I was wondering if anyone has attempted a conversion from electric speedo gears to mechanical.. I plan on using the original speedo in my 59 apache, but have a 700r4 tranny, it is out of a 1986 camaro, which I believe is a electric readout as far as the speedometer... My question(s): Can you just swap electric speedo gears for mechanical and be on my way (without changing the tail shafts, which I think is just wishful thinking), do I have to swap out the entire tail shaft, or do I somehow get a VSS (vehicle speed sensor) and just find some kind of converter that fits under the dash? I am looking for the cheaper route here, but I already have the conversions and know what I need to get as far as a speedo gear. 15 tooth driver gear, 41 tooth driven gear... I am running 225/75/R15's with a 3.90 gear ratio rear end. I already have the driveshaft shortened (dont know if the earlier 700r4's had shorter tail shafts w/ mechanical speedo drives or not) So I am not sure If I want to dick around with swapping tail shafts. Any information would be great
I was TOLD that all you needed was a tail housing and the correct gears on the shaft, a bullet and the correct gear for the bullet. I had a electric 700R4 for my 32 3W ... but found a cable drive 700R4 and used it instead.
Verify you even need to do it first. Trucks didn't go electric until '88 (pickups) and '90 (Suburbans, S10). '86 Camaro unless it's from a TPI car likely isn't electric. Should be obvious by looking at it -
the two pics of the speedo gear, notice the semicircle.. is that what I am looking for if it is an electric speedo? I thought it was... check out my pics and get back to me
Much interested in this myself. Talked with a chev mech and he said I need a 87 or newer tailshaft to get my 91 electric converted to cable drive.
looks like a plastic drive gear to me. You need the proper aluminum bullet and driven gear for 700 - 4l60 trans
Find a new mechanic. Any 700 tail housing with the speed-O bullet design as posted by 1959apache member photo will fit. you must remove the metal reluctor wheel from the 1991 trans shaft.. find proper 700 drive gear and clip for out put shaft.. T-350 speed-O gear is NOT the correct diameter for 700 trans. Install the gear clip in the front hole on this out put shaft NOT the rear hole... pull reluctor wheel off, holes in output shaft should be under it
I guess I am a little confused still... when you refer to the bullet design, are you talking about anything that is in something like this kit? http://www.bowtieoverdrives.com/catalog/catalog_inc/viewitem.php?ITEMID=14 Are you talking about the housing? or is that something that I need to buy separately, in addition to everything in something like that kit? I do not have a housing or anything so a kit really would be my best option unless I salvaged something from a junk yard and just get the driven gear, which is something that I am willing to do.
Any gear housing from a mechanical speedo 700r4 should fit. Or you could use a gear housing from a th350 with a BOP case (Buick, Olds, Pontiac). Use the speedometer calculater from TCI or Bowtie overdrives website to calculate wish gears you need. First calculate wish gears you need because there are two housings, one fits the 34-39 gears and the other 40 to 43 teeth gears.
I think your local GM parts guy can fix you right up. You remove the magnetic whirly thing off the out put shaft and in stall the plastic gear. The magnetic thing will have to be pulled with a puller as it is a press fit.
Thanks for the info. I have already done the calculation and I need the 40-43 gear housing. I will call a local parts guy that rebuilds transmissions and try to get that crap from him to see if it is cheaper.
first; the metal reluctor wheel on the out put shaft is not magnetic.... the magnet is in the sensor.. the reluctor wheel is a press fit The speed-O kit mentioned 1959apache , the kit looks like what you need. Use of the t-350 BOP bullet speed-O insert... watch the O-ring location on the OD of the insert. GM moved that O-ring for some reason. Some of the t-350 Bullets will leak oil because the O-ring will not seal properly. in counting the teeth on the drive gear for the output shafts... count the teeth on the edge / side of tjhe gear , NOT across the teeth face themselves
For those interested-I bought a new trans from GM. 89 camaro was the application=mechanical speedo. The trans had all the new upgrades and not 89 technology. The kicker is that it does NOT come with ANY speedo gears,nor the housing to which the cable is mounted.Just an FYI. Too many horror stories of used trannies(not those kind) that took a dive,or had something worn to begin with. I guess it's ok if it's a known unit. Just offering some info to save some headaches.
I just changed a 1990 700R4 from electric to cable speedometer. You should be able to find a driven gear housing at your local wrecking yard. Keep in mind there are two different ones, 1 for gears up to 39 teeth, 1 for 40 teeth and up. The one for 40 & up will be marked 40,41,42,43, but will take 44 & 45 also. I paid about $8.00 each for the gears. You will also need the clip or retainer that holds the drive gear in place on the shaft. The tail shaft housing is the same. Bob
it looks to me that the guy that "rebuilt" this transmission did most of the work for me.. lol so that is great news for me... one last question.. When installing the speedo gear and housing, how do I get the speedo gear housing to seat all the way without breaking anything as far as the gears?
If you have the proper set of gears and the right bullet ... it should slide right in. I ususally do lube mine with Automatic Transmission fliud to make it slide easier ...
i went on line to bowtieoverdrives.com and ordered a mechanical,speedo drive for my 1953 chev pickup with a 700r4 trans. just give them the rear end ratio and tire size and they will give you the correct speedo gears.
Yeah I am just weary of of putting any force on it because it is plastic because its not just sliding in with ATF (it is the correct one however, but a new o-ring), but I will just have to deal with it. thanks deuce.
i have a 3.90 rear and running 215-60-16 tires and installed 15 tooth drive gear and 42 tooth driven gear and the original speedo reads very accurately.
Just to clear up some of the terminology if you end up dealing with a GM parts guy, especially if he's kind of new to the business. The part you're after is called a speedometer driven gear sleeve. For most TH350 trans the sleeve is considerably smaller, about the same diameter as your thumb, and is bullet shaped. The TH700 and some other models use a larger sleeve to work with the larger driven gears. As mentioned already, make sure the sleeve is marked for the correct number of teeth for your driven gear. The hole in the sleeve is slightly off-center and the sleeve may have to be rotated somewhat to properly index the tooth count number on the sleeve to a certain position in the extension housing, possibly the holdown bolt or a mark on the holdown clamp. This ensures that the driven gear properly engages the drive gear. There's also a small lip seal in the sleeve to seal it to the driven gear shaft. If you're dealing with used parts, check the driven gear shaft for wear where the seal rides on it. If it's worn enough you'll likely end up with a bit of a leak. If you get a new sleeve, make sure it has a seal already in it. A new GM sleeve should.
good deal, same gear ratio here, but my tires are 295-75-15 thanks Got it on by the way, just needed some love.
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