Faster engines, more gears, better brakes and high speed diffs
I've been reading with interest all the recent posts on drivetrain upgrades, I did all this two years ago on my 460 so I thought I'd share my experience to save anyone considering doing this from potential blind alleys.
I bought my G in Jan 2011 rusty, non running barn find 1990 W460 300GD LWB in black. It had been used as a dog kennel so the interior had been well gnawed
Anyway, 2 year leisurely rebuild later it's MOTd and on the road.... loved it to bits but was sooo disapointed with the lack of performance, driving across the Ribble valley on the M6 it wouldn't make it up the bank in top gear.
So more power was needed and having done the research, and taken lots of advice from Mike Axel (Big thanks) The remedy was prescribed
OM606 Turbo, 6 speed gearbox and all the trimmings, this was completed a year after getting the truck on the road, the transformation was night and day, to give an example the bank on the M6 .... I could take that.... in top.... with trailer .... with another G on it
I was loving it, the power, the torque, the cool noise, even does 28 mpg if you stop lovin the power for a while..... but there's a niggle, i'ts a bit revvy, great for towing but motorway cruising was way too noisy
Doing some homework, reading forums searching endlessly on the Mercedes parts system I came up a solution. Doing some calculations I needed about a 25% increase in gearing. The standard gearing is 4.88 to one so to get the increase I needed the nearest ratio was 4.11 to one, 4.35 exists but wasn't worth the effort and 3.72 would have been too tall.
The next task was to source the diff gears, searching the Mercedes parts system revealed nothing that was G specific, the G has a 730 code axle so cross referencing around I managed to find a 4.11 diff set for a 730 axle but at an eye watering £700 the rear was easier because its common to the early sprinters.
The gears were sourced and duly installed together with a an axle rebuild and a brake upgrade, vented G550 brakes to the front and a disk brake conversion on the rear.
The difference is fantastic 80- 90mph cruising is comfortable and sounds right with the engine. The other bonus is that first gear is now useable instead of being a crawler gear, with the standard gearing it was better to start in second.
For anyone considering this heres a calculator http://www.pxwheels.com/gearingcalc.xls
So now I'm running 28MPH per 1000 revs in top on 265 65 18 tyres
Gordon
As the proud owner of a de-bodgewinned OM606 engine with a six speed manual gearbox (thanks Gordon) this makes eminent sense to me.
That said, I'm all spent up and just pleased to have a driveable G for now.
Well done you
i dont want the hassle or ring gear and pinions i will change gearbox final drive ratio
Changing a box is far easier than swapping or finding rare model diff gears at the money you quoted
Im not tight fisted but i could make some gears for way less and fit to box. Also gears can be swapped to new box cheaply
Machined hardened and nitrided for little cost. Good thing its in uk not china or india
Glad it works but as i said to swap a box is easier than diffs
Well it is for me anyway
Let us all know how it goes. You wont break diffs but if its a gearbox change and gears it seems easier to me and also gears wont break and are transferable to most 6 speed manual transmissions
On the case as we speak
Lets have your input from your conversion please.
I dont mind doing diffs as its easy but long winded. Post some results and i will think on the matter
G Wagon G, that sounds like a very straightforward and experienced solution. I agree that changing the diffs could be very costly and like looking for a needle in a haystack. I would love to know more about this for a 6 speed manual MB box from a cdi engine. Could you please keep us all updated on this as I think this is vital information for anyone considering a 606 conversion? Keep up the good work!
Changing the gears in the transfer box is the middle ground.. making a set of internals gears for the 6 speed would be cost more than the diff swap. I would consider taller tyres as a cheap way forward.. it does mess with brakes and handling but can improve off road ability dramatically... and for snow it is the way forward (lower ground pressure from a longer footprint).
Issue I have is insurance next gets silly.. you will pay many times what you save in fuel on the insurance each year as a "special". I have 3 modified cars and it is pain.. the G only has a turbo which might take it to 100hp plus 31" wheels but that makes it a specialist insurance company only job.. anyway.. sticking nearly stock because of insurance costs (they want more for a100hp G-Wagon doing 3,000 miles a year than for a 300hp ML500 doing 10,000 miles a year.. and the ML is way faster/more dangerous (3 times the power/weight, rolly suspension).
My 280 GE needed help!
I didn't go for the BIG 6 pot diesel conversion, opted instead for the Musso 5 pot swap. I wasn't looking for a racing car, but rather an easy drive that wouldn't break the bank.
The conversion was great! But, highway speed was "challenging". Yes, I could keep pace with motorway traffic - but the engine was working far too hard. So, like the OP, I went for the CW&P swap. From 4.88 to 4.11. As already mentioned - it ain't cheap... But it does do the job.
The result was exactly what I wanted. Local driving was smooth and easy, getting onto faster roads was no longer putting the engine under too much stress. The ONLY downside was that the normal speedometer flattery had been replaced by quite serious understating of the current speed. Travelling at 70 mph was reflected on the speedometer as low 60's, that's a serious problem in the local 30 and 40 mph restrictions, where the speedo is reading less than actual...
A replacement speedo drive did sort out this discrepancy. This replacement of the speedo drive after much consultation and head scratching was ultimately solved by Axel... Granted, not a cheap solution - but, it did solve the speedo discrepancy...
The OP has the same gearing as I now have in my vehicle, but he has tyres with a slightly longer stride than my 245//75 16. That said, my G does 70 mph and shows about 2,800 rpm. I'm happy with that!
Have you any information on the re calibrated speedo drive, I'm still using my sat nav as a speed. I had considered sending the speedo away to speedy cables to be calibrated to the new drive, but I'd much prefer to leave the speedo std
Gordon
Rather than reclabrate the speedo mechanics/drive why not have the face of the speedo re printed to match the new speeds.
I am sure there are instrument specialists who can do this by creating an overlay.
Rather than reclabrate the speedo mechanics/drive why not have the face of the speedo re printed to match the new speeds.
I am sure there are instrument specialists who can do this by creating an overlay.
Bit of a poor compromise as the odometer would still be wrong
Hi
Thanks for your kind comments
I will keep posting for the few who are interested
Some essays might have spelling mistakes when i have had a beer lol, or even if i have not
They are not in any particular order its just as it comes to my head
You would not think i got an o level in English language and literature. I honestly have
Thanks again just pm me about any 6 speed box advise
The conversion will never be perfect but its 10 times the standard rod set up and to put it plainly its easy just time and measuring and a few brackets
Gaz
You have way more time on your hands than me
Work out what would suit and i will look into gear prices
Have you not any old 6 speed and 5 speed boxes we could strip and see if gears fit shafts
I dont think with an om 606 or good 603 top gear is high enough
I think 3000 revs at 70 in top would be nice, or even a touch low still
Should it be for 6 speed boxes or should we look into both
The killer is the price to build a 5 speed up with bearings
The 6 speed killer is the best boxes are in line and not off set bell housing needing crossmember modification
If you drove my 6 speed i have roughed in it needs a little tweak but is raelly good with a nice short gearchange and has not jumped out of gear yet even over bad bumps
A little word of warning for you and any other people reading this. When modifying gear selector tube
If cutting to size you must remove the plastic plug and remove all sound deadening media from shaft
I have seen this and people cutting with a grinder and it grabs and shatters disc. No drama but if you were using a bandsaw or chop saw it could be nasty
Hi
I agree
The speedos on g wagons, every one i have seen read miles higher than actual speed any way so you are fine i would think anyway
IE says 50 your probably doing 42
Hi Gaz, I thought you had a viable plan? So is it just ideas then?
Re speedo, having had the speedo drive gears shear on mine, I think due to mot test on rolling road ? When buying replacement noticed a huge choice in them but unsure if viable to allow a 20% increase? Tho a digital speedo might be the cheaper option?
Viable plan is to strip boxes first
Then look at suitable 6 speed boxes that will work well, not the old type
Thencheck difference from 5 speed to 6 speed top
Work out ratio of gears which will be easy once boxes are stripped
We could make gears but i have a few contacts who would be able to make some cheaper
I have a 5 speed in bits i just need a spare 6 speeder and confirmation shafts are the same on the 6 speed boxes that need to be fitted
Change ratio by 15%from 5 speed top@.77 i think it is
I will do it and see how it goes
Diff gears is the other option but people will be bothered about speedo
G
I think I'll leave mine standard, no more power, no problems with gear ratios, no problems with brakes and I get up half hour earlier in the morning. Probably not a useful post, just an opinion! Hope to see some of you guys on a few of this years trips.
On a 463 the factory way to raise the high ratio by 10%, but unfortunately these as rare as hens teeth so higher top gear would seem viable alternative. Thought you could get overdrive s for 460??
Any further updates on the final gear G Wagen G? Really interested to hear how this works out for you. If successful it would be of fantastic benefit to a lot of people I'd imagine.
Well its a simple as this now
I will keep it as short as poss
Jason said someone might sell their transfer box
Ours are 1.05 ratio and his is 0.8
I have fitted 6 speed with .70 ratio. It was at 3000 rpm at just under 64mph with bigger tyres and thats why i thought about gears or the easiest thing to swap
I dont know what axles mine has without looking but when i looked at transfer box it was a 2.1. I just assumed jasons g wagon and mine would be the same
I did buy some parts from Canada Axles and steering parts, yes i know lhd but they were in the deal and a transfer box
I went out rat shooting last night for a farmer who had a rat problem. Now he has 174 less to worry about and so i rolled in at 3.30 pm.Dinner and bed was needed
It did never occur to me until that night and all the time i was out i thought i wonder what ratio the transfer box was that sat in my garage for about 3 years. I nearly fitted it before but stuck with mine as i had rebuilt it fully. I would of took the risk but not without checking the spare t box for basic wear etc
It was a 0.8
I was up late and had a lie in. Up at 11.30 and tired. I thought i would try transfer box and see how much difference it made
I took the risk not knowing if it was any good
Lying on the floor under my truck. Why do i do it i thought
Anyway from 1.30 pm till 6 pm it was ready for a test drive. Worst part is up for tools and from under car up and down fetching tools and altering jacks etc. Not right out and around again then back under the car
I have a pit but i am doing a big bhp 190 mercedes om 606 and could not be bothered to shoe horn it out without moving loads of junk
I will ache tomo lol
It is absolutely spot on
Now it has something to pull against instead of revving too much at no speed
So any merc 6 speed and a 0.8 transfer box is the way
As luck would have it which does not usually happen for me it is super quiet and as good as my old one i rebuilt
Low box is even lower too
Happy days all round
Its the truck they should of made many of
Om 606td and the ratio of axles transfer box as it is now
six speed box but they were not around at that time so a non linkage affair 5 speed would be fine
I love my g wagon. So many options un like other 4x4 vehicles on the market
Hi Guys
A total cock up with revs for speed
A speedo head from a spare car and its close but not perfect
How did i never get any speeding tickets lol
It is exactly now 2000 rpm at 50 mph on sat nav. I know its not 100% accurate but its better than a seedo ,so what it was telling me on original speedometer was totally wrong
I thank Howard for me to have to check it out
Many thanks
Any way a 200 mile round trip proved all is well. Its nice to cruise at 72 mph at less revs
Pease ignore any other speed figures i have posted previous as they could be 10 mph wrong
So its 50 at 2000 with bigger tyres
Im happy at that
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Gaz, what would the overall top gear ratio be on the modified gearset?