JamieDaugherty

I've promised some folks an update once I got this ready, so here it is:

This is the first CBR954 shock that I've converted to fit the 6th gen VFR's. Pretty straightforward and similar to the conversions I already do with the exception that the extension is at the top mount instead of the lower. That took some interesting/expensive fixtures and tooling, but I'm really happy with the way it turned out.

If anyone is interested in converting a CBR954 rear shock to fit their 6th gen shoot me a PM.

New spring is pretty much required unless you are disgustingly light.

This particular shock was revalved as well.

As if you needed another opinion - yes, springs by themselves is an improvement. Any suspension setup assumes that the proper spring rates have already been installed. I'd suggest getting the correct spring rates on both ends before tackling the damping.

Run 5w fluid even with the higher rate springs, heavier fluid will not really help the performance.

Ah Ha! Just asking as I have Tony Foales suspension setup software which when analysing linkage ratios, types and dimensions needs the shock travel length.

I've been using the 57mm travel of a honda CBR954 to give rear wheel travel of 120mm. looks like i'll have to buy one and measure before continuing MK11 hossackviffer. bummer.

Very pleased you pointed this charts error. So thanks again Jamie.

Red

I looked it up in my spreadsheet then double checked on a couple of CBR954 shocks I have:

CBR954RR shock travel = 38mm

This is the stock shock, aftermarket shocks may be different. The rear wheel has a travel of 135mm for an overall linkage ratio of 3.55:1. I hope this helps!

Useful info Jamie :blush: , can I ask where you found out? is it on a Ohlins website somewhere? many thanks. Red

I guess just from being around and doing a lot of work on shocks. As mentioned previously, I have my own spreadsheet that details the length, stroke, mounting dimensions, spring rates, etc for the various shocks that I deal with regularly. I first noticed this when I guy stated that his Ohlins CBR1000RR had an advertised stroke of 58mm and I measured the one on my bench at 42mm. Ohlins sometimes designs in more stroke to their shocks, but not that much. You can find the Ohlins "advertised" shock travel using a Google search, probably what the author of this spreadsheet did.

FYI - The data for the shock stroke is not correct. This information must have come from Ohlins as they show the stroke without bottom out bumpers, etc. This is not the functional stroke of the shock. Please disregard that information in the spreadsheet!!!

redmarque - Can you just attach the xls file to your post?

I've created my own spreadsheet wit this information and have been populating it over the years. It's by no means an exhaustive list, and it would be interesting to compare my actual measurements with someone else.

Linky no workie..... for me anyway.

Hey Jamie, any update on the 929 shock upper mount extension?

For the 6th gens I'm working a CBR954 upper extension. I think the oreintation of the reservoir on the 954's will suit those bikes better. I've got the first CNC parts made I just have a few more details to sort out before building some prototypes.

Yeah, I'm very interested also. Given the correct length of the extension, It would be PERFECT to put a 929 shock in a 4th GEN. :fing02:

I've been doing lots of CBR929's for the 4th gens and it works great!

My question is will my firmer blackbird spring swap to the 929 shock?

Nah, it's too long.

20 - 8 = 12 mm x 2 = 24 mm which is just about an inch.

Sometimes an inch can make all the difference in the world. Ask your wife/girlfriend. :happy:

I don't about you guys, but if 24mm is enough to make-or-break, I'd be rethinking what I'm trying to move my bike through.

So, help me understand: you don't like the bar ends because they make the bars too long, yet you make them longer to install longer grips. Did I miss something? The bar end weights that I run are only about 20mm long. That's more than the 8mm you refer to, but is it really that much of a difference? I'd think the mirrors are what keep you from going through a doorway. Which begs another question....

What was the spring rate on the different years 900rr's?

Thax

The 92-94's had 15.0kg/mm and all other years had 14.6kg/mm stock. Why?

Just finished up the Accel coil brackets... I think I might paint them and then install the carbs in the bike! I'll have to double check the float heights first... pics hopefully sooner than later!

Were you sure to get the right coils? You should have Accel part number 140403, it's the opposite of what you think it would be. Your bike has CDI ignition but if you use the CDI Accel coils you will see flames come out of the spark boxes - seriously.

At first I thought it was some kind of welding jig, but I wouldn't use 7075 for that. My official guess is a piece for the rear shock linkage.

Has anyone tried using 93-99 CBR900RR shocks? I am replacing my CBR's shock with an Ohlins and it looks like, at first glance, that it should fit well.

Thanks.

That would require the same modification as a CBR929RR rear shock. It's also too short to fit the VFR directly. You might be more specific, the shocks changed about three or four times during the 93-99 period and the relative performance of each varies somewhat. The leghts changed as well.

The shock is from a '93 CBR900RR. I don't have the data from Honda regarding length and stroke, but from Ohlins, for comparison purposes, they list the 900RR shock length at 319mm, stroke of 54mm. For the 6thGen VFR, for which Ohlins has 2 models, they list length for both models at 317.5mm, and strokes of 53.5 and 54.5mm.

At least from this data, the CBR shock is 1.5mm longer, and smack in the middle of the two VFR shocks wrt stroke at 54mm.

Thanks in advance for any insight.

Yes, the 93's are the longest of the 900RR shocks. My notes show the 93 900RR shock to be 326mm and the 02+ VFR as 315mm, that's a huge difference. I'd measure the 900RR shock to be sure. Ohlins probably makes the shocks shorter to cover more years and let's the user adjust the length to suit. Adjustable ride height is a great thing.

Ok got the shock in but coils a no go for stock placement. Anyone with a 4 gen have an idea what you did? Do the coils need to be grounded via the bracket? Thanks Brian

Coils? Are you talking about the shock spring?

I bought a 929 shock yesterday, $41 shipped.

I cant find much info on installing it on a vtec. I know it's been done.

Can anyone give more info on what is required.

The shock needs to be lengthened in order to fit the VFR. The conversion that I've been doing involves making a CNC machined lower clevis extension and machining the CBR shock to accept it. Once complete the CBR shock becomes a direct replacement for the original. Here are some pictures of what it looks like:

A friend was supposed to make me a drill bushing from tool steel, but I haven't heard from him in a couple weeks. You busy lately Jamie?

Slammed. Spent so much time out in the shop yesterday that I lost feeling in my toes. I can move them now so all is good. One of these days I'll be able to work on my own parts. I've been saying that for two years now and I haven't done it yet....

Have you tried breaking the piece out with a punch? Hard is ok, but that usually comes along with being brittle. A couple of good smacks (don't be a wimp!) and it should bust out. This also helps loosen the broken bolt too by the way.

I've not had much luck with easy-outs. I think I've only had them work once or twice. I now prefer to just drill out the bolt. Keeping the drill on center is the key, that way you can continued drilling out with increasing size bits until almost all of the bolt is gone. At that point it often just comes out by hand. I'm sure you know this, but I mention it just for those who are following along that might not be as familiar with a problem like this.

F4/F4i rotors do not interchange with the CBR900RR or VTR1000F. They do, however, interchange with CBR929 and 954 I believe.

I would have let my daughter put any sticker she wanted on it. I don't care what dudes think, even though she is the oldest of my kids she is always going to be Daddy's little baby!

Another progress report...

The new shock is in place. The battery box was a pain to reinstall. The ignition coils did not fit (the oil reservoir occupies a part of their private space) and had to be relocated. I was going to take pictures, but I lost my camera somewhere. Oh well...

Are you sure that you have a 929 shock and not a 954 one? They are often mislabeled on eBay or labeled as fitting both (they don't). They only battery box interference problems I've seen have been with a 954 shock, the 929 should fit without any problems.

More ride height helps on these bikes. I usually suggest at least 5mm but you can run up to 10mm if desired. It's about a 3:1 ratio of shock length to ride height. That means an increase of 5mm at the shock translates to 15mm at the axle.

So... I decided to follow the trend and replace the rear shock on my 4th gen VFR with a newer CBR929 part. Here are the measurements I got:

- 4th gen VFR shock, eye center to eye center fully extended - 324mm

- CBR929 (yellow spring) shock, eye center to eye center fully extended - 288mm (36mm shorter)

- 4th gen VFR shock bracket, eye center to top surface - 25mm

- New bracket to be made, eye center to top surface - 61mm

Any corrections and suggestions would be greatly appreciated.

The VFR shock should be 325mm and the CBR929 one is 287mm for a difference of 38mm. That would make your bracket 63mm long. I'd even err to the side of more ride height and make thet bracket at least 65mm, maybe even longer.