View Full Version : HP Loss- Which Rear End Is Best


38FLATTIE
07-18-2010, 05:41 PM
I'm looking for an as efficient rear end as I can find. I know Ford ' lose more HP than most, and that a GM 7.5" 10 bolt is better than a 12 bolt.

I would assume that a Halibrand V8 QC would be better than the Champ.

How about the Frankland- is it like the V8, or the Champ?

Overall, which rear end loses/robs less horsepower?

Andy
07-18-2010, 05:49 PM
A ford banjo uses the least power. It is not an offset pinion rear. The offset makes for more rubbing and power loss. I would think the next would be the Ford 8". It has less offset than a 9" and a smaller ring and pinion. I don't know about the Q/C's. They are non hypoid but the change gears would use a lot of power.

Deuce Roadster
07-18-2010, 06:05 PM
In effect ... in the real world ... the less the parasitic drag ... the weaker the rear end. :o

Then you have gear ratio option problems in a LOT of the less common rear ends.

.

38FLATTIE
07-18-2010, 06:10 PM
In effect ... in the real world ... the less the parasitic drag ... the weaker the rear end. :o

Then you have gear ratio option problems in a LOT of the less common rear ends.

.

I'm more concerened with the HP loss from parasitic drag than I am the weak rear end. This won't be for 700hp launches, but for top end, with a flathead. I don't think in this application, that I'm very likely to tear up the diff, as long as it will handle the weight.

I'll have to deal with the gear ratio with the tranny, or tires.

Yo Baby
07-18-2010, 06:26 PM
Collin Casey (RIP) could kill 'em.LOL

Ole don
07-18-2010, 06:59 PM
A Ford 8.8 is the same design as a GM 10 bolts, but more recent. They have ratios, from 3 to 1 to 4-56 to 1, but changing the ratio is not a quicky deal. Design well, and run a close ratio five speed to compensate. If you cant make Speedweek, go to World of Speed in September. Talk to the guy driving the five speed Buick powered Jag sedan. He may be in your class.

jeff/21
07-18-2010, 07:01 PM
Andy is right about the banjo rear Winters makes 2 non quick change rear banjo style with any style of bells even open tube as a for quick change rear a midget rear weighs half as much as a full size, the cheapest and lightest stock rear would be a 8.5" or 10" GM rear

The Shocker
07-18-2010, 07:04 PM
Mopar 8 3/4 is plenty strong ,less drag than a 9 inch Ford and has the nice drop out section for quick gear swaps like the 8 and 9 inch Ford .Lots of gear choices for them as well .I can change out the center section my 8 3/4 in a few hours with hand tools by myself ...

38FLATTIE
07-18-2010, 07:08 PM
Thanks guys! Where do the Frankland QC's fit in?

A Ford 8.8 is the same design as a GM 10 bolts, but more recent. They have ratios, from 3 to 1 to 4-56 to 1, but changing the ratio is not a quicky deal. Design well, and run a close ratio five speed to compensate. If you cant make Speedweek, go to World of Speed in September. Talk to the guy driving the five speed Buick powered Jag sedan. He may be in your class.

Thanks, I will. I think his car is newer than mine- I'll be in XXO/BVGC

Shocker- I'll check those out too!

29bowtie
07-18-2010, 07:09 PM
I'm more concerened with the HP loss from parasitic drag than I am the weak rear end. This won't be for 700hp launches, but for top end, with a flathead. I don't think in this application, that I'm very likely to tear up the diff, as long as it will handle the weight.

I'll have to deal with the gear ratio with the tranny, or tires.

How much torque, is that blown flathead Caddy going to make? Remember, they had enough torque to be used in tanks and tugboats. The amount of parasitic loss is not that much different, as to make it such a priority, as compared to parts availability and adaptability. Put in something proven, like a Ford 9", and never worry about it.

38FLATTIE
07-18-2010, 07:15 PM
How much torque, is that blown flathead Caddy going to make? Remember, they had enough torque to be used in tanks and tugboats. The amount of parasitic loss is not that much different, as to make it such a priority, as compared to parts availability and adaptability. Put in something proven, like a Ford 9", and never worry about it.

I'll grant you the engines have a lot of torque(260fl/lbs stock), and this one will have more than most. That will get me rolling, and pull me through the gears, but top end speed is HP. I'm looking for LSR speed, and I'm pushing a brick, so I need to utilize all the HP I can.;)

69fury
07-18-2010, 07:17 PM
This is some info i've found on certain rears. The quickies tend to be just a little less efficient because the r/p is not hypoid (more efficient than hypoid) BUT there is another spur gear set outback (added inefficiency).

That being said, i'm a huge fan of the frankland- nice people to work with, only $75 set up fee (plus parts/shipping). I love my 8 3/4 but I'm picking up a huge heavyduty one from the 60's so durability shouldn't be an issue.

i still dont think it'll take a transbrake launch on stickies, so i might save it for another project.

complete assembly w/0 brakes:
12 bolt 171lbs
S60 191lbs
9 inch 174lbs

WITH brakes (9 inch guys TAKE NOTE) this is using THE SAME brakes off the 12 bolt and putting them on the dana. The Ford Brakes weigh a TON, now you could put lightweight disks on the 9 but you could also do it to a 12 or Dana60.

12 bolt 210lbs
S60 230 lbs
9 inch 238 lbs

the greater the hypoid measurement, the more power it consumes in friction
the hypoid offsets are:

12 bolt 1.5 inches
ford 8.8 1.5 inches
ford 9 inch 2.25 inches
Dana 60 1.125


ring gear diameter.

12bolt 8.875"
ford 8.8 8.8"
ford 9 9"
Dana 60 9.75"

pinion shaft diameter (one of the weakest parts)

12bolt 1.625"
Dana 60 1.625"
ford 8.8 1.625"
ford 9 1.313

stock Dana 60's have 35 spline axles ( you have to spend bucks on a carrier and axles to upgrade to that with any other rear)

The ONLY downsides to a 60 are the cost (but it's not atrocious), and not being able to drop out the center at the track for another ratio- but how often do you guys do that.

barrelvalve
07-18-2010, 07:22 PM
I might consider weight also.

barrelvalve
07-18-2010, 07:25 PM
Never mind, I see Fury addressed that.

gearguy
07-18-2010, 07:26 PM
If power loss is a concern look into getting your rear axle super finished and coated. Winters offers an option for this but any gear set can be treated by after market suppliers. Google "super finishing" for many interesting articles on efficiency in axle gears.

Temperature rise is your best indicator of efficiency. Poor setting on the bevels will affect efficiency and noise. Noisy gears are wasting energy.

Just avoid the temptation to run a thin axle lube. Never trade viscosity for temperature. Before you know it the tooth surfaces are permanently damaged.

Almost 40 years in the gear business and people still fall for the snake oil salesmen. Gear companies make a bundle on spare parts!

Truckedup
07-18-2010, 07:31 PM
Supposedly a chain drive uses less power than a 90 degree power change when using a shaft drive in a motorcycle.So turn the engine sideways and use chain drive :D Or,hate to think it,a front driver might have less loss??

LM14
07-18-2010, 07:43 PM
A quick change flat out uses more HP and has a lot more drag than any of the other mentioned OEM rearends. You are turning an extra shaft and an extra set of gears. You can get it close by using the ceramic bearings and REM finishing on the gears, shafts and races but you can also do all those on a std type rearend and pick up even more.

I would suggest using a 9" Ford rearend with a GM 12 bolt hybrid carrier made by Williams. This allows you to use the strength of the Ford with the better drop of the 12 bolt. It also gives you the full range of 12 bolt gears to choose from.

To pick it up even more, get the gears, bearings and almost anything else REM finished to pick up the maximum amount of HP and minimum drag. Makes a big difference.

Check out these guys for more information.

http://www.pemracing.com/Gears.html

They manufacture the parts, do the finishing and have a great motorsports background. Talk to Randy and tell him Steve (SPark) sent you!

Good lcuk,
SPark

Brahm
07-18-2010, 07:59 PM
Depends how much money you want to spend, and how much damage it needs to hold up to. If you want as light as you can, but still keep strength you can always go with some gun drilled axles..but they aren't cheap.

Something like wheels/tires combo will make a bigger difference then axles in most cases. Same with transmission ect.. When it comes to rear end...sacrificing a little hp to not blowing up your diff and wrecking your car is the choice I'd always make.

Stovebolt
07-18-2010, 08:23 PM
The thing with a Quickchange is the ratio of the original ring and pinion will vary the mount of power used to drive it.

Overdriving the pinion uses more power.

Using a rare 3.25 ring and pinion will use less power than a 3.78 ring and pinion when its geared to say 2.8:1 final ratio.

Its like an overdrive transmission - you loose power when you drop it into overdrive as the engine has to "climb" the overdrive.

Hope I'm explaining myself adequately.

gasserjohn
07-18-2010, 08:33 PM
lm14 x2..........
look at markwilliams site for this setup
they can make it lite weight too

wfo guy
07-18-2010, 08:56 PM
In the lower econo dragster classes, people used small foreign pickup rears. The carrier has smaller diameter and fairly light weight. At Bonneville, you're limited on traction so you don't need quite as strong of rears until you make huge power. Might be an option.

Hot Rod Packard..
07-18-2010, 10:34 PM
I know a guy here in slc that ran a stock bodied merc to over 150mph with a 260 non blown flattie and he used a 9" so it must have worked cause his records still stand. He hused a richmond trans and ran the course as if he was running a 1/4 mile drag, short shift and lots of throttle. The man is very smart and know his shit. So I would trust him to the end. Once you get a gear that is close and the jump to another gear is too far, you would use tire size to dial in the gear that works best.

gemcityrenegade
07-19-2010, 02:22 AM
I'm building a non c clip 8.5" ten bolt right now for my 490 HP Trans Am. Probably run 3.90 with some cromo shafts and a stock style posi.


Love that Huffed Packard 8 btw and the liquid gauges really make it rad chad.

38FLATTIE
07-19-2010, 05:57 AM
Great stuff guys, thanks!

I think I'm down to running a GM 7.5" 10 bolt, which is supposed to be very efficient, or a QC, for ease of changing gears. I have a Champ, but supposedly the V8/sprint style is more efficient.

Anyone know what the Franklands are based on?

69fury
07-19-2010, 03:15 PM
Great stuff guys, thanks!

I think I'm down to running a GM 7.5" 10 bolt, which is supposed to be very efficient, or a QC, for ease of changing gears. I have a Champ, but supposedly the V8/sprint style is more efficient.

Anyone know what the Franklands are based on?

he invented them,lol..... not really but He was welding up so many, that he started casting them based on the timken 3/4ton truck rear- had one in my 49 willys jeep delivery.

most guys used two right side cases (i think right side) and the newly cast center section to hold the guts.

-rick

38FLATTIE
07-20-2010, 07:19 AM
Decided to just go with the 7.5" 10 bolt. Should work just fine in this application.

1936hotrod
07-20-2010, 07:27 AM
Believe it or not we have in the last 3-5 years been using the 9 inch ford with 12 bolt Gm gears. Its not cheap but is very low on drag and very strong in the oval track stuff. Tons of gear ratios. The 7.5 has been limited as far as what you can get lately.
I dont use these but it tells about how its done http://www.strangeengineering.net/catalog/index.html

randydupree
07-20-2010, 08:09 AM
Jamie Frankland is still in the rearend business,hes down in Balm,Fl.
South of Tampa.
Frankland welding is what his business is,look him up and give him a call.
He built my quick change thats in my Fiat speed racer.

storm king
07-20-2010, 08:13 AM
8 3/4 Mopar is 15% more effecient than a 9 inch Ford.
We ran them for years with high HP hemis, even top fuel guys used them into the rear motored era (light wieght cars)

1936hotrod
07-20-2010, 08:25 AM
Jamie Frankland is still in the rearend business,hes down in Balm,Fl.
South of Tampa.
Frankland welding is what his business is,look him up and give him a call.
He built my quick change thats in my Fiat speed racer.
How long has he been there? Do you have a # i will try to Google it......thanks

Brahm
07-21-2010, 03:06 PM
I'd be a little weary of the 7.5" 10 bolt if I recall it's what came in the mid/early 90's camaros. I used to have alot of friends that raced those style cars and they blew up a lot of rear ends even with decent parts, and we aren't talking very quick cars either. Mid 12's to High 11's

38FLATTIE
07-21-2010, 05:26 PM
I'd be a little weary of the 7.5" 10 bolt if I recall it's what came in the mid/early 90's camaros. I used to have alot of friends that raced those style cars and they blew up a lot of rear ends even with decent parts, and we aren't talking very quick cars either. Mid 12's to High 11's

Oh, it'll be all right! If I was running Mid 12's to High 11's, I'd use the quickchange.

For the salt, it won't be abused as much as I'm sure your friends' were.

temper_mental
07-21-2010, 06:58 PM
How long has he been there? Do you have a # i will try to Google it......thanks



813-634-9556 very nice guy with tons of info.

Hank
07-21-2010, 07:28 PM
One trick I've used is to use a thinner oil. At LSR speeds the torque in the rear will be fairly low and you won't need the EHD that the thicker oil provides. A thinner oil will have less parasitic pumping losses than a thicker one. Also, if you lower the oil level the power losses go down. Air is a lot easier to pump than light oil. The tricky part to both of these is to figure out when the oil is too thin and too low. The only way I know of doing this is to monitor the bearing temps. Dry sumping the rear axle would be the ultimate but take some time and thought to get it right.

Good luck with your speed quest.