I have been out of the TC scene for awhile. I see now that a lot if not all of the TC cars have front spools instead of ball diffs. What are the advantages and disadvantages to running a spool instead a ball diff. Running 17.5 and 25.5 motors.

James

Practically Zero maintenance with a gear diff
More fine tuning adjustment
Impossible to slip
Smooth as butter

A spool will have a more aggressive feel exiting the corner. It's also a bit harder to drive vs a ball diff.

Nobody really runs a ball diff anywhere in a touring car any more. They've been eclipsed by gear diffs instead, which use different weight oils to give different characteristics. Currently, im using dual gear diffs in my xray t4. Rear has 500cst and front has 2.5million

I feel like the exit is smoother with a gear diff with very thick oil up front, as well as having increased entry steering.

Lightweight spool up front is the way to go, and ball diff in the rear gives you faster adjustibility than gear diffs, and also little maintenance, if built properly... Ball diffs are also not susceptible to leaks and don't explode at high speeds(mod racing) when they are run in the rear with a spool up front.....

Nope but if your ball diff is a little bit too much free, a run in mod will just ruin it...

For your classes I would recommend a 2000 gear diff in the rear and a putty-full gear diff in the front...

Spool could be better on low grip surface, but it will kill your cornerspeed...

A ball diff is always good to have if you are at a new track, it's much easier to do a few laps tweak the diff and the try it out again than messing about with a gear diff. One I have a setting I like I can then make up a gear diff with the correct oil etc.

Ball diff and gear diff up front can't handle the power of a 3.5t boosted, let alone a 2.5t boosted.... You need a Spool....

Ball diffs are just fine for these classes. Yes gear diffs are the new thing and have their advantages. But in the spec classes espicially vta 75% or more are running ball diffs. I say for now run what you have, get the feal of driving back then, upgrade if you want. Gear diffs tend to be heavier than ball diffs and for the spec classes rotating mass means alot. So it might be adventgous to stay with ball diffs

I have both gear diffs and ball diffs, also a spool, the spool up front will give you wheel chatter, more on some cars then others, while turning. This chatter or vibration will unsettle the car, Manufactures have made djc, to help with the chatter, so if you use a spool up front djc will help. I run 17.5t boosted and ball diffs front and rear are fine, never had a problem, geardiffs leaking and having cheap plastic that wobbles are something that I do not like, they do last longer between rebuilds. but having to rebuild and setup a car is the fun of this hobby.

I ran a ball diff in my vta for a loooong time and after running a gear diff in my 17.5 sedan decided to test it out in my vta. Went faster by a few tenths (our track was around 14s lap for vta at the time) and haven't looked back.

Spool in the front always with a set of ECS's. Don't quite understand the rational behind running putty/jb weld/ anything else that makes a gear diff essentially a spool....

Don't know about HPI, but Xray's gear diff is 10g lighter than their ball diff!

Also, if rotating mass is everything, surely you're better off using a spool as they weigh even less again.

Spools tend to offer better stability and don't suffer the problems of requiring rebuilding regularly and varying in tension from run to run.
Spools also have much better drive out of corners

Skiddins

I prefer driving a car with a front ball diff. The only issue I have with it in VTA is getting more front drive coming out of the corner (without slipping the front diff).

Can someone give me some advice on how to improve the drive off the corner with a front ball diff? Thanks.

More front end droop than rear droop.Just keep that inside front tire in contact with the road as much as possible. If running on low-grip, try finding a setup that uses no front sway bar, otherwise a really tight diff or spool may be necessary.

Thanks for all of the feedback. A lot of good information. It seems as though not much has changed over the years accept going back in time to gear diffs. I will try one with front oneway and one standard ball diffs and adjust from there.

James