Author Topic: Milwaukee Midget  (Read 3255349 times)

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Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #6765 on: February 07, 2018, 02:33:00 PM »
And here is our rod design -

Saenz rods are of good quality. Some of the best racing transmissions too. I used to visit them occasionally when doing business in Buenos Aires.

John

They're what I put into the short-stroke A-Series - took a 9500 RPM clutch dump with a three-main block and never said "uncle".  If I'm not mistaken, they also make aftermarket gear-sets for older ZF transaxles.  I know they're a preferred supplier to Cosworth.

Chris;

I suggest specifying an overall rod bend & twist spec. Bolt seating surfaces need generous radii, flatness & parallel spec.

Good luck with this project!

Regards, Neil  Tucson, AZ

Neil, yes, good suggestion - I'm not discounting it.

If I were the one in direct contact with the supplier, I probably would.  The issue at this point is that Mel is stuck in the middle every time I have a question, and he has a shop to run.  

While I need quality parts, I also need to respect Mel's time.

I'm banking on my past experience with Saenz - the rods for the Grenade were excellent, I can inspect and likely have corrected any radius issues - there were none on the A-series rods - and given the short stroke we're dealing with, if I get to the point where bend and twist are an issue, then somebody bolted up a turbocharger while I wasn't looking.  :-D

And if that's the case, there are things behind the engine that will give up the ghost well before a rod heads south.

I just got back from Lunch and Mel has been made aware of the width issue.  I'll wait for Saenz to get back to him.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline manta22

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Re: Milwaukee Midget
« Reply #6766 on: February 07, 2018, 05:30:23 PM »
Chris;

Don't misunderstand the "bend & twist" spec--- it is to make sure that a straight rod is still straight after heat-treating.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #6767 on: February 07, 2018, 05:34:05 PM »
Ahhh . . . I DID misunderstand.

So I need to be straightened out as well!  :wink:

Thanks, Neil!  :cheers:
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline kiwi belly tank

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Re: Milwaukee Midget
« Reply #6768 on: February 07, 2018, 06:52:54 PM »
Clueless Kiwi here Chris, :-D so what engine are you working with here? It's obviously not the BMC-A any more.
  Sid.

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #6769 on: February 07, 2018, 08:45:19 PM »
Clueless Kiwi here Chris, :-D so what engine are you working with here? It's obviously not the BMC-A any more.
  Sid.

Sid - WHERE HAVE YOU BEEN?

2005 MG ZR take-out - the K-Series Rover from Great Britain.  Destroked 1.4 to 1 liter, DOHC, 16 valve - essentially the same engine that Lotus used in the first iteration of the Elise in Europe.

So we're going from 8 valves to sixteen, one cam to two, and 5 ports to 8.

And the design is STILL 30 years old!

https://en.wikipedia.org/wiki/Rover_K-series_engine

The only other one I'm aware of that has run on the salt was Terry Kilbourne's 1997 MG F - they ran for time only.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline kiwi belly tank

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Re: Milwaukee Midget
« Reply #6770 on: February 08, 2018, 02:07:43 AM »
Thanks Mate! This long car I'm building has consumed my life making it easy for me to loose the plot on somebody else's build. I'll try to be more observant. :dhorse:
That little sucker will have to be a vast improvement over the 5 port 3 bearing dinosaur! I did my apprenticeship on those things in NZ but I was always a Hot Rodder with a V8.
  sid.

Offline fordboy628

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Re: Milwaukee Midget
« Reply #6771 on: February 08, 2018, 08:06:19 AM »
As the Connecting Rod Turns,  episode 1 . . . . . . .

Now that the epoxy fumes have cleared out of my brain, I've had some time to peruse what is obviously a pre-production, "approval print" to be put in front of ? ? ? . . . . .

Some of my observations, which address some concerns, follow:




Shows 74.8 across the flats big end, into a 75mm bore!!?? Like IO says.
 

Jack,

See my comments below:



Hypotenuse of 79.25 - I need more detail.


Transpositionalerrormidget . . . . . . .

A/    Hypotenuse of 74.8mm x 27.0mm IS: . . . . .  79.52mm        AAAhhhhmmm, please explain your number.

2/    ADDITIONALLY:   Your numbers and interpretation are not what is drawn on the "print".      The big end does not have a simple rectangular section.    It is notably narrowed, although that width is: "unspecified",
       the resulting hypotenuse is significantly smaller.

d/    Did anyone notice the 3mm tapered drilling specified in the left view? ? ?     The purpose of this "center hole" is no doubt to provide an "anchor point" for radial turning of the big end to: 74.8mm Ø ! ! !
       Viola!   Fitment through 75.0mm bore now is a moot point, especially when combined with the large "cheek reliefs" shown on the drawing.    I realize that the "print" is unclear about this dimension.     That is
       what "approval prints" are about.     Communication ironed out at both ends . . . . . . .

z/    If we further postulate that the designers at Saenz know what they are doing, have made rods before, and accept communication to allay client fears, well then, no problem.


I recommend a Collegiate level Engineering Graphics Course for those who wish to gain expertise in interpreting "prints".     Take one that includes Geometric Tolerancing pratices.

https://www.google.com/search?q=geometric+tolerancing+examples&rlz=1C1CAFB_enUS728US730&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiAgoG7rpbZAhVrtlkKHVA4AtkQsAQIOw&biw=1920&bih=949

Not every racer needs to be an engineer.    But we all need to understand "engineer speak" and "engineer show & tell" or we end up with bright, shiny, new, useless, expensive bits.     And if we are too critical, we end up friendless as well . . . . . . .

JMHO . . . . .

 :dhorse:  :dhorse:  :dhorse:
Voiceofreasonboy   
Science, NOT Magic . . . .

I used to be a people person.  But people changed that relationship.

"There is nothing permanent except change."    Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former."     Albert Einstein

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #6772 on: February 08, 2018, 08:34:21 AM »

A/    Hypotenuse of 74.8mm x 27.0mm IS: . . . . .  79.52mm        AAAhhhhmmm, please explain your number.
 

A) I did it with yarn and a tape measure on a piece of cork board with push pins with a degree of accuracy of .3%?
2) I flipped the numbers when I went to post this?
x) all of the above?
5) I f@#^ed up?

 :oops:
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline Interested Observer

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Re: Milwaukee Midget
« Reply #6773 on: February 08, 2018, 09:03:20 AM »
Quote
Did anyone notice the 3mm tapered drilling specified in the left view? ? ?     The purpose of this "center hole" is no doubt to provide an "anchor point" for radial turning of the big end to: 74.8mm Ø ! ! !
       Viola!   Fitment through 75.0mm bore now is a moot point, especially when combined with the large "cheek reliefs" shown on the drawing.    I realize that the "print" is unclear about this dimension.     That is
       what "approval prints" are about.     Communication ironed out at both ends . . . . . . .

The 3mm hole shown in the left view is, in fact, the oil hole at the top of the rod.  The two small curves at the bottom of the rod cap in the front view are apparently just an indication of a curved surface there.  The alleged centering hole appears nowhere else in the drawing.  If the 74.8 mm dimension is indeed intended to indicate a cylindrical feature, it is not properly so presented.  Also, that area in the isometric view is shown as a flat along the split line.
Saenz may know what they’re doing, but that is not what the print says.

Offline forker

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Re: Milwaukee Midget
« Reply #6774 on: February 08, 2018, 09:12:56 AM »
Dear all

I hesitate to sound like I know what I'm doing here but it seems to me that an object of 74.8 on its' long axis that is to fit into a circle of dia 75 needs to be comparatively slender.

My arithmetic suggests that an object 74.8 * 5 has a diagonal of less than 75, albeit by a hairs' breadth. Main cap cheek width on the rod in the draft dwg is a bit more than 5, even if making a generous assumption about the undimensioned chamfer.

I'd think the dia3 hole in the 'Left view' ( in america? Left? surely no good can come of this!) is in the small end, into the bargain.

Perhaps a call to the supplier to check that he grasps the need might be an idea. Perhaps some of the dimensions can be refined without critical loss if acting now. Or the rods and pistons could go in to the block from the bottom side, before the crank, maybe...

Or I've just not read the pix well. Probably that, then.

F
« Last Edit: February 08, 2018, 09:17:01 AM by forker »

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #6775 on: February 08, 2018, 09:21:11 AM »
Mel has been made aware of the concern, and I haven't signed off on the drawing yet.  

Hopefully clarification will be forthcoming today.
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline forker

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Re: Milwaukee Midget
« Reply #6776 on: February 08, 2018, 09:40:40 AM »
Yes, that is in an earlier post, now that I look back. Too excited from a February day in Blighty with no rain.

F

Offline Milwaukee Midget

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Re: Milwaukee Midget
« Reply #6777 on: February 08, 2018, 09:56:45 AM »
Yes, that is in an earlier post, now that I look back. Too excited from a February day in Blighty with no rain.

F

The upside of rain is you don't have to shovel it.  We're looking at an additional 8 inches of snow tomorrow.

I noticed your email address - you work for Rover?
"Problems are almost always a sign of progress."  Harold Bettes
Well, I guess we're making a LOT of progress . . .  :roll:

Offline wobblywalrus

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Re: Milwaukee Midget
« Reply #6778 on: February 08, 2018, 10:06:32 AM »
The rod small end in post 6749 is blue.  Something bad is happening there.

There might be some distinct advantages to using a steel or ti H-beam rod where the troughs between the flanges direct lube up to oil holes for the pin that are at the upper ends of troughs, at 4:30 and 7:30 clock positions.  Like Carrillo does. 

Offline jacksoni

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Re: Milwaukee Midget
« Reply #6779 on: February 08, 2018, 10:17:26 AM »
section views c-c and d-d both show the pin end lubrication hole.  roughly measuring the flat at the big end which the drawing shows as 74.8mm diameter are in the neighborhood of 12.4mm wide (compare the 3/8"= about 9mm rod bolt hole) That would give Chris' hypotenuse times 2 diameter at 75.8. Some judicious polishing to help "balance" the rods probably could fix that but it is a close deal.  JMHO  :cheers:
Jack Iliff
 G/BGS-250.235 1987
 G/GC- 193.550 2021
  G/FAlt- 193.934 2021 (196.033 best)
 G/GMS-182.144 2019