Front end options: FZR400 3EN1

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kagari15
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Front end options: FZR400 3EN1

Post by kagari15 » Wed Jul 29, 2020 4:57 pm

So...My bike had a pretty harsh past.
This time, it is about the forks. To fully explain this, I would need to lay 'em all out, from the beginning.

When the previous owner(s) seen that they already worn down their brake discs to the limit, they cannot easily get a new or used rotors, since, this is a 3EN. What happened? They decided to modify things to use the 1WG discs.

First, since the 1WGs are smaller than the 3ENs they began by cutting the caliper mounts and re-welding them to align with the discs. But, that's not it. Since the 3EN discs have more mounting offset position (deeper) than the 1WG discs which are shallower, they did a reaaallly bad thing.

They decided to grind down the left fork leg (the one where the axle screws onto) to pinch the forks closer, bringing the calipers about close to the discs! :o
What a massive blunder it is! :oops:

The wheel bearings were seized, and since they seized, the wheel kept rotating against the axle and the speedometer gear drive. Axle is scored.
Brake calipers are in okay shape, but one of them has their thread area ground down to fit the pinch on the right fork leg.

Now, what could be my options? A front end swap(upside-downies sure delish) sure is common and easily doable, but keeping the stock ones as much as possible saves budget. Could it be possible to re-weld those mounts to use the later FZR600 or even FZR1000 discs? The calipers can be had from older R1, R6 and perhaps even MT-07s.

Hoping to NOT give up on my very first solo project bike :lol:
~Rui

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Re: Front end options: FZR400 3EN1

Post by Evilchicken0 » Sat Aug 01, 2020 10:55 am

Jeeeeeez !!!!
Um I would definitely want to swap all that.
The ThunderCat front end bolts straight in and uses a 41mm dia fork with rebound + compression adjustable cartridge forks. This is probably the easiest one to do.
The early R6 uses 43mm dia forks but I'm not sure if it's a bolt in, you might need the steering stem pressed into the R6 yokes. I dont think theres a speedo drive so you might need a different wheel or go for a GPS speedo ... the cdi will limit the bikes rpm to 12,500 in all gears so you would need a MMax derestriction box (there are other makes)

kagari15
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Re: Front end options: FZR400 3EN1

Post by kagari15 » Tue Aug 11, 2020 3:45 pm

Evilchicken0

Yep, confirmed...that's one of my options, a Thundercat, an FZR600 or the chop shop's GSX-S or GSXR

The R1 and R6 never had speedometer drives, they use a speed sensor(electronic) Not a drop-in, the bearing sizes are different, angular ball bearings instead of the taper roller, size different as well (30 mm inside dia, the FZRs(yes, FZRs and YZFs) are 25mm)

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Re: Front end options: FZR400 3EN1

Post by Evilchicken0 » Tue Aug 11, 2020 11:31 pm

I would be a bit careful of the gsxr - I rode 3tj (600 engine) with gsxr / rgv triples and kwak 636 forks, the steering was heavy.
Thundercat, foxeye is probably the best option

kagari15
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Re: Front end options: FZR400 3EN1

Post by kagari15 » Fri Aug 14, 2020 4:05 pm

How about the upside-downies from the 06+ R6? I'd avoid them because of the fork size...

I think the early R1 (41mm stanchions) would be good, better is a (rare) YZF750 front end (same 41mm, the R gives you Ohlins forks), lets you keep the speedometer.

Question though: Does the speedometer gear differ with the Thundercat, FZR1000, 750 and the 400? Since they use similar speedometers, I think so but want to be sure

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Re: Front end options: FZR400 3EN1

Post by Evilchicken0 » Sun Aug 16, 2020 3:36 pm

The sweep of the needle on the various speedos might be different but it think you should be ok using the 400 unit

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Re: Front end options: FZR400 3EN1

Post by kagari15 » Thu Aug 20, 2020 3:26 pm

The ThunderCat does have a 3.50 wheel, right? So that does that mean I would have to swap the rear wheel, which is a Bandit 17 inch swap, a 4.00?

The 3.50 front does allow use of proper radials, but with the current rear that would be a problem, being such thin tires needed

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Re: Front end options: FZR400 3EN1

Post by Evilchicken0 » Fri Aug 21, 2020 2:28 pm

Yes it's a 3.5 wheel but you could go to a 150 rear I dont think you'll notice too much difference

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Re: Front end options: FZR400 3EN1

Post by kagari15 » Fri Aug 21, 2020 4:43 pm

I heard from the racers back at Japan that doing that isn't good for overall performance, particularly in wear pattern unevenness. It is a wheel supposedly used with a 140, and better listen to the professionals. I will NEVER put on those 150/70 ones, they look wonky.

Sure it won't have adverse effects? In geometry of the bike, having quite a wide front wheel just can make you push the bars off the scale for the rear to be tracked properly, make steering a bit heavier, or as the theory goes...

If it has (I'm a tad too sensitive to bike behavior, given that I was a crash test dummy) then I'll probably shoot for the frontends that has a 3.00 wheel on it instead, or proceed to a rear end/wheel swap

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Re: Front end options: FZR400 3EN1

Post by Evilchicken0 » Sun Aug 23, 2020 9:43 pm

I'm guessing you're not going to be riding this at race bike speeds ???
If youre going to keep the 3" front then the later front ends will usd a larger dia spindle, you might be able to change the bearings and spindle tube but it gets more complicated


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