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Author Topic: 1977 Rd400 Front End / Rear Swingarm Swap?  (Read 3083 times)

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Offline Mikeb4

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1977 Rd400 Front End / Rear Swingarm Swap?
« on: November 29, 2010, 06:23:02 PM »
First time poster here guys, seems like an awesome group and a ton of eperience :thumbsup:.  I just bought a 1977 RD400 project and would like to upgrade the front and rear ends.  Brand new to RD's but have built many other bikes, always wanted a RD or RZ and just liked this one I ended up buying.  Needs a ton of work but has a lot of potential.

Are there any common front and rear end setups that folks have done with a popcorn trail on how they pulled it off?:science:  I have seen a few pics in Google images but coming up short on knowledge ...... any suggestions welcomed!  Thx Mike
2 strokes currently in my corral:
1977 RD400
2008 KTM 300 XC-W
My bike builds photo video ->  http://www.youtube.com/watch?v=wytMnUwnoFA

Offline cabits

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #1 on: December 10, 2010, 07:04:04 PM »
Glad to hear your joining the world of two strokes. I'll bet my RD400 conversion was one of the finds when you looked for front and rear conversions. As far as I know there are NO direct replacement major upgrades. There is a new aluminum 2 shock swinger out there but mono-shocked is lots of cutting and welding. As far as the front goes lots of possibilites as long as you re-use the steering stem from your original RD. I used a donor 1999 FZR600 front end and rear end on mine.
« Last Edit: December 10, 2010, 07:07:55 PM by cabits »
77 RD400 30mm VM, Banshee cages & crossover, K&N pod filters, Stage II porting, polished ports, milled head & barrels, SpecII F1 pipes, Chinoy ignition, welded crank, RZ rods bearings & Wiseco pistons, FZR front end, FZR monoshock conversion rear, 520 o-ring chain & sprockets, LOTS OF CHROME BLING

Offline Mikeb4

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #2 on: December 10, 2010, 08:46:50 PM »
Your bike looks just awesome, great work and inspiration ..... actually after all I could read out there I ended up going with a 1990 FZR600 front and rear end also!  Parts should be here in the next week ...

After talking to All Balls it seems like the RD400 tapered stem bearing kit will fit the RD neck and the FZR stem to marry the two with some shimming or reduction of stem length.  The FZR stem is supposed to be the same diameter bearings as the FZR ... did you find that with your conversion?  Why did you re-use the RD stem instead of modifying the FZR stem?

Another thing I don't know yet is the swingarm mount width of the FZR and what is the chain alignment?  I went with a 520 narrow X ring conversion also just in case I needed more wiggle room.  I plan to stay with dual shocks and avoid the mono shock mods.  Does the FZR swingarm need to be cut down to fit in the RD frame and any mods to the bushing needed?  different swingarm shaft size?

Sorry for all the questions but you did a nice job .... :science:

Thanks!  Mike
2 strokes currently in my corral:
1977 RD400
2008 KTM 300 XC-W
My bike builds photo video ->  http://www.youtube.com/watch?v=wytMnUwnoFA

Offline ripperdog

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #3 on: December 11, 2010, 09:34:44 AM »
Welcome Mike, great to have you on board!  I watched the video in your link...you've done some very impressive work and built some beautiful bikes.  An RD will be quite a departure from your previous builds (much smaller and lighter) and I'm sure when it's done you'll be hooked for life like the rest of the crowd around here.

The surest and most straight forward way to accomplish a front-end conversion is to swap steering stems.  When done, everything should bolt together like stock with stock sized bearings, etc.  If you can find the correct bearings than shimming/shortening is a viable method.  I did an R6 conversion on my RD400 using nothing but shims and a Kawi Triple bearing set...kinda ghetto but it works.

The FZR swingarm will require narrowing at the pivot end to fit between the RD frame tubes.  I chose to install a FZ600 swinger (aluminum) not the FZR (steel) so I'm afraid I can't give you the exact spec's but I'm sure the proceedure is similar.  You might find that the bearing pockets and or end caps will require some attention in order for everything to fit together properly as well.

Twin shock should work well with that swingarm but do yourself a favor and stick to shocks with a small (ie. stock) diameter spring.  I used Ohlins with a larger diameter spring and ran into clearance issues on both sides of the bike.  If you run the FZR rear wheel than the rest of the intallation should go smoothly using stock FZR hardware.

I asked Cabits a while back what sprockets worked for his combination and he told me that a 7/16" offset countershaft sprocket fit perfectly.

Good luck with the build and be sure to post some pics as you move along!
'77 RD400
'01 Italjet Dragster 180

Offline Mikeb4

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #4 on: December 11, 2010, 10:20:09 AM »
Super, thanks ripperdog ...... I have the FZR full wheels and brakes as well so other than the obvious issues I hope it goes together without too much aggravation.  I noticed there is a lot of case room for an extended countershaft sprocket, do you know of a good source for offset countershaft sprockets?  I am going to a DID 520 X chain as well for added flexibility.

Thanks!  and by the way you are right, this is very different than anything I have worked on, I'm excited, always wanted to do a RD or RZ .....
2 strokes currently in my corral:
1977 RD400
2008 KTM 300 XC-W
My bike builds photo video ->  http://www.youtube.com/watch?v=wytMnUwnoFA

Offline ripperdog

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #5 on: December 11, 2010, 02:03:28 PM »
I've seen several forum members post good experience with using Advanced Precision Products (located in Oregon).  A lot of the RZ guys get there offset sprockets from RZ's Unlimited.  I ordered mine from www.twostrokeshop.com.
'77 RD400
'01 Italjet Dragster 180

Offline cabits

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #6 on: December 12, 2010, 07:21:00 AM »
mikeb4 I ended up grinding the welds off both the FZR & RD bottom tripple clamps and removing the steering stems. I then welded the RD stem into the FZR bottom clamp. Make sure you weld with the stem straight and at the same overall height as the original RD if using stock bearings. I found, along with others, that All Balls has tapered bearings but they tend to not seat as deeply as the originals. There for you need to adjust the over all height of the new steering stem by adding about 3mm to make up for this. As far as the rear swinger goes I have measurements I can give you but I'm working right now and can't access them from my work. I did have to machine the swinger sides and ream the bearing hole deeper to allow for the machining. Send me an email with your email and I'll send you all the info I have on what I did and just use what ever you want of it. I did use Advanced Precision out of Oregon and had them make me 7/16" offset sprockets for 520 chain in 16, 17, 18 tooth and did not have to modify the rear wheel but used an FZR rear aluminum 520 sprocket on the rear wheel. The clearance between the tire and chain becomes quite small, I'm talking about 1/4" at most but chains don't have much side to side movement. I did add a chain roller to the rear swinger on the top too. One note, I found that using both front brake discs was really on the touchy side, if you like doing lots of front wheel stands by all means leave em on it'll make it real easy. I ended up going with just one disc up front and it feels much better.
« Last Edit: December 12, 2010, 07:21:50 AM by cabits »
77 RD400 30mm VM, Banshee cages & crossover, K&N pod filters, Stage II porting, polished ports, milled head & barrels, SpecII F1 pipes, Chinoy ignition, welded crank, RZ rods bearings & Wiseco pistons, FZR front end, FZR monoshock conversion rear, 520 o-ring chain & sprockets, LOTS OF CHROME BLING

Offline Mikeb4

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #7 on: December 12, 2010, 12:42:53 PM »
Awesome ....thanks ... that will save me a lot of time and guesswork.
2 strokes currently in my corral:
1977 RD400
2008 KTM 300 XC-W
My bike builds photo video ->  http://www.youtube.com/watch?v=wytMnUwnoFA

Offline BOOGS

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #8 on: December 12, 2010, 04:14:51 PM »
check out my '77 400 with RZ front and 400F/RZ rear!
http://www.2strokeworld.com/forum/index.php?topic=7954.msg62803#new
'77 Yamaha RD400 - RZ wheels/susp/TZ tank/ducktail seat
'86 Suzuki GSX-R750R Limited - bone-stock family heirloom
'01 Suzuki RM125 - 144cc

Offline Mikeb4

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Re: 1977 Rd400 Front End / Rear Swingarm Swap?
« Reply #9 on: December 12, 2010, 08:46:48 PM »
check out my '77 400 with RZ front and 400F/RZ rear!
http://www.2strokeworld.com/forum/index.php?topic=7954.msg62803#new

Looks outstanding ..... love the TZ tail a lot .... Hmmmmm ...
2 strokes currently in my corral:
1977 RD400
2008 KTM 300 XC-W
My bike builds photo video ->  http://www.youtube.com/watch?v=wytMnUwnoFA