[123pugsy]

I have a guy interested in a th400 for his derby car.
He says they run straight hydraulic fluid as that is cheaper than ATF....comments??

He says he needs only 1st and reverse.
Any insights on how to toughen this tranny up for this application?

[cobalt327]

Keep it cool.

A derby car often has the radiator knocked out, a remote cooler w/fan would help- but an engine w/no rad. won't last anyway.

[Crosley]

the transmission ATF is lite weight hydraulic fluid with several additives in it.

There should be no problems from the short use of the straight hydraulic oil

[fast68]

yep all trans or power steering fluid is is hydraulic oil anyways, just real thin.


hell i use motor oil for my p/s on all my daily drivers

have for almost two decades and never any trouble and it makes for a slicker easier steering big time, and it doesnt leak out like p/s fluid does, because its thicker.


i use p/s fluid for brake and clutch master fluid also,

same stuff, hydraulic,
got an 89 F250 5 speed out here right now i just pulled up in about 5 minutes ago and its got p/s fluid for the clutch master


ppl worry alot about fluid types etc

it does matter in some trannies though

such as fords and chryslers

alot more than any others


temp resistance and clutch pack disc materials, etc

good luck

[123pugsy]

A few more thoughts....

How about clutch pack clearances?
Should these be set up looser than stock recommendations?
Can I add frictions? Are the grooved friction better to use?
I noticed the 4l60e has steels with holes thru them. I am figuring that's for better lubrication?
Could I drill the steels on the th400 like those?

Thanks.

[cobalt327]

For a derby car, you want reliability.

I'd keep it to the stock spec's AFA clutches/steels but use a good quality set. Looser clearances aren't wanted or needed, IMO. No extra holes, other than ones to help drain fluid from the clutch basket, if they're not there already..

A 34 element sprag and a tight converter (less heat) and you might consider boosting line pressure and/or shift kit might help transition quicker from reverse to low. Someone else might be able to say what would be needed to help with this.

I'd use a good, racing-type fluid if it were me. B&M and others sell high performance fluid that resists heat better than normal fluid.

I don't know what will happen if you were to use the hydraulic fluid on a daily driver, or switched from it to ATF. If the tranny is only gonna be used in a derby car, prob. moot point.

[madbomber]

hydraulic oil in derby cars....you must replace all the plastic components internally w metal components or they will melt. the hyd oil takes longer to break down/heat up, but when it does, it is very hard to cool down. my guys who do run hyd i usually run water/ice coolers or big air to air hydraulic coolers out of skid loaders. you lose about 200rpm stall speed as well.

other things...leave out the center seal on the forward drum.....drill the rev port on the spacer plate just a bit, but not bigger than 7/64th's.

for 1st/rev only.....plug the direct/3rd gear port on the center support and remove the center seal of the direct clutch. esencially do the same thing as most people do to improve the 3rd gear shift except backwards. although it sounds pointless it actually slows the apply down slightly to keep the direct drum backing plate in one piece longer. the constant back and forth shifting just tears them right out...taking out reverse.

.005" of clearance per clutch disc works well...leave out the wavy steels they will just break. use an aluminum piston in the direct drum.

you must replace the 3rd gear accumulator w aluminum if it is plastic. when it breaks....and it will....you lose reverse.

there are numerous other things you can do for a derby tranny, especially for low 1-reverse only operation. pm me if you would like more details. thanx

[123pugsy]

Sounds like some good advice.
We'll see what pops when it goes.
I sponsored the derby guy with this 400 and he'll
bring it back to me when it goes.