Triumphrat

adrienna

Hello, everyone. We're new here, though we've been lurking for quite a while. My girlfriend owns the S4 and I get the privilege of working on it.

Anyway, she's 5'4" and wanted the bike lowered so I did some research and found out a CBR600F4 dogbone is about 1/4 in. longer than the stock Triumph link. This lowers the bike around an inch (I think) and can be done for $15. It looks and fits just like the stock Triumph link.

However, when I raised the forks (one inch) in the triple clamps to match the rear of the bike I was a bit concerned at how close the fork sliders are to the triple clamps. At full extension, the tops of the sliders are only around 4 in. from the bottoms of the clamps. With the S4's advertised 4.7 in. of travel, the sliders will likely hit the clamps under hard braking. I've read a lot of posts about lowering where people mention sliding the fork tubes up in the clamps, but no one says anything about the fork sliders hitting the clamps. Is this something I should be worried about?

Also, I have a question about stock rear ride height. I managed to misplace the piece of paper I wrote my stock rear ride height on. So I lowered the bike, but I'm not 100% certain where I started. Could someone please post a stock rear ride height measurement (including where you're measuring from/to) with the rear suspension completely unloaded? I'll use this for comparison to see exactly how much I need to drop the front end.

Thanks in advance for your help.

-Aaron

dynagroove

nice tip on the F4 dogbone - you should post that in the sticky parts swap thread above. took me a second to understand what you meant about the forks hitting the triple clamps, but i think i understand - you are worried about the top of the fork legs hitting the bottom of the lower triple - correct? i think that you are probably ok. i'm guessing that your GF will not be really getting heavy on the front brakes and even if she does, she most likely won't compress the springs that hard. if the springs are compressing hard enough to even be close to the lower triple, new springs are in order anyway. an easy way to see how far the fork compresses would be to fit a zip tie to one fork tube (also the easiest way to measure suspension). can't help you with the stock ride height - i'm running a different shock set to me.

jeff h

adrienna

Thanks for the quick reply.

I already tried the zip-tie trick you mentioned. In the shop, with the assistance of the front brake, I can compress the fork to the point that the zip-tie ends up against the lower triple. Granted, I'm around 100 lb. heavier than my girlfriend and the preload's set a bit soft (even for her), but it still concerns me. Fortunately, the sliders will hit the triples before the fender can, but that still can't be a good thing.

Will

If the fork bottoms out before it hits anything else, you are golden.

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adrienna

Cool. Now if someone happens to know that rear ride height measurement ...

BombFactory

Quote:

Originally Posted by adrienna Fortunately, the sliders will hit the triples before the fender can, but that still can't be a good thing.

Hey, welcome to the club. Correct me if I'm wrong, Adrienna (or Aaron I should say), but when you say the 'sliders' hit before the fender, are you referring to the larger outer fork tubes (the black ones)? In no case do you want the outer tubes bottoming out on the lower triple clamp. If this happens on hard braking it can force the rear wheel off the ground resulting in losing control or a roll-over.

Now for my two cents on the raising of the forks in the triples: you say you raised them one inch. Is this a measurement of the fork showing from the top triple clamp surface to the beginning of the fork cap, or is this a measurement of the fork showing from the clip-on top surface to the start of the fork cap? From what I have read, you don't want to raise the fork much more that 0.25-0.5 inch from stock. By raising the forks you will change the trail of the bike which affects the handling. By shortening the trail, which is what has happened, the bike will be more sensitive and quicker steering. The TT600/S4 is already a very agile bike, so any more quickness in the steering could present problems in turns and will especially lead to tank-slapping when hitting rough/uneven surfaces. Someone please correct me or add to this if I'm mistaken.

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The Resurrection: ’02 CE Speedtona w/GSXR Forks
Project Straight-Line: The TT600 Drag Bike
The philosophers have only interpreted the world, in various ways; the point, however, is to change it. - Karl Marx

adrienna

Yes, the larger, black outer tubes could hit the lower triple when the fork is compressed.

The measurement I'm talking about is the fork showing from the clip-on top surface to the start of the fork cap. The silver fork tubes have been slid upward one inch in the triple clamps from their stock location.

I've heard of other people doing this, but upon doing it myself I have obvious concerns. However, I wasn't concerned about making the handling quicker, as both ends of the bike are being lowered.

I definitely appreciate the input. Oh, and does anyone know the stock rear ride height?

-Aaron

BombFactory

I wanted to clarify that you have raised the fork 1 inch above stock. Just to reemphasize what I was trying to convey: the shorter trail changing the bike’s handling isn't a side-benefit but could be a problem in your case--and probably will be with 1 inch raised forks.

The largest problem I can see will come with the bike being less stable at 45 mph+ speeds resulting in easier tank-slapping and the bike following differences in the road. Lowering the rear will not compensate for the change in trail, so they do not cancel each other out. I’m speaking from a safety point, as I’d rather be on my tip-toes at stops than trying to handle a wild bike.

__________________
The Resurrection: ’02 CE Speedtona w/GSXR Forks
Project Straight-Line: The TT600 Drag Bike
The philosophers have only interpreted the world, in various ways; the point, however, is to change it. - Karl Marx

adrienna

Hmmm, hadn't thought about the change in trail, just the effective rake due to the rear of the bike being lower. However, other bikes (especially Buells, for example) have much more radical rake and trail numbers and are still stable. I'm not trying to argue, though, as you've brought up an excellent point.

As I said before, I've read more than a few lowering threads where people nonchalantly mention sliding the forks up in the triples, but I don't want to screw anything up or make the bike an ill-handling deathtrap.

BinarySpeed4

I think what BombFactory is trying to convey is that you have changed suspension geometry greatly by lowering the front. This can cause the symptoms he noted, especially on rough roads or emergency executions of manuevers that could cause the symptoms to rear their ugly head. Saving a bike from a problem is one thing when its properly set up, now changing it could drastically effect recovery.

Also comparing another bike to ours won't work. The Buell chassis is completely different, hence its need for the different rake. The chassis and suspension geometry all comes into play on keeping a bike stable.