Adapting a Q4 FWD trans for use with the Fiero 60 degree V6

[fieromadman]

http://cgi.ebay.com/ebaymotors/GM-Chevy ... 240%3A1318

These Q4 transmissions have been tantalizingly inexpensive for a long time now. I'm seriously concerned about the Fiero transmission being able to hold up to my power levels when its all done especially since I plan on doing some hard driving with it. This seems like a damn good route to go because its BRAND new and has the stronger diff and better gearing (I think).

The only thing holding me back is that bell housing pattern and the clutch slave cyl. The speedo doesn't scare me as I can program the Haltech to receive any amount of pulses per mile and I can get the dakota digital speedo conversion thing. Its the bellhousing swap that concerns me the most and then the throwout bearing/slave cyl thing that concerns me the second most. When you swap out bellhousings wouldn't you in effect be converting the slave cyl setup to a Fiero type anyhow? What should I know about swapping bellhousings?

[The Dark Side of Will]

Look on http://www.car-parts.com for the transmission from a '93 Beretta with 3.1. It's the same trans and has the hydraulic throw out bearing, but it will bolt up to your 3.4. There are several listed for less than $200.

[Shaun41178(2)]

swap the bellhousing.

[fieromadman]

Will: Thats not a bad option, but the transmissions on ebay are brand new. Might be a little bit more work to get them to work but in theory they should last a longer time than one with high miles and once I do one bellhousing swap it wouldn't be hard to do another.

Shaun: How easy is that? What is involved. This is why I made this thread... I KNOW that you can swap bellhousings and get it to work, I'm just not sure what is involved in putting a fiero bellhousing on that Q4 tranny.

[The Dark Side of Will]

1. Get the "splitting the case" instructions from Rodney Dickman.
2. Do the job

You'll need to adjust the diff bearing shim, since you're mixing and matching case halves and diff carriers.

[CincinnatiFiero]

I like how they advertise it as a fiero transmission, despite it not working without modification.

[TheFieroBoy]

Swapping bellhousings isn't hard. But you do have to follow a specific procedure, or it won't come apart. And as mentioned above, you have to check the bearing clearance and re-shim if necessary. You can read about that in the Getrag Service Manual.

[fieroguru]

When I had an 89 Gretag and my 93 HTOB getrag apart (back in 2005), I noticed that one of the bellhousing cases had a bolt on plastic cup to hold a shaft (I think it was the HTOB case) and the other one had a recessed boss into the bellhousing side and used a longer shaft. I suspect the HTOB case was machined deeper to allow room for the HTOB and took the space that shaft used to occupy and the plastic cup was added to support the shorter shaft.

When you tear the tranny's down side by side, check for any differences and swap the needed parts to allow the bellhousing swap. I think you will need to change atleast 1 shaft (I think it was a shifter rail) to do the swap.

[The Dark Side of Will]

When I had an 89 Gretag and my 93 HTOB getrag apart (back in 2005), I noticed that one of the bellhousing cases had a bolt on plastic cup to hold a shaft (I think it was the HTOB case) and the other one had a recessed boss into the bellhousing side and used a longer shaft. I suspect the HTOB case was machined deeper to allow room for the HTOB and took the space that shaft used to occupy and the plastic cup was added to support the shorter shaft.

When you tear the tranny's down side by side, check for any differences and swap the needed parts to allow the bellhousing swap. I think you will need to change atleast 1 shaft (I think it was a shifter rail) to do the swap.

Other way around... The plastic cup is used in mechanical throw out transmissions, while the longer shaft and cast-in boss are used in HTOB applications. The throw out shaft goes through the space that would be occupied by the boss in the case. I believe that the shaft in question is for the reverse idler.

[fieromadman]

Well I bid on it so yeah I'll have a nice backup tranny when I need it. I have a spare getrag in my garage already but the case is a little messed up. I think that the case is messed up on the opposite side though, so I'll just swap the two and have a nice new getrag.

[befarrer]

That is a 93-94 Quad 4 tranny, and some 92's used the hyraulic bearing. The name this tranny carried in the quad 4 was a New Venture T550 or something along those lines, but it was a New Venture Tsomehing. From what I read, it is the same basic design as teh Getrag 282, but with diffrent synchros to make shifting better. This will have the 3.92 FDR.

[fieromadman]

I should not have trouble with getting the bellhousing swap done though? I would assume everything is the same besides the synchros? And I was hoping for a higher ratio final drive!

[The Dark Side of Will]

As long as you go HTOB -> HTOB or mechanical throw out to mecanical throw out, the bellhousing is a direct swap. If you mix and match, you will have to change at least the reverse idler shaft (which isn't very hard, actually).

[fieromadman]

Okay, well I have been having transmission difficulties ever since I got the turbo setup going so I'm moving forward with the trans swap. I'm going to try and give you people detailed information and pictures of what needs to be done to get the ebay trannys working in the Fiero with the normal bellhousing pattern.

First I gathered all the transmissions that I needed. The eBay quad four transmission with the shorter final drive and closer ratio gearing, the 93 vintage fwd Beretta transmission, and a stock Fiero getrag. I got the eBay trans paid for and shipped to me for $200, the Fiero one was one with a bad case (the original from my car) so that was free, and the Beretta one was $150 from a local junk yard.

After I had all three I set about splitting all the transmission cases following Rodney Dickmans directions for doing so. They are very straightforward and can be found here: http://www.rodneydickman.com/n36.html

After I had the transmissions apart I set about swapping the parts that I needed to. The Fiero VSS unit uses a gear setup instead of a magnetic reluctor type in all the later years. The only reason that a Fiero getrag will be needed for this whole process is to swap the reluctor setup with the gear driven setup. That avoids having to buy the dakota digital speedometer conversion box which is $75 dollars. If you don't have a spare Fiero getrag sitting around and would rather buy the box then this isn't necessary. The reluctor wheel and the Fiero plastic gear both are friction fit and I didn't have any trouble (carefully) prying them off with two flatheads. Then you just push the Fiero one onto the new transmission. Mine has some slop but will be held in place by the case and the tabs to keep it from rotating.

Then I set about taking the reluctor pickup out of the Beretta case and putting in the Fiero gear driven VSS unit.

At this point the only thing left to do is shim the differential bushings to get the Beretta case to mate well with the quad 4 case. This will require use of the specialty tool J-26935. I have yet to do this so I will have to detail this process later.

Here are pictures that bring us up to date:

Left to right: quad 4 (eBay) trans, Beretta trans, Fiero getrag.






Beretta trans with detent cover removed:


Detent parts:


Reluctor type speedo wheel on the left, Fiero gear driven style on the right.


Where the speedo wheels go on the diff:


Difference between the Fiero and the Beretta bellhousing cases. Notice the difference in material around the input shafts:

Beretta:


Fiero:


Thats it for now. More pictures once I recieve the specialty tool for use with the differential shims.

[The Dark Side of Will]

Keep the reluctor and ditch the gear driven VSS. You're using the '727 ECM (or '730) with your car, so with some slight rewiring, you'll have no trouble using the reluctor VSS.

The stock Fiero runs the VSS signal at 2000 ppm to the instrument cluster where it is frequency doubled to 4000 ppm and sent to the ECM.

If you route the reluctor VSS signal to the '730 ECM, you can set the VSS frequency divisor and output a 2000 ppm signal to drive the speedometer off the ECM instead of the other way around.

IOW: You're doing it wrong.

[coinage]

Hes running the Haltech unit

[The Dark Side of Will]

My bad. I went back to his "ultimate 3.4 TDC" thread and saw 727...
Anyway, the reluctor ought to be useable with the Haltech... but of course so is the worm gear.

[Series8217]

Difference between the Fiero and the Beretta bellhousing cases. Notice the difference in material around the input shafts:

Beretta:

I like!!

[fieromadman]

The reason I'm not using the reluctor is because I wanted to aviod having to buy the Dakota Digital conversion box. I'm trying to make this low cost as possible (without sacrificing strength and durability) because I dont have a ton of money floating around.

[fieromadman]

Well I just recieved the shim selecting tool, so tomorrow I will probably go about doing that. I dont have any shims yet, I was planning on ordering them individually using those chrysler part numbers, this should work, right?