Welded differentials

[jcg3813]

I like to know the pros & cons of using them, what you people suggest ?.
Thank you.

[Dano77]

pros,both wheels apply power,con,both wheels subtract power...you will most likely develope a massive push until you smash the throttle enough to break the inside wheel loose,then balance becomes your best friend. You can overcome the cons with stagger but we turn left & right so weigh your option at the track. Pro,wayyyy cheaper than a quaife or detroit locker,con,still pushes. good luck.
Dan

[Weaver7]

Like Dan said it will make the car push like a stuffed pig however it will teach you how to rotate the car properly!! Had one in our first Gen RX7 only ran it for a couple of races though.

Bill Weaver
ITS RX7 #63

[Tak]

Pro's of a welded diff: Cheap. Almost as fast as a fancy diff IF the car is set up right. You'll never lock up just one rear tire...
Con's: Properly set up cars for a welded rear end will wear tires faster; they will be scary to drive over the range of high speed and low speed corners; if the welds fail, it's bad; if it's not set up right, you will get lots of understeer (as in hello wall); impossible to roll the car around in the paddock, driveway, garage etc.

For a road coarse, a car with a welded diff needs to be set up like a go-kart--that is it MUST lift the inside rear wheel when going around corners. This is typically done with significant rear anti-sway bar. Suspension springs must then be selected that will result in a somewhat balanced car when it's on 3 wheels. A roll cage structure that really stiffens the chassis will help tremendously. It will eat rear tires (because only one is on the ground while going around corners). Good damping will also help. If you are not afraid of oversteer, it can be fast. Note that extra care is required in esses and chicanes--the car will require more time to transition from one direction to the other than a car with all 4 wheels on the ground (the suspension physically moves more and transfers more weight around in a welded diff car).

FWIW, many many moons ago I got to play with a formula SAE car that could run either a Torsen or a spool. Properly set up, the spool was as fast as the torsen around an auto-cross type track. Around a faster track, it had too much oversteer with a spool. Very comfortable with the Torsen though.

Hope that helps,

Tak
#29 ITA SFR SCCA

[Tak]

Whoops, must qualify my previous response--all that applies to a rear wheel drive car. I haven't got the foggiest about setting up a front driver. I expect you still need to get the inside drive wheel off the ground, but have no experience there.

Tak

[RX3]

I have run a welded differentials for many years on a rear wheel drive car and like it.

[shwah]

With this post being in the VW/Audi forum, I will guess it is in reference to fwd.

They work great, cost less than 'real' differentials, but do require/allow some different setup and driver habits.

Understeer is not the problem you might assume. Just get your foot on the loud pedal and it will go where you point it.

When I started using one, I got myself ready for the higher driver effort/concentration that would surely be required to tame a cantankerous fwd locker. In fact it is much easier to handle than you think - except in the paddock.

[Drew Aldred]

+1 to what Chris said above. I've driven both on a VW and prefer the welded diff. Not as much push as some people will tell you. Point it where you want to go, stomp on the gas and hold on, because you are going right NOW !!!

Pushing it around in the paddock is a pain with the welded, be careful not to backup while driving and make too sharp of a turn - easy to snap an inner CV joint.

[chewy8000]

I run a welded diff and love it. It does push like crazy, but you learn to control it.

Pro's:
1 - you can brake incredibly late and deep.
2 - With good rain tires you can win races.

Con's:
1 - Pain in the arse to move around in the paddock.
2 - plan on eating up a few CV joints over the season.
3 - If you early apex a turn don't lift! Stay on the throttle or you'll end up in the wall.

Just my experience in the rabbit GTI.

[shwah]

replace 'lift' with 'left foot brake' for most situations

never broke a CV - of course now I will break 5 this weekend!

[jcg3813]

Thank you guys for all your inputs !. I forgot to say that this is for a 84' VW Rabbit. We have a tremendous inside wheel spin coming off the corners and this will be the easiest and cheapest way to fix this problem .

[Knestis]

My next "sprint" gearbox for the Golf will have a spool.

K

[Grumpa]

My next "sprint" gearbox for the Golf will have a spool.

Kirk,
Any particular reason for the spool? Rotational mass?

I ran my first race with a welded unit a couple of weeks ago and loved it. Gotta change the setup to some softer front springs to get the car to rotate better, but I like steering the backend of the car, as opposed to the frontend, with the loud pedal. VW's are a lot more fun to race with a little oversteer, and they can really brake deep.

[OTLimit]

You would have to fight Chris tooth and nail to removed the welded boxes from the ITB and HP cars he drives. Hated the Quaiffe. Haven't seen good evidence that there is a faster way with the VWs that fits his driving style.

[RacerBowie]

My next "sprint" gearbox for the Golf will have a spool.

K

Good thing I've already driven the important sprint in Pablo. Ugh.

[seckerich]

A spool or welded is usually the last result of failing to get a proper limited slip. Proper being the key word. An LS equipped car will always have less power loss through the driveline. Can't fight the physics of dragging the inside wheel.

[Knestis]

I put a lot of stock in slip angles - the reality that the tires REALLY aren't ever completely hooked to the ground.

My opinions are influenced by the fact that I'm a curb-jumping, grass- and dirt-hooking type. The point at which the inside wheel is on a low/no friction surface (grass, mud, air) one of the primary arguments against the spool go away. And they are minimized to a significant degree in other conditions.

Recognize too that this is another Old School moment for me. It's what we had, so we got used to it. They can be diabolical in the wet.

They also don't break (the spool option, that is) and are lighter, both in terms of mass and rotational inertia.

K

[shwah]

Toss that spool on the scale when you install it Kirk. The standard version is heavier than a welded. I do think there is a lighter version available today though. That said, the durability and servicablility of the replaceable spline shafts are enough justification for me to use an honest to goodness spool next time around.

For welding up a diff, be sure to get it crack checked by an expert before and after the process. It is quite common to find them not up to the task before you touch them, letalone after welding.

[nsuracer]

A driver who is just a whole lot faster than me (not mentioning any names but his car is yellow and has a 4 on it) said that a locked diff forced you to keep your foot in the gas (fwd). That being said, I hated it. My current car has an open diff. I may not be as fast, but al least I don't fall out of the car at the end of the race.

[OTLimit]

A spool or welded is usually the last result of failing to get a proper limited slip. Proper being the key word. An LS equipped car will always have less power loss through the driveline. Can't fight the physics of dragging the inside wheel.

May be true on a RWD car, and Chris would probably agree with you. However, that has not been our experience with the FWD VWs.