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sean
Member
Date registered: Dec 2015
Location: austin texas United States
Vehicle(s): 88 300gd 460 swb right hand 85 280ge 617a turbo di
Posts: 48
| What transmission will increase top end?
Hi friends I have a 280 GE 85 year with a 617 turbo charged motor and 300sd transmission I can barely get 60 miles an hour with the engine screaming wondering what transmission I could swap into that may have an additional couple of gears or at least a taller gear set sounds like swapping out the ring gears in the differential would be a more expensive route to go any help would be appreciated thanks so much |
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: What transmission will increase top end?
The 5-speed manual Getrag has a final aspect of 0.813. Many folks say this tranny has a weak spot in one of the bearings; but I drove one for 111,000 miles with no problems other than a short life of the clutch slave due to exhaust heat causing it to fail. |
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sean
Member
Date registered: Dec 2015
Location: austin texas United States
Vehicle(s): 88 300gd 460 swb right hand 85 280ge 617a turbo di
Posts: 48
| RE: What transmission will increase top end?
Thanks Dutch
I may go in that direction but I'm really enjoying the automatic thats in it now except for the top speed .is there another Mercedes transmission out of maybe a sedan that would fit the 300 SD motor and obviously fit in the transmission tunnel to the transfer case? thanks again
I know there are some 6 and 7 speed trannys so just wondering what my options are.
Is there somewhere i can get info of what will mate to the 617 turbo engine
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bram_r
Expert
Date registered: Apr 2007
Location: the Netherlands
Vehicle(s): 1984 MB 280GE, 1982 MB 300GD, 1986 Subaru XT 4WD
Posts: 1659
| RE: What transmission will increase top end?
sean - 9/5/2016 6:25 PM
Thanks Dutch
I may go in that direction but I'm really enjoying the automatic thats in it now except for the top speed .is there another Mercedes transmission out of maybe a sedan that would fit the 300 SD motor and obviously fit in the transmission tunnel to the transfer case? thanks again
I know there are some 6 and 7 speed trannys so just wondering what my options are.
Is there somewhere i can get info of what will mate to the 617 turbo engine
Basicly any manual 717.4xx or 711.11x will fit your engine. The older 717.420 / 422 are known to be less durable than the iron box 711.113 / 116 overdrive boxes, but under normal driving all will do just fine. More modern Getrags you can find with code 717.44x (Sprinters, E-class etc).
The 6 or 7 speeds with extra low overdrive only fit on CDI engines, so these require adapter plates or something.
Other 6 speeds which do fit your om617a got the same overdrive gear ratio as the gearboxes mentioned above. So you only get an extra gear between 1st and 5th.
I'm not that familiar with overdrive automatic gearboxes. I think that most of them would need some sort of transmission controller to make them shift properly, as these are mostly computer controlled, whereas the 4 speed ones are not.
If going to 5 speed manual, take into considiration short lenght propshaft between transfer case and transmission, shifter, shifter rods.
gr. Bram
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Boy G
Expert
Date registered: Feb 2007
Location: Bushveld, South Africa
Vehicle(s): Diesel G's: 617A and 602
Posts: 1683
| Re: What transmission will increase top end?
The easiest is a 5th gear manual box.
The nicest is to try and find a set of 4.11 diffs as per 290 GDT and leave the 1:1 final drive auto tranny in there. |
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Aircruiser
Extreme Veteran
Date registered: Aug 2011
Location: Atlanta GA
Vehicle(s): 2000 G500, 1986 300GD, 2017 Porsche Cayenne Hybrid
Posts: 364
| RE: What transmission will increase top end?
What size tires do you have?
In my '86 LWB 460 617A, 280ge automatic with 31" tires it can hit 80+ mph at the max IP governor rpm. Obviously it can cruise comfortably between 60-70mph. There are many tire size/speed/gear ratio calculators available online. |
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sean
Member
Date registered: Dec 2015
Location: austin texas United States
Vehicle(s): 88 300gd 460 swb right hand 85 280ge 617a turbo di
Posts: 48
| RE: What transmission will increase top end?
I'm running 33 inch tires.
Would ring gears out of a 300 sd sedan work
I have 3 parts cars 2 sd one 300d
85 year model.
2400 dollars for new ones is a bit out there
For more top end.
I could go wrong 5 speed. But like I said I'm
Enjoying the automatic transmission. |
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WEBIII
Extreme Veteran
Date registered: Oct 2010
Location: Inlet Beach, FL
Vehicle(s): 461.318, 463.241
Posts: 315
| Re: What transmission will increase top end?
Sean, are you saying you can't go faster than 60mph? You definitely should be able to hit at least 70 without any problems other than a little road and engine noise. Have you done things like valve adjustment and check/replace injectors? Do you know how much boost you're getting?
Also I don't know how much off-roading you do but if you could find a 280GE auto trans like Aircruiser mentioned instead of the sedan trans I think you'd be very happy with it off-road. The way the 280ge trans holds itself in first gear makes it a very capable crawler when you factor-in the lockup torque converter. |
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sean
Member
Date registered: Dec 2015
Location: austin texas United States
Vehicle(s): 88 300gd 460 swb right hand 85 280ge 617a turbo di
Posts: 48
| Re: What transmission will increase top end?
Hi webllll
I can get to 70 but the motor is
Screaming.
Is it OK to run it that hard.
I love this thing and want it to last
It is a daily driver
Mostly on road.
I just feel like another 2 top end gears and it would
Purr along instead of screaming.
Do they make a 2 speed rear end that would fit.
Low gear for 4 wd and high gear for on road 2 wdb
The motor starts quick idles well I
Have had many 300sd sedans and this engine seems to be running great |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| Re: What transmission will increase top end?
Some (Australian or British) guy installed an overdrive into the rear shaft path. Some googling might find it. That would give you the best of all worlds, nice low range for off road and good on-road manners.
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sean
Member
Date registered: Dec 2015
Location: austin texas United States
Vehicle(s): 88 300gd 460 swb right hand 85 280ge 617a turbo di
Posts: 48
| Re: What transmission will increase top end?
Alright guys
Been researching my options .
I'm looking at the 722.5 transmission
Wondering if anybody knows if that will bolt up to the 300sd turbo charged motor.
It appears that the 7225 transmission is a 4 speed with 5th being an Overdrive my concern is fitment to the back of the engine.
I'm not crazy about the idea of changing out the ring gears because you lose the lower crawling ability and it's like 2500 bucks |
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bram_r
Expert
Date registered: Apr 2007
Location: the Netherlands
Vehicle(s): 1984 MB 280GE, 1982 MB 300GD, 1986 Subaru XT 4WD
Posts: 1659
| Re: What transmission will increase top end?
sean - 9/8/2016 3:39 PM
Alright guys
Been researching my options .
I'm looking at the 722.5 transmission
Wondering if anybody knows if that will bolt up to the 300sd turbo charged motor.
It appears that the 7225 transmission is a 4 speed with 5th being an Overdrive my concern is fitment to the back of the engine.
I'm not crazy about the idea of changing out the ring gears because you lose the lower crawling ability and it's like 2500 bucks
It looks like the 722.5 got the starter on the LH (driver) side, whereas your om617a got the starter on the RH (passenger) side.
This will not fit.
Basicly all engines of the om60x series got the same bolt pattern, only the starter location left or right can be different.
gr. bram |
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Boy G
Expert
Date registered: Feb 2007
Location: Bushveld, South Africa
Vehicle(s): Diesel G's: 617A and 602
Posts: 1683
| Re: What transmission will increase top end?
Sean, I advised that the easiest thing to do would be to buy a 5 speed box that fits. That box is available ( I think) from Bram amongst others, who has also advised you on this thread. It is called 711.113.
Changing the diff ratios is more expensive. But it works very well, even for very slow / rockcrawling work. I have a 290 turbo with 4 spd auto tranny and faster (4.11) diffs and it is excellent on and off road. The auto makes it amazing in low ratio, and the longer diffs make it comfortable on the road.
I also have a 617 turbo with a manual 5 speed 711.113 gearbox and the standard 4.89:1 diffs common of that vintage. It is agreeable but not in the same space as the 290
Edited by Boy G 9/17/2016 3:25 PM
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bram_r
Expert
Date registered: Apr 2007
Location: the Netherlands
Vehicle(s): 1984 MB 280GE, 1982 MB 300GD, 1986 Subaru XT 4WD
Posts: 1659
| Re: What transmission will increase top end?
Boy G - 9/17/2016 9:20 PM
I have a 290 turbo with 4 spd auto tranny and faster (4.11) diffs and it is excellent on and off road. The auto makes it amazing in low ratio, and the longer diffs make it comfortable on the road.
I also have a 617 turbo with a manual 5 speed 711.113 gearbox and the standard 4.89:1 diffs common of that vintage. It is agreeable but not in the same space as the 290
That's funny, I got two G's with the same set up as you 
Only my 290GDT converted G (with the matching 4 sp auto) needs to have the diffs changed to 3.72:1 (I got two of those sets). Now it's on 4.88's which is not ideal on highway cruising.
I already wondered how the 4.11's would work, but that would be a good option hearing from your experience. I know the 3.72's are the factory set-up, but with 255/85R16 tires, the 4.11's may give a pretty similar overal ratio.
Sorry for the off-topic.
gr. Bram
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hipine
Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
| Re: What transmission will increase top end?
Remember also that "there is no free lunch."
Of course, when you do things to increase top speed, you also reduce torque, and the motor only has so much of that. When you use things like big tires and differential gears to increase top speed, you automatically reduce available acceleration torque in all the gears. There's only so much a 3 liter indirect-injection motor with 35 year old technology can do to push that brick through the wind. You may find a limit where the speed and revs are theoretically available, but the car can't reach that speed in that gear due to the reduced available torque at the wheels being insufficient to overcome the wind resistance and other losses.
I didn't read closely but don't remember seeing any RPM-at-speed numbers from you, but I have a 617a ahead of a 5-speed overdrive manual gearbox with 4.88 gears and 235/85-16 tires. At the 2900 RPM torque peak of the motor, I'm going about 58 mph in 4th (1:1) and 70 mph in 5th (overdrive). These are numbers from an Isspro tach sensing off the crank damper, and GPS providing the mph numbers.
I've used different 617a's in my G. They have all "felt" differently at speed. The one I have now is the best of the bunch (a low-mileage factory crate motor of 617.950 spec) and it cruises happily at 68 mph all day long running in it's most efficient rev range with a full load of camping gear and roof-top tent in place (just came off a long trip that way). But I've used motors that felt like they were "screaming" in trying to maintain 65 mph. Significant contributions to the feel of the motor are made by how well it's balanced and how well the injection pump timing is set.
In my opinion, the 460 G with 617a in place is a 65-70 mph vehicle with everything in top condition and using a 5-speed manual transmision. Asking more of this motor in this vehicle will be to over-stress the combination. If one wants more speed, a different motor should be used.
Just my opinion of course, but based on a little over 180,000 miles of driving 617a's in the 460 using three very different motors with 4 and 5 speed manual transmissions .
Good luck making your G what you want it to be!
-Dave G. |
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Boy G
Expert
Date registered: Feb 2007
Location: Bushveld, South Africa
Vehicle(s): Diesel G's: 617A and 602
Posts: 1683
| Re: What transmission will increase top end?
@Bram. As Dave has mentioned, and I agree, 70 mph / 110 km/h is probably the best possible speed of a 460 / 461. My 290 is very comfortable at 110 km/hr and still has a little with which to overtake. And it may give 11l/100 at that speed.
AFA Sean is concerned it sounds like tall tyres and a fifth gear will give him a comfortable 70mph.
Btw Sean, another thing that I have found with the 617 a engine is that it does not like a small exhaust pipe. I am not sure what you have, but i completely removed the silencer on mine and fitted a 63 mm straight through pipe and it made an amazing difference. |
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bram_r
Expert
Date registered: Apr 2007
Location: the Netherlands
Vehicle(s): 1984 MB 280GE, 1982 MB 300GD, 1986 Subaru XT 4WD
Posts: 1659
| Re: What transmission will increase top end?
Boy G - 9/18/2016 7:45 PM
@Bram. As Dave has mentioned, and I agree, 70 mph / 110 km/h is probably the best possible speed of a 460 / 461. My 290 is very comfortable at 110 km/hr and still has a little with which to overtake. And it may give 11l/100 at that speed.
Totally agree with that.
Both in terms of comfort/wind noise and in terms of fuel economy. |
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diesel_jim
Veteran
Date registered: Jan 2014
Location: N Wiltshire. UK
Vehicle(s): LR Defender 110, 1989 W460 SWB
Posts: 114
| Re: What transmission will increase top end?
AlanMcR - 9/7/2016 11:33 PM Some (Australian or British) guy installed an overdrive into the rear shaft path. Some googling might find it. That would give you the best of all worlds, nice low range for off road and good on-road manners.
That was Mike Axelberg (Axel606) over on Gwagen Register. He fitted the overdrive into his superG. although it only fits the LWB as there's no room on a SWB. It works on the rear axle only, so disengages when you select 4wd
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bram_r
Expert
Date registered: Apr 2007
Location: the Netherlands
Vehicle(s): 1984 MB 280GE, 1982 MB 300GD, 1986 Subaru XT 4WD
Posts: 1659
| Re: What transmission will increase top end?
diesel_jim - 9/18/2016 9:22 PM
AlanMcR - 9/7/2016 11:33 PM Some (Australian or British) guy installed an overdrive into the rear shaft path. Some googling might find it. That would give you the best of all worlds, nice low range for off road and good on-road manners.
That was Mike Axelberg (Axel606) over on Gwagen Register. He fitted the overdrive into his superG. although it only fits the LWB as there's no room on a SWB. It works on the rear axle only, so disengages when you select 4wd
I once gathered some data on an APA overdrive unit, to maybe install in my G when I was contemplating the possibilities then.
Google for APA getriebe for some more info.
gr. Bram |
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hipine
Date registered: Jul 2006
Location: US, CO, Bailey
Vehicle(s): 460 1980 280GE w. 617A
| Re: What transmission will increase top end?
....
Btw Sean, another thing that I have found with the 617 a engine is that it does not like a small exhaust pipe. I am not sure what you have, but i completely removed the silencer on mine and fitted a 63 mm straight through pipe and it made an amazing difference.
Good point! Look at the turbo exit and carry that pipe size all the way to the rear if you can. Mine runs a Timevalve stainless setup from a 280GE (M110) from the t-case joint back. I don't know the size but it's at least 2-1/4" (57m) I'm also on the "old style" exhaust without any transverse silencer under the transmission.
-Dave G. |
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