Triumph Sports Cars

engine swaps and other performance upgrades, plus "factory" V8s (Stag and TR8)

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BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5812 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
TR7 V6 gets a new tranny (auto)
Posted by: BlownMGB-V8
Date: May 28, 2013 09:27PM

Well, not new really. It came from the local pick-n-pull so it's sort of a roll of the dice. Anyway, the car has the John's Cars Buick V6 conversion with the 700r4 transmission so the remove and replace was an unknown. I can now confirm that it is possible to just swap out the tranny without having to disassemble the rest of the car, but it definitely is a little tricky in spots.

The biggest thing is that if the headers are not unbolted and the exhaust system is left alone, it is necessary to rotate the transmission about 45 degrees clockwise (from the front) and judiciously use a large prybar to get the ears of the bellhousing past the headers. It can be done, but it isn't easy. We had the car on the lift and used an engine hoist converted into a transmission jack, and as you might imagine putting it back in was more difficult than taking it out.

The other difficult part was the dipstick tube. There is just no easy way to deal with that. It might be possible to do something like taping it up about where it needs to go. We tried putting it into position before the transmission went in and it just got in the way. (Twisting the tranny is an added complication) Putting it in afterwards was a compromise. There was only one way it would go in, (from the top) and that put it on the wrong side of the engine wiring harness. There is enough slack in the harness to allow this, but not enough to get the bolt tab past the wires so that they are on the other side where they should be.

Everything else is about as you would imagine. It's all very tight and somewhat of a chore getting to each part of the job. However, the replacement tranny is now bolted in, has the lines hooked up, and will get the rest done tomorrow. With this one we should get the use of the lock-up clutch which was bypassed on the other one, and it should run a little cooler because of that.

Matthew helped with the installation and that definitely made the job easier. Hopefully all will go well on the check out drive.

Jim


Dan B
Dan Blackwood
South Charleston, WV
(972 posts)

Registered:
11/06/2007 01:55PM

Main British Car:
1966 TR4A, 1980 TR7 Multiport EFI MegaSquirt on the TR4A. Lexus V8 pl

authors avatar
Re: TR7 V6 gets a new tranny (auto)
Posted by: Dan B
Date: May 28, 2013 09:44PM

Sounds like great progress! Glad to read that Matt is helping out in the shop now. I guess having his own set of wheels has helped.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5812 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: TR7 V6 gets a new tranny (auto)
Posted by: BlownMGB-V8
Date: May 29, 2013 06:45PM

Looks like a home run on the junkyard transmission. It runs and shifts perfectly and feels strong under full throttle. I didn't have the wiring completed for the lock-up converter so I couldn't test that but based on the general appearance of the gearbox I'd say it's going to do fine.

Before I forget, let me make a recommendation. For anyone considering an automatic I'd strongly suggest that you DO NOT install a shift kit. It totally screws up the shifting characteristics and is unsuitable for a street driven light weight car such as this. Comparing the two is like night and day and the car is MUCH more pleasant to drive with the stock build.

This tranny came out of a 1992 Pontiac V8 Firebird which showed 179,000 miles on the clock. But, the car had been totaled in a front end collision so obviously it had been running on it's own power when it met it's demise. When I dropped the pan the fluid was clean and had no burn smell. The converter had a sticker on it which to me suggested a rebuild. The o-ring on the speedo pickup looked fresh and still had a round cross section, and the inside of the extension housing was clean as a whistle. There was some particulate on the magnet in the pan but not a great deal. So all in all everything would indicate to me that this tranny had been rebuilt somewhere in about the last 50K miles of that car's life. For $132 including a 6 month warranty, that seems to me to be about as good as you can do. Heck the transmission fluid and filter was about fifty bucks!

In my opinion the oil cooler is marginal and is very likely the thing that caused the other transmission to go bad. The best thing for this car would be a new and larger radiator with an integral transmission cooler.

I may get a chance to look at the lock-up wiring over the next few days and see what the TR7 requires to make that work. I'm guessing a simple relay triggered by the brake light circuit is all that will be required and I already have one of those in place, it just needs to be connected. That does mean removing the console but the wiring should be simple.

Jim


DiDueColpi
Fred Key
West coast - Canada
(1259 posts)

Registered:
05/14/2010 03:06AM

Main British Car:
What if the Hokey Pokey really is what it's all about?

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Re: TR7 V6 gets a new tranny (auto)
Posted by: DiDueColpi
Date: May 29, 2013 09:08PM

The simplest way to hook up that converter lockup is to just use a 4th gear pressure switch.
You can replace the one on the valve body with an ordinary engine oil pressure switch. Or if you don't want to pull the pan again use the 4th gear pressure port on the right side of the trans case.
The third option is to use the current 4th gear switch but it is a N.C. switch and would require a relay to work.
Power the lockup solenoid through terminal "D" on the trans connector (tan/black wire if you have the original plug) from a fused switch.
Run the solenoid ground "A" (purple wire). To the oil pressure switch or relay.
If you use the internal trans switch the terminal is"B" (light blue)
Now you have lockup in 4th gear only. And it will engage on and off without having to flip switches or run vacuum units, brake switches etc.
This is for a 92 trans. GM changed the wiring and switches around quite a bit over the years so use care.
Cheers
Fred


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5812 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: TR7 V6 gets a new tranny (auto)
Posted by: BlownMGB-V8
Date: May 29, 2013 09:57PM

I really don't care if it locks up in 3rd as well as 4th, I think I'll leave the internal wiring alone. I already have the connector with two wires coming up through the shifter plate and one of them grounded. I used that to confirm that the old tranny was incapable of locking the converter. So I'm thinking I should just be able to apply power to the remaining wire to get lock up. In that case the simplest thing then would be to connect that to the rocker switch I installed on the console cover with the other side hot. (fused of course) Unless I have to reverse the wires for some reason.

This overlooks the brake lite disengage, and in some situations could cause the car to take longer to slow down, as it would have to get to 2nd before the clutch would disengage. I'm not sure how big an issue this would be with this light of a car but I can do some testing over the next few days.

I had the 700r4 in my old I-H Travelall behind the SV-392 V8 which was a pretty hot engine. I really wasn't that wild about the pressure switch (external) or the vacuum switch (about 6" of vacuum) but felt like the brake switch was a good thing. The automatic functioning was not very much to my liking to be honest. But this car is going to my niece as her first car so I figure the closer it is to a stock automatic in operation the better. Only thing is, that Firebird may well have had an ecm controlling lock up. In which case a manual switch could be a bonus.

Jim


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5812 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: TR7 V6 gets a new tranny (auto)
Posted by: BlownMGB-V8
Date: May 31, 2013 10:28AM

More test driving has indicated that the car is quite driveable with the lock-up circuit always energized. The V6 has enough torque to compensate. However, below about 40 mph it drives better with it unlocked in almost all circumstances, and releasing it upon application of the brakes does in some situations make a small difference. This is usually when decelerating at a low to moderate rate to a near stop where the transmission lags a bit in downshifting to 2nd. Not what I would consider much of a problem.

Previously I had wired in the momentary pushbutton on the shifter knob to a standard relay socket which only needs the connection to the transmission to work. However the button would have to be held for unlock.

Tyco Electric now makes a ratcheting relay which uses the same form factor but I have not found it in the market yet. I have requested a sample or retailer from them so it should be a simple matter of swapping out the relay once it comes in. Cascading the signal line through an adjacent relay (there are two spares) with the brake lights controlling it will complete the circuit. If desired, a vacuum switch could be added to supplement kickdown, but if so a vacuum gage should be hooked up and the car driven to determine the best vacuum value for the switch to open.

The rocker switch on the console of this car is there to be connected to the seat heat. Just needs to be hooked up.

Jim


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