Never said I knew very much, but wow, I just learned more about a speed trials car than I ever knew before and I didn't even ask. THANKS.

Maybe this year will be the time I can finally get out there to witness this type of racing firsthand.

       A  L  A  N   F  R  A  K  E  S   ~  Tulsa, OK    

Hey, guys, great thread on parasitic drag from the 3rd member.  I believe this will help lots of others out there who either haven't thought about it or knew about it and didn't know what to do.  As for me, I have about a half dozen 9" housings and just about every conceivable 3rd member ratio to pick form, so, the extra cost of changing is just not in the budget (Tim will just have to make more power!).

Bill, good point about the synthetic lube.  I do run synthetic in the t-10 trans and diff now.  I think I remember Karol Miller saying that he changed the trans and diff to straight 30wt up on arrival to the events and then changed back to 90wt to drive back to Texas.  I will be changing to a T-5 and I'll have to check, but I think it uses auto trans fluid.  Perhaps there is a synthetic for that light of weight too.

The ring and pinion sets I use are NASCAR take-offs.  The sellers list them on Ebay as "polished".  When I get them they are extremely smooth and look just like chrome.  I don't know if they are just polished or have one of the treatments that have been mentioned before.

Good job on the thread guys.  Let's keep it going.............

By the way, I have spent many hours internet searching, talking to techs at IFS manufacturers like Heidts, and bending the ears of other Bonneville car builders to determine the best caster range for the Comet.  Straight axel users like 15 degrees or more (positive of course) while IFS users are all over the map (there are racers with +3 to +9).  I rolled the solid axle back 8 degrees in the race truck, but big time bumpsteer kept me from knowing if 8 degrees was enough.  The best advise for the Comet seems to be to set the rake of the frame and body at 1 percent (1" rise in 58") for best aerodynamics (NASCAR numbers), rotate the crossmember about 5 degrees positive from the  horizontal ground (not the frame) and then do the final settings with the top A arm adjustments.

Here we go.................

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

No actually it was in reference to the rear end itself. I've seen plenty of chrome housings. Maybe I'm thinking of some hardening process. CRS! Makes it difficult. Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Chuck.  I believe they were referring to the housings being chromed.  I had a chromed housing in the roadster when I originally built it but hard launches warped it to the point it was difficult to get the axles out.  What I have now is a very heavily braced powder coated rear end housing.

Lorena, Texas (South of Waco)

I seem to remember some early racers talking about "Chromed" rear ends. Did they chrome the ring and pinion for less drag? Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I’ll add to what John and Steve have brought up regarding rear end drag.

 

The lowered pinion offset on the 9” Ford rear gears allows the teeth on the pinion to have more contact or surface area which is where much of the strength for the 9” is derived from.  Unfortunately that increase in surface area is also a detriment as far as drag goes.  If not concerned about the overall life expectancy of the rear, then there are several other rearends out there that will reduce the friction and in turn allow more of the engines horsepower to be delivered to the rear tires.  For the 9” housing, both Mark Williams and Strange Engineering have offered unique ring and pinion sets with a specialized gear housing that raises the pinion back up and frees up some of the hosepower that's lost in using the standard design 9” ring and pinions.  These specialized ring and pinion sets do have have some horsepower limitations but are used in those cases where getting just a bit more power to the rear wheels makes the difference between running like everyone else or being just a tad quicker (or faster).

 

For the 9", there are also some low drag pinion bearing supports that are also of benefit in reducing rear end drag.  I have one of these in my roadster and essentially it does away with the tapered bearings and the crush sleeve or bearing spacer and instead uses a stack of roller bearings without a crush sleeve.  With the pinion nut tightened in excess of 200 ft/lbs, the pinion still rotates freely with this setup.

Lorena, Texas (South of Waco)

Y-Guys:        While we are on this subject,of trying to utilize every small tidbit

             of help, using a thin(75 wt) synthetic gear lube as well as synthetic

             wheel bearing grease should offer some small friction losses to help

             those small "pony's" in that 258" Y-Block......

                                                     Maybe 1 or 2 mph

                                                             Bill

     

Bill

Pelham,Al

I was doing a little tounge-in-cheek about the 8-10 mph gain with a different rear, rather I was inferring that with a small engine trying to push a brick through the air, any little help is a plus.  I certainly don't deny that the 9 inch is, pound for pound, the best production rear end I've seen.

John - "The Hoosier Hurricane"

Ok -So we're not really working hard at our regular engineering jobs today.....so the "boys" are checking up on the articles / tests / tech info, etc. for the rear ends. Here's another one to look at with a Ford 8.8:

http://www.carcraft.com/techfaq/116_0701_mikronite_surface_treatment/results.html

Results of our "study" so far......

(1) Yes   The Ford 9 inch appears to have a slightly lower efficiency - and the difference appears to widen as the rev's increase. The greater hypoid offset is thought to be the culprit (but I didn't locate any textbook engineering reference data that backs that supposition). Doesn't mean there isn't something somewhere - but I haven't stumbled over it. The reduced efficiency is a very small amount - and it could be negated by the micro-polishing processes mentioned in the magazine articles.

(2) Yes    The "micro-polishing" of the ring and pinion has shown an advantage in improving gear efficiency (by a small amount percentage-wise) - several automotive tests have shown similar results. Of the two mentioned processes - Mikronite and REM - neither shows an advantage over the other for performance. One abrades and smooths the surface with contact pressure - one uses ceramic powder and chemical etch - both end up at the same place, a very smooth silky surface - and still true to the engineered geometry (mating curves remain). REM seems to have a clear price advantage over Mikronite - and also is mentioned by more than a few NASCAR users of this technology.

(3) From a racing standpoint - the second benefit of the micro-polishing is a reduction in surface fatigue from contact loading of the "rough" (ground) finish the parts start out with. Rough is a relative term here - the ground finish of most ring and pinion sets is by machine tooling standards, very good. The NASCAR references hit this feature as hard or harder than the friction reduction. In short terms - it provides a surface that is already "broken in" - polished - without losing the proper contact surface shape through wear.

We think....use the 9 inch (its a Ford part and the punkins are handy at the track)......and find a good source of getting your choice of ring and pinion sets polished by REM.   

 
 Steve Metzger       Tucson, Arizona

This is the Mikronite site I found - interesting stuff.......

http://mikronite.com/documents/dragsterMag.pdf

http://remsuperfinish.com/rem/rem_benefits.html

Creeping into my head......Do you suppose this would work on automatic transmission parts too?

 
 Steve Metzger       Tucson, Arizona