Hilux autobox brake question.

Post questions, advice and pictures of Engine conversions here
Post Reply
User avatar
pampoen
LR 4WD Full Lockers
LR 4WD Full Lockers
Posts: 514
Joined: Thu Jan 24, 2008 10:31 pm
Town: Gordons Bay
Vehicle: Hilux..Duh!
Real Name: Luke

Mon Sep 21, 2015 6:32 pm

Heres a question for you guys, i'm running a v8 with autobox in a hilux, how can i find a work around so that i dont have the engine and vehicle weight all pushing as i brake to a stop. Just thinking of taking my van to Durban from Johannesburg has got me really exited but with 4 people and a small load im scared of what the brakes will do.

I did notice that with the auto Fortuner, as you slow down, there is no push from the engine, even when youre in drive,and on a steep descent. How do they do this, i want to copy that and add it to my van.

User avatar
Dirka
Low Range 4WD
Low Range 4WD
Posts: 187
Joined: Tue Jul 07, 2015 2:16 pm
Town: Doornpoort Pretoria
Vehicle: Hilux 4.0 V6 4X4 Auto DC
Real Name: Dirk

Tue Sep 22, 2015 2:56 pm

Hi Luke. Did not understand your question/ problem at first, but upon contemplating some reasoning for a
while I might share some things here.

You don't say what v8 and which auto transmission you have there.
Is it carburetted? Do you have rev hang/ match through vacuum dashpot?
Is your rev drop instantly on throttle release, or does it decay slowly? What is the general throttle response?
Do you have non-linear throttle control? Is the autobox lockup? Is it ecm or pressure valve controlled?
What is the gear ratios? etc, etc, etc..

You see..there's only one thing that might cause push from the engine, and that's by gooing the juice.
Other than that, upon throttle release, engine braking will occur from the wheels, through the drivetrain,
auto box and TC...dependent on alot of variables that comes into play here.
Second aspect you need to understand is that there is unfortunately nothing you can do about the physical
weight of the vehicle...unless you leave the cleanmother and baggage at home.

As far as the tuna is concerned, I don't know which one you drove, but on the 1GR-FE it is very, very low
geared that upon throttle release will not have a substantial adverse or opposing affect unless you stick
it into 3 or 2L...and that is exactly what the manual recommends.

I'm not currently aware of any auto trannys out there that mechanically disengages the TC turbine from the
output shaft or shifts the a/box into N or any of those solutions upon throttle release and braking.
I do however understand that the TC lockup does release under these circumstances.

So it basically comes down to autobox properties, TC dynamics and gear ratios. Which in good harmony with
whats under the bonnet and in good balance will give you the wanted effect.
So not an easy thing to achieve here.
Hope it helps. :thumbup:
I got arrested for driving naked. I guess I shouldn’t have put four wheels, an engine, and a steering wheel on my bathtub.
I’m a do-it-yourself kind of lover.
” ― J. Kintz

User avatar
pampoen
LR 4WD Full Lockers
LR 4WD Full Lockers
Posts: 514
Joined: Thu Jan 24, 2008 10:31 pm
Town: Gordons Bay
Vehicle: Hilux..Duh!
Real Name: Luke

Tue Sep 22, 2015 8:59 pm

Dirka, thanks for the reply. I couldnt exactly put down what i had in mind so thanks for understanding. So its a Lexus vvti with 5spd box and standard ECU and Gearbox controller. I haven't fitted this engine yet (in a few weeks though) and i was wondering. The reason i was worried though was because of the 4sd lexus box i originally had with another 1uzfe, engine braking was not as good as i though it could be, but i think it could have been down to the 4 long gears and bad Spitronics setup. The Fortuner i drove was the diesel 3.0d4d.

Post Reply

Return to “Engine conversions (Lexus/7M-GE/3RZ-FE etc)”

  • Information
  • Who is online

    Users browsing this forum: No registered users