Changing front springs and oil

[Twodogs]

Hi all, I am going to fit some progressive rate front springs in the front of the T100 and Thruxton and was after some opinions and facts on what brand of springs is the most recommended.
What grade and Brand of oil is best suited,

How much oil is needed (Metric),

(I know I should look at the manual but) Is it just simply remove the fork tube, undo the cap, remove the original spring and spacers (If any), tip the fork over to drain the oil and then fit the new springs and fill with oil and refit the forks?

What is the general opinion on fork oil change intervals, I have been told to do it with your engine oil every 6000Klm (I do my engine oil every 5000Klm or 6 Mths what ever comes first).

I have to be honest and have never worried about it in the past with other bikes as I have never owned them for much more than 10,000 Klm or there abouts but the Triumphs will be staying around for awhile and growing old with me. Cheers TD

 

[northcountry]

ricors

Might check out ricor intiminators.

 

[Easy13]

I'm 6'2" and about 260 lbs and I'm running Ikon fork springs with 1/2" preload spacers and Belray 7w fork oil. No complaints. I like the progressive and fairly stiff damping of the springs and the slightly quicker rebound from the light oil. Just my personal preferences.

 

[Kirkus51]

I have intimidators with stock springs and 5wt oil in my forks. I have to cut the spacers down and mebbe get some progressive springs in there. The Intimidaors seem to work well since the forks don't bottom out anymore, but the ride is stiff.

484cc in each fork is the right amount according to the manual. I think that's enough to cover the springs.

 

[tv guy]

What grade and Brand of oil is best suited,

How much oil is needed (Metric),

(I know I should look at the manual but) Is it just simply remove the fork tube, undo the cap, remove the original spring and spacers (If any), tip the fork over to drain the oil and then fit the new springs and fill with oil and refit the forks?

What is the general opinion on fork oil change intervals, I have been told to do it with your engine oil every 6000Klm (I do my engine oil every 5000Klm or 6 Mths what ever comes first).

Oil weight is a fork tuning choice. Lighter weight (e.g. 5w) is softer riding than heavier weights. Unfortunately you can’t compare oil weight brand to brand Belray is not the same as Honda is not the same as Amsoil etc. Belray Honda, Amsoil are all high quality brands of oil and there are certainly others as well. I use 5w Amsoil in my Bonnie and like it. Unless you have very smooth roads I would recommend staying between 5w-10w (10w is factory).7.5w is a good middle of the road weight

The oil fill is around half a liter (a bit less). For me it was easier to measure the air gap distance which is another fork tuning factor to fool with (more gap equals softer ride). Some progressive spring install guides recommend 140mm the factory says 106-140mm depending on model.

Yes it is simple; remove the fork and cap pull out the spacer, washer and spring. Dump and pump the fork to get all the old oil out. Fill 500mm and pump again to get the air out. Compress the fork, don’t force it you will feel it bottom out. To measure the air gap I bought a turkey baster, marked the depth and sucked out the extra oil. It works like a charm (and for a cheap bastage like me cost $1.49 US). Stick the business end of the baster into the fork slide it down to the mark you measured for your air gap and squeeze the bulb. It will suck up a bit of extra oil (you may have to empty it more than once). One word of caution when putting the fork back together be careful not to cross thread the fork cap. You have to compress the spring a bit to push the cap down to the threads and the cap is made of soft aluminum.

I don’t know if Triumph has an oil change schedule but I recall BMW used to recommend changing fork oil every other year. Changing it with every engine oil change would be over kill IMHO.

Cheers!

 

[fender]

Nice write up!

What I found to work well for measuring the oil level was a paint stick (new one of course). I put a marking across the stick for the desired level measuring front the bottom of the stick up. Simply hold the stick at your mark even with the top of the fork tube and use the turkey Baster to add or remove oil as necessary.

 

[Demar]

Nice write-up TV. One question.... the air gap and oil level adjustments are done with the springs OUT of the fork tube... correct?

 

[tv guy]

Nice write-up TV. One question.... the air gap and oil level adjustments are done with the springs OUT of the fork tube... correct?

Sorry for the late reply the weather here has been spectacular and I’ve been putting on miles

Yes you measure without the spring and spacer but if you have a cartridge emulator e.g. Race Tech or Intimidator you DO put them in before measuring.

The Progressive springs (brand name) I installed recommended a 140mm air gap due to the longer than stock spring.

I wish I had a magic formula for the front end, right now I have a Progressive spring with a 140mm air gap and preload matching the stock one (the spacer with the new spring ended up being 2 1/4" 57mm), Ricor intimidator and 5w Amsoil . The bad news is it still pounds me over things like expantion joints etc. I'm now looking again at the rear shocks I have Hagon Classics bolted on now.

cheers!

 

[Demar]

Thx Tv

 

[Jimbon]

You don't have to change the fork oil (I'm 12 1/2 stone and have kept the original oil. The rebound seems fine to me: quick return with no bounce): just take the tops off the forks and slowly remove the old springs (coat hanger job) so that the oil runs back into the forks, then pop the new forks in (tight wound end up) and put the caps back.

I found the tricky bit was getting the caps back on when pushing them down on Ikon progressive springs and the half inch spacer they're supplied with (for a harder, more sporty ride) but using the correct size socket on a four spoke wheel nut leaver gave me a balanced two handed leaverage to push down and tighten the caps without scagging them.

 

[tribear]

Fork Air Gap Anomaly

Need some help here gents and gals. Old thread I know but it's a good one and my issue seems to line right up with it rather than a start a new one.....

I'm refreshing my Scram's forks with new seals, oil etc. and was planning on a minor tweak mainly to increase my air gap to say 140mm to hopefully help curb some of the harshness of the Scram's forks.

Here's where it gets interesting.....
Pulled forks off, measured air gap for fun to see where the factory had it. According to the manual and common knowledge the stock Scram's air gap should be 123mm measured from the top of the slider to the top of the oil with the springs and spacers out, forks compressed.
Both of mine were at precisely 165mm. ?????
I have always noticed the forks are very harsh on sharp bumps which I am hoping to remedy. However, if I raise the oil level to 140mm from 165mm they are going to be brick abrupt if not just flat lock up?
What might ya'll think is going on here? Only thing I can think of is I didn't have the sliders all of the way compressed therefore giving me a false or larger reading. The manual states to not push too hard in compressing the forks to avoid damaging the damper tubes/mechanism. I experimented a few times and definitely pushed them down firmly to where I could feel the spring loaded mechanism at the bottom... They sure felt bottomed out to me. I wish I had thought of draining the oil solely from one fork and measuring the volume that came out to cross reference but I didn't think of that until too late..... It's all mixed up in one of my oil recycle jugs now. Woops.
Anyone have any suggestions? I'm stumped on this one.
Thanks for any help or advice.

__________________

 

[bonZa]

just changed the fork oil today in my Bonnie. measured what came out and was very close to what is meant to be in there. but a lot does cling to the spring and spacer when you draw them out. I stood them in a separate container and a good 10 millilitre or more drained off the spring that would equate to about 10mm or more in height. maybe that's why yours was measuring low.

 

[tribear]

Could be, bonZa. i did let them drain back into each fork leg for a minute or so but no question some was still on the springs. Also, both fork seals began leaking last summer so I know they pumped out a fair bit as well. Just seems like 40mm low was a lot but???? Starting to think more and more it's possible since it takes so little oil to make a 5mm or 10mm change.

Now my conundrum is working out the harshness on the Scrambler forks on sharp edge bumps. The theory I have read is to lower oil level to curb this. Stock oil level for an '06 Scrambler is 123mm. My Scrambler's forks have always been harsh on abrupt bumps and just as harsh with the 165mm air gap. I read that oil viscosity only affects rebound damping and air gap affects compression. I'm starting to think that with the basic inards of our forks that oil viscosity does in fact affect compression. I'm going with a 7.5w oil (10w is stock) with a 160mm air gap, (to keep one factor close to how they came apart), to test. Hoping the lighter weight oil will smooth 'er out a bit on the bigger hits. I know dropping valves in the forks is the way to go. Just experimenting to see if the stock forks are tunable enough to make them better and save a few bucks. I'll report back my impressions. It'll be a while though.... -10 deg and snow bound round here.
Thanks for your input bonZa.

 

[slartybartfarst]

I spent a few years on and off recently getting my 1969 CB750 K0 to handle like I remembered it did (had it 25 years +!) Strangely its always handled good, ( I also run GSXR 100 K6, Cagiva Raptor 1000, Yam MT01 so i've a reasonable benchmark for whats possible)

The Honda probably handles better that the Bonnie ive just bought.

I simply removed all the oil figuring the remaining coating would suffice while I rode a local bumpy road so I could check out the feel of the springs in isolation.

The Bonnie does pound your hands a bit and when cranked over on a bumpy road it will flick the bars around so i figure without the oil in I cab sense more whats happening .

1) Remove all the oil leaving enough to lube the forks, sit on the bike look for about 15mm of sag> no sag then springs too hard/too much preload, lesson preload or spring rate to get the sag, thats needed before I start.

2) Try it down the road. If it now absorbs the initial hit it will be the compression damping is too great > put in thinner oil.

3) If it flys right up and bottoms out Im guessin the air gap was too small before > open up the air gap.

I know the end result is a balance of, spring rate, preload, oil viscosity but I need to separate as much as possible the effect one each on each other to find a better set up.

My guess from riding both bikes is the Bonnie needs thinner oil, I run the Honda on 2.5 and not much of it. It handles great as the bumps get absorbed before they get to the chassis.

Ill report findings here.

 

[neuroboy]

what's the nut size on the caps for a thruxton? i have an '06 and am changing to progressive springs after work today. . . just want to make sure i have the right size. I'd prefer not to use a crescent wrench if I can help it. Thx.

 

[KingOfFleece]

A race tech gold valve system works wonders.