Auto Gearboxes and racing

[Howitzer]

Hi guys.

I'm slowly getting on with more bits of the MK1 toy and have a question regarding the gearbox.

I'm using a 4 speed unit from a 560 SEL Merc as that's also the engine i'm using. I'm giving it a go as mainly i'll be using it on the road and the Merc box is a strong unit, also it will save having an adaptor plate made up for the Merc engine.

For control i'll be using a regular Merc shifter as it does everything I need it to do plus again it's easy enough to plumb up.

My issue is with the load it's going to take. I don't mind destroying a gearbox in the process of driving the car and seeing if it will be capable of taking the torque i'll be throwing at it, which will be double what it was intended to handle but in a car which is now half of the weight, but with far more traction.

So, what happens to an auto box when it gives up the ghost? Does it simply split, fart its guts out or is it going to attempt to fling spinny bits of metal at my feet and turn me into a midget? If that is the case i'll need to take some precautions.

I'm running a 9" back end which will be built with a big safety margin so that should cope so the box is the weak link.

Dave!

[veryoldfart]

I think your best bet would be to ask Mr Frost. he sometimes dabbles with autoboxes, a bit....

[Tet]

Howitzer said:

Does it simply split, fart its guts out or is it going to attempt to fling spinny bits of metal at my feet and turn me into a midget? If that is the case i'll need to take some precautions.

Get yourself a scatter shield, just in case. For racing (if you're going quick enough), you'll need an SFI 4.1 certified one. For American boxes, they're widely available. As you're using a Merc box, you may need to look further afield, or get a universal blanket instead. Be warned that blankets can move around, however. IIRC, someone (one of the Outlaw Anglias?) had a transmission failure at Shakey a couple of years ago, and although he had a blanket, it had slipped down the box, and the remains of the gearbox were still able to escape and fly around in the driver's compartment.

[veryoldfart]

will it be a merc box or an outsourced item?

[eliot]

To much power through an autobox usually results in burnt clutches (or bands) - rather than them "exploding" - unless you are revving it significantly higher than OEM.
Best bet is to get the exact model number and do some research.

[leecb05]

Firstly think of this how many other cars are running merc box's???????? non i know of
there is a reason for this.
Mercs are great cars but the only weekpoint they have is there gearboxes my advice would be junk the merc box and get an adaptor plate made and fit a glide or th400 this will save you a whole heap of cash in the long run you can proberbly pick up a good glide or th400 for less than the merc box plus there are proberbly more about than the merc trans also i used to be in the motor trade and merc boxes are expensive just to service i think our garage paid 300 quide just for a service for an ML box which will proberbly be a similar box to yours my advice would be give Andy Frost Penn autos(red victor 2) a bell he knows more than most about gearboxes

[Howitzer]

The box came cheap from a running car and to be honest I like the idea of being different, the boxes are a very new area for me though so I know virtually nothing.

From what I understood the box in the 560SEL was pretty much bullet proof? I know this doesn't mean it will last more than 2 seconds in the car but maybe that's me being optimistic. The tunnel is more than big enough for a Glide anyway luckily incase it all goes horribly wrong.

Thanks for the replies guys, much appreciated.

Dave!

[veryoldfart]

veryoldfart said:

I think your best bet would be to ask Mr Frost. he sometimes dabbles with autoboxes, a bit....

despite his junior years and misspent youth, he does come recommended.....