Installing early XL trans in XB cases (other cool stuff too!)

[EricZ]

I finalized the install of the Andrews 1991-2003 XL transmission shafts and gear set in 2007 XB cases.

If you want different gear ratios or need a stronger transmission, you can install a 1991-2003 Sportster transmission in a 2003-2005 XB case using the XB bearings. Everything drops right in, but the XB shift forks need extra clearance to fit over the XL dog rings, and the XB shift drum needs to be modified to fit with the larger diameter XL 5th main drive gear.

Here are lots of pics of the setup and little notes on each:

Stock XB shift fork trying to fit over XL dog ring:

Stock XB shift fork on left, Modified XB shift fork on right:

Modified XB shift fork fitting over XL dog ring:

XL main drive gear hitting on 2003-2005 XB shift drum:

Modified XB shift drum on left, Stock XB drum on right:

If you have a 2006-2010 XB that came with the helical cut transmissions, they use different countershaft bearings and a different RH main bearing. To swap an older transmission into a set of these cases, the bearings for the helical trans have to be used, so several additional modifications are needed. The step on the main drive gear, where the inner race of the main output bearing seats against, needs to be machined back 0.085" to allow the main drive gear to locate correctly, when pressed into the double row angular contact main output bearing, in relation to the 2nd gear dogs. It also needs an o-ring groove, which replaces the quad seal used on the older single-row bearings. The counter shaft also needs to be spaced .074" to the right, to compensate for the thinner left side countershaft bearing.

Stock XB left countershaft spacer:

Modified Big Twin countershaft spacer:

And darn it if I didn't take any pics of the Main drive gear after machining!! Oh well, I guess you will have to understand what I wrote.

I also finished the boost controller microswitch mounting. I made an aluminum top plate that is slotted for switch engagement adjustment. The outer 4-40 button heads thread into the shift shaft arm, and the inner screws thread into the switches.

And here are some shots of the dog alignment and engagement in each gear:

1st Gear:

Neutral:

2nd Gear:

3rd Gear:

4th Gear:

And 5th Gear, without the cases together you can't tell, but trust me, they fully engage without loading the fork:

Here are some general pics of the transmission:

Here is also the dash I machined today. It came out really nice and will hide behind the Showyomoto Iron headlight unit just right.

 

[oh9bolt]

[up][up][up][up]

 

[Bairframe]

Very clean work. Nice write up, however you didn't mention what the difference in ratios are. Have you ridden with it yet? How well does it perform?

 

[Crescent1101]

I want that dash without the boost gauges though (speedo instead)! I assume with the lEDS you have all the old warning lights?

 

[EricZ]

I went with the standard gear ratio set and used the stock XB first gear since it has the same big tooth design as the XL gears.

1st: 2.78
2nd: 1.87
3rd: 1.48
4th: 1.21
5th: 1.00

You can see all of what Andrews offers here:

http://www.andrewsproducts.com/PDF_files/catalog/32_EVSportGears-pg32.pdf

My gearset was back-cut, micro-polished, and cryo-treated by R&D Motorsports here in Florida.

I am still building the motor, but should have it up and running by the end of the month.

Yup, The LED's replace the warning lights.

 

[Crescent1101]

I can't wait to see the dash installed. I really like that. If you decide to sell those I might be interested.

 

[firefighter1c57]

Eric, question for you. If you're using the XL transmission, would it be possible to use one of the 6th gear kits out for these? I know, I know, the 6th gear went into the trap door area, and these cases don't have a trap door, got it... but, can a trap door be modified into this case to use the 6th gear? I've been thinking of this for a while, I guess I need to get a donor transmission and get to work lol. Just wanted your thoughts on it.

 

[EricZ]

I am only speculating about this, but as far as I can tell, the trap door for the 6 speed transmissions may use different LH countershaft and main shaft bearings, and makes more space on the left side of the transmission for the extra gear.

You would have to machine away the trap door area of the XB case and machine a new trap door piece to accept the 6 speed bearings.

You would also have to either retro fit the XL style shift drum, which is a completely different design than the XB, or make a special shift drum for the 6 speed gear set in the XB case.

There are a lot of changes to make it work, but it sure seems possible. It would just take someone to do it! Go for it!!

 

[onelogue]

Eric great write-up! The pictures definitely help me follow you. Those gears should definitely help with the power.

 

[firefighter1c57]

Eric, the kits come with a new trap door with the bearing in it already. Also come with a XL shift drum with the 6th gear already machined... Basically, the XB case would have to be machined to accept the trap door. Here's a pic

From here

kit works with tube frame Buells and the XL series... guess I need a donor tranny...

 

[ct1200]

You had me at "boost controller microswitch"

 

[EricZ]

Firefighter, I have seen the kit, but not in person.

The first issue is the XL6 shift fork design vs the XB design. The XB forks ride on two separate shift fork shafts while the XL forks ride on the drum.

The second issue is the bolt pattern for the XL6 trap door is not even close to the XB case bolt pattern, since the stock XL cases are so different. A custom trap door is a must.

Also, how does the location of the XL shift drum centerline compare to the XB? If those are different, the XB shift shaft is going to be different. You would solve that with the XB specific trap door, but you would still have to machine a new shift drum if so.

Lots of unknowns! You will run into lots of problems if you don't verify the fit of every part when you tackle a project like this.

I would love to see someone take on the project! It would be a cool setup!

 

[loose1]

The XL and XB trans have the same locations, center lines. The shift drum on the XL has a bigger diameter on the right side case. Other than that it drops in the right side case. What I was planning on doing for the trap door is draw up the stock door and make a ring to match it and then weld that into the stock/modified xb left side case. If I do it this way the six speed will bolt right in.

I had the trap door half drawn up but my hard drive went south and I lost it. So I'll have to start over. I wish I could use the cmm at work but there's no way that would happen.

A xb 6 speed is in the works, and I want to be the first.

Matt

 

[firefighter1c57]

Ok, I see what you are saying about the shift drum now. I work in a machine shop that can basically make anything. I think I'll try this.

I know the Blast transmission shifts like the XL with a XB style case. I'm thinking a blending of those three parts and making whatever else I can probably do it.

Thanks Eric.

 

[Bairframe]

Let me know if you guys need some help on this. I am interested in doing the mod myself. I do aircraft prototyping for a living and can literally make anything. I just haven't dug into the tranny yet (other things on my to-do list first). I will have to wait until next winter for that but if anyone needs some fab or design help then let me know.

 

[Bairframe]

Also I found this engine case (see link below) with a trap door already built into it. This guy is right up the road from where I'll be this weekend so I'm going to try and stop by - see what details I can get out of it.

Engine case on eBay

 

[loose1]

The door is different than the XL and those cases are unfinished. You would have to machine the decks and jug bores.
Matt

 

[firefighter1c57]

Yea Bairframe, it's really a waste of time to look at those. They have been on ebay a hundred times. They are nothing special, basic XB cases. They are race use only, meaning where the serial number goes on the case they are stamped "race use only" That's about the big difference in them and regular XB cases.

They also need a LOOOOOOOT of machining.

 

[EricZ]

Those cases are very unique. They are set up for dual crankcase reed valves, have a MUCH thicker right crank bearing race and the aluminum alloy is stronger than oem cases uses.

It would be a great set of cases to build a powerful engine from.

I would really be interested in finding a 3.6 crank!

 

[firefighter1c57]

really... I was unaware they had a different crank bearing race. When you say stronger case, are they T7 vs say T6 of the same alloy or are they say 2024 vs say 1050?