Z3 Transmission speedomter/rpm questions

[ryboto]

So, I just swapped my stock 5speed for an RSX case with 06 Si internals and a VSS. Using this calculator- http://www.zealautowerks.com/transcalc.php, and this picture- http://img.photobucket.com/albums/v504/MJ23FE/Tranny%20Gear%20Calculations/K-SeriesTransmissionTablev3-28-08re.jpg
I am seeing that I should see reduced rpms at highway speeds. Specifically, at 60 and 80mph I should see 500-400 rpm drop, respectively. What I see instead is the exact same RPM in 6th at 60 and 80mph that I was seeing with my 5th gear of my 5 speed. Does this mean the internals aren't from an 06 Si, is the calculator wrong, or is my speedometer incorrect?

Engine is stock A3.

[mitchlikesbikes]

your VSS could be set wrong. best way to find out if your speedo is correct is to have someone drive next to you with their cruise on and have your phones ready haha.


if your speedo is correct and your RPMS really are the same, you got jewed and bought a regular rsx 6 speed

[ryboto]

This was the user who sold it to me - http://www.k20a.org/forum/member.php?u=13541, seems like he's got rep, so I figured this was legit. I figured the only way to check was as you suggested, or get buddy-buddy with a cop and his radar gun.

[ryboto]

Someone on facebook is suggesting I was scammed...how does one reset the vss so that it's correct? Even if it was an RSX-S internals, I should see lower RPMs based on the calculator I linked.

[USAF EP3]

What year RSX did it come out of? I'm assuming it was an 02-04 since you would've had to use a signal converter with an 05-06 Type S trans and change out the shifter selectors from the EP3 selector.

Technically, yes you should see lower RPM's in 6th gear when compared to your old 5th gear. Your old 5 speed had a 4.7 final drive and the 02-04 Type S has a 4.3 final drive. Even if the new 6th gear was the same ratio as your old 5th gear, you WILL see lower RPM's regardless due to the lower FD. It could be possible that they swapped an 06 Si helical limited slip differential and with it the 4.7 FD that comes attached. That could be a cause why you're seeing the same RPM's at that speed.

I would right away pry open your driver side axle and take a flashlight to look inside and if you see a shaft at the end of the spline gear then you don't have LSD. If you see the input spline shaft of the intermediate shaft then you have LSD.

NOTE: All years 02-06 Type S do not come factory with LSD.

[ryboto]

What year RSX did it come out of? I'm assuming it was an 02-04 since you would've had to use a signal converter with an 05-06 Type S trans and change out the shifter selectors from the EP3 selector.

Technically, yes you should see lower RPM's in 6th gear when compared to your old 5th gear. Your old 5 speed had a 4.7 final drive and the 02-04 Type S has a 4.3 final drive. Even if the new 6th gear was the same ratio as your old 5th gear, you WILL see lower RPM's regardless due to the lower FD. It could be possible that they swapped an 06 Si helical limited slip differential and with it the 4.7 FD that comes attached. That could be a cause why you're seeing the same RPM's at that speed.

I would right away pry open your driver side axle and take a flashlight to look inside and if you see a shaft at the end of the spline gear then you don't have LSD. If you see the input spline shaft of the intermediate shaft then you have LSD.

NOTE: All years 02-06 Type S do not come factory with LSD.

So, I can see clear through the spline, and the guy who helped me install it said it clearly had an LSD. Also, last night, I pulled up alongside an FG, saw their digital speedo and saw I was going 5mph faster than my speedo said I was. Confirmed it again this morning with another FG, I was going 63-64, their speedometer said we were actually going 70. This agrees with another test I did where in 3rd I checked my speed at 3k rpm, speedo said 25mph. The calculator for the z3 says I should be at 30 mph, 5mph difference. So I'm almost positive it's just reading incorrectly by 5mph, possibly a little more at higher speeds.

[ryboto]

drove with a Tom Tom this morning, according to that gears 1-4 are ~5mph off, in 5th it's 5-6mph, and in 6th is ~9-10 mph, the difference seems to increase with speed. So 70mph is actually 80..

[sleepy ep3]

drove with a Tom Tom this morning, according to that gears 1-4 are ~5mph off, in 5th it's 5-6mph, and in 6th is ~9-10 mph, the difference seems to increase with speed. So 70mph is actually 80..

I have a z3 trans. This is true. Even with VSS converter it's still off.

[ryboto]

I have a z3 trans. This is true. Even with VSS converter it's still off.

Is yours in a Z3 case?

[ryboto]

it's in an rsx case. So, update-
Got kpro installed. Tried using the correct gear ratios for the new trans, no change on the speedometer. Tried using the RSX kal and using a 12% speedometer correction, and there's no change. What can I do in kpro to attempt to correct this???

I've done the math, based on the odometer, the speedometer is off by ~12.3%

[ryboto]

No ideas of what I could try...?

[cyllarus]

Ryboto, couple of things:

1: the VSS correction parameter only corrects the ECU internal speed, it does not affect the speed signal sent to the cluster. So the fact that you adjusted your edu correction factor and did not see a change in the cluster.. is expected and normal.

2: ALL VSSs are NOT the same.
Like USAFEP3 I assume you are using the VSS that is driven off the final drive, and not the 3rd gear
(FD style VSS has the sensor / plug in the rear of the case, near the rear tranny mount
3rd Gear VSS has the sensor on the FRONT of the case)

If you are infact using the FD VSS, know that a there is a VSS designed to work with the 4.4 FD , and one set to work with the 4.7 FD ( and im sure one for the 5.1 FDs too)

If you use a VSS designed to work with the 4.4 FD on a 4.7FD Tranny you will see MPH be understated from actual.
If you use a VSS designed to work with the 4.7 FD on a 4.4 FD Tranny you will see MPH be over stated from actual.

I had this happen when i swapped my car to a 02/04 RSX tranny.

I would expect that the combination of the new gearing, + having the wrong VSS for the FD you have is causing your issue.

Visually, you cant LOOK at the VSS and see if its a 4.4 or 4.7 one. When i bought my 4.4 VSS to correct my issue, i put the 4.7 one next to the 4.4 one.. they were identical

* off topic, where did you get your z3 tranny internals and how much did it cost. I'm looking at this as my next upgrade.

[USAF EP3]

Ryboto, couple of things:

1: the VSS correction parameter only corrects the ECU internal speed, it does not affect the speed signal sent to the cluster. So the fact that you adjusted your edu correction factor and did not see a change in the cluster.. is expected and normal.

2: ALL VSSs are NOT the same.
Like USAFEP3 I assume you are using the VSS that is driven off the final drive, and not the 3rd gear
(FD style VSS has the sensor / plug in the rear of the case, near the rear tranny mount
3rd Gear VSS has the sensor on the FRONT of the case)

If you are infact using the FD VSS, know that a there is a VSS designed to work with the 4.4 FD , and one set to work with the 4.7 FD ( and im sure one for the 5.1 FDs too)

If you use a VSS designed to work with the 4.4 FD on a 4.7FD Tranny you will see MPH be understated from actual.
If you use a VSS designed to work with the 4.7 FD on a 4.4 FD Tranny you will see MPH be over stated from actual.

I had this happen when i swapped my car to a 02/04 RSX tranny.

I would expect that the combination of the new gearing, + having the wrong VSS for the FD you have is causing your issue.

Visually, you cant LOOK at the VSS and see if its a 4.4 or 4.7 one. When i bought my 4.4 VSS to correct my issue, i put the 4.7 one next to the 4.4 one.. they were identical

* off topic, where did you get your z3 tranny internals and how much did it cost. I'm looking at this as my next upgrade.

Feels so good when pupils of mine listen, learn and teach others! :mcool:

P.S. Yes, the FD VSS sensors LOOK identical but they are inf act two completely different part numbers. I remember verifying this awhile ago with IPB pictures from Honda.

[Ba82Ep3]

All of this combined brain power and no one thought to ask about tire size?

[Ba82Ep3]

it's in an rsx case. So, update-
Got kpro installed. Tried using the correct gear ratios for the new trans, no change on the speedometer. Tried using the RSX kal and using a 12% speedometer correction, and there's no change. What can I do in kpro to attempt to correct this???

I've done the math, based on the odometer, the speedometer is off by ~12.3%

KPro adjustments will not affect your speedo. Only the tune and its results...

[USAF EP3]

He would need a ridiculously large tire size to get an error of 10+mph on the speedo. And given that the most common sizes on our cars are 16" and 17" wheels, the diference made by tires on those size wheels is minimal and not enough to make a 10mph difference.

[Ba82Ep3]

Agreed. My point was its a variance that wasnt mentioned... either when comparing car speedometer to car speedometer side by side, or what one person said they had when compared to what another person had at X RPM. Add that to individual speedometer inaccuracy when compared to tachometer inaccuracy (KPro will show how far off your dash tachometer is), you have enough variance to equal about 7 or 8 mph when measured between several different cars.

Individually its not a lot... when compared between several different inaccurate setups it can be a good amount. A radar gun would be most accurate.

I wish i knew a solid way to know without visual inspection if you were screwed or not on the gears. : (

[cyllarus]

He have to be running some really really small tires to show a 12% speedo inflation, and have changed the tires at the same time as the tranny.

[ryboto]

* off topic, where did you get your z3 tranny internals and how much did it cost. I'm looking at this as my next upgrade.

Thanks for the info, people on FB seemed to think the ECU gets the signal and then sends it to the cluster. The VSS is supposedly the same as the original EP3 VSS, so it would indeed be for a 4.4D, not the 4.7 of the 6spd that's in it.

I got mine off K20A.org, I think I ended up only paying $1100 shipped with the VSS? Probably could have offered less if I could have picked it up



KPro adjustments will not affect your speedo. Only the tune and its results...

Like I said, people on FB were telling me it was possible to fix through the ECU.

[ryboto]

He have to be running some really really small tires to show a 12% speedo inflation, and have changed the tires at the same time as the tranny.

Yea, even with the stock tire, I'm seeing that difference. Speedo is 12% lower than it should be. Tach is right where I expect it to be when I drive with the GPS and check my actual speed.

[USAF EP3]

Thanks for the info, people on FB seemed to think the ECU gets the signal and then sends it to the cluster. The VSS is supposedly the same as the original EP3 VSS, so it would indeed be for a 4.4D, not the 4.7 of the 6spd that's in it.

I got mine off K20A.org, I think I ended up only paying $1100 shipped with the VSS? Probably could have offered less if I could have picked it up




Like I said, people on FB were telling me it was possible to fix through the ECU.


The EP3 VSS sensor is for a 4.7 FD. The stock EP3 tranny has a 4.7 FD. Only the 02-04 RSX Base and Type S models had the 4.3 FD.

[Ba82Ep3]

The VSS just sends a voltage signal, it doesnt display it. If i remember right there is no physical difference between the RSX and the EP3 speed sensor... regardless of the FD difference...

[USAF EP3]

The VSS just sends a voltage signal, it doesnt display it. If i remember right there is no physical difference between the RSX and the EP3 speed sensor... regardless of the FD difference...

The teeth are different on the bottom of the mechanical portion that rides on the ring gear of the diff. Also the fact that they are two completely different part numbers between the RSX sensor and the EP3 sensor.

[Ba82Ep3]

Silly rabbit... the part number difference is because of the Acura/Honda badging. lol So many parts have different numbers but are ideally the same when compared.

Think about it... the VSS ring on the diff can go from diff to diff regardless of the FD. The rings position in relation to the VSS sensor isnt changed by changing the FD. Why would there be a need for a different gear on the VSS for either FD?

IF there is a difference i would imagine it to be electrical... as that would be cheaper to manipulate for mass production than mechanical variances between models. From what i remember though, there is no difference between the two.

[USAF EP3]

Silly rabbit... the part number difference is because of the Acura/Honda badging. lol So many parts have different numbers but are ideally the same when compared.

Think about it... the VSS ring on the diff can go from diff to diff regardless of the FD. The rings position in relation to the VSS sensor isnt changed by changing the FD. Why would there be a need for a different gear on the VSS for either FD?

IF there is a difference i would imagine it to be electrical... as that would be cheaper to manipulate for mass production than mechanical variances between models. From what i remember though, there is no difference between the two.

Well who knows. He's still having the problem and the only thing that would make sense would be the VSS. He doesn't have much else to try to fix the issue.

[Ba82Ep3]

Agreed. I wish trans internals were easy to identify without teardown... it makes it hard to be sure you arent being taken when buying used. : (

[USAF EP3]

Agreed. I wish trans internals were easy to identify without teardown... it makes it hard to be sure you arent being taken when buying used. : (

Honestly, he really didn't get had. He got what the seller told him what it was. An RSX-S trans case with 06-11 K20Z3 trans guts. The problem lies within his speedo reading incorrectly. His revs and speed are spot on with what mine are. around 3700-3800 RPM at 80MPH in 6th gear. That's the tall .659 ratio 6th borrowed from the TSX with the 4.7FD of the 06-11 K20Z3 trans.

[cyllarus]

I can attest, and demonstrate that the 2 sensors ARE different, and indeed send a different signal.

I've got both in my garage and can swap and shoot vid if you disagree.

I agree with Ba* though, i bet the difference is in the pulses / rotation, NOT in the number of teeth.

[usedep3]

I can attest, and demonstrate that the 2 sensors ARE different, and indeed send a different signal.

I've got both in my garage and can swap and shoot vid if you disagree.

I agree with Ba* though, i bet the difference is in the pulses / rotation, NOT in the number of teeth.

This. I agree. I believe the 2 sensors are different. I had an issue with the speedo being off after I rebuilt my tranny. It turned out it was the VSS. I had 2 laying around and must've pick up the wrong one when i was frankenstein-ing the tranny back together..

[Ba82Ep3]

Yes please if you dont mind. Makes me wonder if i have the wrong VSS myself, there wasnt a VSS specification for K swapped chassis with ITR trans (that i found anyways).

I know physically they cant be different (gear and ring). Ive been through enough trannies to know that for a fact.

[ryboto]

So, I likely have the RSX VSS? I will be PISSED if that's the solution. I sold the EP3 trans with the VSS because everyone swore up and down they were the same.

[ryboto]

'04 RSX-S: 78410-S6M-N01
'04 EP3: 78410-S6M-N01
'03 RSX-S: 78410-S6M-N01
'03 EP3: 78410-S5T-901
'02 RSX-S: 78410-S6M-N01
'02 EP3: 78410-S5T-901

Are those part numbers correct? I have an 04', so I'd need the N01, but it seems like it's the same as the RSX VSS??

[USAF EP3]

You need this sensor:

78415-S5T-901

Hondapartsunlimited.com has it for $72 brand new, if you can afford that.

[cyllarus]

Yes please if you dont mind.

OMG you're killing me ! Do you know what a PITA that was to get out with the tranny in the car.

But for the sake of K-series geekery I will try this weekend.

[ryboto]

You need this sensor:

78415-S5T-901

Hondapartsunlimited.com has it for $72 brand new, if you can afford that.

For an 04 EP3??
If I look it up on that website, I find this page-
http://www.hondapartsunlimited.com/parts-catalog/honda/civic/2004/3dr-si/ka5mt/transmission-manual/mt-clutch-release

and it says it's this one-
78410-S6M-N01 SENSOR ASSY., SPEED

[Ba82Ep3]

OMG you're killing me ! Do you know what a PITA that was to get out with the tranny in the car.

But for the sake of K-series geekery I will try this weekend.


LOL! Yeah i feel yah... one plug and one bolt... but its harder to get to in the EP than it is for me. Sometimes i forget i have more room to play with. : (

Ive been scouring k20a.org and i havent found anything stating a difference between the two VSS sensors (as far as swapping into another chassis is concerned). Its funny because i would think it would be something important they would list, because so many make a huge deal over which primary o2 sensor youre supposed to use... but the EP3 sensor works fine (they suggest OE RSX-S *ONLY*).

[ryboto]

Ive been scouring k20a.org and i havent found anything stating a difference between the two VSS sensors (as far as swapping into another chassis is concerned). Its funny because i would think it would be something important they would list, because so many make a huge deal over which primary o2 sensor youre supposed to use... but the EP3 sensor works fine (they suggest OE RSX-S *ONLY*).
Well, they're two different part numbers, but some years the RSX and EP3 share the same part....there HAS to be a difference, or mine would work, yea? They're all about the same cost though, ~$70.

[Ba82Ep3]

Well, they're two different part numbers, but some years the RSX and EP3 share the same part....there HAS to be a difference, or mine would work, yea? They're all about the same cost though, ~$70.


Is your VSS 04? Mine is off my 05 EP trans... what years VSS's are shared? I still cant find anything definitive on k20a. : /

[ryboto]

Is your VSS 04? Mine is off my 05 EP trans... what years VSS's are shared? I still cant find anything definitive on k20a. : /

Only way to know is to look up part numbers, which I'll do now. I don't know what year the VSS in the trans came from, just swapped it and figured it'd be fine since the seller said it should be the same.

[ryboto]

02-03 78410-S5T-901 SENSOR ASSY., SPEED

04-05 78410-S6M-N01 SENSOR ASSY., SPEED

RSX Base 02-04 78410-S7A-G01 SENSOR ASSY., SPEED (NS)

RSX Type S 02-04 78410-S6M-N01 SENSOR ASSY., SPEED

Oddly, for the 05-06 base, it shows the picture for the speed sensor, but doesn't list it in the parts below. Same for the Type-S, but the picture is different for 06.

[poeticfinesse21]

05-06 RSX had an electronic VSS just like the 06+ civic si so you should just disregard those years. 04-05 EP3 and all 02-04 RSX all have the same VSS as they all shared the same size wheels and tires (16"x6.5" +45 wheels and 205/55/16 tires). 02-03 EP3 came with 15"x6" +45 wheels and 195/60/15 tires but even if for some reason you had a VSS from a 02-03 EP3 then your speedo should only be off by 2.7%. This is truly a head-scratcher

[gtimportfanatic]

like said before Ryan, it's 05-06 rsx's use electrical speed sensors, they wont be the same.. if you don't figure it out by the time you come over to do the swap, i can swap mine with yours, do a test drive before the swap and see what happens.

[gtimportfanatic]

step by step how i got mine corrected:

when i did my 6spd swap which is set up identical to how Ryan has his, 02-04 case with inside of an SI, realistically the only difference is the 6th gear and the LSD.

i used my 5spd VSS, and the speedometer was really off, i thought my car was stupid fast, but then i got next to my boys SI and his speedo read 70mph, mine was around 82 or so. i dealt with this for a few weeks then things started to get weird. The speedo would jump around, work when it felt like it until one day it just stopped all together. i hit up my friend that built the trans for me and he said it was probably just the speed sensor, he said he had one laying around i could use and if it worked i could keep it. Tried it, problem fixed, did the same thing with my friends SI and we were pretty much spot on when it came to speed.

But, one day i decided to wash my bay and for some reason i had unplugged my sensor and water got in it, speedo started acting up again i thought for sure i fucked it up, but when i got home i used air to blow it out, then i applied Di-electric grease to the plug. Problem fixed, never had an issue again, this was over a year ago