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Swapping From A T5 To A 700R4 Questions

Old 12-20-2018, 01:48 AM
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Swapping From A T5 To A 700R4 Questions

OK, so I can find threads about swapping TO a T5, but not swapping FROM one.

I have some questions need answering:

1. Do I have to change the crossmember, torque arm, or driveshaft?

2. Any issues with the ECM?

3. Does the switch on the clutch pedal that won't let it start unless it's pushed in just become the neutral safety switch?

My car is just a driver; I just want something one-step up from stock. Whose transmission would you recommend?
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Old 12-20-2018, 09:29 AM
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Re: Swapping From A T5 To A 700R4 Questions

Torque arm and driveshaft will be the same for a 700r4, you'll need a new memcal for the PCM, and you'll really need to wire in the PRND switch so you have reverse lights and the neutral safety switch. Honestly, it isn't worth it going that way, you would be better off just selling that car and getting an auto
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Old 12-20-2018, 09:52 AM
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Re: Swapping From A T5 To A 700R4 Questions

Not to mention you'll need to patch the hole in the transmission tunnel where the shifter comes up through the floor. You also need to add some more metal to support the automatic shifter properly (I stole this pic off TGO, it's not my car).:

You can see there's a raised piece near the front of the shifter, and mounting holes for four bolts - none of that is present on the T5 car and will need to be fabbed up. You'll want to patch the hole for the clutch master cylinder too, and you'll need to swap in a non-manual brake pedal. Sorry if you already know this stuff - just wanted to point out some body work is required to get everything done "right".

And since scooter didn't explicitly mention it, the crossmember is the same too (unless you somehow got a V6 T5 crossmember on the car now).

Since most people are interested in swapping to manuals and not the other way around, there's a decent market for the manual stuff you pull off the car. Heck, I'd be interested in some of it.
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Old 12-20-2018, 10:33 AM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by BovineZro View Post
And since scooter didn't explicitly mention it, the crossmember is the same too (unless you somehow got a V6 T5 crossmember on the car now).
I have never had a T5, but I thought it used a different crossmember than the 700, I had no idea it would be the same
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Old 12-20-2018, 11:56 AM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by scooter View Post
Torque arm and driveshaft will be the same for a 700r4, you'll need a new memcal for the PCM, and you'll really need to wire in the PRND switch so you have reverse lights and the neutral safety switch. Honestly, it isn't worth it going that way, you would be better off just selling that car and getting an auto

Thanks for the response, Scooter. Why do you say it isn't worth going that way?
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Old 12-20-2018, 01:46 PM
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Re: Swapping From A T5 To A 700R4 Questions

The wiring needed to be completed makes it a bit more difficult for people to go to an auto. Most people don't even bother doing it right when they go from an auto to a manual trans, so going the other way is more difficult in that regard. As Bovine said, you'll also need to close up the hole for the T5 and put in the auto selector too, most people don't want to bother welding the hole closed. The clutch master can be plugged with a grommet or something since nothing is going in that location. You will also want to get an auto brake pedal and swap out the whole assembly since you need to remove the brake pedal anyway, makes more sense to just change the whole thing.
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Old 12-20-2018, 05:46 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by scooter View Post
I have never had a T5, but I thought it used a different crossmember than the 700, I had no idea it would be the same
Well, to be fair I haven't exactly checked every combination of year and transmission out there. I can say for sure that the crossmembers from my 91 (700R4) and my 90 parts car (T5) are identical. I don't know if the transmission mount was the same (probably not), but that's something that would get replaced anyway. Also, some V6 T5's had a different two-part crossmember - I think that was only for pre-85 cars though, and I don't think the OP has one of those.

For what it's worth I agree swapping manual to auto is more trouble than it's worth, unless the car has sentimental value. And if it's a low-miles car in good shape, the swap will probably reduce the value.

One thing someone else might be able to comment on - I think the manual transmission cars usually have higher rear gear ratios. So that plus the different transmission will probably mean you need to recalibrate the speedometer to be accurate. Not sure what's required for that, or how far off it would be.
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Old 12-20-2018, 07:01 PM
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Re: Swapping From A T5 To A 700R4 Questions

You might get lucky. The TBI cars generally have the dash wiring harness setup for both auto/5spd. Look around the wiring coming out of the main loom behind the radio/hvac area and see if you already have the PRND connector. If so you'd just unplug the clutch neutral switch and plug in the auto shifter. If not, you'll need to run wires from the auto shifter to the green and blue wires that used to go to the transmission through C100, and you'll probably need to run a wire to C207 from the shifter to let the ECM know if it's in park/neutral/drive. Also you would need to extend the park/neutral wires from the clutch switch to the auto shifter.

Some T5 cars use the same crossmember as the 700R4, except that some later V6 cars use a different fluid-filled style trans mount that requires a different crossmember, and a lot of the V6 cars have the two piece crossmember. In either case, the one piece typical 700R4 crossmember is easy to find.

I've got the auto shifter mounting bracket from my project on the workbench right now. I was eyeing it for potentially becoming a patch panel. LOL Got the shifter, brake pedal, etc laying around too.
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Old 12-20-2018, 07:10 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by Drew View Post
You might get lucky. The TBI cars generally have the dash wiring harness setup for both auto/5spd. Look around the wiring coming out of the main loom behind the radio/hvac area and see if you already have the PRND connector. If so you'd just unplug the clutch neutral switch and plug in the auto shifter. If not, you'll need to run wires from the auto shifter to the green and blue wires that used to go to the transmission through C100, and you'll probably need to run a wire to C207 from the shifter to let the ECM know if it's in park/neutral/drive. Also you would need to extend the park/neutral wires from the clutch switch to the auto shifter.

Some T5 cars use the same crossmember as the 700R4, except that some later V6 cars use a different fluid-filled style trans mount that requires a different crossmember, and a lot of the V6 cars have the two piece crossmember. In either case, the one piece typical 700R4 crossmember is easy to find.

I've got the auto shifter mounting bracket from my project on the workbench right now. I was eyeing it for potentially becoming a patch panel. LOL Got the shifter, brake pedal, etc laying around too.
Think you might be interested in parting with them?

Had a REALLY frustrating day today. Called TCI, the guy was an absolute dick. Called B&M. Took 4 calls to get through their insane AI t a human being, who didn't know ****. His more knowledgeable colleague was going to call me back. Never did. Called Monster, sat on hold for 11 minutes .. twice, only to have the A.I. hang up on me. Emailed them. Haven't heard anything.

Doesn't anybody want to sell a transmission?

OH, and the crown that came off that I've been carrying around in my coat pocket till I could get in to the dentist's today? Yeah .....

Can't find it. That's gonna be a grand.
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Old 12-20-2018, 08:14 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by seanof30306 View Post
Think you might be interested in parting with them?
Yep, they need to go. I'm sure I've got the connector that plugs into the auto shifter park/neutral switch too. Just not too sure when I'll be able to get at the rest of the parts since they'd be in the attic. But if you need em...

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Old 12-27-2018, 05:35 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by seanof30306 View Post
OK, so I can find threads about swapping TO a T5, but not swapping FROM one.

I have some questions need answering:

1. Do I have to change the crossmember, torque arm, or driveshaft?

2. Any issues with the ECM?

3. Does the switch on the clutch pedal that won't let it start unless it's pushed in just become the neutral safety switch?

My car is just a driver; I just want something one-step up from stock. Whose transmission would you recommend?
1. No.
2. If you want the ecm to control the trans lockup- yes. There are a few other parameters such as idle and the "in-drive" signal that the ecm uses which would ideally need to change, but it's not mandatory. If all you want is converter lockup you can use the 5 speed ecm and lock the converter with a switch. There are a lot of suppliers who can help. If you also do a Moates flash tune conversion or convert over to an ecm such as the EBL Flash and address all of those potential and on the plus side you can actually tune the program. There will be wires to add for the ecm to control the converter. If you don't want lock up then you can run the manual ecm.
3. Yes, move those wires to the neutral switch on the shifter.
All of the other comments regarding shifter holes and other modest mods will be necessary.
I swapped from auto to manual and now considering swapping back. I kept my auto brake pedal assembly and shifter. I am leaning toward Monster or TCI trans unless I find a good deal on a trans to build. Remember, you'll need a trans with a torque arm mount bosses on the tail shaft. I expect it to be an extra cost.
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Old 12-27-2018, 06:02 PM
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Re: Swapping From A T5 To A 700R4 Questions

Easy enough to make a non-fbody 700R4 bolt into a thirdgen. 4-bolts, pull off the tail shaft housing, make any necessary changes to the speedometer drive and slide a thirdgen housing back on. Must be nearly half a dozen 700R4 tail shaft housings laying around the garage. Ironically the only one I've ever been able to get rid of was one without torque arm mounts. LOL
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Old 12-27-2018, 06:05 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by antman89iroc View Post
1. No.
2. If you want the ecm to control the trans lockup- yes. There are a few other parameters such as idle and the "in-drive" signal that the ecm uses which would ideally need to change, but it's not mandatory. If all you want is converter lockup you can use the 5 speed ecm and lock the converter with a switch. There are a lot of suppliers who can help. If you also do a Moates flash tune conversion or convert over to an ecm such as the EBL Flash and address all of those potential and on the plus side you can actually tune the program. There will be wires to add for the ecm to control the converter. If you don't want lock up then you can run the manual ecm.
3. Yes, move those wires to the neutral switch on the shifter.
All of the other comments regarding shifter holes and other modest mods will be necessary.
I swapped from auto to manual and now considering swapping back. I kept my auto brake pedal assembly and shifter. I am leaning toward Monster or TCI trans unless I find a good deal on a trans to build. Remember, you'll need a trans with a torque arm mount bosses on the tail shaft. I expect it to be an extra cost.

Thanks for the response.

I'm still trying to decide what to do about a transmission. As I said earlier, the guy at TCI was a dick. Also, he won't have a transmission till February. I still haven't gotten through to anyone at B&M. While I was sitting on hold trying to get through to a human being at Monster, I searched their reviews ... they've got A LOT of bad ones.

I talked to a guy at GearStar today. It was a pretty good conversation, but they're about a grand more expensive than TCI, B&M and Monster ... of course, they'll talk to you.

I'm down to talking to guys on ebay. Not very comfortable with that. Only considering vendors with over 1,000 feedbacks and at least (*% positive, but still ...

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Old 12-27-2018, 06:10 PM
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Re: Swapping From A T5 To A 700R4 Questions

REGARDING THE LOCKUP:

Most of the transmission guys I've talked to build the transmissions using a vacuum lockup. Would it be better to use that, or to find an ECM out of a L03 auto car?

Last edited by seanof30306; 12-27-2018 at 06:27 PM.
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Old 12-27-2018, 06:28 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by Drew View Post
Easy enough to make a non-fbody 700R4 bolt into a thirdgen. 4-bolts, pull off the tail shaft housing, make any necessary changes to the speedometer drive and slide a thirdgen housing back on. Must be nearly half a dozen 700R4 tail shaft housings laying around the garage. Ironically the only one I've ever been able to get rid of was one without torque arm mounts. LOL
Drew, I may be needing that tailshaft housing too!
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Old 01-06-2019, 03:17 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by seanof30306 View Post
Thanks for the response.

I'm still trying to decide what to do about a transmission. As I said earlier, the guy at TCI was a dick. Also, he won't have a transmission till February. I still haven't gotten through to anyone at B&M. While I was sitting on hold trying to get through to a human being at Monster, I searched their reviews ... they've got A LOT of bad ones.

I talked to a guy at GearStar today. It was a pretty good conversation, but they're about a grand more expensive than TCI, B&M and Monster ... of course, they'll talk to you.

I'm down to talking to guys on ebay. Not very comfortable with that. Only considering vendors with over 1,000 feedbacks and at least (*% positive, but still ...
Gearstar seems to be the best choice. And Zac, the owner, called me back on New Years Eve. I was impressed and he gave me a lot of advice and suggestions. Also, in comparing vendors make sure to consider whether the torque converter is included and what converter they offer. Gearstar is a Yank vendor. Again, top quality and has a direct relationship. Zac said he wouldn't even build a 700 for my application. (nitrous) 400 or 4L80E is what he recommended. When I checked build quality/level and include the converter, Gearstar was right on point with the other vendors. 4L80 built to top level, with converter and controller was $5k. He also has something available that everyone else said didn't exist, a mechanical speedometer drive for the 4L80. If you need one they are the only source I have found.
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Old 01-06-2019, 03:24 PM
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Re: Swapping From A T5 To A 700R4 Questions

Originally Posted by BovineZro View Post
Since most people are interested in swapping to manuals and not the other way around, there's a decent market for the manual stuff you pull off the car. Heck, I'd be interested in some of it.
If you're interested, I am offering mine. Complete TKO swap - Everything available together. I may entertain some trades. Here's the ad;
https://www.thirdgen.org/forums/engi...tko-600-a.html

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