RT rear end on a GS

[bmwrich58]

Today I installed an '05 RT rear end on my '05 GS.
Why you say...?????????? Well experimenting for the gas mileage and to help keep up with riding buddies at sonic speeds!!!! So far I like it a lot.
Bike seems to be not so twitchy at low speeds, I guess would be a good way to explain.
The bike still gets up and goes, at least good enough for me...
I know from previous experience having owned two other GS's,their not the best bikes for returning great gas mileage at high speed. This bike was never bought with intensions to go offroad with either..but the ergo's fit my monkey like arms an legs.
I usually cruise at 80mph when doing the slab's, but the GS's stock gearing ain't really geared for that. At least for me it ain't! And I like to get where I'm going............................. today.!!!!!!!!!!
Yes, I backroad most of the time, but here in the midwest,it takes sometime to get to some good backroads and time is precious in my book.

here's a comparison list of the speeds & rpm's of the two different rear ends
where I feel the bikes sweet spot is.

bike gear @4000rpm's GS gearing then @4000rpm's RT gearing

1 - GS 25mph RT 29mph +4 mph
2 - GS 38 RT 40 +2mph
3 - GS 45 RT 50 +5mph
4 - GS 56 RT 60 +4mph
5 - GS 64 RT 69 +5mph
6 - GS 71 RT 78 +7mph



on the slab at speed.....
GS gearing then RT gearing.

5th gear @55mph GS 3500rpm RT 3100rpm -400rpm

6th gear @55mph GS 3100rpm RT 2850rpm -250rpm

6th gear @60mph GS 3250rpm RT2900rpm -350rpm

6th gear @80mph GS 4600rpm RT4100rpm -500rpm

tommorow I'll do a little riding and check the gas mileage....c-ya

 

[Fanum]

Today I installed an '05 RT rear end on my '05 GS.

Being a bunch of tarts though, you do know that the first thing that everyone's going to want are pictures???

 

[bmwrich58]

Being a bunch of tarts though, you do know that the first thing that everyone's going to want are pictures???

A rear end is a rear end. Nothing different but the crap catcher bolt holes are missing that's all. Took all of about 4 hours to do the swap. Had to swap the brake rotor over from the GS to RT which consumed a lot of time.
The cold rear end lube was a bit sluggish at 40F so it was a while for it to fill.

 

[wildbeeste]

Being a tart though, you do know that the first thing that Fanums going to want is pictures???

Fixed it for you

 

[Fanum]

A rear end is a rear end. Nothing different but the crap catcher bolt holes are missing that's all. Took all of about 4 hours to do the swap. Had to swap the brake rotor over from the GS to RT which consumed a lot of time.
The cold rear end lube was a bit sluggish at 40F so it was a while for it to fill.

Ahhh.......I understand now

I thought you were talking about the plastics/seat/rack etc etc, rather than the final drive and so on

 

[bmwrich58]

Cloudy day 47°F,strong wind outta the southwest at 20mph. Closest rain 50 miles away (on radar) and weather guys haven't predicted any for my area.

Well so far so good and so BAD!!!

Feckin; rain...............Did about 29 miles then the rain started. Weather guys are always wrong anyway.
No fear,rain jacket in the saddle bags.
Pull over at a gas station with a canopy to done my rain gear and...FECK!!!!!!!!!!!!
Where's my feckin' rain gear!!!! (probably sittin' on the work bench in the garage where I left them last..)
Well, time to hit the highway and zoom home in the wet.

The first 39 or so miles were two laners cutting through a few towns averaging about 40 miles an hour. Figured I'd ride into the wind on back roads at a slower pace. Then hit it hard with the wind to my back on the slab heading home.
So far,I like the new gearing,bike coasts a lot longer than with the original gearing. Like I said,the bike seems more milder,less twitchy at the slower "in town" speeds. I know ,I know,this bike was built to supposedly go off road. But even with this RT gearing,she's not all that bad at snail paced speeds.

On the higher speed back roads at 40-50mph's,cruising was still very comfortable and really a no need for 6th gear.
Coming home on the interstate 75-85 miles per hour in the rain in 6th gear stayed with flow of traffic.
Actually passing most of them but still continuing at a good pace.
Engine speed was kept in the 4-45000 rpm range. Never at all felt like she was struggling,in fact I did get her up to 100mph with no problems and she still wanted to go! Bike felt very,very comfortable cruising at 80mph,just a hummming along like a good ol' gal, and not buzzy at all in the grips.

If you've ever ridden a "pipey" motorcross bike, you'd understand when I say that the bike comes alive at 5000rpm's.
She just hits like a 2 stroke bike with "midrange pipe". Get the "R's" up and she breathes quite comfortably and effortlessly. If your used to the "GS gearing engine braking,this RT gearing is missing that mucho!"
Before with the stock GS gearing,the bottom end is full of torque. Even with the RT rear gear, she's still no "slouch" but really gets up and rocks when in the higher rpm range!
Tomorrow when my leathers dry and the rain disappears,I'll have another go.