Rearend problems on Speed Demon?

[robfrey]

Did anybody know was was happening at Speedweek 09 that the Speed Demon streamliner was breaking rearends?
What kind of rear were the using / breaking? What kind of rear is Fast Freddie using?

[Seldom Seen Slim]

SpeedWeek and the Shootout, too, and probably any other time the Speed Demon was run in '09.  I think I remember the trouble being traced to all that torque, put quite simply.  I received a photo/email from Ron Main a few months back - showing the building of a new rear for the car.  It was being built to be bulletproof - knowing how much power they were planning to put through it.  I guess their bullet was more powerful than they expected.

It appears that I didn't save the photos -- but maybe Ron will lurk through here and see your question and send 'em again.

No information about Mr. Dannenfelzer's rear end (nor that of his car).

[desotoman]

It is pretty simple really. It all boils down to your combination of Race car and driver. If you build a car like a dragrace car (very aggressive) then you better have a bullet proof drive-train. Quick-change rear ends with 10 spline gears were never made to go dragracing and take the shock load of a air shifted liberty transmission pushing a 4200 lb. car. The minor diameter of the shaft is under 1". The weakest link will break with the torque of the shock load.

On the other hand, cars that have drive-trains that are not as aggressive (softer shifts, or drivers that lift) have gone very fast with Quick-change rear ends, with more HP and torque than P&M.

It all boils down to your combination and what you are trying to accomplish. If you want things to last don't try hitting them with a sledge hammer and expect them to survive. Unless you have lots of money to keep chasing the weak link.

Common Sense goes along way.  Just my $.02.

Tom G.

[robfrey]

Do you guys think we will be okay with the Extremeliner rear that is our lakester or are we going to break it as soon as we get her hooked up. We are making over 1600 lb/ft of torque with our mild tune. I am concerned since I heard what was happening with the 300 ci small block breaking the rearend several times. Desoto Man, do you know if they were breaking it during the shifts? Do they have an airshifted Liberty in that car? Those are brutal on drive line parts. We can lift during the shifts and have been doing just that.

[jl222]

   Freddys quick change is the same as Arley Langlo's [see build diary] built from billet stock by Brian Gary, Goleta Ca.

   I believe that a lot of rear ends break from jackhammering [ mostly solid suspension cars, ever hear the

   uh uh uh of a car accelerating]? I once heard Darrel Waltrip commenting about nascar cars breaking the rearends
from jackhammering also.


                   JL222

[robfrey]

I ran my LeMans at the dragstrip yesterday. I am having a lot of trouble with it shaking the tires and I know that if I keep it up, I'm going to break the rear.

[racergeo]

   I believe I have seen streamliners with the V8 size diff ( that I have) run over 370mph. I choose that diff for my car based on that observation. I think the champ diffs, If like Tom stated, are not shifted under full power will do the job.

[maguromic]

The quick change in that liner is one of the units that Don Ferguson builds and is stout as they come, not to mention a work of art. Don’s liner also has an air-shifted liberty and has run 300 with a GMC. I remember Al Teague was telling me the liner ring gear in his converted trans-axle was cracked after his last run. A lot of things happen at the speeds these cars run.  Maybe Don will chime in give the scoop.  Tony

[desotoman]

Rob,

I believe the Extremliner takes a different spline Q-C gear than a standard 10 spline. For some reason I think it is a 22 spline gear and or shaft. Out of curiosity what is the minor diameter of the shaft in the Extremeliner? I think you will be fine with that rearend. As RacerGeorge said many V8 Quickchanges rearends have gone very fast.

My Brother and I own a Modified Roadster, with a one off 1-1 QC. The QC was broken when we bought it. Seems the 10 spline Pinion shaft would occasionally sheer in two when the previous owner ran the car. The car was run with a Blown Fuel KB, which put out 3000 HP and 3000 torque. It only went to Bonneville once and with that rearend recorded the fastest 1/4 mile time ever at 296, at least that is what the previous owner told me. I have no reason to doubt him as the car still holds 3 El Mirage Records ranging from 266-280 set back in 1994. All records were set using 10 spline Q-C gears.

Tom G.

[robfrey]

Tom,
That is correct. It does not take the standard 10 spline QC gearsets. I will check into the diameter of the bottom shaft.

[Rex Schimmer]

There is a reason for long tail shafts on most transmissions. It acts like a big torsional spring and attenuates the large shock loads that happen when you shift fast. It is certainly not uncommon that the long tail shafts are shortened to make everything fit inside a car and when that is done the shock peak loads to the rest of the drive train go up. If the peak loads are above the strength of the QC shaft or gears then they fail, period. Some Doug Nash 5 speeds used to have a long shaft that was actually splined to the very front of the main shaft and ran thru the complete length of the tranny and it was simply to reduce shock loads imposed by fast shifting.


Rex

[robfrey]

What your saying here is sometimes it is better to flex than break. Correct?

[John Burk]

The weak point in a qc housing is the missing through bolt at the pinion . Fred's billet qc housing is wider to strengthen the weak point with custom narrower side bells . Franklin used to fabricate 6 spline qc's using a ford steel banjo that would be hard to break .

[robfrey]

I actually know a little about this as I am friends with Gentlemen that now owns Frankland. I designed the fixturing that is used to machine the bells and center section. I see a lot of the destructive testing that goes on by their customers. Most of the time it is wear problems due to everything flexing under the 800hp loads that it sees lap after lap. We are not too worried about this type of wear, we are concerned with catastrophic failure due to severe overload. I don't think we have anything to worry about with the Lakester but our streamliner that is in it's conception stage will have over 3000hp eventually. We will only start off with 1600hp but we need room to grow.
I can build any kind of case that I need for this rear but I am looking for the limit of what the 10" "champ" actual ring and pinion can take.
We will not be making as much hp as Fast Freddie so whatever he is using will be strong enough for us.

[jl222]

 

   I'm pretty sure that Freddy uses a ring and pinion from a helicopter.
   I'll find out a lot more at the annual Christmas party at J AND S East Valley Garage that Fred his crew and Arley go to.
   Is the Speed Demon a solid mounted rear end?

                    JL222