splitty gear box

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kiaora
Posts: 171
Joined: Thu Dec 05, 2002 12:01 am

splitty gear box

Post by kiaora »

Hi,

My van will be needing a new gearbox soon. Ive been looking at SA/IRS conversions to lose the reduction boxes for cruisin', but im pretty happy with the rear ride hieght as it is.

So, would rather not loses the reduction boxes if poss. (been readin that the SA conv' would mean dropping the van more?)

So... Any suggestions? Freeway flyer perhaps??


Thanks...
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Marc
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Joined: Thu May 23, 2002 12:01 am

Re: splitty gear box

Post by Marc »

What reduction gears do you have? Almost all ½-tons (36mm axle nut) are 1.40 or 1.39. The 46mm axle nut boxes in the US market are 1.26 - with those your final drive ratio is nearly identical to that of an 002 IRS trans.
kiaora
Posts: 171
Joined: Thu Dec 05, 2002 12:01 am

Re: splitty gear box

Post by kiaora »

Hi, Im not sure,

its a 67 camper, italian import. not sure that helps.

How can I find out?

Ta
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Marc
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Re: splitty gear box

Post by Marc »

Jack one rear tire off the pavement. Chock at least one wheel on the other side since you'll need the parking brake off. Select 4th gear. Make a mark on the sidewall of the tire and turn the engine over by hand, counting how many turns it takes to rotate the tire once.
With the opposite tire stopped, the action of the differential will halve the overall turns ratio.
If it's a 4.125 ring & pinion with 1.26 reduction gears (assuming the stock .82 bus 4th) it should take ~2-1/8 turns of the engine for one turn of the tire:
(4.125 x .82 x 1.26)/2 = 2.131 ...that's the tallest "stock" configuration ever offered.

If it's a 4.375 R&P it'll take 6% more, ~2¼ turns...a 4.375 with 1.39 boxes would take ~2½.

If you're having trouble discerning the difference, repeat for 2 or 3 turns of the tire.
Accuracy will be improved if you have a buddy apply light resistance at the tire so all of the slack in the drivetrain is taken up before you start counting.
kiaora
Posts: 171
Joined: Thu Dec 05, 2002 12:01 am

Re: splitty gear box

Post by kiaora »

Thanks Marc, Ill check it out.

How does this help with my prob though.? (Sorry.. blonde moment going on)
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Marc
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Re: splitty gear box

Post by Marc »

Just sayin' that there may be other ways to get taller gearing without losing the red gears.
If you have a 4.375:1 R&P, going to a 4.125 will gain 6%.
I'm not familiar with Italian specs. You probably have 1.26 red gears already, but "Mountain" gearing was available. If you happen to have 1.4s and changed them to 1.26s you'd gain ~10%.

There are other possibilities (like a 3.875 R&P from a late Bug trans, or even-taller aftermarket R&P) but unless you're compensating for small tires I really wouldn't recommend going any taller than .82 x 4.125 x 1.26.
kiaora
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Joined: Thu Dec 05, 2002 12:01 am

Re: splitty gear box

Post by kiaora »

Thanks Marc, Ill check it out.



Marc.
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Jadewombat
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Re: splitty gear box

Post by Jadewombat »

kiaora wrote:Hi,

My van will be needing a new gearbox soon. Ive been looking at SA/IRS conversions to lose the reduction boxes for cruisin', but im pretty happy with the rear ride hieght as it is.

So, would rather not loses the reduction boxes if poss. (been readin that the SA conv' would mean dropping the van more?)

So... Any suggestions? Freeway flyer perhaps??


Thanks...
The 1303 trans swap on mine was well worth it, only a slight drop in the rear, but I wanted that. Easy enough to reset with torsion bars.

http://www.shoptalkforums.com/viewtopic ... 4&t=121939
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