BIG_MODS

iTrader: (9)

I'm in the process of installing a Jerico trans into my 87 Camaro with a 7730 ECM. The Jerico is a full race trans without a speedometer pick-up but I plan on driving on the street as well as the track

I'm not so concerned about not having a speedometer but it would be nice. I did a search to see what kind of problems I would have from not using a VSS and have decided that I really should have one. So my main concern is the VSS.

Question is, what is the easiest and cheapest way to add one? I was thinking of pressing a sleeve onto the output shaft with a reluctor ring and then drill and tap the tail housing to hold the sensor. I have access to a lathe so I could possibly modify a ring to fit the 32T output shaft.



Thinking back to my 700R4 that I pulled out; I don't remember it having a electronic sensor on the tail housing but it did have a 4 wire by the shifter lever. Do the 90-92 cars have a sensor on the tail housing? If so maybe that's where I should source my parts (ring and sensor).

For reference this is the best info I can find for VSS stuff: http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf

RBob

iTrader: (1)

The 3rd gen 700r4's & T5's with a VSS still used the old 2-gear setup. Instead of a cable drive bullet a sensor was used in its place.

Your best bet would be using a reluctor sensor and toothed wheel such as the Chevy trucks used. Along with the DRAC to buffer the signal. The DRAC will allow you to set the pulses per mile (ppm) with whatever rear ratio and tire diameter you may use or change to.

From the DRAC to the ECM use the ECMs optical input. The ECM is expecting a 2000 ppm square wave input. Which the DRAC can provide.

RBob.

The_Punisher454

go to www.jagsthatrun.com and see what they have. I do know they have a bolt on kit that goes onto the back side of the yoke on youre rear end. cost about 60-80 bucks IIRC.

BIG_MODS

iTrader: (9)

Thanks for the info guys.

It looks like that rear axle yoke will be the easiest way to go. I emailed jagsthatrun and we'll see what they have to say. Only problem I see is that I have a 1350 yoke so the ring might require some modifications.

I'm not sure exactly how the DRAC is going to be wired to the computer but the info is probably on their site somewhere.

dimented24x7

iTrader: (2)

I think theres some info on this site on the '93-'95 buffer boxes that where used in the trucks (the one you want). Shouldnt need to much to run it. Power, ground, VSS signal from the pickup, and the 2000 PPM output to the ECM/speedo. You will also need to mod the jumpers within the buffer box to get the correct scaling of the signal so the speedo reads right. Theres a table floating around here somehwere that shows the various values vs. jumper positions.

Fast355

iTrader: (2)

I think I posted some on the TBI board when I switched my TBI S10 4x4 Blazer to a 4L60E. I've got an interesting VSS solution from JagsThatRun as well. Its a reluctor ring that bolts to the yoke of the rear-end.

BIG_MODS

iTrader: (9)

I had a look at my pinion flange yoke and it doesn't look like that ring will work mounted from the back side since it is a 1350. I might be able to mount it in front of the u-joint straps however. I don't know how I feel about doing that.

jagsthatrun hasn't responded to my email and it's been a week now.

BIG_MODS

iTrader: (9)

This must be the thread: https://www.thirdgen.org/forums/tbi/...t=speed+sensor

Am I going to need hard code to make this work? That's going to be an issue for me since I cheated my way through Pascal in college

It turns out that I already had the Jags That Run TPI Engine swapping book and I've now read the VSS chapter about 4x. They sell 40 pulse per driveshaft Reluctor rings that I could probably make work on my output shaft one way or another. Then drill and tap the tail housing for a 15547452 speed sensor. That doesn't seem too hard since I'm a ME and I like things that I can see and touch!

But what is getting me is the DRAC / Buffer. Here's a quote from the book:
Ok, the 7730 ecm uses the 4 pulse VSS but they were only configured using the "bullet" that is gear driven off of the output shaft (or it appears that way). So by using the 40 pulse ring I do not need the gear drive, which simplifies the installation greatly. I get that.

here's another quote from the book:
So hopefully these DRAC's send a 4 pulse signal to the ECM, correct?

So now how do I find the right one? Since I have a 3.42 rear gear in my Camaro I assume that I look for one from a vehicle mentioned above with rear ABS and a 3.42 gear, correct? The S10 might be best since they have a similar tire size. But does it really matter how accurate the VSS is so much as long as it is there? If it is off 10% for example, will the ECM care? My plan is to eventually get an Autometer Speedo which I can calebrate so that shouldn't be a concern.

If I go to a salvage yard looking for a DRAC, where can they be found in the vehicle?

Also from the sounds of things, I can get the speedo signal from either the DRAC or the 7730 ECM, correct?

RBob

iTrader: (1)

The DRAC output is 2000 ppm square wave. The '7730 has an input for this, so they will work together. In the $8D calibration is an option bit to change for which VSS input to use.

By using the DRAC that will need to send a pulse stream to the speedometer. No issue there as it has several outputs.

The DRAC is programmable for input/output ratio. That is the main purpose of it. There are jumpers internally that are moved to set this ratio. Nifty, which is why I mentioned to use one.

Over on diy-efi.org, incoming, are a couple of files on the DRAC. They show the jumpering ratios and pin-out of the unit. The word 'drac' is in the filenames of the files.

In the blazers and such the DRAC is attached to the ECM via a bracket. Small white plastic box with some connectors, and a large paper label with a three letter code on it. {edit: under the dash on the passenger side is the ECM/DRAC combo}

RBob.

{edit: I wanted to add that the DRAC also has a 4000 ppm square wave output. This normally goes to the cruise control. To use that output as the 4000 ppm input to a '7730 it needs to be AC coupled (add a capacitor). The 4000 ppm input to the '7730 is an AC signal as it is directly from the magnetic VSS.}

BIG_MODS

iTrader: (9)

So it sounds as if the 7730 can use a 2000 or a 4000 pulse / mile, even though the book said 4000. That must be what I changed when I converted over from the 165 to the 730.


One more thought that I had. Is there any reason that I couldn’t use a wheel speed sensor on an axle shaft instead? That would save me from tearing up the trans. I have the reluctor ring boss on my axle shafts so I’d just need to find a reluctor ring from a 4th gen 4 channel abs and make a bracket to hold a sensor. I’m not sure how many teeth are on those rings but is the DRAC capable of that range of adjustment?

I’ll definitely follow up with DIY ECM DRAC info. Thanks for your help

RBob

iTrader: (1)

Yes to the 165 to 730 conversion and the VSS input. The '165 uses a 2000 ppm square wave input from either an optical buffer behind the speedometer or a 4-out buffer box. The 4-out buffers the magnetic 4000 ppm magnetic sensor (A/C signal).

The '730 uses a 4000 ppm A/C input directly from the magnetic VSS. At least in 3rd gens. It also has a 2000 ppm square wave input. The A/C buffer is built into the '7730.

For the ring on the axle, just may be able to use it. The tranny ring is 40 tooth. The axle spins at the rear gear ratio lower speed then the tranny. Say 3.42's as an example, for each revolution of the axle the trans output shaft spins 3.42 times:

40 teeth * 3.42 = 136.8

So if the axle ring has about 136 teeth it is in the ball park.

RBob.

BIG_MODS

iTrader: (9)

Please forgive me. I searched at the diy-efi site using this: http://www.diy-efi.org/diy_efi/archive_search.php and the twiki and couldn't find anything with the word "drac". I also tried typing this "drac site:http://www.diy-efi.org/" in google and found 14 results but none of them had DRAC in the title.

Is there another way to search?

RBob

iTrader: (1)

Looks like that site took another hit. Attached here is the zip file of one of the drac files. The other is 2.2 meg and is too large to attach. For the most part it is a re-print of what is in these files.

RBob.

BIG_MODS

iTrader: (9)

Hopefully I'm not doing something wrong, but I couldn't open that file. I just downloaded winzip. It tells me that it does not appear to be a valid archive, whatever that means.
Can you try email, austingerding@hotmail.com? Thanks

RBob

iTrader: (1)

I emailed the file.

If you have FireFox try that for the attached file. It seems that IE has an issue downloading .zip files from TGO.

RBob.

DM91RS

Yep...............IE still full of problems.........

BIG_MODS

iTrader: (9)

Here are the pictures of Bob's attachment http://s116.photobucket.com/albums/o...CZ/Jerico/VSS/ with exception to one of the pics is mine. Its the Corvette VSS and that is actually a friction disk for the C6 diff but it might make a good reluctor ring

I'm wondering if I can use a wheel speed sensor to do the job. The clip ratio chart shows that the DRAC can ratio from a 0.5 to a 2.0, which means that it might have the range of adjustment to compensate for the 3.42 gear depending on what is the "baseline", for lack of a better term.

That corvette VSS shown in the one pic actually uses the ring gear as the reluctor ring. So I'm also considering drilling a hole in my cover pan and welding in a bung to hold the sensor. That would be slick. 3.42 has 41 teeth. Problem is that the panhard and panhard brace are in close proximity so I need to be careful. I could use that C6 VSS or find/buy the 15547452 GM sensor as shown by Jagsthatrun.com. What I like about the 15547452 is that it is threaded so I can adjust the depth with a jam nut. What I like about the C6 VSS is that it is free and that it is low provile so I will have clearance with the PHB.

BIG_MODS

iTrader: (9)

I just answered my own question. I didn't see the txt file that was attached in Bob's attachment until now. I went throught the calculation and it looks like a 25.5 tire and a 41 tooth ring gear / reluctor ring at axle speed will require a multiplier of 0.253 and the DRAC only goes as low as 0.5. Damn.

BIG_MODS

iTrader: (9)

I scavenged a DRAC from the junk yard. It is this one:

Here's the pin-out chart:

If you look closely you'll see that the chart has 1-7, but the DRAC has 1-7 then 7-1 and opposites are connected. For example, on the first 1-7 mine has 1 0 1 0 1 0 1 and on the next 7-1 it is the opposite 0 1 0 1 0 1 0. The 7-1 coorosponds to .79057 ratio which makes sense for a full size chevy truck with 28" tires and a 3.42 so here is my assumption: the 2nd 7-1 part is the part that the chart is refering to and the 1st 1-7 I just wire up the opposite.

Can someone smarter than me confirm? I need a .845 for my car to make it accurate.

Everything else looks pretty straight forward.

BIG_MODS

iTrader: (9)

Ok, I got the car on the road finally but without a VSS. I have a track day on Friday so I was hoping that I could get a safe tune on the new engine and run it without the VSS. I drove it around the block a few times and noticed that it stalls on decel almost every time and bucks pretty violently when I try to lightly cruise. I'm assuming it does this because the IAC would normally (if I had a VSS) try and calm this down.

I just got a used, older version of the autoprom and I have been trying to learn how to use it. For some reason I can't get it to data log and I always have to fuss around with a bunch of things to get it to "initialize attached hardware". I'm using a serial/usb cable from radio shack. I've had the pocket programmer for years but never had to tune anything semi-radical like I have now (hence why I wanted to emulate).

The car still has last years gas in it as well, so I need to get some fresh stuff in.

Also, I was using the SAUJP V3 from the previous engine so it is made for an auto trans. I'm going to try the V4 today. Anybody know how to change it over to the manual transmission selection? The V4 doc says to I don't really know what that means. I'm sure this has been covered a billion times on this board but if someone could just point me to a quick link or something hopefully I can figure it out.

I can't get Tunerpro to data log. I can get it to do everything else it seems, but it gives me an error when I try to record.

Also, the engine won't stay in closed loop for longer than a few seconds. I can let it idle for a few minutes and it seems if I rev it for 30 sec or so it might go into closed loop briefly. I'm not sure what is going on there.

I haven't been able to drive it long enough to get a good taste of the Jerico. It's pretty violent when it comes to shifting, but it is supposed to be I tried clutchless shifting, and it works good hehe, it makes me giggle like a school girl. Definitely has some gear noise, which I would argue is cool. I got quite a few odd looks from neighbors one of which will probably call the cops on me soon.

The engine is a 350 with Trickflow 195's, a 224/230 .509/.511 and 114 LSA hydraulic flat Comp, and a single plane intake. Again, I’m using the 7730 ecm. Car is mostly gutted so half of the electronics are gone. I also have a LM1.

Not ideal but I’m tying to tune this new engine first time with a new trans that doesn’t have a VSS. I’d really like to get to a track day on Friday. You guys might tell me that is impossible without having anything closely resembling a tune, not having a VSS, and only having a little bit of tuning experience. What do you think? Any “crutches” I can use to make this work safely, temporarily?

BIG_MODS

iTrader: (9)

I'm going to try to open up the idle set screw so that the engine uses air through the butterflies more than air through the IAC. Hopefully that helps with the decel stalling (temporally). Right now I have the idle set to 800 rpm in the prom. I'm going to open the throttle set screw until that RPM is raised. I might even raise it to 1000 or 1200 rpm. Not a big deal at least for temporary reasons I don't think.

I've ordered all the parts that I should need to make the VSS on the trans tail housing. And I now have 2 junk yard DRACs so I can afford to ruin one by screwing around with it. I think the rule at my local yard is $5 for parts that they don't know what they are

I'm going to carefully do some WOT pulls tonight even though I've only touched the part throttle stuff. I think I'll add excess fuel to the high MAP areas and pull out as need just for safety sake. I realize I'm breaking TRAXIONS part throttle tuning rules by doing this, but does anyone see issues with that? I have a WBO2.

I can't get my computer to datalog and my single wire O2 isn't going into closed loop very often at all. I'm going to get a 4 wire heated sensor tonight but I'm not sure if I'll have time to install it before Friday.

I just might make it to the Friday track day even if it is for very limited / gentle driving. Good opportunity for tuning if someone can ride along to help.

I'm just throwing this all out there hoping someone more experienced than I is reading this and if there is a major flaw or something dangerous that they would speak up. Even if some of this is a good idea, I would appreciate some reassurance

Thanks!

BIG_MODS

iTrader: (9)

Just a quick update since it is late.

The idle screw trick I described above works perfect, or so I think. It hasn't stalled yet. I opened up the screw pretty much as far as it would go and that put the idle at about 1100 rpm (most of the time). I then re-set the TPS to .54V. I was able to get the ALDL to work briefly and it showed 0 steps for the IAC at idle, so that tells me that the IAC isn't doing anything, which is fine IMO, for now. I might even be able to lower the set screw some more since it is working so good. I modified the bin to 1000 rpm idle.

I burnt about 7 chips tonight (all using the old school pocket programmer). I was having trouble giving it enough fuel. I kept giving it more and more and it still showed 16-17:1 on the wide band part throttle around 24-3000 rpm. The VE table was maxed out in some places so I modified the injector constant from 32-30 and that did the trick. I tried some WOT after that, wow was that fun. I'm a big fan of the jerico right now. One thing that is curious is that low map stuff (bairly pushing the pedal) was very close to stoch before I change the injector constant (14.5-15:1) but after I lowered the injector constant the it got leaner ~15.5 ish. Not what I expected, but WOT was improved.

And I've decided to go to the track day

5678TA

just interested, how did you stumble upon a jerico?? and how much??

BIG_MODS

iTrader: (9)

Someone from another forum that has a Jerico in his GT1 Camaro got me interested in it. I found a good deal on ebay on this one and it already had almost perfect ratios in it for what I want to do (almost the same ratios as a T56 1-4). There are a lot of cool things about the jerico. Dog rings instead of syncros makes shifting very harsh but it is very fast and much stronger than syncros. Many people don't use the clutch for upshifts, just let the rev limiter hit and then pull the shifter HARD. The straight cut gears are strong and sing a nice song. There are over 200 gear ratios available, so pick what you want. Angular contact ball bearings make it efficient. Mine (with the aluminum case and shifter) weighs 85 lbs, which is 40 lbs lighter than a T56 (magnesium is available whcih will make it even lighter). Almost all of Nascar, Busch, and Truck use them so they are very proven (thats where mine came from). They are a clean slate design made for racing, not some factory design that is "beefed up". There are always limitations when you start with a factory design. One benefit of the clean slate design is that a Jerico can be rebuilt without a press, so I'm told.

I've been watching these on ebay for several months and it seems that $2200-2600 is the going rate for a complete used trans depending on options and condition etc.

I'm building a multipurpose car. Mainly I just want something that I can beat the crap out of and it will take it. Primary purpose is road race, auto cross, and maybe a few trips down the 1320. And I want to drive the car to-from.

DM91RS

I bet it's a blast to drive. Gonna be fun at the track......

BIG_MODS

iTrader: (9)

Thanks, I hope it will be more fun to drive soon.

My LM1 crapped out on me. Mine is an early version that I got it when it first came out on a group purchase through TGO. Evidently these early versions didn't have seals in the connector to the sensor. It was raining on the way to the track and water got in and shorted it out. So my only tuning tool that was working no longer was.

I found a VW dealership and bought a new sensor ($112 ) but that didn't fix it. To make a long story short, I have to send the box in for them to take a look at.

I have a pretty big hiccup at about 3700-3800 rpm. Not sure what it is. When the LM1 was working it would breifly go to 16:1 and then go back to a better AFR. I added more fuel there 2x and it didn't go away. Not sure that is going on.

It is always fun to be at the track but I wish I could have tuned the beast. Instead I kept the revs below 3500 which means I curised down a 1/4 mile straight at 75mph and drove all but one corner in 4th gear. No sense in burning up a new motor.
----------
Oh and I got 15 MPG on the way home cruising at 3000 rpm (~65 mph). Hopefully I can improve that with some tuning. Can Highway Mode be used with a manual?

DM91RS

I don't believe that it matters, manual or auto. Too bad about the WB.

I have a ZT1 and IIRC I wrapped the connector so it would stay dry. Those things aren't like buying a $20 stock Bosch

BIG_MODS

iTrader: (9)

Ha, tell me about it

I might try and return my to the VW dealership and buying it somewhere else cheaper. Innovate said $78. Not sure if I could find them cheaper anywhere else.

BIG_MODS

iTrader: (9)

I've been working through many tuning issues: https://www.thirdgen.org/forums/diy-...maxed-out.html

I'm tired of giving the ECM excuses for running like crap so I finally pulled the trans to install a VSS.



I bent a 1.5"x1.5" piece of 1/4" AL to fit the countours of the extension housing then brought it to a welding shop to have it welded on. Then brought it to my machine shop and had the top milled flat and the 3/4-16 hole drilled and tapped.


I got this 40 tooth tone ring from http://www.jagsthatrun.com/ The tone ring that I got was made for a T-case so it wasn't a direct fit on my trans, but close. I needed to turn part of the ID a little bigger and I needed to use a piece of shim stock to close the gap on the clamp side. It's clamped on a spline that is used for the Jerico oil pump option.


Here is a pic of it all together.

Fast355

iTrader: (2)

Nice work on the trans.

BIG_MODS

iTrader: (9)

Does it matter which 2000 ppm DRAC output I use (C11, C14, or C15)?

The speed sensor has 2 wires. I assume one goes into the DRAC at C7. What is the other wire connected to? 12 Volts or C12 or?



Where does the 2000 ppm DRAC output go into the the 7730 ECM?
VSS (low) = BB9
VSS (High) = BB10
VSS {Buffered} = BC6 (used for 165 => 7730 conversion)




Top Box: I assume that I change the top box to 2000 ppm. Could I tweak the PPM to accomodate ratio changes instead of unsoldering/soldering/jumpering in the DRAC?

Bottom Box: I assume that I uncheck the VSS Magnetic?

Any other Prom Changes?




Thanks in advanced for spoon feeding this to a dumb ME.

BIG_MODS

iTrader: (9)

So I tried it out today.

I wired the VSS into C7 and C12. That made sense when I looked at the harness coming out of the DRAC since they were twisted together. C8 and C9, ground and power obviously.

Initially I put C15 into BB10 on the ECM. That didn't work according to tunerpro, so I tried changing from Option word 3 bit 6 to unchecked, that didn't work either.

Brought the car in and switched from BB10 to BB9. Didn't work.

Tried BB10 and BB9 at the same time. Didn't work.

Finally got the rear of the car up on jack stands and ran it while I tried every combination I could think of (C10, C11, C13, C14 each to BB9 and/or BB10). Nothing. Turned the car off.

Decided to get my digital volt meter out and do some checks, but the next time I tried to start the car and put it in gear my hydraulic throw out bearing blew out and I lost control of my clutch So I pulled the trans. Good news is that only takes me 40 minutes now.


Any help is appreciated.

BIG_MODS

iTrader: (9)

I just read this from a different thread I found in a search:
Maybe I should be using BC6 instead.

Above it he makes it sound as if I can put the VSS directly into the BB9 and BB10???

DENN_SHAH

iTrader: (1)

im not certain, but i believe i have my DRAC C4 output wired to C6 input on my ECM.
changing the VSS pulses has no effect when you use a DRAC.
yes, unchecked the box for magnetic VSS.
with a DRAC, the only way i know of to change the speed the ECM sees & displays is to change the jumpers in the DRAC.

if you want to be able to change the speed the ECM sees & displays in the data stream in the bin, you can wire the magnetic speed sensor to the ECM like it was originally,
but the 40 tooth reluctor won't work right. i believe 40 pulses per revolution is more than the 7730 can handle at any kind of speed. depending on your rear gear, the PPM
can be quite high with a 40 tooth reluctor.
there is some info about it here,
https://www.thirdgen.org/forums/diy-...-v-sensor.html

BIG_MODS

iTrader: (9)

You mean BC6?


Thanks for the link, I don't know how I missed that.

RBob

iTrader: (1)

Yes to BC6. The pins C6 & BC6 are the same, just different nomenclature. I don't know GM did that with some of the ECM diagrams, just makes things confusing.

When the pin is listed with 2 letters then a number, the first letter is for the color of the connector: B for black, G for green, etc.

Which doesn't make sense either as the '7730 ECM has two black connectors, and the green color for the other connector replaced the yellow. Yellow now being reserved for air-bag connectors. So for the '7730 can find them with either a green or a yellow connector.

RBob.

BIG_MODS

iTrader: (9)

I'm happy to report that it works!

DENN_SHAH, that was the money shot, The C4 is the 4000 PPM, which is what I am using as well.

With my 40T ring, a 3.42, and not messing with the jumpers on the DRAC my MPH is close. Roughly 60 mph shows 67, which is pleanty good for the ECM for what I need it for. I might change the jumpers when I get around to hooking up my AutoMeter speedo but I'm not going to mess with it now.

I should also mention that driveability is much better and I was able to fix the idle so that the IAC is actually being used. Car runs smoother and bucks much less.

DENN_SHAH

iTrader: (1)

glad to help

i don't think i mentioned it, but very nice job on adding the VSS to the Jerico