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Gearing changes - Auto VS Manual


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I'm looking into engine and gearbox options for my 90. I have a question on the gearing which I can't get my head round at the moment.

The autobox I'm looking at is the 722.6 Mercedes 5 speed.

I have changed the diff ratios to 4.7s and the transferbox is a newly rebuilt Ashcroft 1.2. the combination of the diffs and the 4.7s make the ratio nearly identical to the standard gearing (little lower offroad and a little higher on road).

Now the autobox ratios compared with my old LT77 are very similar. (off the top of my head they are within 0.2).

Looking at the ZF4HP22/24 the ratios are higher than their contemporary manuals.

So, will the lower ratios in the 722.6 make for a very revvy drive? or are the higher ratios in the ZF boxes there to make up for a lack of 5th gear?

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HP22 would be less simple.... And not good enough for the engine option I'm looking at (merc OM606). The 722.6 is what comes with the engine and is good for loads of power.

Well if it wasn't for the torque convertor it would be simple, hence the question :).

The gearbox controller has lots of options for the TC lockup (which it can do in all gears).

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But the 722.6 bolts right up to om606, why make life hard :)

Thing you also have to remember is the merc engine likes to rev, no 4k limit on them.... Quite happy up to 6, so a revvier drive is likely to suit it better, especially if you start going silly with turbos ;)

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If the OM606 route is what I do, it will be with the merc gearbox.

The only mention of the ZF boxes was because they are the normal comparison against the LT77.

Good point about the revvy-ness Bowie. The plan would be to run the LT230 still, but divorced. Turbo would probably end up as a not too silly VGT so as to get the best all round usability.

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You didn't mention it was a merc engine in the first post :P I *assumed* it was LR.

Are these the ratios you're on about :


Mercedes-Benz Transmissions
Gear                    	1	2	3	4	5	R1	R2
5G-Tronic (W5A330/Small NAG)[2]	3.951	2.423	1.486	1.000	0.833	-3.147	-1.93
5G-Tronic (W5A580/Large NAG)[3]	3.595	2.186	1.405	1.000	0.831	-3.167	-1.926

If so, i wouldn't worry. It's only first that is lower in comparison to the 22/24. After that you're ok. Having a nice low first would be quite nice actually. My th400 for my race truck has a 3.x first gear and i know my F250 has a really low first gear, that it only selects in the cold weather.


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