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Building a strong 8 3/4 rearend.
#2799143
07/20/20 09:28 PM
07/20/20 09:28 PM
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Joined: Jan 2003
Posts: 21,637
San Jose,CA
migsBIG
OP
YouTube is my go-to news source
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OP
YouTube is my go-to news source
Joined: Jan 2003
Posts: 21,637
San Jose,CA
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Hi all. Looking for some ideas, tech and info for the 8 3/4 rearend. I was thinking the race section would be a good section to ask than the Pro-Tour section as this question is more for strength and durability then handling. I have a 1970 Barracuda and will eventually be putting an Indy headed 440 I traded for as a swap engine. It's speced for high horse power and figured the rearend in it will not survive due to my 'aggressive' driving style (also making very bad noises already). Though my car will be mostly a street car, I will try for a few times at a straight line drag and eventually Willow Springs Raceway. Currently I have a 1969 b-body housing I plan to use with 'Cass' Doctor Diff inboard kit with Hotchkis springs and Viking shocks. I don't have a welder to make a back brace, but I was thinking of improving the internals. Doctor Diff offers a new 3rd member case with his Helical Gear Sure-Grip ("Sure-Trac") that would work well and looks like the strongest option without going to a spool. Looking for axles, bearing, gears and WILWOOD brake options for this. I do not want to go to a DANA 60 due to weight, noise and price (out the door prices have put them at over $3.k before shipping).Rear tires will be larger than the 295/50R15 Cooper Cobra's I currently have on it, but like the profile to be low for driving and looking for a radio around 3:23/3:55. Any help/info would be appreciated.
Last edited by migsBIG; 07/20/20 09:32 PM.
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Re: Building a strong 8 3/4 rearend.
[Re: migsBIG]
#2799160
07/20/20 10:07 PM
07/20/20 10:07 PM
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Joined: Jan 2003
Posts: 11,705
Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,705
Portage,michigan
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Hi all. Looking for some ideas, tech and info for the 8 3/4 rearend. I was thinking the race section would be a good section to ask than the Pro-Tour section as this question is more for strength and durability then handling. I have a 1970 Barracuda and will eventually be putting an Indy headed 440 I traded for as a swap engine. It's speced for high horse power and figured the rearend in it will not survive due to my 'aggressive' driving style (also making very bad noises already). Though my car will be mostly a street car, I will try for a few times at a straight line drag and eventually Willow Springs Raceway. Currently I have a 1969 b-body housing I plan to use with 'Cass' Doctor Diff inboard kit with Hotchkis springs and Viking shocks. I don't have a welder to make a back brace, but I was thinking of improving the internals. Doctor Diff offers a new 3rd member case with his Helical Gear Sure-Grip ("Sure-Trac") that would work well and looks like the strongest option without going to a spool. Looking for axles, bearing, gears and WILWOOD brake options for this. I do not want to go to a DANA 60 due to weight, noise and price (out the door prices have put them at over $3.k before shipping).Rear tires will be larger than the 295/50R15 Cooper Cobra's I currently have on it, but like the profile to be low for driving and looking for a radio around 3:23/3:55. Any help/info would be appreciated. There is nothing you can do to make an 8.75 live with weight and horsepower like you are talking about. Nothing. Been there, done that. 3400 pounds and 10.30’s took one out i had on the 4th pass. The ring and pinion just wont survive. Light and lower power, sure. Weight and power kill them in tandem
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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Re: Building a strong 8 3/4 rearend.
[Re: B3422W5]
#2799162
07/20/20 10:14 PM
07/20/20 10:14 PM
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Joined: Aug 2003
Posts: 4,670
On the parachute mount
n20mstr
master
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master
Joined: Aug 2003
Posts: 4,670
On the parachute mount
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Here we go ........
9” or Dana 60 , or even Ford Explorer 8.8 , all better rear ends than 8 3/4
This will go on for days now ..... lmao
....BAD A$$ STREET CAR.....
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Re: Building a strong 8 3/4 rearend.
[Re: n20mstr]
#2799169
07/20/20 10:35 PM
07/20/20 10:35 PM
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Joined: Oct 2003
Posts: 11,684
W. Kentucky
justinp61
I Live Here
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I Live Here
Joined: Oct 2003
Posts: 11,684
W. Kentucky
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Here we go ........
9” or Dana 60 , or even Ford Explorer 8.8 , all better rear ends than 8 3/4
This will go on for days now ..... lmao Yes, there will be guys come forward who have ran 8's at 5000 pounds with a stick and a stock 8 3/4 and never had an issue. My experience mirrors Don's, the second pass my then new 408 hooked up it shucked the teeth on a pretty fresh 4.30 geared 8 3/4. It ran high 6.50's at 3260#.
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Re: Building a strong 8 3/4 rearend.
[Re: justinp61]
#2799172
07/20/20 10:40 PM
07/20/20 10:40 PM
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Joined: Jan 2003
Posts: 20,158
Park Forest, IL
slantzilla
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,158
Park Forest, IL
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I have never seen anyone slow down from adding a Dana. I have seen a lot of people slow down from shelling out an 8-3/4.
"Everybody funny, now you funny too."
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Re: Building a strong 8 3/4 rearend.
[Re: justinp61]
#2799178
07/20/20 10:50 PM
07/20/20 10:50 PM
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Joined: Nov 2009
Posts: 3,082
St. Paul , Mn.
tubtar
master
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master
Joined: Nov 2009
Posts: 3,082
St. Paul , Mn.
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The best you can do isn't cheap , and won't be good enough.
Billet cap on the driver's side for sure.
Mark Williams sells them.
If you don't have access to a mill and measuring equipment , you are paying to have it fitted.
Some guys do both caps , but I don't know that it is necessary.
Good gears.
Excel by Richmond are made by the people who brought you Covid 19.
Regular Richmond are made in Italy.
US Gear are made here , but were recently acquired by an investment group , and I am having trouble getting the set I ordered through Strange. ( 4.30's for a 9" Ford )
A back brace is mandatory , and you cannot just fire up sparky and cook it on there.
The housing will warp.
Stitch weld , and take a long , long time.
You should move the leafs inboard if you stick with them , so you are moving the perches.
And I found out the hard way that the stock shock location and a back brace on an early A body will require some creativity.
I am not sure on the E body.
I don't bother with the 8 3/4's any more.
90 % of the racers on the planet seem to like the 9 " , and so do I.
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Re: Building a strong 8 3/4 rearend.
[Re: migsBIG]
#2799183
07/20/20 10:57 PM
07/20/20 10:57 PM
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Joined: Aug 2003
Posts: 43,096
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,096
Bend,OR USA
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On your deal a used pickup core Dana 60 would be my choice to use based on me breaking many 8 3/4 rear ends bracket racing  I bent a 8 3/4 housing bad enough in my old pump gas street race Duster to make it break the welded on ladder bar rear end brackets off of the housing   Luckily it happened on the starting line and not going around a corner on the street   That car pushed a bunch easier after swapping to the cut down Dana 60 pick up housing, a bunch easier No noise and maybe twenty Lb. heavier with the thicker pickup axle tubes with the 35 spline race axles  I'm a dedicated Mopar racer, Dana 60 came stock in the hi po muscle cars with stick tranny after 1965 for a reason
Last edited by Cab_Burge; 07/20/20 10:59 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Building a strong 8 3/4 rearend.
[Re: migsBIG]
#2799193
07/20/20 11:35 PM
07/20/20 11:35 PM
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Joined: Jan 2003
Posts: 30,989
Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 30,989
Oregon
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Hi all. Looking for some ideas, tech and info for the 8 3/4 rearend. I was thinking the race section would be a good section to ask than the Pro-Tour section as this question is more for strength and durability then handling. I have a 1970 Barracuda and will eventually be putting an Indy headed 440 I traded for as a swap engine. It's speced for high horse power and figured the rearend in it will not survive due to my 'aggressive' driving style (also making very bad noises already). Though my car will be mostly a street car, I will try for a few times at a straight line drag and eventually Willow Springs Raceway. Currently I have a 1969 b-body housing I plan to use with 'Cass' Doctor Diff inboard kit with Hotchkis springs and Viking shocks. I don't have a welder to make a back brace, but I was thinking of improving the internals. Doctor Diff offers a new 3rd member case with his Helical Gear Sure-Grip ("Sure-Trac") that would work well and looks like the strongest option without going to a spool. Looking for axles, bearing, gears and WILWOOD brake options for this. I do not want to go to a DANA 60 due to weight, noise and price (out the door prices have put them at over $3.k before shipping).Rear tires will be larger than the 295/50R15 Cooper Cobra's I currently have on it, but like the profile to be low for driving and looking for a radio around 3:23/3:55. Any help/info would be appreciated. For your application buy a Ford 9 inch. Doctor Diff can build one for you that will drop in and be ready to run.
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Re: Building a strong 8 3/4 rearend.
[Re: 4406bbl]
#2799235
07/21/20 07:49 AM
07/21/20 07:49 AM
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Joined: Jan 2004
Posts: 8,233
fredericksburg,va
cudaman1969
master
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master
Joined: Jan 2004
Posts: 8,233
fredericksburg,va
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I bought my 64 with a Stock 440 8/3/4 lasted 10 passes put the Dana in 1994 still there and cover has not been off since. You put them in and forget them for years, literally. By the way, when done you’ll have the same money in both, fords are more $ but they do have better gear selection
When I built the Dana I used the 8-3/4 35 spline axels, housing ends, bought used 4.88 gears and spool and truck housing. When done I might’ve had $300 in it. A friend bought an S60 for his Duster, right at $2000 from Dr Diff, setup and ready to install or it you scronge for parts the housing is around $600 from Strange and you fill in the blanks.
Last edited by cudaman1969; 07/21/20 07:59 AM.
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Re: Building a strong 8 3/4 rearend.
[Re: cudaman1969]
#2799244
07/21/20 08:21 AM
07/21/20 08:21 AM
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Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
an8sec70cuda
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 13,351
Marion, South Carolina [><]
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Unless you're a glutton for punishment, sell your 8.75 and move on to a stronger rearend that will actually take some abuse. If you make decent power and the car isn't a featherweight, you will fill the bottom of the housing w/ teeth. You CAN build a Dana for your car from a truck housing for a LOT less than what a new rear costs if you're willing to put forth the effort. You will not go slower due to the weight of a Dana...that's been proven over and over, yet people refuse to accept it.  A 9" IS A BETTER OPTION, but do the math on it and see what you're willing to spend. You have to realize a good 9" won't use any factory parts other than maybe the rear housing (not the center section). That rear housing also needs a backbrace.
CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
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Re: Building a strong 8 3/4 rearend.
[Re: an8sec70cuda]
#2799264
07/21/20 09:16 AM
07/21/20 09:16 AM
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Joined: Dec 2013
Posts: 4,663
Wichita
GY3
master
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master
Joined: Dec 2013
Posts: 4,663
Wichita
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You CAN build a Dana for your car from a truck housing for a LOT less than what a new rear costs if you're willing to put forth the effort. You will not go slower due to the weight of a Dana...that's been proven over and over, yet people refuse to accept it. I have under a $1000 in a cut down Dana 60 we pulled from a truck. I had way more than that in the 8 3/4 that was all new and died within the first year. I ran identical times (11.41) back to back weekends with both rearends.
'63 Dodge 330
11.19 @ 121 mph
Pump gas, n/a, through the mufflers on street tires with 3.54's. 3,600 lbs.
10.01 @ 133mph with a 250 shot of nitrous an a splash of race gas. 1.36 60 ft. 3,700 lbs.
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Re: Building a strong 8 3/4 rearend.
[Re: A/MP]
#2799275
07/21/20 09:33 AM
07/21/20 09:33 AM
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Joined: Jul 2008
Posts: 30,424
Florida STAYcation
dOc !
The village idiot's idiot
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The village idiot's idiot
Joined: Jul 2008
Posts: 30,424
Florida STAYcation
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Weight-HP... I had an 8 3/4 in my slingshot in the 80's. The 340 maybe made 450-500HP. About 500+ passes before I sold it. They had 8 3/4s in TF cars many years ago ! That old gEeZeR from BendOver Oregon mentioned this me thimks !
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Re: Building a strong 8 3/4 rearend.
[Re: migsBIG]
#2799365
07/21/20 12:47 PM
07/21/20 12:47 PM
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Joined: Aug 2003
Posts: 43,096
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,096
Bend,OR USA
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I forgot to mention that you should buy and use a steel cap on the drivers side of any 8 3/4 that will get abused by spinning tires that hook up quickly while spinning 8 3/4 ring gears get cracks in the outer edge of the teeth that eventually break off and fall into the rear end ending up getting jammed between the ring gear and pinion gear breaking both gears in a major way, which can lock up the rear end momentarily, NOT GOOD  Good luck on your car and decision
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Building a strong 8 3/4 rearend.
[Re: moparx]
#2799381
07/21/20 01:35 PM
07/21/20 01:35 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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a stoopid question, [i'm sure] but those that have back-braced an 8 3/4 and moved the springs while running the brace to the very ends of the tubes, have you inserted tubes into the brace for the U bolts to pass through ? if so, how did that work out ?  Before you weld on the brace just cut the holes in the brace for the bolts.. I did that years ago when I ran leafs.. since that time I ran either a ladder bar or a 4-link.. the last 2 are easier to set up.. the ladder bar needs one more brace for the street for cornering 
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....btw that one guy isn’t me. Stopped the bleeding and went Strange S60.
