Rear end advice for racing with a 4 speed

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Nuthing like the look of a Dana under a Mopar.
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Get one of those TA covers with the cap supports in it for the 60. They are somewhat expensive new but used ones ain't bad...
Takes less power to run a Dana vs 9inch also
Ain't much difference but when ounces count, so does every bit of power robbers.
Spools are nice but on the street not so much. JMO
Can't drive em in town like you do a reg diff but once you learn a couple of tricks, it really isn't a big deal.
I know it's blasphemy....

Ford 9"

Parts are cheaper and readily available.
Many think that a 9 is much stronger than the 8 3/4.....well, although it is stronger, it isn't that much. Imo, they do not hold a candle to the 9 3/4 (60). Lots of people like the drop out but for those that set up their own gears, you can swap gears in a Dana fairly quickly too if you save the shim package and keep them with the gear set you just removed. That way if you want to go back to them later, it's fairly easy and quick.
 
450 hp with a 8 3/4 is do-able with an auto trans. With a four speed I would plan on a Dana 60 or Ford 9". A Ford rear might not help resale value (if that means anything) but a Dana certainly will.
You can spend money on the 8 3/4 to make it stronger, but it still might not be strong enough, and upgrades are expensive.
If it were me? Id get a strange 60, and sell the 8 3/4 before you break it again.

When the clutch is right for a dead hooking manual trans radial car, the hit on the drivetrain will be softer than with an automatic. I've ran low 5.70's with 1.30 60's on radials with 28 spline axles in an un-braced chevy 10 bolt housing, using an overkill 800hp clutch that was 'tamed. Only failure was a twisted driveshaft, that was when I un-hooked the 'tamer for a with/without test back in 2013. Instant failure without the 'tamer hooked up...

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Same 28spl axles until Nov last year, then only retired because the driver's side axle/tube was severely bent in a near head-on collision.

Grant
 
Takes less power to run a Dana vs 9inch also


It depends on the ratio but yes, that is true. And the lower the gear ratio (higher numerically) the better the D60 is.

Gear selection is getting thin and that’s a shame because except for one small flaw it’s as good as the best 9 inch and far cheaper to build.
 
In the photo of the housing getting narrowed up. That's a Dana 60 HD housing. Those are boat anchors with and not something I would ever use under a car.

Getting a housing from 60's or 70's Ford F250 is a great place to find one, but you have to be careful in the mid 70's up because you could end up with a Dana 61.

The later they get past the 70's the heavier the housings get and worse yet the axle tubes start getting really thick. Some are close to 3/8" wall.

Tom


That’s the ones I look for. Those thick tubes make the unit more rigid.
 
One small point. Disregarding the other parts of the strength equation.....a Ford stock 31 axle is about 25% stronger than the 28s.
A 35 spline axle is almost 50% stronger than a 30 spline.
And a chromemoly axle of the same spline is about 40% stronger than a stock material axle.
So, just the axles, good 35 spline axles are at least 100% or more stronger than stock 30s
35s are available in good material for an 8 3/4, but I believe ONLY for a spool. (Unless dapco offers side gears for their locker)
 
Please post up your math because I’ve built both and the 9 is never cheaper.
For all brand new parts, depending on what you want from the nine, I think you are right. Kinda depends on your starting point, and what mods you can do yourself.
Especially if you can narrow a truck Dana yourself, a strong Dana will be a bunch cheaper than a similar strength nine.
 
Strange S60 is what a lot of guys went to. Strange S-60 for Mopar, Ford, Chevy/GM Scott destroyed his 8 3/4 and went with the S60 many years ago.

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Damn, not only is that a sexy car, you just about can’t make a door car leave better than that.

Nice front suspension drop, about 20-25% of the rear tire is wrinkled and not smashed to death and the rear of the car isn’t all stink bugged out with separation.

And the car is flat with perfect pitch rotation.

Good thing the wife isn’t here because that gets me excited.

PERFECT!! The dude that set that car up had his poop in one nice, neat pile. Awesome.
 
Okay, Okay!!!

Dana 60 because of the position of the pinion is actually a very efficient rear end, and is not a power robber even though it has a 9-3/4" ring gear.

I run a Mark Williams billet cap on mine (actually I have Mark Williams caps on both sides, but totally not necessary) I just did it because I could. I think the covers are band-aids.

Dana 60 housing can be as cheap as $50 around here, used gear sets are $100, Strange spool (35 spline here) $350, and axles all cost the same.

Use car ends, or in my case I had a junk 9-1/4" housing I robbed them off of.

The one I have in my 63 only cost me $800 complete because I did some thrifty shopping. No 9" Ford can be built anywhere close to that, and as already mentioned.

Dana 60 rules when you look underneath and probably adds at least $1500 to the value of any vehicle that has one.

Tom
 
Damn, not only is that a sexy car, you just about can’t make a door car leave better than that.

Nice front suspension drop, about 20-25% of the rear tire is wrinkled and not smashed to death and the rear of the car isn’t all stink bugged out with separation.

And the car is flat with perfect pitch rotation.

Good thing the wife isn’t here because that gets me excited.

PERFECT!! The dude that set that car up had his poop in one nice, neat pile. Awesome.
I think Scott did it himself. I posted a pic of a pro street 66 from the Nats many years back. He liked it so well he found one, took out the slant and added a 360. That lasted on the street for a short time and he decided to stroke the 360 and go racing. That was over a decade ago.

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Damn, not only is that a sexy car, you just about can’t make a door car leave better than that.

Nice front suspension drop, about 20-25% of the rear tire is wrinkled and not smashed to death and the rear of the car isn’t all stink bugged out with separation.

And the car is flat with perfect pitch rotation.

Good thing the wife isn’t here because that gets me excited.

PERFECT!! The dude that set that car up had his poop in one nice, neat pile. Awesome.
Must have a anti roll bar in it t
 
Okay, Okay!!!

Dana 60 because of the position of the pinion is actually a very efficient rear end, and is not a power robber even though it has a 9-3/4" ring gear.

I run a Mark Williams billet cap on mine (actually I have Mark Williams caps on both sides, but totally not necessary) I just did it because I could. I think the covers are band-aids.

Dana 60 housing can be as cheap as $50 around here, used gear sets are $100, Strange spool (35 spline here) $350, and axles all cost the same.

Use car ends, or in my case I had a junk 9-1/4" housing I robbed them off of.

The one I have in my 63 only cost me $800 complete because I did some thrifty shopping. No 9" Ford can be built anywhere close to that, and as already mentioned.

Dana 60 rules when you look underneath and probably adds at least $1500 to the value of any vehicle that has one.

Tom
I bought an aluminum section for my 9", 4.10s and a spool, at about 40% off, at a black friday sale..... and it still cost me $600 plus. (well over $1000 sticker).
 
Wow thanks for all the replies everyone. To be honest I wouldn’t consider putting in a Ford 9”, my car is a lot of things, cruiser, the odd car show, drag racing now, and of course a mopar, I just can’t cross that line of putting in a 9” even though a lot of guys do.

It’s definitely sounding like a Dana60 is the way to go with the 4-speed, my car’s insured for another few weeks and then that’s probably what I’ll follow through with over winter.

Thanks for all the replies guys! Mike N.
 
Wow thanks for all the replies everyone. To be honest I wouldn’t consider putting in a Ford 9”, my car is a lot of things, cruiser, the odd car show, drag racing now, and of course a mopar, I just can’t cross that line of putting in a 9” even though a lot of guys do.

It’s definitely sounding like a Dana60 is the way to go with the 4-speed, my car’s insured for another few weeks and then that’s probably what I’ll follow through with over winter.

Thanks for all the replies guys! Mike N.
What clutch are you running? Also, what weight is flywheel?
 
Your clutch is what twisted the axles. The more torque capacity a clutch has, the faster it pulls the engine down when you dump the clutch, which results in a sharper impact sent to the drivetrain. Most install an aftermarket clutch and think nothing of putting a 650tq capable clutch behind a 450tq engine, not realizing that excess clutch torque capacity is counter-productive and leads to bog/spin/broken parts problems. A proper clutch for the OP's 340 only needs about 2500lbs of clamp pressure on an organic disc to hold the engine after the shift into 4th gear. Aftermarket PP typically has quite a bit more, simple solution is to shim the aftermarket pressure plate until it barely holds after a WOT shift into high gear.

A pretty common misconception is that you only want the clutch to slip during launch, truth is there is more to clutch tuning than just dialing in the launch. For proof just look at the data logs from any fast adjustable clutch car, it's pretty common to see half a second to a full second of clutch slip after the shift into high gear. They could easily adjust their clutch for less slip after the shifts, but data tells them the car is quicker and more consistent with the slip.

Even after the PP clamp pressure is optimized for the application, you still won't have enough clutch slip for a proper radial launch. Simple way to get what you need during launch is to add a ClutchTamer. A 'tamer momentarily reduces clutch clamp pressure, which in-turn allows the clutch to slip longer than it otherwise would in 1st gear. That gives the car more time to gain ground speed before the clutch locks up, which helps keep the engine operating up where it makes more power.

Grant
Hey Grant,

I have a McLeod Super Street Pro clutch. I actually bought a clutch tamer from you earlier this year but to be honest I haven’t been able to get it dialed in and I wasn’t using it when my rear end broke. I’ll PM you and hopefully I can get some pointer’s from you on getting it dialed in.

Thanks, Mike N
 
What clutch are you running? Also, what weight is flywheel?
I have a 22lb McLeod lightweight steel flywheel and McLeod Super Street Pro clutch.
As far as the abuse I throw at it I’m launching at 4500 and shifting at 6500 when racing.
 
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I have a 22lb McLeod lightweight steel flywheel and McLeod Super Street Pro clutch.
As far as the abuse I throw at it I’m launching at 4500 and shifting at 6500 when racing.
Good evening,
I have recently been discussing clutches with some very knowledgeable stick racers. My learnings as of recent are that clutch companies want to overclutch every car out there, hence dual disc clutches being sold in large numbers. I notice you have 440hp, and a 550 HP rated clutch. Clutch companies are not wanting their clutch to slip, so high base pressures and discs with very high coefficients of friction are being spec'd. I myself fell to this kind of thinking, not knowing any better. As we speak I have pulled my rxt dual disc out of my Dart and replaced with a Borg Beck and Long PP with 2400lb static base, which will be paired with an aluminum flywheel and organic disc.

After speaking with very successful racers, the realization is that clutches have to slip, or parts break, hence soft lok full race slipper clutches. In fact I'm learning that 60 foot and ET's actually improve with some slippage, while also being much easier on mechanical parts. While I certainly don't imply you need a soft lok, perhaps re evaluate your clutch vs output.

Please be aware, I have no direct experience with these setups yet as I am in the install process currently. I simply express to you the idea to reach out to people actually running this stuff. I find it most interesting that you can call any clutch company you want, you will likely get over spec'd from every one, and likely get a different answer from various techs within the same company.

My suspicion is your parts breakage is more a clutch issue, rather than 8 3/4 weakness.
 
Wow thanks for all the replies everyone. To be honest I wouldn’t consider putting in a Ford 9”, my car is a lot of things, cruiser, the odd car show, drag racing now, and of course a mopar, I just can’t cross that line of putting in a 9” even though a lot of guys do.

It’s definitely sounding like a Dana60 is the way to go with the 4-speed, my car’s insured for another few weeks and then that’s probably what I’ll follow through with over winter.

Thanks for all the replies guys! Mike N.
Nothing wrong with brand loyalty at all. I guarantee, Mopar guys would rather see a 60 than a 9.
I've got a 4.10 Dana in my rr, and an 8 3/4 dapco locker in my savoy.
My nines are in an Opel, and an English Ford. But brand loyalty has nothing to do with those two.
 
The problem with a leaf spring Mopar having a back braced rear end is shock clearance. If you run the back braces all the way to the housing ends to be most effective you have to hack out big chunks of the bracing to make room for the shocks.

That is correct but you can make clearance for the shocks and close it up with no loss of strength IMO. I've been there:

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I ran a 4 speed on the track with some history. I twisted stock 8-3/4" axles, broke a 4.56 489 case setup (ring gear/posi failure), broke a 489 5.13 (ring gear failure), and bent the rear end housing itself. I cured those problems by back bracing the housing, using aftermarket axles, using a 4.86 pro gear setup in MP 742 aluminum housing, spool, but most importantly, using a McLeod Soft Lok clutch to eliminate the launch shock.

Long time since I raced but it was all living without failure in my '65 Barracuda running 10.80s in the quarter mile. I think I was launching at 4000 rpms or so. I suppose a clutch tamer may have helped me but the holy grail for me was the Soft Lok clutch. It is fully adjustable and I loved it. They are fairly expensive nowadays though. FWIW.
 
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