Fifth gear mod

[DavesXS]

Re: what a mesh

Originally posted by xschop
What is critical is the gear mesh tolerance. To do this mod correctly, you would need to have an XS motor split in half with the clutch shaft and main shaft installed in their places and mic the ridge to valley of the pinion and drive gears.....There is another way by mic'ing the distance between the centers of both shafts, then mic'ing the pinion and drive gear diameters, counting teeth ratios and reconfiguring the new gears......Of course I won't be tearing into my motor to figure it out....

Thats something like what I figured. We'll need a spare motor torn down to get it right.

Maybe this winter if one of you guys plan to tear into yours, or plan on major down time we can do this.

Or theres this...Motor

[xschop]

simple

Hey Todd that's just too convenient.....Just Count the teeth on each.....I may be onto somethin

[psycoreefer]

Hey guys, I've got a semi-complete (missing clutch basket, pans, side covers ect.) bottom end sitting in my garage. It came with my bike for the 1st and 2nd gear parts. I'd have to re-assemble it a bit because I dremeled it's gears to put in my bike but all the parts are there. I'm not sure I have the equipment to measure what we need to know though. I'd be happy to open my garage to anyone that wanted to come over and take those measurements though. Or if anyone wants the bottom end I'd sell it dirt cheap, its just taking up space as far as I'm concerned.

[DavesXS]

Pinion = 34T
wheel = 30T

[xschop]

Talk about laxation

would definitely be cool to cruise 70 mph at @ 3k in 5th.

[DavesXS]

Originally posted by DavesXS
Pinion = 34T
wheel = 30T

4th pinion has 31T. 4th wheel 32T

What would we want, 36T pinion, and 29T wheel?

I am just looking at the difference from 4th to 5th gears.

[DavesXS]

Originally posted by DavesXS


4th pinion has 31T. 4th wheel 32T

What would we want, 36T pinion, and 29T wheel?

I am just looking at the difference from 4th to 5th gears.

They went up 2 teeth on the pinion and down 1 on the wheel going from 4th to 5th. I am thinking if we use that interval, that we can easily calculate our rpm.
Ride down the road and look at the difference in rpms from 4th to 5th. Then multiply that by 2 or 3 or what ever untill we find the rpm we want in 5th. +2 -1 would be 2x what ever it is now. +4 -2 would be 3x what it is now.
Does it even work that way? Or am I waisting space here?

[xschop]

thinking

collective XSive thoughts on what the ideal RPM would be in 5th?

[DavesXS]

3k at 75 is what my Z does in 5th. And thats high for a car. Probably just right for our bikes.

Edit: maybe more like 3.5k at 75 for our bikes.

[xschop]

sip sip

easy on the gas there....Are you talking the old 240z? My buddy had one with an LT1 and T56....pure sin....

My s10 work truck has been converted to an IROC T5 manual and it now cruises in 5th Gear at 2350, and can still scratch the tires in first and 2nd......saves alot of gas now......How did you find out the teeth # of the 5th gear combo's?

[psycoreefer]

240/280z guys - awesome. I've got a 73 I'm building up right now. Something about 350 - 400hp in a car that weights in at just over 1500lbs just tickles me the right way.

Anyway, I think about 3.5k at 75 would be about right. Just coming into the big power so passing wouldn't require a down shift. Might be to tall to use for anything other then the free way though, You'd be able to idle at 55 or 60.

[DavesXS]

Re: sip sip

Originally posted by xschop
easy on the gas there....Are you talking the old 240z? My buddy had one with an LT1 and T56....pure sin....

My s10 work truck has been converted to an IROC T5 manual and it now cruises in 5th Gear at 2350, and can still scratch the tires in first and 2nd......saves alot of gas now......How did you find out the teeth # of the 5th gear combo's?

90ZTT 400 hp
Had an 85 Iroc years ago stock
And a 77 280z 300 hp


I looked up the parts at Yamaha and they have the teeth next to them.

[xschop]

I looked up the parts at Yamaha and they have the teeth next to them.

.....Ok. now find out what the 5th gears are for an xs750 and the 850. Although I think that the gearing change between the 750-850 was done in the middle gear ratios so the trannys may be the same....member DooLee may know for sure

[psycoreefer]

1980 XS850 G - 5th Gear
Wheel = 22T
Pinion = 23T

1979 XS750 F - 5th Gear
Wheel = 22T
Pinion = 23T

Just looking at the parts fiche I don't think they would swap. The 750/850 transmission looks like it goes together quite a bit different then our 1100's do. I'll bet if it was that easy someone would have done it already

[xschop]

wrong way

so the 5th gear 750/850 ratio would be the wrong direction for the swap since it is 1.045 as compared to the xs11's 1.133 pinion to wheel ratio....I figure the best ratio to swap in would be a 36/29.....just my $.02