Welding the spider gears
 

Anyone ever welded the spider gears of the diferential together or know what i am talking about tell me the pros and cons to doing it.

P.S. I am making a pavement oval track racecar and obviously want to get it around as fast as possible. The track i will be racing on is short so the straight aways are short.......if this matters


__________________

Not recommended unless you have no money.
If you have no money, you shouldn't be racing.
There are lots of very good options in terms of a drop-in aftermarket LSD - why not get one of them?


-Ted

I don't know much about circle track set-ups, but it seems like a welded/ locked rear end would make the car push really badly. Then, all your handling adjustments are trying to compensate for that. Unless you are planning on driving around all the turns with the back end loose... but that's not really the fast way around on pavement.
I would think a stiff clutch style LSD would be a good compromise.
Good luck

Well this idea has some goods and some bads. I did it in my first car and won a bunch of races that way but it does make the car push. So you'll need to tune the chassis to compensate. Sure the LSD is the best way to go and that is what I'm using now, but welded is far better then an open dif and somewhat better then a stock FC diff (untill it rains). Since your doing oval tracks and the cash is low, it sounds like just the ticket. I'm looking forward to your post titled "I welded my dif and now it wont turn". :)

BTW there is never enough money to go racing! I've tried to spend it all and allways have things left on my want list after the money is all gone. Racing is all about doing the best you can with what you got.

Welding Spider gears is more for drag racing than turns, you may snap an axel if you got to much grip and power.

Weld that sucker
 

Where do you people get this stuff? MAZDATRIX tell you in their catalog how and why to weld up a rear end. They go in to great detail about why its better than a posie. On a circle track car you run rear tire stager to keep it from pushing, and to make it turn in better in the turns. A posie will not last on a circle track. That why spools and welded rear ends are what are used. And no one said this guy was poor! He justs wants some facts so he can go fast. No one makes a Mazda spool so welding it up is next best. Make sure you seal up the outer axle tube with a large washer, or all your oil will end up there. Put two breather tubes on the inside axle tube on the rear end too. You've got to get rid of the pressure in the rear end, or you'll blow seals every race. Run the rear end at least 1 qt over or you'll lose the gears. Mazdas make very GOOD circle track cars, but most tracks have band them because their so fast. Hope this helps you out. Good luck in your racing.

DICK

i read mark donohues book and they ran no diff, even in the 917's...

How about this spool at the bottom of the page?
http://iscracing.net/axle.htm

double post!

SPOOL
 

Looks like the way to go except alum might not work on a circle track for long. Cost 100 times a welded rear end too.

Say What????
 

Say What???? Of course they ran a diff unless they had chain drive. What they didn't use was a posie. Read the book again.

Re: Weld that sucker
 

Wow, I guess you negated to mention all the downsides of a welded diff...

Can at LEAST spell "posi" correctly???


-Ted

:scratch: Wha?

An open diff with welded spider gears effectively becomes solid; it turns the diff into a spool as it no longer has any differential action whatsoever. Anyone running on ovals use spools because they use tire stagger (outside rear tire larger in circumference than inside rear tire) in order to help the car turn. Spools are not unheard of in roadracing either. Typically found on very powerful cars with rear grip issues (mostly in the past).

Re: Say What????
 

Ridiculous. Just because a car has gears between it's drive and axles doesn't mean it has to have a differential of any type as well. I mentioned the spool already above.

I don't have the book in front of me but I too recall the Porsche having no differential even though it certainly still had a ring and pinion. A spool is merely a solid carrier for the ring gear that drives the axles. Since it has no moving parts in it both axles always turn at the same speed as they are 100% locked together.

At the same time just because something is chain drive does not mean it has no diff. There are lots of sports racers out there with motorcycle derived drivetrains that run chain drive and yet still have a diff.

Well Ive mostly seen them on V-8s running the drag, and of all the times Ive been to the track (lol 5) I have not really seen anyone that did that.

Re: Re: Weld that sucker
 

Dont correct me! Why don't you contact MAZDATRIX and correct them. I'm only repeating what their catalog says. Since posi or posie is not one of the Kings english words, I can spell it anyway I want to. Right? Aprox 1/2 the cars on a road course today run a locked diff. The axles never know if its a weld job or a spool. Even a Detroit locker is a locked rear end when its engaged. Sorry about the spelling, but thats life. Were not all perfect.

Re: Re: Re: Weld that sucker
 

WTF???

So you're telling me you're regurgitating the Mazdatrix website and you have ZERO experience with it yourself?


-Ted

Re: Re: Re: Re: Weld that sucker
 

The only rear ends I have ever used, were not posi or posie or welded, but detroit lockers. For the past 40 years ( thats 40 years) I have used nothing but detroit lockers in all mine and customer cars that I have built in NHRA-AHRA-IHRA-SCCA-IMSA-NASA-USAC-Hooters-ETC,ETC. So you see that in those 40 years, I or my customers have always raced with a locked rear end, even in my Mazdas. Locked rear ends were here before WW2 and will be here long after you or I are gone. It makes no difference to the rear end if the spider gears are welded or it has a spool or detroit locker. It never knows. All it knows is its LOCKED. Now I dont know what you do for an income, but me? I'm 70 and retired. If you don't know any more about locked rear end than you stated here, you should try retirement too. Have a happy day.

If I had the money, I would love to retire.
Looking for a job tires the shit out of me.

I still don't get it.
If an LSD is designed and pre-loaded right, wouldn't it be superior than any locked rear?
Don't take this the wrong way, but welded diffs or spools is the "cheap" way of doing things, and it's widely done in redneck motorsports?
I don't think touring car (British / Aussie / Japan) and or real open wheel race cars use them.
Or is this just an oval track thing?


-Ted

More useless Mazda B/S
 

In all of my 40 years of racing, I never broke a detroit locker! That alone is a good reason to use one. One car was a 3940 lbs Ford in 1963, that broke just about ever thing under the car drag racing that could be broken, except the detroit locker. Once at the 64 AHRA nationals, I found the locker on the ground, under the car after a burn out. Still hook'd to what was left of the drive shaft. This was before nodular third members. You quess'd it, locker was the only part ok. I broke many axles with this car but never broke one in later cars road racing or stock car racing. I drove cars funded by Ford, GM, and Mazda, and all were built with detroit lockers, just like all Shelbys were built with. All factory Mustangs, Cobras, GT-40s were locker equiped. Good axles are a MUST! Once you get use to driveing a locker, it no diffrent. In fact I use to love racing in the rain with one. I see articles in mags about how to make your posie more slip proof by adding more to the clutch pack. If you do this , you've got a locker. Posies also make the oil run hotter in the rear end. NASCAR uses them on road courses, and they fly. Theres a story here. Just think about it a while. Lockers are the perfect example of the KISS method of racing. Keep It Simple Stupid.

Has someone mention that nearly all oval track cars run spools? The original question had nothing to do with road racing, autocross, etc. It's related to oval track racing.

The stagger that oval track cars have wouldn't work without a spool and would over work any type of differential. And likewise a spool won't work real well without stagger. If you're running a roundy-round car a welded diff or spool with the proper stagger is the way to properly set it up. And yes, you will have to turn right a bit to get it to go straight.

Detroit lockers are cheap, reliable solutions but leave some things to be desired compared to other designs. A Detroit locker fully locks under power but when there is a wheel speed differential the outside wheel will unlock completely and so the car is now driven only be the inside tire. When power is added the unit will once again lock.

All of this of course happens when you are trying to get through a corner. As the diff locks and unlocks the car is actually going from two wheel to one wheel drive and this tends to make the car hunt or jump around when you're trying to place it into the corner. Life really gets complicated if you also decide you need to modulate the throttle for any reason while you're in the corner.

They are cheap, tough diffs. They are also terribly noisy and upset the chassis as they lock and unlock. Nearly every other type of limited slip diff is much more linear in function and also allows you to still drive both wheels when the things is unlocked. Cam and pawls, clutch packs, viscous diffs, Weismans and Torsens do not have these all off or all on power charactersistics; they are much more fluid in operation. Mostly Detroit lockers were only ever used because they are very cheap and hard to break.

Detroit Lockers
 

If what your saying was true, NASCAR wouldn't use them on road courses would they? But then maby thats why they all spin out in the turns. Right? Wrong! A detroit locker will not un- engage as long as power is on. And any racer worth his oats, will brake in a straight line, and be back on the power as he enters the turn. And cheap! Really now! Don't you think NASCAR could pay for a better item if there was one. Plain and simple, there is no better locker in the world or they would use them. Please dont tell Shelby he used a cheap item in his cars. He never liked to be told that by anyone. All other posi come and go but the detroit locker has been here for over 40 years and still going strong. Try one. You only need one. No spairs required. What more could a racer ask for?

People are getting insulted, cause they are screaming experience and the shit works.
Although it's significant, there is something to be said about current technology.

Are you telling me CART / IRL / Champ Cars or whatever the fuck they are called now are running spools in the rear on top of the tire stagger???

It-works-why-fix-it-if-it-ain't-broke is a very strong argument, but we're still taking about an RX-7 which has a lot more options with clutch-pack LSD's than a Detroit Locker.  Or is there some way to drop a DL in there with very little fuss that I don't know of?


-Ted

I am. On ovals yes.

Google is your friend...

"In the IRL everyone uses an IRL mandated transmission, whereas in CART the transmission is a unique design by each car manufacturer to maximize car performance. In addition, a CART transmission case is made from light weight Magnesium, whereas the IRL unit is an aluminum case. The differential on a Champ car is a limited slip unit. On ovals they are fitted with a spool. The IRL car runs a spool for all races."


http://www.autoracing1.com/MarkC/200...RLCloseFar.htm

Hell while I'm at it I'll piss everyone off. Carroll Smith says to throw the Detroit Locker in the dumpster. Yeah, some of his ideas are dated and the book that comes from is dated, but if it belonged in the dumpster then where does it go now? I really don't care. This discussion just got me thinking and doing some re-reading. I'm just stirring the pot. :D

Re: Detroit Lockers
 

Check your rulebooks. I believe both NASCAR (on roadcourses) and TransAm by rule MUST run Detroit locker diffs. Why? I don't know and it doesn't matter; thems the rules.

For your NASCAR reasoning are you going to convice me a carbuerated pushrod V-8 is also the most perfect racing engine or do they run them because that's what the rulebook tells them to do? Never make the mistake of saying "So and so does it so that means it's the best". All racecars are products of the rules under which they are required to compete. You think guys building Formula Vees are just inherently dumber than everyone else and haven't figured out that wider tires and some power would make those things go a hell of a lot faster? Insisting that NASCAR uses Detroit lockers because they are the "best" is folly. NASCAR competitors use them because the rulebook tells them they have no choice.

I haven't checked the schedule but NASCAR still only races on 2 roadcourses a year? And 50+ oval races I think? Maybe NASCAR has no real desire to encourage teams to develop even more new parts for only 2 races and instead enforces a "spec" rule on the diffs used?

I said that.

He doesn't get on the power and lock the diff until he is ALREADY in the turn. It's initial turn in where it tends to unsettle the car. You also don't get the chance to change your mind. Once the car is turned in and set if you back out of it for any reason you could possibly be in for problems.

Your taking my point of view as some sort of attack. Detroit lockers are not pieces of shit but like any other device they have their own set of problems. Only people running them in modern days that I know of are those that are mandated by their rulebooks to do so. Detroit lockers don't suck but there are better alternatives IMO.

As for Shelby I respect him but when's the last time he built a real racecar??? If you're going to tell me 'ol Shel would step up today and put Detroit lockers in new Shelby Cobras he planned to take racing I will have to turn my back so you don't see me laugh ;)

If you wish to see what modern technology is doing look no further than F1 and and especially 4WD rally cars over the past 5 years or so. The rules have fluctuated in both to at different time allow computer control of diffs and at other times insisted on pure mechanical devices. Damn near everything has been tried again and again recently.

The good qualities a Detroit locker diff has are cheapness and robustness. It by no means has any inherent performance advantages and in fact has quite a few limitations due to it's operating characteristics. Hence people tend to use other designs that can be made just as tough and yet perform the limited slip differential function better. I ask you, isn't THAT what any racer asks for?

Every oval track car runs a spool in the rear. Sprints on dirt or asphalt, CART on ovals, IRL on ovals etc. If you have any kind of diff at all then you have no use for tire stagger... It defeats the purpose of running stagger.

CART only runs diffs on road courses.


Anything can be made to fit if you're willing to build it. The FD guys think a Kaaz makes some racket, they'd freak if they had a Detroit locker! They basically sound like they are trying to grind themselves into pieces anytime they are not locked.

LOCKED SPIDERS
 

Hey this thread has got you people thinking, and that really what it here for. To make you think. I never said the detroit locker was the best for all race cars. I only stated who was useing them and how strong they are. A person who races gathers over time a list of things in his head, that works for him. This cam co, this clutch co, this locker co, etc,etc. This is the way it should be. Racing is hard enough, without changing vendors every race. Run what you want to. Its a free country. The orignal post was asking about welding spiders in his RX-7 circle track car. Thats all he asked. What we've done is re-invent the wheel for him. To answer the orginal post, all I can say is do it. Its done every day in the USofA, and will keep on being done every day we race. As for a locker in a RX-7, well do like we did, use a 8" or 9" ford like every one else did and still do. Factory told us to. From RX-7 street stock to CART/IRL in one day. What a trip!!!! What can we re-invent tomorrow?

Tricky Dick Elliott

Re: LOCKED SPIDERS
 

Any relation to Bill?


-Ted

Re: Re: LOCKED SPIDERS
 

Only when I'm trying to get a freebe out of a vendor. Otherwise no. If I was, I wouldn't live in Arkansas.

An aritcle from noted racecar engineer Mark Ortiz on pros/cons of various diff designs can be found here.

Mark's aricles are also listed in our Suspension and Handling links:

Chassis and Suspension Tech Articles! A wealth of knowledge is featured in this UBB forum! Features many chassis topics from Mark Ortiz along with Brian Beckman's Physics of Racing series of articles. When you get serious, this is the place to read up.

For a short oval track, you would want to keep it an open rear end or LSD at the most because you are cornering more at a short track (bristol) then a superspeedway (Taladega)

No. At a short oval track you keep the spool and run more tire stagger.

Re: LOCKED SPIDERS
 

I learned from this.

My .02 On this one...

Close friend in High School ran a Detroit Locker in his Shelby Mustang GT-350. Pure Race car.. not street.. Was Beautiful.. Till he was on a caution lap in the light rain.. and eased gently on the power coming out of a corner expecting the locker to do just that.. and when it locked the expected slide started.. and he goosed the wall. NICE car bent. Fixed.. but bent. They changed I believe to a Auburn after that.. It was a clutch pack style.. smoother engagement for Road racing.

My RX-3 I ran (Formerly Sharkey's RX-3 for those in CFR) had a welded rear diff. AND After breaking 3 axles.. and really not having much fun coming out of the horseshoe at Daytona sideways through 3rd and 4th... every time.. I switched to the clutch style from a 1st gen.. and it made WORLDS of difference.. the car ACTUALLY handled out of corners.. It didnt just leap sideways when you applied power.

IF you can at all do it.. DOnt weld it.. Try to get some sort of LSD...... BUT.. if it comes down to Weld.. or Not racing.. Weld the fooker..

Thinking of welding mine used mostly as a drag car but see's some street use. I know you guys are going to hate me but it's sbc powered

Im just worried about breaking an axel.

"For your NASCAR reasoning are you going to convice me a carbuerated pushrod V-8 is also the most perfect racing engine or do they run them because that's what the rulebook tells them to do?"

hahahahaha. lol, nascar suxx ass.

hey i have a question..... can you weld up a rearend out of a second gen NON LSD rearend, or does it have to be the LSD rearend?

I can be an open diff. Doesn't matter.