Author Topic: rear end ratio  (Read 484 times)

Offline Lesman

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rear end ratio
« on: July 20, 2021, 07:35:52 PM »
I have 3 rear ends for my Loop project bike that has a 1200 motor
850 GT 8/37
Ambo 8/35
G5      7/33
I think the 850 GT is hideous. I like the Ambo the best . Don't have any issue with G5.  I was told that an Ambo rear end with a 5 speed is too tall. I know that the 850 Gt and G5 are pretty close to the same ratio. The Ambo is about 5% taller. Is it that much different.
Thanks for the help.

Offline Antietam Classic Cycle

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Re: rear end ratio
« Reply #1 on: July 20, 2021, 08:44:17 PM »
Ambo & V7 Sport: 8/35 (4.375:1)
V700, Eldo, 850-T: 8/37 (4.625:1)
G5 (and more): 7/33 (4.714:1)

With a 1200 engine, the strongest one would be the most desirable IMO. That would be the G5. I'll be using a Mille GT (7/33) rear drive in my customer's "1200 Ambo".
Charlie

Offline kingoffleece

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Re: rear end ratio
« Reply #2 on: July 20, 2021, 11:01:59 PM »
You have some seriously nice bikes at your website.  So lovely and proper looking!
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Offline mtiberio

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Re: rear end ratio
« Reply #3 on: July 21, 2021, 06:10:43 AM »
remember, you have to insert a 2mm shim between the rear drive and swingarm when you use a drum brake rear drive on a disc brake swingarm. Unless you change the pinion holder, there is no way (I know of) to install a disc brake rear drive on a drum brake swingarm. No way unless you are willing to introduce a cocked rear axle, bend some rear drive studs, misalign wheels, and other issues...
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Re: rear end ratio
« Reply #3 on: July 21, 2021, 06:10:43 AM »

Offline Wayne Orwig

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Re: rear end ratio
« Reply #4 on: July 21, 2021, 07:10:12 AM »
I have 8/35 gears in my EV. It came with the 8/33, which was OK at highway speeds, but not so great when I towed the camper. I tried the 7/33 which was nice for towing, but always felt like the motor was spinning too much on long highway runs. The 8/35 is a good compromise for me.
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Offline Antietam Classic Cycle

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Re: rear end ratio
« Reply #5 on: July 21, 2021, 08:44:12 AM »
remember, you have to insert a 2mm shim between the rear drive and swingarm when you use a drum brake rear drive on a disc brake swingarm. Unless you change the pinion holder, there is no way (I know of) to install a disc brake rear drive on a drum brake swingarm. No way unless you are willing to introduce a cocked rear axle, bend some rear drive studs, misalign wheels, and other issues...

I'll be using a Convert swingarm to gain the larger u-joint and carrier bearing.
Charlie

Offline Alfetta

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Re: rear end ratio
« Reply #6 on: July 21, 2021, 08:44:35 AM »
I'd like to decrease the ratio on my V7(3), any body know if there is a taller option gear set out there in guzzi land?
NO, It's not pronounced "moder goosy"

Offline Antietam Classic Cycle

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Re: rear end ratio
« Reply #7 on: July 21, 2021, 09:41:25 AM »
I'd like to decrease the ratio on my V7(3), any body know if there is a taller option gear set out there in guzzi land?

Gearing changes on small-blocks were always done via the primary gears in the transmission, there was only one final drive ratio for all of them (at least on older ones).
Charlie

Offline Alfetta

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Re: rear end ratio
« Reply #8 on: July 21, 2021, 12:27:25 PM »
Gearing changes on small-blocks were always done via the primary gears in the transmission, there was only one final drive ratio for all of them (at least on older ones).

That is unfortunate, as this would require changing 12 gears verses 2... perhaps i should look into a larger rim/taller tire ?
NO, It's not pronounced "moder goosy"

Offline Antietam Classic Cycle

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Re: rear end ratio
« Reply #9 on: July 21, 2021, 01:22:08 PM »
That is unfortunate, as this would require changing 12 gears verses 2... perhaps i should look into a larger rim/taller tire ?

On the five-speed it was only two gears that were changed to alter the gear ratio - one on the clutch shaft and another on the input shaft. I'm not sure if the 6 speed is made the same way or not. From the parts diagram, it does look like it is. One would need to replace the clutch shaft and primary gear shaft (gears appear to be made as part of the shafts). Not an easy job. Perhaps a V9 transmission swap would work - the clutch shaft gear has 21 teeth vs. 18 of the V7, which leads me to believe the primary gearing may be taller.

But, in the end, a taller tire would be easier and more cost effective.
Charlie

Offline Lesman

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Re: rear end ratio
« Reply #10 on: July 21, 2021, 04:57:04 PM »
Thanks for the info. I'm running a Quota rear disk on the Ambo/Eldo swingarm. It's not off centered. Made an internal spacer instead of utilizing a disc brake model spacer. Sorry for the clumsy explain. Running a radial Tokico caliper on the rear. Every single thing needs to be thought out and custom. Next week or three the rear end and tranny will be disassembled.


Thanks

Offline drdwb

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Re: rear end ratio
« Reply #11 on: July 23, 2021, 07:35:59 AM »
When I started towing the camper trailer with the 03 EV, I like Wayne, found the 8/33 was not a good match, in town driving was hard on the clutch with stop lights / signs, once moving at hiway speeds it worked but I rarely used high gear, so I switched to the 7/33 which helped towing a lot on take offs. Eventually I noticed I was using the high gear more without the trailer. So I switched my wifeís 04 Stone over to a 7/33 also and she found the swap helped reduce her hand numbness and fatigue which extended riding time significantly. There maybe some sacrifices but with our style of touring I canít think of any.

Fortunately we have the Norge and Breva to hop on when we want a sporty ride. Bikes are like guitars itís good to have variety.
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