landroversforever Posted February 9, 2015 Share Posted February 9, 2015 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? Quote Link to comment Share on other sites More sharing options...
zim Posted February 9, 2015 Share Posted February 9, 2015 Why not keep it simple and go for a hp22 ? G Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 9, 2015 Share Posted February 9, 2015 But.... You have a torque converter which makes everything different again.... Quote Link to comment Share on other sites More sharing options...
landroversforever Posted February 9, 2015 Author Share Posted February 9, 2015 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). Quote Link to comment Share on other sites More sharing options...
Boydie Posted February 10, 2015 Share Posted February 10, 2015 What about a ZF4HP22 with HP24 internals, such as Ashcroft supply ? They include an uprated torque converter and you can retain the standard transfer box. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 10, 2015 Share Posted February 10, 2015 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 Quote Link to comment Share on other sites More sharing options...
landroversforever Posted February 10, 2015 Author Share Posted February 10, 2015 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. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted February 10, 2015 Share Posted February 10, 2015 You say that now, Ross Quote Link to comment Share on other sites More sharing options...
landroversforever Posted February 10, 2015 Author Share Posted February 10, 2015 Well at least the OM has plenty of potential to go mad . Quote Link to comment Share on other sites More sharing options...
elbekko Posted February 10, 2015 Share Posted February 10, 2015 If the Merc box shifts quickly and smoothly enough, I doubt you'd ever notice the gear hunting, if there's any at all. Quote Link to comment Share on other sites More sharing options...
zim Posted February 10, 2015 Share Posted February 10, 2015 You didn't mention it was a merc engine in the first post 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. G Quote Link to comment Share on other sites More sharing options...
landroversforever Posted February 10, 2015 Author Share Posted February 10, 2015 Sorry I should have been clearer! That's good to know Zim Quote Link to comment Share on other sites More sharing options...
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