How wide have people made the tranny tunnel? I don't have my drivetrain yet so can't try things out, but does it need to open out much at the front?

Cheers

Cozza

IIRC mine's 4".

It depends on whether you've got Live Axle or IRS like mine.

With IRS the tunnel can be narrower as the prop is stationary.

HTH,

James

arent they the same width??

the prop only moves in a vertical plane in Live axle, so it need be taller, not any wider I think

Mark

Whilst on this topic, has anyone considered running the exhaust in the spare space created by going the irs/dedion route? I am still at the stage of designing my chassis in CAD, but like the idea of hiding the exhaust.

Imagine how warm that tunnel will get !! and you will have the fuel pipe/brake pipe and electrics in there as well,, could make for a nice load bang me thinks

Jason

I'd imagine exhaust in tranny tunnel would fail just about every test there is. Bad idea I think for the above reasons.

Put it under drivers seat to keep yerself warm

Mark

Many fwd cars run the exhaust in the "tranny" tunnel - just need to have the fuel lines on the other side of the tunnel. Would pay to heatshield the hottest part of the pipe (and the cat) to avoid hot feet! One of the US guys did this with his rotary (a Rocost?!)

fwd car with a transmission tunnel?

with a prop-shaft?

what hes saying is most fwd car run the exhaust in the centre depression which is like a prop tunnel in the car centre.

having run my exhausts COMPLETLY under the car, I can tell you that the problem will be getting the exhaust out of the tunnel at the back. Its gotta get past the diff, or skirt sideways. If it needs to clear the diff, or go sideways, you need about 3 - 4 ins under the car. The tube is 2 ins and you need an inch of space from floor and a bit of clearance for any exhaust clamps. On a locost thats about 5 ins from the floor this shags your ground clearance at the exhaust diversion point.

my car runs about 8 ins from the ground and only has about 4 ins clearance at the exhaust lowest point.

I used heat shields on mine - you could use a heat deflector / sheild in the tranny - but I dont recon it flies cos of the reasons I described


atb

steve

atb

steve

[Edited on 11/3/04 by stephen_gusterson]

With irs cars the prop runs centrally so the tunnel can have parallel sides but with live axle cars the prop is usually offset to the drivers side (u.k.) In the original post the question is about the front of the tunnel which will be affected more by the type of gearbox used and how far back it is mounted than what type of axle is used. Running the exhaust down the tunnel would mean routing it under the bellhousing lessening ground clearance and somehow getting it over the prop which would mean widening the tunnel and leaving out some bracing and sounds totally impractical in a locost type chassis not even considering the heat problem.

yours, Pete

If you design it in from the start, say with a +2 width chassis, using that extra width in the tunnel you should be able to aviod the routing/clearance problems described above.

But I think you would have to design this in from the start.

Definately easier with IRD/de-dion having the diff fixed.

I would be quite worried about the fuel line(s) though, especially if you want to completely box the tunnel in and cover the underside as I intend to.

The front section round the gearbox really depends on the box used --- a type 9 is bigger than an Escort 1300 box. My tunnel for a type 9 is more or less as per book on the nearside but has some extra kinks on the offside to clear the type 9 5th gear case, my engine a gearbox sit as far back as they will go . With Pinto engines some builders offset the engine towards the left by about 25mm., this give more room for the steering shaft to pass
-

On live axle the prop runs central BUT extra room must be on the driverside (rhd) to accomodate the web of the diff carrier. How much depends on the axle used and the length of trailling arms - some builders have used 25 mm longer trailing arms., which apart from other advantages means the nose of the diff intrudes less into the pasenger compartment.

At the narrowest point inside my tunnel is 105 mm wide with an extra 53 mm at rear bulkhead on the drivers side. --- of course the external dimensions are 50mm wider to allow for the the 25mm RHS.

I should add my spec is CVH engine, type 9 box, MK1 Escort English axle.

[Edited on 15/3/04 by britishtrident]