Another update.

It's Official. Pro Street will be offering T5 cbeam adapters, and I'll do the final 'writeup' on the swap. A T5 tail shaft is on it's way to Pro street for mockup on the Jig.

Once I get the prototype cbeam adapter from Pro Street I'll snap a billion pix for everyone. I don't know what the turn around is right now, but I'm considering summer over so I'm in no rush. My vette will stay on my right bay lift until this project is complete.

I'm doing a 700R4 to T5 swap, but for folks with a 4+3 this will be a more 'direct' swap. I chose to use the 4+3 BH and hydraulic setup because I think that will be the more likely scenario for folks, and most direct. (Folks replacing worn 4+3 transmissions).

The drive shaft WILL BE THE SAME, the T5 + 700R4 share the same yoke. Apparently the 4+3 yoke is the same too..

As far as clutches go, for a few years now I've been using clutches from Fort Worth Clutch. They sell a 2200lbs pressure plate and 'dual friction' knockoff clutch for about $165 shipped, that has more holding pressure than a centerforce and the same or better quality. Contact Scott at Fort Worth clutch for specific requests. (He will do custom pressure plates/discs if needed).

If you need a new flywheel, kajunjon-whitneytx transmissions offers a 16lbs lightweight flywheel for $173 shipped. It's about as light as you
want to go for a street flywheel, and surely better than having your old flywheel turned.


-- Joe

 

What happened to using the Fbody bh and rotating the T5 for better shifter location?

The only benefits I see for you on the 4+3 bh is saving 4+3 owners from buying a $25 junkyard part, and getting to use a 10.75" clutch. But you already said you were using a 10.4" clutch.

 

I believe they are the same but I've never seen the 700R yoke.


Spline count and yoke OD are the same.

Driveshaft p/n's for '84 auto and 4+3 are the same. (only year where both had same rear end)

Driveshaft p/n's aren't same for 85-88, but I suspect that's because of the change to D44, which is longer.

 

The ZF-6 BH won't fit with the LSx FW which is necessary in order to engage the starter at its location on the block.

 

How big is the LS flywheel/clutch?

Does it move the starter further away?

Can the starter be move inwards?

I looked at the blocks side by side but didn't check that.

 

Your PM box went full so I couldn't update you on that.

The Fbody bell housing hydraulics won't clear the exhaust like you suggested. To make it work, you need to saw off the slave cyl mount, and run a hydraulic TOB for a T5 ($165 + shipping), which won't work
with the master cyl, so you need a 3/4" bore master ($73 + shipping), hoses ($25 + shipping). You also need to make sure the master you get has a travel stop, or you have to buy a pedal stop to keep from blowing the seal on the TOB.

Yeah I'm gonna use a 10.4" clutch probably. I couldn't find any part #'s on the 10.75" clutch for the 4+3. (for the flywheel rather). Any scoop on that?

-- Joe

 

That clears that up I think then. They won't need a yoke... Great!

-- Joe

 

From a previous thread

More info i found from some F-body stuff:
-LT1 has a 153 tooth 12.75" diameter flywheel
pull type with slave and pivot fork

-LS1 has a 168 tooth 14" diameter flywheel
push type with hydro throwout bearing

So the mounting pad for the starter on an LS motor is .625" further out than on SBC and FW too wide to fit under BH.

 

Why can't you use a 10.4" clutch and pressure plate, since it's a hydraulic TOB ? That would let you use the 153tooth starter.

-- Joe

 

Great thread..

Thanks CC and Anesthes

You guys start out fighting and then collaborating.

sometimes a bit of discourse leads to a solution

 

For what it's worth, Astro Performance sells heavy duty gear sets and beefed up T5s that can handle 550hp/425 ft lb of torque ($1,650). These are intended for Fords, so I don't know if it is the same as what would work with GM. I know stock T5s are always a weak link at least with 5.0s (third gear can break). That would be my concern with running a T5.

http://www.astroperformance.com/prod...roducts_id/209

 

I wanted to get your expertise on a problem I am having with an 1984 Corvette Doug Nash 4+3.

1) All gears shift smoothly without noise or grinding.

2) Overdrive works well

3) Transmission pops out of 2nd gear while decelerating.

Questions:


I have had people tell me it could be motor mounts or worn transmission mounts. How much travel should I have?

Should I have the Doug Nash 4+3 repaired / rebuilt? Cost?

Purchase a good working Doug Nash 4+3?

Automatic Swap? Low cost option? How difficult? Parts needed?

Swap for another manual?

What are my best possible solutions?

Please help

 

Spoke with pro street today. They're almost done the cbeam adapter for the T5. Should be done by the end of the week, then they will be sending me the prototype.

Once I get it i'll put everything in place and snap some pix, and write up a short 'how to'.

-- Joe

 

What is the estimated cost of replacing the Doug Nash 4-3 with the T5?


I am looking forward to see the write up on this conversion. Thanks for all the effort guys!

 

Gonna depend on how much you get a T5 for. I got mine at a swap meet for $50. I was offered about 5 more locally for $200 each, and will probably buy another as a spare. Figure $200-250 for the T5.

I'd expect the Cbeam adapter to be about the same cost as the T56 adapter, figure $150-200 for that. So lets say $450 so far.

The Fbody shifter is offset. It can be modified for about $40 at a welding shop if you can't weld, OR you can get a hurst pro-comp shifter. Thats $165 new. Need to take it apart, and put a lever in the other way. I have not got to the shifter part yet, but the stick is probably going to need to be cut, and offset about 1.5-2" and welded as well. if the 1.5-2" offset scares you, go look at a 60s mustang. The offset is like 8", or a 80's mustang at 3"

So worst case scenario $650 or so, if you get things cheaper, do things yourself closer to $500. You can do it as cheap as $350 if you can modify the stock shifter yourself.

-- Joe

 

Joe,

Thanks for all your help. I have a 84 Corvette with a Doug Nash 4+3. I checked the OD filler for fluid. I believe I found gear oil. Or dirty ATF oil.

Could 80-90w gear oil from the gear box be transfer to the Overdrive section of the Doug Nash 4+3?

Joe, I like your idea of using a T5. I want to keep the cost down and have a dependable transmission. On my 84, I can reuse the bell housing, hydraulic slave setup, flywheel, clutch disc, pressure plate and drive shaft. The 84 driveshaft in the same for automatic and manual.

My swap will need a fbody v8 T5 manual transmission, shifter and cbeam.

Please let me know on cbeam too

Does this sound correct? Again thanks for your help.

 

A ZF-6 swap is much more direct and probablyt costs less. I did one on my 84. Great swap. Its a whole different car to drive.

 

Hi Dominic,

I live about an hour north of Rockford IL. I believe a need to replace the Doug Nash 4+3.

You have an 84 Corvette too! What will I need to perform the swap? Parts list? Modifications? What can be used from the 84 Corvette? Any sugguestions are very welcomed. I am very interested in learning more.

How does it drive now? What do you like about it?

Rick

 

A ZF6 swap isn't more direct. You have to change the hydraulics, bell housing, flywheel, clutch, transmission. On a T5 swap, all you have to change is the transmission. The tunnel mods are the same.

And the costs are not even close. Like I said, worst case scenario $650, but more likely closer to $500 - and if you break a T5, you can get replacement transmissions for under $250 all day.

The ZF is surely stronger than the T5, and if you have a tall enough rear end gear you can actually use the 6th gear off the ZF6. If you're worried about strength + having 6 speeds, your much better off going with a T56 which is also a direct bolt in using a Cbeam adapter from pro-street.

You can't go near a ZF for under 1k.

ixlor8: You need a T5 + cbeam adapter. You can use the stock Fbody shifter with the T5 (need to modify it) or an aftermarket shifter (still need to modify it). Your bell housing, driveshaft, clutch, hydraulics, and cbeam will all be the same.

 

Thanks Joe. I will be looking for a T-5. I would like to keep the cost down. I am going to keep the stock engine, so horse power is not an issue.

Do you have to do any changes for the speedometer?

About how many hours does it take to take out the Doug Nash 4+3 and replace with T-5?

Thank you very much for your help,