the rotors.

[Milwaukee Midget]

...also, don't let your brake pads drag on the rotors.

I only have drums for back brakes - which prevents me from running ECTA.

[Interested Observer]

Some considerations on differentials:
Open diff = equal torque to wheels        Welded diff = equal rotation to the wheels

"...since you are going in a straight line."

Welded diff OK as long as rollout is matched and the straight line is the desired direction.  If deflected from the desired direction by any number of possible causes, the diff will resist steering correction.  Mismatched rollout (in as-raced condition, with operator weight) will induce a directional bias and imbalanced steering response.

Welded diff on a poor surface, with loss of traction on one wheel, the "good" wheel will induce a torque on the chassis tending to cause a change of direction.  Open diff on poor surface, wheel thrusts are equal (assuming balanced rollout) but reduced.  Little effect on directional heading.

Given ultra short Midget wheelbase, directional stability probably a plus, but hard to say welded diff wouldn't be satisfactory.   On a marginal traction surface or where Hp can overwhelm traction available, either diff would produce the same thrust.  Welded thrust advantage would only occur in one-wheel loss-of-traction situations.

Another consideration is how much rear axle wheel load is transferred right-to-left due to the solid axle, driveline torque, and suspension stiffness.   [Who's got some strain gauges?]

[fordboy628]

Some considerations on differentials:
Open diff = equal torque to wheels        Welded diff = equal rotation to the wheels

"...since you are going in a straight line."

Welded diff OK as long as rollout is matched and the straight line is the desired direction.  If deflected from the desired direction by any number of possible causes, the diff will resist steering correction.  Mismatched rollout (in as-raced condition, with operator weight) will induce a directional bias and imbalanced steering response.

Welded diff on a poor surface, with loss of traction on one wheel, the "good" wheel will induce a torque on the chassis tending to cause a change of direction.  Open diff on poor surface, wheel thrusts are equal (assuming balanced rollout) but reduced.  Little effect on directional heading.

Given ultra short Midget wheelbase, directional stability probably a plus, but hard to say welded diff wouldn't be satisfactory.   On a marginal traction surface or where Hp can overwhelm traction available, either diff would produce the same thrust.  Welded thrust advantage would only occur in one-wheel loss-of-traction situations.

Another consideration is how much rear axle wheel load is transferred right-to-left due to the solid axle, driveline torque, and suspension stiffness.   [Who's got some strain gauges?]

OK, so with the locked/welded diff assembly, a former non-issue; inflated, rolling, loaded tire circumference, becomes a critical issue for acceptable "torque steer", or perhaps even "wind induced", yaw angle.

I'm thinkin' even a small effort should be able to handle this variable, since all it would take would be a dress maker's cloth tape measure to measure inflated circumference of the tire/wheel assemblies.   Some close attention needs to be paid during "shaving" for equal diameters, or as equal as possible.    TOTAL equalization can also take place via pressure increase/reduction.   Just like NASCAR . . . . .

Just as long as the tape measure is not used to check any bust sizes . . . . or ass circumferences . . . . . OR ? ? ? ? . . . . . .           SOME THINGS HAVE TO REMAIN SECRET AND SACRED . . . . .

 
Perhapstoothinkyboy

[fordboy628]

midget,

For your laptop:

https://superflow.com/windyn-data-viewer/

Did not try the download myself, as I already have copies.   You NEED to follow the installation instructions to the letter.

Dynodataboy

[fordboy628]

midget,

Drive arrived in mail today.

Will copy files when I return to T&T after vacation.   Will then return to your location above the "curtain".      NEED to lower my BP & drain my "coping bucket" a bit.

Too many members of the "Dunning-Kruger University" out there.    It's a interpersonal problem for me, never have dealt well with omnipotence . . . . .

Fishyboy

[Peter Jack]

Even better than a cloth tape is a 1/4 inch wide steel tape measure. They are flat in cross section and wrap smoothly around a tire without crimping. Just make sure you get one that's long enough. The dollar store ones tend to be too short. I used to buy Lufkins that were ten feet but I don't know what's available these days.

Pete

[Interested Observer]

Or, actually measure the rollout, wheels installed on the car with driver and car in ready-to-race configuration:
On flat, smooth garage floor, mark the tire sidewall/tread at a floor contact point.  Make corresponding mark on the floor.  Roll forward one or more turns.  Make another corresponding mark on the floor.  Measure between the marks on the floor.  Then adjust pressures etc. etc.  Has the advantage of accounting  for tire deflection at the contact patch.
Doesn't account for tire growth at speed, but should be close enough.

[ronnieroadster]

Lots of figuring and theory's going on. Don't forget about the tire ruts when the coarse gets bad that's probably going to play havoc with all this math.

[Milwaukee Midget]

I'm intending to measure the rollout with the open diff in place in the alley behind the house. I'll chalk the tires and measure out 5 revolutions and take an average.