planning a wider rear wheel. 82 750 seca.

yess you read it right, another xjer dreaming of a wider tire.

after a pm to injuhneer, i started to plan widening the rear rim. the left side of it to be exact. the mod includes cutting and welding and i would like to ask if anyone knows exactly what material the wheels are?

 

I just swapped the rear wheel from my 750 Seca for one from a 750 Mawim (18" to a 16" rim) with a wider tire. It will increase the rpms a bit while riding, but takes off like a raped ape! Lowers the rear of the bike 1-1/2" and looks better too!

 

nice one painterd, i had that in mind for a sec too but i like the 18'' rim..


back to original question exactly what material the wheels on these bikes are? i have the spiral spoke ones on my seca.

 

The wheels on the Seca is cast aluminum.

 

The wheels would be made of cast aluminum and/or magnesium mix (why some people call them mags). Unless you like road rash, plan to have the wheel CNC cut, then find a certified welder to tig it back together. This is not to say someone couldn't do this on their own. Without sounding rude, if you need to ask how to do it then you need to have it done by a machine shop. This is because there are many grades of cast... but in most cases the metal is whatever the factory had left from machining or failed castings from the day before... plus a select amount of new metal. A wheel, for example, would not be the same grade cast they would use for a engine head. A GOOD and SAFE weld on dirty cast could only really be done by a pro welder and even then a good jig would need to be setup to keep the wheel true.

 

Just a random thought if you're going to do this- -
Wouldn't you want to split 2 rims apart so you only end up with one continuous weld, as opposed to splitting one rim and coming up with a filler material of a different alloy??

Would that much heat and welding pull the rim out of true, or change the temper of the area where the "cooler" spokes meet the very hot rim??
Like a hidden stress crack from expansion?? (just asking)

Because I have many burned rims, and I see cracks (just saying)

 

Why not make it less work....Run a skinnier rear fender, and the wheel will look wider. Problem solved

 

thanks everyone.

i know they are cast aluminum but i was afraid of something like 79xs said about the composition. thats why i asked. i can weld aluminum but i dont have the equipment to pull this off in my garage. it requires machining.

time, your random thought of using a donor rim is brilliant!

cmccully your idea is just as brilliant but i dont have a rear fender



more ideas and thoughts are welcome

 

It may be easier or more feezable to just cut out the hub from the rear wheel (with the spline gear intact) and re-weld it into a wider rear wheel from another bike. Getting it centered and straight would be the key to getting it to work, but I'm sure it can be done.

 

the spline gear is a separate part of the wheel hub, and it may be possible to use only that. drilling a bolt pattern should be no problem but finding a suitable wheel to fit the spline gear could get difficult. then theres the question of bearings and axles.. modding the oem wheel sounds easier to me..

and i like my spiral spokes and id prefer to have my rims matched.

 

id love to see you do this, but it would probabably cost more than you have into the bike

 

Wouldnt that change the center line of the wheels?

 

Wouldn't a wider wheel hit your shaft drive?

 

you will wish you did have a rear fender the first time you ride in the rain, or ona gravel road. I tried without, and it was horrible, you hit your self with stones, and water and everything, it sucks!

 

yes it would. but the awesomeness would be something else! its a pretty difficult mod and it is under consideration.

yes but only the rear wheel. the plan is to offset the wheel to the right by putting a spacer between the splined gear and the wheel.

no after i offset the whole thing to the right. maybe a notch on the shaft housing is in order also.




cmccully, i have a plan for a rear fender. i dont have one right now but i dont fancy things pouring on my back when i ride either..



i have lots of other possibly suicidal plans for my seca. i hope i can show them off someday


:wink:

 

I think if you do this you will end up with something like this:
http://video.google.com/videoplay?docid ... 0489184913

 

waldo with your confidence i would stay away from motorcycles.

the idea is to mess with the rear end of the bike and if you would have thought it a bit the riding condition in the video is because of problems in the front.

but thank you for your thoughts. nice contribution.

i didnt laugh.

 

Sorry, but I was not trying to be humorous. I was just trying to point something out to you.

 

ill repeat myself. if you think this mod would cause that, i have to disagree.

 

Quote from your post,:
"waldo wrote:
Wouldnt that change the center line of the wheels?

yes but only the rear wheel. the plan is to offset the wheel to the right by putting a spacer between the splined gear and the wheel."

While it is mechanically possible to do this the center line of the tires has to remain in the center of the bike its just physics.

 

No it doesn't

I've seen a very successful BMW twin race bike with a widened rear wheel that was out of line

 

( a bit off topic - - )
I built me a swing bike !! Like these -

http://www.youtube.com/watch?v=R5P70XtI4zQ

 

Cool when are you going to post video of you riding it?

 

thats a sick bike!


i also have seen (well, pictures of) bikes that have rear wheels out of line. but a racebike? the ones i have seen are more like showbikes. i would think the rear being offset affects handling? was it an oval race bike?

the plan on mine is to have the rear centered. waldo sorry i dont think i was too clear with my answer, let me rephrase:

the wheel hub will be offset to the right, but with widening the left side of the rim the tire on it will be centered with the front wheel and the backbone of the bike.

 

I bought those mini video cameras, but am video illiterate still.
It's important to get the angle of the rear "head bearing" more vertical than the front. I've only fallen off once.
From what I've read, a motorcycle can run "out of true" by 20 MM.

Another random thought - - if you have a mill cut the rims apart, have them cut a "Z" section, so that the 2 pieces press together totally aligned, and square, then weld. You don't have to jig anything then. You could then use the mill to "true" the bead surface, as long as you're spending money.

 

you have some good thoughts time. i was thinking the same, not to cut it straight but with an angle or this z you suggested, and it will drop right in place. i was thinking of cutting with a lathe, then weld, then finish with the lathe.. lots of thinking to do.. thanks for ideas & help so far!

 

Have you thought about adapting a Yamaha Venture rear end to it/ Its runs a 140 rear tire and is a Mono shock swing arm is about 4" longer and sports a disc brake

 

good thought, i have looked into that idea (not the venture yet but others) and in my opinion theres a lot more to do adapting a new rear end than modifying the existing one. and 140 is not wide enough

 

Have this been completed yet :?: :?: Want to see some pics.
I am busy myself customizing a 83 xj750 SECA :twisted: