8.75 Strength?

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The biggest difference between the 9" and the 8.750 in terms of strength to me is the 9" has pinion support at the gear, whereas the 8.750 does not. I'm no engineer, so I don't know what that adds, but it seems like it would add something. I may be off base there. Just from looking at it, it makes sense.

As far as the turbo 400 thing, I like sticking all MoPar too. But the mathematical fact is the turbo 400 is way easier on the budget at those power levels.

No sense agruing over any of it as I will be surprised if any of it comes to fruition anyway. ;)
 
No sense agruing over any of it as I will be surprised if any of it comes to fruition anyway.

You hit the nail on the head here Rusty.
Unless our young gun has over 30 grand to do this properly.
However, my idea of ''budget build'' and John Force's are different.
 
RustyRatRod said:
The biggest difference between the 9" and the 8.750 in terms of strength to me is the 9" has pinion support at the gear, whereas the 8.750 does not. I'm no engineer, so I don't know what that adds, but it seems like it would add something.
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That doesn't add any additional strength, the design of that diff with that bearing is because the pin is so low on the ring and the pin so short that the 2 major bearings have so much force on them in that position that without that bearing you wouldn't get out of the driveway without this happening , but when you see this



The inner case bearing had a problem and now you need gears, housing, trans and shaft usually, may get away with the trans depending.
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Sorry for not replying, I've been working a lot lately. The motor will hopefully be a stroked r5. I'm still waiting to hear the price of big inch r5 cranks. Also looking into an aluminum block, but I won't be getting one unless I can get a deal. I can get the parts really cheap for myself, so it won't be a $20-30,000 motor. At the least, I can make 875 hp with a stock stroke r5 using 100 octane fuel. I know what I'm doing with the engine and have plenty of well experienced friends, but I am still aquiring parts. It'll be a while before I build it. I've been told that a Jerico would be cheapest for a transmission and I think that'll work well. Yeah, It won't get great mileage, but it won't bother me. They get 4-4.5 mpg in a Cup car that weighs 4,000 lbs so I know to expect around that. It'll be an r5-Jerico-Dana 60 if plans stay the same. As for the car, It may be in my Duster or something a little more safe. I'll decide that when the time comes depending on what I have.
 
Now, I'm pretty sure the reason the 9 in. and the Dana are "stonger" is because of tooth contact area..

Decades ago, I read a few articles that lead readers to believe that the bigger ring gear of the Ford and Dana, - spread the load to 3 teeth, as opposed to the 8 3/4 only had contact with 2 teeth..

And from the same sources, I was lead to believe that the 8 3/4 and the Dana shared the same pinion yoke, thus making the minimum diameter of the pinions of the 8 3/4, including the nefarious 741 "small pinion".. AND the DANA... all use the same yoke... thus same pinion size at the narrowest (weakest) point.. were the same....

As to the trans.. back in the day, - Ferds and Chebbie fuelers all ran MOPAR "Clutchflites".. before specialty tranny makers came along...

I'll wait to be corrected by our more knowledgable members..
 
inertia said:
Now, I'm pretty sure the reason the 9 in. and the Dana are "stonger" is because of tooth contact area..

Decades ago, I read a few articles that lead readers to believe that the bigger ring gear of the Ford and Dana, - spread the load to 3 teeth, as opposed to the 8 3/4 only had contact with 2 teeth..

And from the same sources, I was lead to believe that the 8 3/4 and the Dana shared the same pinion yoke, thus making the minimum diameter of the pinions of the 8 3/4, including the nefarious 741 "small pinion".. AND the DANA... all use the same yoke... thus same pinion size at the narrowest (weakest) point.. were the same....

As to the trans.. back in the day, - Ferds and Chebbie fuelers all ran MOPAR "Clutchflites".. before specialty tranny makers came along...

I'll wait to be corrected by our more knowledgable members..
Click to expand...

I haven't had a Dana but I have seen pics and see it's a fine spline unit so it could possibly be the size of the later 489 fine spline gear set.. The 741 and 742 and early 489 cases used the smaller diameter (and weaker) 10 spline pinion. The later 489 case that used the fine spline yoke had a much larger/beefier pinion
 
Thnx Fishy,, but I guess my question would be ,.. do the 8 3/4's break pinions,, or break teeth?? v/s Ford 9" or Dana??
 
fishy68 said:
The only broken 8-3/4's I've seen had broken teeth. But I haven't seen a lot
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and thats from deflection at that...

as for the trans a jenco or jerico have down shifting abilities. think the diff between the two is one is a mag case like a lenco and the other is aluminum.

on the second motor build for my Altered it will be getting a 605 Aluminum Hemi with Stage V Millennium heads, EFI and a 727, unless i cant resist the sticks!

but that monster will put me in the low 9's in a street car if not faster.
 
I've seen 1 garbage 83/4. It was an open diff I. A 69 coronet sedan. The entire diff assembly was rotating 1/4" inside the case! Seems like the was a hole for a 3/8" pin and it was the hole that broke. Asa's driveshaft would make a 1/4 turn before the wheel would turn! ...and that dude still pulled that 4,000lbs down the road when they decided to put 3.23's in it

This was about 10yrs ago give or take
 
inertia said:
Cool,, so ... maybe fords break cases, and dana's break .. hmm.. pinions ? ? ?
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dana 60's were used in top fuel for almost 20 years as i recall. were talking blown nitro dragsters, floppers, slingshots, you name it... if a dana wont do it then a strange liveaxle will...
 
805moparkid said:
dana 60's were used in top fuel for almost 20 years as i recall. were talking blown nitro dragsters, floppers, slingshots, you name it... if a dana wont do it then a strange liveaxle will...
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Just curious,, if you ever saw one break,, what broke?? any-one?

Sorry... didn't mean to hijack thread,, apologies..

I have more hair growing on the inside of my head, than outside,, and sometimes it tickles my brain, and things get fuzzzy.. ;-)
 
805moparkid said:
but that monster will put me in the low 9's in a street car if not faster.
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Only if you improve on your tuning skills. Look at the slant. lol

Sorry. I couldn't help myself.
 
Thank you SuperShafts for your description for my question and thank you Fishy, moparkid, rustyrod, inertia and everyone else for a sensible read...

This may sound real lame to some yet, I would rather change a carrier or an axle on the side of the road than have to call a tow service from the middle of nowhere.



In the early days of street racing, I carried these in the trunk..
 
HotLines said:
Thank you SuperShafts for your description for my question and thank you Fishy, moparkid, rustyrod, inertia and everyone else for a sensible read...

This may sound real lame to some yet, I would rather change a carrier or an axle on the side of the road than have to call a tow service from the middle of nowhere.



In the early days of street racing, I carried these in the trunk..
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speaking from experiance, when u start blowing an 8 3/4 every other week-end, you`ll wish u did the dana 60 to start with!
also, a 727 can be built way stronger than people here are saying.---bob:wack:
 
inertia said:
Now, I'm pretty sure the reason the 9 in. and the Dana are "stonger" is because of tooth contact area..

Decades ago, I read a few articles that lead readers to believe that the bigger ring gear of the Ford and Dana, - spread the load to 3 teeth, as opposed to the 8 3/4 only had contact with 2 teeth..

And from the same sources, I was lead to believe that the 8 3/4 and the Dana shared the same pinion yoke, thus making the minimum diameter of the pinions of the 8 3/4, including the nefarious 741 "small pinion".. AND the DANA... all use the same yoke... thus same pinion size at the narrowest (weakest) point.. were the same....

As to the trans.. back in the day, - Ferds and Chebbie fuelers all ran MOPAR "Clutchflites".. before specialty tranny makers came along...

I'll wait to be corrected by our more knowledgable members..
Click to expand...


That's pretty close, the 9" has the most tooth contact from the pin being moved so low on the ring, it has actually more contact area than any other diff.
However it has more power loss and even more stress trying to rip that pinion out than another diff, and the reason for that 3rd bearing NEEDING to be there and not there as hey lets make it even stronger...
The Dana has a better pin location, and larger ring, housing and tubes and will do more with all it's factory parts and no bracing than the 9" will do in factory form and no bracing.... you can live that same pic above using ford factory parts.

The pin on the 8.75 is larger than the 9" in two ways, length and diameter.

I have 8.75's in many classes of drag racing and even road racing, drag racing in just about every SS class, and in the more serious SS classes the move to the AL housing and Mikroniting the gears has given us the best results, but the NHRA just recently said the AL case is illegal, so we're back to the Factory style case, still using the Mikronite gears and we'll see if it was the Mikronite or something about the AL.
Before Mikronite and AL cases pretty much the best we could do was 2 full seasons before a tooth pulled, with the AL case and the mikronite i have had them beyond 3 seasons and still going, and now 5 of them are back in the stl case with more than 3 season and we'll see what happens.

However there is a issue with the AL case on the street, so don't run out and buy one, one AL case used on the street developed a noise after some time, i am believing that it needed a different adjustment to compensate for the AL movement when hot, something that does not happen in drag racing. I never bothered to play with it, just that i found it better to not use them for the street.
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Again, at the higher hp levels of SS before Mikroniting we would get a tooth pull around 2 seasons or just over 2 seasons...

With a Dana i don't see you again unless you consistently drive thru wheel hop or tire shake (which is not smart, but it's done), but of both diffs the D-60 and the 8.75 when they do have a issue it is usually a R&P or axle, not the entire center housing, shaft and trans...
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Yes the 727 can handle well beyond what some people are saying, just have to use the right builder.... not the guys using the parts of the pioneers and lack the rest of the knowledge.

.
 
inertia said:
Just curious,, if you ever saw one break,, what broke?? any-one?

Sorry... didn't mean to hijack thread,, apologies..

I have more hair growing on the inside of my head, than outside,, and sometimes it tickles my brain, and things get fuzzzy.. ;-)
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personally no. but i think its the same deal as a 727, ford and chevy guys tell you they are a waek trans, "just look how they blow there guts at the line all the time", and we know thats driver error from buning and hooking in first with a non low band apply MVB.

with the dana it has to be setup correctly like anything else, to tight here or to loose there and something has to give because it wasn't designed to work that way.

RustyRatRod said:
Only if you improve on your tuning skills. Look at the slant. lol

Sorry. I couldn't help myself.
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hey thats a fair jab! just takes time and a track and i dont have either right now
 
famous bob said:
speaking from experiance, when u start blowing an 8 3/4 every other week-end, you`ll wish u did the dana 60 to start with!
also, a 727 can be built way stronger than people here are saying.---bob:wack:
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I think you're misunderstanding on the 727 thing. No one said they couldn't be built to withstand the power.......quite the opposite in fact. They certainly can be. The turbo 400 would be way cheaper at that power level. I'l never have that decision to make as I'll likely never make half as much power as we're talkin about here anyway.
 
Supershafts said:
That won't work, the best you can get is a 600hp hit with a cam and heads that have good work, and at that you won't make many passes before you break the wrist pin area....
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Killjoy.
 
inertia said:
Just curious,, if you ever saw one break,, what broke?? any-one?
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I broke one a few years ago, still don't know how I did it, :D.

Took it apart and I had chunks of ring gear and pinion teeth in the bottom of the case.

Funny thing is it would still move me down the road with the occasional slight vibration.
 
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