Gen I Rostra Install Advice Needed

[NTXFJR]

Ok, so I'm on my way to becoming a full time feejer farkle installer. I just got done installing a Rostra cruise control, what a full bore pain that was, and was trying it out today. It is surging terribly when set at 50 to 60mph by around 5 mph. I tried setting it at 70 mph and yeehaw! Hang on! The throttle went full bore with no regulation at all. That was fun! ....not!

My hook ups are per Queensland Ken's install: https://www.forum.fjr13.org/viewtopic.php?f=8&t=5525 .

Ken did a fantastic job at detailing and itemizing everything on his install imo. His was on a Gen II or maybe Gen III I believe, mine is on a Gen I

I found several great posts in here and in other forums too, but there seems to a lot of variations on what people have done compared to what others have done.

I have the gray wire hooked up to vss wht/yel wire and dk. blue hooked up to tach orange wire.

I see some have used a signal divider on their vss connection while some apparently haven't. Some have grounded their dk. blue wire, some hooked it to the tach signal.

My gut feeling is that my Rostra is not processing the Gen I vss signal well in this install, hence the run away full throttle when I tried setting it at 70 mph vs merely poor speed regulation at 50 or 60 mph. I'm wondering if my next step needs to be a signal divider. Any suggestions?

Thanks!

 

[ionbeam]

Make sure that you have the DIP switches all set correctly, this will tell the speed controller that you have a light weight vehicle with high HP so the controller will gently adjust speed.

The VSS could well by your issue, it is much higher frequency than the Gen II ABS signal. The VSS signal was too fast for the Audiovox cruse. A divide by 8 circuit would provide a signal which is slow enough to use and still give good speed resolution.

Does the Rostra offer a magnet and pickup for a VSS sense? I wouldn't advise tapping the ABS wheel sensor as a VSS signal.

 

[NTXFJR]

Ahah! I wondered if the vss pulse rate was different from one gen to another. Thanks for that bit of info ionbeam! Rostra does offer a magnet pickup kit, they also offer a 4:1 pulse divider module and I'm hoping I can rig one of those up and get it working that way. My dip switch settings currently are:

1 off
2 off extra low

3 on
4 on
5 on
6 on 38600 (24000)

7 off
8 off
9 off 8 cylinder / low

10 on Square wave

11 on Automatic

12 off Open circuit

These settings seem to almost work. I don't have a service manual, does anyone know what the vss pulse rate is per mile for a Gen I?

 

[ionbeam]

Ahah! I wondered if the vss pulse rate was different from one gen to another,,,These settings seem to almost work. I don't have a service manual, does anyone know what the vss pulse rate is per mile for a Gen I?

Gen I VSS speed depends, well, on vehicle speed. Figure at cruising speed it's about 22kHz. Divide by 4 may not be enough but if it comes with a /4 it'll cost nothing to try.

 

[NTXFJR]

Ok, I knew I'd seen some vss stats somewhere in my searching. Over at the other forum, I found an old thread posting:

https://www.fjrowners.com/discus/messages/9/41621.html?1100572953

This member named damocles claims that a Gen I vss signal is around 80k ppm (pulses per mile). If that's true, then a 4:1 divider would put out around 20k ppm with hopefully a cleaner / mayble more stable pulse pattern. With a setting capability of 38600 ppm, it's looking to me like the Rostra could deal with that signal. I wonder what happens with leaving the Rostra set to 38600, and having actually a 20k signal coming in vs. changing the dip switches to as close to 20k as possible? I'll post back up when I get the divider in and find out.

<edit>

There seems to be some disagreement on the ppm rate, but maybe some confirmation in that the divider module might clean up the signal and give a stronger pulse pattern that might make the Rostra happier.

https://www.fjrowners.com/forums/9-fjr-technical/13339-first-post-rostra-help-2.html

This is a quote in the link above from member Silverback:

"I have to disagree with the PPM on that one. The Factory Service manual says 42 pulses per wheel revolution. The rear wheel is a 180/55-17, which makes the sidewall 99mm high, which is 3.90 inches. Times two is 7.8 and add to 17 is a 24.8 diameter. Times pi is 77.90 rolling diameter. 63360 inches in a mile is 813.35 revolutions per mile. Multiply by 42 and you get 34162.19 (if you don't round anything when you enter it in the calculator) pulses per mile from the VSS. From what I read of Damocles' post, he was using the VSS with a pulse divider. I think his success came from the fact that he converted the analog signal, which I found to be too weak to trigger the Rostra reliably, to a digital signal. Unless I am missing something, he was feeding the Rostra something more like 4,270 PPM. This would work just fine, all things considered. If he was expecting a 10,000 PPM and set it up that way, I suspect it just made the tap up and tap down functions and minimum set functions different."

 

[lnewlf]

don't know about GenI but if I remember correctly a Gen II ABS trigger wheel has 42 teeth....x@800tire rotations/mile= 33,600 ppm...easily handled by the Rostra.. I don't know how the 80,000 ppm for the Gen I was arrived at [more teeth?]......but in a hail mary attempt to cure the random dropouts on my GenII I tried a 4x pulse divider which did no good whatsoever. I did find however that as might be expected the dip switch setting must be reduced by a factor of 4 to 8000 ppm [@ 33,600 divided by 4] or the CC was very rough.

FWIW....for my bike most of the problems were a result of the occasional abrupt throttle response which wigged out the CC...disconnecting and grounding the blue tach wire cured all.

 

[NTXFJR]

Had too much going on the past couple of weeks to do anything with this. I had installed a 4:1 pulse divider in hopes that it would offer some love on this project. No go. Went back to researching some more and ran into another 80k ppm explanation for our Gen I's:

The speed sensor looks at an output shaft that turns 2.852 times for each rear wheel revolution. The sensor is looking at a gear with 35 teeth.

Thus, the pulses per rear wheel revolution =

35 x 2.852 = 99.8

And, pulses per mile =

Rear Wheel Revs/Mile =~ 836 (varies with pressure, etc.)

99.8 x 836 = 83,433 pulses per mile

Those figures are from a really old thread made in '04 on the other forum that took some searching to find. All things considered, it seems that given the symptoms I was seeing, that the Gen I vss signal is not only too fast, but is too weak at speed for the Rostra pulse divider to reliably trigger. All I know is the unit won't even try to engage now.

In a separate post, Damocles who is an EE, got his Gen I set up working by making his own pulse divider, He made mention that the oem vss signal was relatively weak. I'm wondering if this is why the Rostra 4:1 I installed doesn't seem to trigger under speed even though it triggered on the center stand while performing the diagnostics.

So, at this point I'm tired of screwing around and have a Rostra magnetic vss kit coming. I don't much care for accessories that look jake legged, so I found some M6 bolts with magnet inserts made by Koso specifically made for speed sensor setups like this. I plan to pull the six button head bolts on the rear brake disc, replace them with these magnetic trigger bolts, and rig up the pick up coil in there somewhere where it's safe from damage and not too noticeable, like the inside of the swing arm maybe.

By my calculations, it looks like our rear tires turn somewhere in the neighborhood of 815 revs per mile. My set up will have 6 magnets on it, 815 x 6 = 4890 ppm. Wouldn't ya know it, the Rostra can be set to 4k, or 6k, not 5k. Gonna have to play with it a bit to see if one is better than the other.

Waiting on parts, more to come.

 

[HotRodZilla]

Jeeze...Sometimes you guys sound effing smart.

 

[NTXFJR]

Jeeze...Sometimes those guys sound effing smart.

Fixed it.

 

[mcatrophy]

Stupid question, why not just use the engine speed from the coil?

I used that arrangement for years on my '10 Audiovox installation. The only disadvantage is that, if you change gear, the set speed changes, which is only really relevant on using the Resume function after changing gear.

It never, ever, concerned me.

 

[ionbeam]

Stupid question, why not just use the engine speed from the coil?

For some reason the Rostra wants both an engine tach signal and a vehicle speed signal. The coil alone isn't enough to satisfy the Rostra.

 

[PJ4863]

<blockquote class='ipsBlockquote'data-author="ionbeam" data-cid="1291587" data-time="1456747358"><p>

<blockquote class='ipsBlockquote'><p><br />

Stupid question, why not just use the engine speed from the coil?</p></blockquote>

For some reason the Rostra wants both an engine tach signal and a vehicle speed signal. The coil alone isn't enough to satisfy the Rostra.</p></blockquote>

There's a safety feature in the CC. It cuts the cruise if it notices a jump in revs without the associated jump in speed... IE neutral safety switch.

 

[ionbeam]

Same as an Audiovox CCS100 with just a tach signal.

 

[PJ4863]

Beats me then... and why can't I quote correctly? Ah.. that's for another thread.

When I hooked mine up, I never got the neutral safety to work correctly.

 

[lnewlf]

as per the Rostra manual the dark blue [tach] wire can be left unhooked and grounded and the CC will work normaly...altho with the loss of the over rev safety. In the unlikely event that the CC causes an over rev just turn it off.. and the engine does have a rev limiter.

 

[Richouse]

I installed a Rostra on my '07 and it never worked quite right. I did wind up having to use the magnetic sensor on the rear wheel. That got it working. When it was set to a specific speed it would start to pulse speeding up and down just getting worse and worse until you manually over rode it, was very aggravating. After getting my 2010 FJR I didn't even consider the Rostra I went straight to the CC-100. It has worked flawlessly! Very happy with it.

 

[PJ4863]

<blockquote class='ipsBlockquote'data-author="lnewlf" data-cid="1291620" data-time="1456752962"><p>

as per the Rostra manual the dark blue [tach] wire can be left unhooked and grounded and the CC will work normaly...altho with the loss of the over rev safety. In the unlikely event that the CC causes an over rev just turn it off.. and the engine does have a rev limiter.</p></blockquote>

I'm pretty sure this is what I did.

 

[lnewlf]

the Rostra can work without the tach signal [page18- E] but must use a VSS signal from the grey wire [page 8-note1]..if an acceptable signal can't be found the grey wire is not used and a signal generator or magnet and pickup coil must be used and connected to plug "J" [page 19-F] ...This seems to indicate as Ionbeam noted that a tach signal alone will not work altho I have not tried using only a coil signal thru the tach wire.

 

[NTXFJR]

Thanks guys for all of your ideas and input. I'm leaning toward going forward with the Rostra kit which just came in along with the magnetic bolts.

So, when I was looking at the vss kit from Rostra, they included a shematic that showed where the vss kit signal input wire is connected inside the Rostra control unit to the gray wire. Makes sense in light of the posts I guess.

Next question: For those that have used the vss pick up coil and magnets, either for the CCS100 or the Rostra, how many magnets did you use? I'm thinking a higher pulse count is better?

The Rostra vss kit is drawn up for automotive applications and shows 1 or 2 magnets on a drive shaft (faster rpms) of a rear wheel drive car, or 2 or 4 magnets on the cv joint (slower rpms) of a front wheel drive car. I'm thinking that the front wheel drive car type is the most similar to a bike wheel mounted method.

After deciding to go with the vss kit, I had planned to replace all 6 button head bolts on the rear brake rotor with the Koso hex head bolts that have magnet inserts, thinking that more pulses would give better resolution and better speed regulation. I'm now thinking that may not be enough dwell time between pulses to allow the signal to go low enough before the next magnet comes around. So the other options I see are 1 magnet (815ppm) and thinking to rule this one out based on Rostra's install manual, 2 magnets (1630ppm), or 3 magnets (2445ppm). Thoughts?

Thanks