I have swapped a th350 into my 89 trans am that had a 700r4 in it. How do I get the speedo to work?

 

Its funny, I am doing this same swap soon. I have a '91 GTA aluminum driveshaft, I'm going to buy the th-350 trans conversion kit, then yeah the speedo, lol. And I think I can use the same 700-r4 stall too right? They're both 30 spline, so and since the driveshaft will also work, this is pretty sweet.
How'd your swap go? Hows it feel in the car now?

 

You need a signal converter and a speedo cable to get the speedo to work. Summit sells them for around 60 bucks I think. Your 89 already has a electric sender for the speedo, you can just tie into that wiring. The stalls are different between a th350 and the 700r4 I believe.

 

cool about the speedo, but the stall says 30 spline on the trannys from summit vs the th-350, so I'm wondering can the swap be done using the same converter? Anyone know about this?

 

I just looked at summits site for converters. They are different part numbers for the tranny's. The differences are more than likely internal and perhaps the depth of the shaft to the pump. Just because they share the same spline count does not neccessarily mean that they are the same.

 

My 89 has a cable drive. However, whether you have a VSS or cable, I've discovered that the TH350 has the same sort of speedo equipment as a T-5. I'm actually using TH350 cable driven gear in my T-5 swap. Therefore a T-5 VSS might do the trick if you have a VSS car.

http://www.transmissioncenter.net/sp...____va.htm#350

Or these guys sell a kit.

 

Thanks allot for the help on the speedo looks like a easy fix. my 89 is a v6 model firebird that I am converting into a trans am. I am ripping my 87 trans am apart for this do to rust. The big thing that I found about the turbo 350 trans is the cross member. You need that kit from summit to get it in right. which you can get here

http://www.summitracing.com/parts/BMM-30299/

I think that it should come with the speedo kit do to the fact that it is a conversion kit but it don't. But it will allow you to attach the trans to you torsion bar that runs to rear end. I would think that the converters are different do to the fact that the 700r is a overdrive trans with the locking converter for cooling. There is a large difference in feel do to the no overdrive and no 4th gear. It will kill your fuel millage! And also watch you gear ratio in the rear-end. I think you can help the fuel millage thing there in the rear-end.

 

one other thing that I am finding is that it may be the same price to have a 700r built then to do the th350 swap right. you are gonna spend $100 on the x member and then you got the speed o problem that looks like it is gonna run up around 300 bucks to get it working right (gotta have a pulse generator that is adjustable) That's 400 bucks in just basic parts to get it in right. And your fuel millage is gonna goto ****.


heres the parts

#350E. Kit to convert your TH350 transmission to an electronic speedometer. This is used when your vehicle has an electronic factory speedometer and your transmission was converted to a TH350 gear driven type speedometer. This kit consists of a 8 pulse generator and an electronic ratio adapter to adjust the signal. Can be used to drive a speedometer cable at the same time. Cost $228.00


I dont know if this one will work or not.

#350E2. Use this kit if you removed a 700R4 transmission and replaced it with a TH350 transmission with a 6 inch tail. This is a 40 pulse per revelation of the output shaft. Cost $102.00

And then it looks like there is allot of crap involved in getting it set right. The guy that deals with this stuff is out for the day so I am gonna call them back tomorrow and talk to him. I will post what he says to do tomorrow.

All of this came from

http://www.transmissioncenter.net/sp...____va.htm#350

I called Summit and they dont seem to have anything.
I called Jegs and the guy said that he had the same problem with a van that he did the swap in and he took the 700r tail shaft off and took the pulse parts out and put them in his th350. I have no idea if that will work but if it will then there is a (free!) fix. If that will work then there is no worries about it being set right because its the same stock parts. Im gonna do some more checking on this I will keep ya posted.

I called my tranny guy and he said that it wont work with the 6in tail shaft. there is not enough room in there for it.

 

This is my combination for the speedo to work.
http://www.summitracing.com/parts/SUM-G2887-1/ (I think its the one)
http://www.summitracing.com/parts/DAK-SGI-5/

The B&M kit covers the torque arm AND an adapter piece for the OEM crossmember. No matter what, its going to cost more to rebuild the 700r4 vs the th350. My deciding factor would be how much you drive it to decide if the OD is worth it. What are your future plans for the car?

 

Hey man, I am thinking about doing the 700 to 350 trans swap too. I was told that all i need is the $99 kit from summit. http://www.summitracing.com/parts/BM...n/?prefilter=1 and also , I was told that the only 350 trans that will work is a 350 with a 9 inch tailshaft. Is this correct?

 

hey guys maybe you can help me i swapped my 700r4 out about 2 months ago and ever since my car has been stalling when i come down to a stop unless i feather the throttle. im not able to plug my speed sensor in because the new tranny i put in has a metal/magnetic gear on the tail shaft i tried swapping the sensors bcause i had to use my stock tailshaft housing for the track arm mount. (getting confusing i know) so my set up now is magnetic sensor to read magnetic gear instead of the standard red mesh gear, i dont know how to take the gears of the tail shafts otherwise i would have done that, but i heard my computer isnt able to read how fast im going from the tranny so it stalls out. if i plug the sensor in as it is set up now the speedo will jump to 110 as soon as i start the car and it stalls... any help would be awesome im tired of not being confident in my vehicle.

 

Hey Gang upon reading these posts about swapping out the 700r4 for a 350 turbo it seems to me that you all still have your ECM still hooked up in the car correct? I took my ECM out and went from TPI to carb. and also replaced the 700r4 with a 350 turbo. Would anyone have a link to the part/parts I would need to get my speedo to work with the 350 turbo since I dont have the ECM?

 

old post man. You can install a 2k vss and use a vss buffer to get the speedometer to work.

http://tpiparts.net/inc/sdetail/7586

 

That would work for me even though I have no ECM? It says on the details ( supplies the ECM with the needed vehicle speed signal) Would I just not hook up wires for the ECM?

 

correct. the vss buffer converts the magnetic pulse signal to a optical 4k ppm to the speedometer. another alternative would be the retrofit vss and a dakota digital sgi-5 to help correct for rear end gear ratio change and tire size although the drive and driven gears to calibrate the th350 are cheap and easy to come bye unlike the 700r4.

 

Thanks for the info. I also have a question on the cruise control. A friend of mine is putting my old TPI in a 56 chevy. Is there a way to set up the cruise control in a car that doesnt have a VSS buffer?

 

If he changes to speed density 1227730 ecm he will not need a speed buffer this is used a 4k pulse per mile input and has a internal buffer. The cruse control module needs to have the optical signal to the cruise control module as a vehicle speed reference.

 

How would we get the optical signal to the cruise control module to get a vehicle speed referance? Sorry for all the questions just trying to fully understand what we need to do. Thanks again for the help.

 

the output of the vss buffer is a optical signal unlike the incoming signal from the vss witch is a magnetic pulse.

 

Lots of good information.

 

Hi. I recently purchased a 92 Firebird with a 406sbc & th350 swap already complete. Speedo was not hooked up.

Figured I share what I did to fix. Reasonably simple:

Purchased a 4000 pulse per mile / 4 pulse per revolution signal sensor from TPI Parts.net

http://tpiparts.net/inc/sdetail/7587


Then went to Performance Automotive Transmission Center and determined the gear set to buy and install based on rear tire diameter and gear ratio:



http://www.transmissioncenter.net/sp...n_______va.htm


Ebay also sells these gear combos. Search for:
"TH350 SPEEDO SETUP w/ Sleeve Housing Gear Seal Retainer Speedometer"

Never doing this before also found some useful illustrations/pictures of the tailshaft gear and how to install the clip.

http://www.nastyz28.com/forum/showthread.php?t=246096

From there all I needed to do was plug in the existing VSS cable and "Whala!" speedo worked. My car was a previous v6 car, so I already had a VSS Buffer module installed. There is no longer an ECM installed.

Lastly -- I referenced this link as well:

http://www.hotrod.com/techfaq/hrdp_1206_700_r4_or_th350_early_trans_in_an_89_firebird/


It took a bit of piecing all this info together, but overall the job went well.

Hope this helps!

 

Hey I got a turbo 350 trans in my 91 firebird which clip would I buy? And I dobt nerd any cables or wires?