Triumphrat

athomas · 12-22-2007

I've had my Bonnie for a year now, and it's time to make some mods. I want to get rid of the front end dive when braking. Which springs work best, and what weight fork oil and how much should I use? I'm not a real hot dog, but I do like to ride "spiritedly", and want a comfortable ride. I just don't like the way this thing dives when I stop. Any suggestions? Thanks, Arnie

keef · 12-22-2007

Hi Arnie - welcome to the zoo.

There are a few things you can do to improve the performance of your forks, ranging from simply replacing the fluid, through fitting progressive springs to installing cartridge emulators. Indeed, further improvement can be achieved with even more drastic mods such as replacing the forks altogether, as with the F3 forks mod detailed by SCCTrim and the SV650 front end replacement bysweatmachine - more details on these and others can be found on the "Suspension" section of the Mod Links pages HERE.
For my part, I fitted a pair of progressive fork springs and slightly thicker fluid. There are a few makers of such springs out there, most notably "Hagon" and "Progressive". I went for the "Hagons" which cut out the diving almost entirely. I also found that the overall handling was vastly improved, especially when accompanied by a pair of "Hagon Nitro" rear shocks. Fitting replacement fork springs is fairly straight forward - here are some instructions which might be of help...
CLICKIE.
Good luck.

BishRat · 12-22-2007

+1 for the Hagon.

As far as fitting is concerned, the quick'n'dirty way is to put the bike on a stand (pressure off forks), carefully whip off the caps (carefully because they'll still be under pressure from the springs), pull out any spacers and the springs with a bent coat-hanger (slowly, letting the oil drain back into the forks) and replace with the new springs.

At about $100, it's pretty much the best bang-for-the-buck as far as handling is concerned.

SHILOH · 12-22-2007

The easiest improvement is upgrade the springs to a progeessive or dual rate spring set. As Bish outlined, a simple inframe upgrade.

The cheapest is change fork oil to a heavier weight, (10 to 15 or 20). But requires the forks be remove from the frame, and is far more work. See Keef's link as a guide.

An unmentioned path is to upgrade your current fork internals to full cartridge, about $1300. This corrects the inherent design limitation of damping rod forks to a very large degree.

I would do the springs first, and if that get the front end dive on braking corrected to your satisfaction, your done. The simplest, quickest, and nearly the cheapest.

Cheers----------

itcha · 12-22-2007

I recently put on Hagon's front and back and the bike rides like a beast now. I can't believe I went a whole year on the stock suspension. Not alot of money for a huge difference. Best mode you can do IMO.

chedd · 12-23-2007

I decided to change my fork oil after putting ikons on the back. I did it the slack way by sucking the oil out with a Turkey baster and some tubing. While I had the springs out I compared them to the stock springs that had been removed from my Fazer 600. They looked allot more substantial than the triumph springs so I decided to give them a go along with 10W oil and I couldn't believe the improvement, so I've left it that way. The front seems to be very well matched to the rear now. I wouldn't describe myself as a hard rider but I like to chuck it around a little sometimes and the handling suites me fine.

ChuckT120 · 12-23-2007

I changed out the springs and fork oil and am still enjoying the change. I went with 20 Wt Bellray oil and Progressive springs from Progressive Springs, Inc. I got them through Phat. You can tune the front springs to your weight and riding style by adjusting the lenght of the spacer. My typical bording weight is 235 lb and a half inch of pre load works well for me. Also, if you are going to install gaters, this is the time to do it. And be sure to cushion the wrench when you loosten the fork caps so you don't scratch the finish.

ohiorider · 12-23-2007

Here's some additional info re Progressive springs. It's an eye test, for sure, since I scanned the Progressive install instructions, then saved them as a JPG file and posted them to Photobucket.

http://s115.photobucket.com/albums/n...t=Slide1-2.jpg

http://s115.photobucket.com/albums/n...ent=Slide2.jpg

The following is info I sent to another forum member a few months back
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I just got back from a ride on the Bonnie after dropping the fork oil level from 140mm (max recommended by Progressive when using their springs) to 175mm from the top of the fork tube with spring removed and fork fully compressed. As you recall from Progressive's instructions, they show a 'safe' fork oil level using their springs anywhere between 140 and 190mm below the top of fork tube. They discuss oil levels on pg 2 of their install instructions under 'fine tuning'.

I believe what reducing the oil level has done is to remove the sharp 'edge' from the small bumps I hit at normal riding speed (35-75mph). My bike is equipped with a short low handlebar, so I really notice if the front end is rough.

Now the only issue is I notice the rear end. I have a set of Progressive 440s that I'd like to reserve for trips where the bike is loaded down, but I may (once again) pull the stock shocks and reinstall the 440s. ( I did reinstall them. Also had Progressive install a slightly lighter wt spring on the shocks. I weigh in at approx 165, and the stock springs were too heavy for me.)
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Note – I spoke with Beth (ext 748) at Progressive Suspension. Knowledgeable. Based on the above information, she said their application charts showed I should be using the following shock spring with my Shock Model: 4404244-B
Spring Model: 03-1368-B, with a spring rate of 105/150 vs 120/170.
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Hope this is useful info. BTW - the springs are Progressive Model 11-1126.

Bob
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bmetz99 · 12-23-2007

Sounds like a lot of shooting in the dark around here.

The only way to properly set up your suspension is to match the spring rate to your weight and riding style, then match the damping (oil viscosity) to your spring rate.

If your stock fork oil is over a year or two old, it's shot. Go ahead and pull the fork tubes and drain 'em- you'll be amazed at the dirty, watery fluid that pours out. Find out what the stock springs are rated at and what weight of fork oil that is recommended. Simply changing out the fork oil can make near-miraculous improvements. Be sure to completely drain your tubes, and then replace the oil with the proper amount. Too much or too little oil will adversely affect your suspension, as the air above the forks also acts as a spring.

Springs should be purchased from someone who offers differently-rated springs and the ability to match a particular spring to your particular needs. There's a huge difference between springs appropriate for, say, a 140 pound rider who uses his bike for commuting, and a 220 pound rider who's aggressive on back roads. The seller should also be able to provide you with proper figures for preload (the length of the spacer that goes on top of the spring). Sometimes you can get away with re-using ro shortening the stock spacer, many times you need to fabricate new spacers (either provided by the spring seller or made from schedule 40 PVC pipe). You want static sag to be about 1/3 of the spring's total travel.

Google "motorcycle suspension setup" and do some reading. Blind "it worked for me" recommendations may or may not get you what you want.

BishRat · 12-23-2007

I agree wholeheartedly. The best way to set suspension for optimal performance should take into account rider weight, use and riding style.

To extend the "shooting in the dark" analogy (and let's include a dart-board here)... the stock suspension shoots in the dark and usually gets us on the board (some would say not though). This suits a lot of people and they're happy with it. If someone decides that their own particular style/weight/use needs something a little more "accurate", then replacing the stock items with better quality units will generally produce handling improvements that get them nearer the center of the board. This may be something as simple as minimizing front-end dive under heavy braking or firming up the back-end so it's a little more sure-footed and doesn't "wallow" as much. Some of the adjustments available on the non-stock components allow for a reasonable amount of personal tuning.

To hit the bull dead center... then spring ratings, rebound damping, oil weight/level, ride height and a whole bunch of other stuff can be fine tuned to suit an individual rider. I've set up race bikes, and for 10/10 track work these things are critical... for improving a road-ride, simply upgrading the stock components can produce a significant improvement for a lot of riders.