Spool or open diff in a front engine dragster?

What is preferred, a spool or and open differential in an FED? Seems like a no brainer for the spool but I seem to remember reading and old article that quoted Don Garlits as recomending an open rear. What do you think?

 

uh...spool...one tire on a dragster is just pointless

 

Yeah, that's why I said it seemd lke a no brainer. I'm just trying to remember why Big Daddy would have said the open differential thing.

 

Spool. Your nuts are sitting on top of a set of spider gears.... Would you risk it?

 

Found it. In a Hot Rod article about his then new rear engine car he said the following.

"There are three unbreakable rules," discloses Garlits. "If you break any one of those three rules, the car won't work." Don lists them in order of importance: "Drop in a rear end that's completely open in back. I beg 'em not to put spools or posis in these cars. Hit the least little funny thing (uneven surface, oil) on the track and . . . zappo! You're into the next lane -- or worse. Posi rear ends work okay with a slingshot car, because when the posi throws you around, you have enough time to catch it."

http://www.northernthunder.com/upfront.html for the whole article.

So what are you front engine guys using?

 

ooh, the thought of that just made them tuck back up for a second...

 

Hell Kerry most of us only dream of that shit!..................But the Vagabonds fully support anything you do!

 

full dress pit crew et al

 

I'm just in dreaming mode myself right now but... the urge is getting stronger and I'm starting to gather a few pieces. I've got a spare hemi and was just given a header flange kit with starter tubes from a HAMB member who shall remain anonymous(You know who you are). Thanks!!! I'll probably use the 4 Stromberg setup I ran before I put the blower on the coupe. Thinking strongly of an early two hoop Dragmaster Dart style chassis. I'll not mention the parts I might be bidding on in the next few days. Wish I had some real spending money.

I do wonder how long till my dear wife kills me. She keeps saying I've got to many projects. She's right but I can't help myself.

 

We run spools in ours

 

Yep !

However....if I had it to do over I'd use a spool because it might help eliminate the fishtailing. At my age I don't worry about the nuts that much.

 

Open differential is preferred if you like to be able steer your car. Mine is open with the spiders shimed on the tight side. Broke spiders won't get yer nuts anyway. Broke ring gears/bearing journals do that.

 

There was a brief fad in top fuel in the late 60s to use an open rear end, but it didn't last long. Not even the made-for-top-fuel, Ed Pink spider gears were up to the task. I ran an open 8 3/4 Chrysler in my old injected car in the early 70s, and it worked fine, but it was a very light car with small tires, so there wasn't much load on the rear end.

An open rear will pull (or spin) both tires if you have enough power. I never, ever, saw or heard of any broken rear end parts come through an Olds, Chrysler, or Ford housing, but there was a good reason they ran a steel shield over the old banjo rears in the old days. I have seen a few pumpkins come apart in the pinion snout area. I haven't personally known of anyone not using a spool in a high horsepower dragster (front or rear engine) in the last 35 years.

My old car with the open 8 3/4. With the clutch locked up it would smoke both tires to about the 1/8th mile.

 

I think part of the reason for suggesting an open rear end back then was that the parts were simply marginal- axles broke, gears broke, etc etc - when stuff started breaking it made better sense for the rear to be open.
Nowadays we have the advantage of using far better parts - the likelyhood of them breaking is far less.

The next big factor in todays parts as it's simply NOT even a consideration because the minute you step up to the better stuff your ONLY OPTION is a spool. I don't ever recall seeing an open center or posi setup available for 35 or 40 spline axles.

If you're running stock spline sizes - it's a bit of a double edged sword IMHO.

I have a spool in mine, 35 spline axles and the PRO gears ("softer") and they also have a bigger pinion in them. The only thing OEM in mine is the outter housing. I don't think I'll make near enough power to ever hurt it.

 

I used a spool in my dragster (127"FED),until I broke an axle on the starting line,almost went into the gaurdrail...and it never turned tight enough at the turnaround also...I switched to a 9" Ford with shimmed spiders(tight). it kept straight, steered tight at the turnoff,and smoked both tires!! Something about a solid mounted rear,I'm told because there was very little 'tire lift". Rear tire pressures,were adjusted so the slicks were the same circumfrence(use a cloth tape),despite pressure diffrences..sometimes 12# on the right and 9# on the left!!! Oh a 1/4" shield over the 'Jewel" area on the pig ,for shure!!! Do a google search for John Kranenburg(my ex-father in law) Be safe.. have fun!! Sparky

 

Do it Kerry.

 

is your old dragster in the new car craft.....? brandon

 

Dunno.....don't ever read Car Craft.

 

Dana 60s had 35 spline posi (think 4 speed mopar muscle cars), but yeah, parts availability would be an issue

 

try this....looks like it could have been you.... brandon

 

The spool will turn the car if you break an axle,but in these days of good axles,how many aftermarket axles do you see break?
On a marginal track with some good power if an open rear car begins to get loose it's very difficult to drive through and will spank your ass like a step child if you try.A spool car won't.It will either drive through it or loop.
Reason being with an open rear if you try to drive through a little loose,one tire will hook and then unhook and the other side will hook and then unhook and so on and like that,and the resulting gyrations will wow the onlookers but beat the pilot up.
A spool and quality axles are worth the expense. It's not 1971 any more and I bet Garlits 3 rules would be different today.

 

Hummn....I didn't realize that they ever used Dana 60's in Front engine dragsters

 

I'll be damned !

 

I f you ar e building a drag car you are going to want NEW parts,old ones will get you killed.For your question ,run a spool with new ring and pinion and new axles.

 

There is a lot of difference in 400hp and thousands, and I think the answer to the question depends on this. We used an open Olds and were perfectly happy with it, but we never ran anything hotter than a SBC in C/D.

If you sit in the pits with a FED, every third person that comes by gawking makes mention of the tender area issue, particularly when they peek inside and see the 1/4" nut plate. This reminds me of overhearing a conversation among some seasoned old timers on the subject. The bottom line of the conversation was that none of these guys had knowledge of any drivers being injured by shrapnel exiting the differential. There were some injuries involving the entire rear end breaking loose from the chassis. The Kranenburg accident was mentioned, and from what I remember, it seemed to be the understanding of these guys that this accident involved a lock-up that caused the rear end to break from the chassis. Sparky, is this correct?

 

seems like read a deal on jack chrisman about the rearend twisting ....seems like the same was mention about the guy that had the pure hell altered... brandon

 

I actually use a factory 8 3/4 3.90 posi unit in mine.

 

Broke spiders then cross pin coming out housing would hurt nuts. I've broke two 9" very badly and had parts come out the back so I don't risk it anymore. Also a buddy of mine had a set of spiders pile up on him and sent him for a ride into the weeds.

 

Hey Johnny Fast , fess up, that is the car you used to pilot,but now belongs to Pete Stamm of Waukesha,Wi. That car couldn't have found a better home ,Pete deserves a lot of credit for the way he cares for the car and even has the balls to thrash it once in a while for others to enjoy!! Give up the attitude and get in on the fun. Ancactrau

 

BFD !! I'll "give up the attitude" when that car is back in my shop where it belongs. I'll write a check today in the amount I sold it for.