Hobao H4e Diff oil for polished wooden floor

[rhbmcse]

Hi again folks.
No doubt a few of you will have been reading my threads with interest.
I'm building a h4e now to replace my TT02's.
First time I've built a touring car with a proper diff!

Havent looked at the destructions yet but I'm assuming it's a gear diff.

Guessing for a polished wooden floor I need very thin oil.

What does everyone recommend?

Also, I know this car doesnt have a front diff, but what exactly is a spool???

One of the other guys at our club running this put a diff in the front too as he said it was a pain to drive on a slippery floor but Im going to give it a go anyway!

Thanks guys.

Rob.

[ratman]

It comes with 1000cst oil.in the kit, when the back end is loose people generally go thicker. Maybe try 3000cst on wood floor.

A spool is basically a solid axle with no diff action

[qatmix]

Dont forget a build review here for any tips on the build

http://www.thercracer.com/2013/11/ho...kit-build.html

[rhbmcse]

Originally Posted by ratman

It comes with 1000cst oil.in the kit, when the back end is loose people generally go thicker. Maybe try 3000cst on wood floor.

A spool is basically a solid axle with no diff action

Why do people go thicker when the back end is loose?
I'd have thought in that situation you'd want the diff to give more rotation, hence thinner.
Clearly Im wrong but this seems to go against my logic.

Anybody explain?

Cheers.

Rob.

[neallewis]

Originally Posted by rhbmcse

Why do people go thicker when the back end is loose?
I'd have thought in that situation you'd want the diff to give more rotation, hence thinner.
Clearly Im wrong but this seems to go against my logic.

Anybody explain?

Cheers.

Rob.

I don't race touring cars, but my experience with rear gear diffs in buggies on polished floors is certainly thicker is better upto a point.

With light oil, in a corner, all the drive goes to unloaded wheel resulting in it spinning up which causes the car to over-rotate, spin out or fishtail depending on the nature of the corner and where traction is lost. Using a thicker oil combats this, and helps to keep the axle more locked and the drive more consistent to both wheels in the corner. Too heavy and the axle is fully locked, which does result in traction being lost as the wheels can not rotate at different speeds (loosing the diff action).

Going back to a ball diff setup (with a 2wd or 4wd buggy), I would normally run a tighter ball diff in a low traction situation, so this theory carries through to a gear giff setup. It's hard to replicate the feel of a ball diff with gears/oil, and some may prefer the ball diff (over a gear diff) in a low traction setting.

On the polished floor tracks I run at, with yokomo diffs I find in 2wd 3000cst-5000cst the right spot, and 7-10k cst in 4wd. The size of the diff, diff gears and volume for oil will also dictate what oil is best for you. You need to experiment to find it, but I'd avoid starting with too high or too low weight oils.

[rhbmcse]

Great advice - thank you.
So why are my LHS recommending I drain the diff an just put a spot of oil in to make it as slack as possible???
That sounds COMPLETELY wrong, doesn't it?

[ratman]

Ignore ur lhs, thatl make it as loose as a loose thing

[rhbmcse]

Exactly - thats what theyre recommending I need???
So we're saying try 3000 CST (not 3000WT) for the diff.
I'll start a fresh thread for setup recommendations as this will no doubt go off topic for this thread.
Thanks to all concerned!

[fletcher]

go with what the guys above are saying. I used to always run on wooden floor at Sevenoaks (was quick on the stuff) and i came to around 2000 in the end as the issue with a spool in a tc is the lack of steering, i used to drive on the ragged edge sideways every were as with a spool it was the only way to be fast. If you run with a diff you can be a lot smoother.
hth

[Essex2Visuvesi]

Seconded on the front diff, We found that the car corners much smoother with a front diff as opposed to a spool or one way. Not so entertaining to watch but the lap times were noticeably quicker and a lot kinder to the tyres