Automatic to Manual Conversion - Worth it?

[303Radar]

I've been toying with the idea of using a manual transmission rather than an automatic in my '59 El Camino. I have a feeling for the usage and driving I'll be doing, a conversion wouldn't really be worth it.
Although I won't be putting the PG back in, I like the idea of a six speed manual over four speed auto. It seems to me the cost of the transmission would be cheaper for the manual than the auto. However, I'm afraid the cost for clutch, z bar, pedal assembly, etc would take away most if not all the cost advantage.

With the Pro Charger, I should be (theoretically) capable of making close to 650 hp with 10 psi of boost. However, I doubt I'll often push the engine to the limits.

I guess the question is, am I better off with the automatic?
Thanks!

 

[Don Jacks]

A properly built automatic will be eaiser on the car,and out last the stick parts.I dont know of any factory 6 speeds that will handle the torque that your engine's going to make..Your Jag rear end is basicly a Dana 44,decent,but limited.

 

[tripower]

It all comes down to what makes you happy, two pedals or three?

 

[MRHP]

I agree with Don. An automatic will help the 44 survive. Even at that it is definitely the weak link.

 

[62BillT]

All my cars and trucks were/are Manuals. It all depends on what you really like, as mentioned above. But if you do go Manual, I would recommend a factory set-up with a factory type trans (4-Speed).

Bill

 

[303Radar]

A properly built automatic will be eaiser on the car,and out last the stick parts.I dont know of any factory 6 speeds that will handle the torque that your engine's going to make..Your Jag rear end is basicly a Dana 44,decent,but limited.

I'm not too worried about the Dana 44, since I won't be making max power off the line and I don't plan on neutral drops at 5000+ rpm either.
The other part which will help the rear is, not using a stall greater than 2000 (might go as low as 1500) and 3.54:1 gear.

I think I'll keep the automatic. My wife is having sticker shock on how little value there is in a cast iron PowerGlide and how much a good overdrive transmission will be. If it wasn't going to be too much trouble and cost less for a modern six speed manual, I was thinking it might be a way to lower some of the sticker shock.

On the upside, this whole adventure has been sticker shock on her part , so this is nothing new.

4L80, here I come.

 

[Don Jacks]

With the cam specs. that you posted,go with a stall speed of 23-2400.That cam will need a little breathing room at idle and bumper to bumber traffic speeds.The car will likely break the tires loose before the rear end parts are overstressed to the point of breakage,unless youre planning on drag radials or slicks.

 

[Phil Reed]

My wife is having sticker shock on how little value there is in a cast iron PowerGlide .

how about ZERO!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[tripower]

how about ZERO!!!!!!!!!!!!!!!!!!!!!!!!!!!

Phil, Have you forgoten scrap is up... Those things weigh a ton...

 

[1961BelAir427]

The other part which will help the rear is, not using a stall greater than 2000 (might go as low as 1500) and 3.54:1 gear.

4L80, here I come.

At your power level, I would advise you to go with a nice long tail TH400 and put all the $$$$ you save towards the gas. It'll be at least half the cost of the 4L80E. Sure you'd get better mpg's on the highway with the OD, but for anything other than highway driving you won't. Also you're 3.54 gears aren't so low that they'll "require" an OD for highway use.
A 4L80E will require a computer and harness along OR a "Little Black Box" so that you can use it as a Manual Valve Body. It'll also require a custom crossmember and it's not as long as a Long tail TH400 so you will have to do more mods to run a 1 piece driveshaft. A stall convertor for the 4L80E is big bucks too, unless you stick with a stock one. Also, have you ever lifted one of those things? (Not that a TH400 is light by any means, but it feels like it is compared to the 4L80E.) Forgot to mention that a TH400 crossmember is available from Showcars so you don't have to fabricate one. I'd estimate a 4L80E conversion will set you back at least $3000. You could probably do a rebuilt TH400 with quality convertor for half that. If you find a used transmission you could do it for under a grand. Around here, used TH400's that are claimed to be good pop up often for $150 or so on craigslist. Taking a gamble that way, but I've seen lots of people get good used transmissions.

After saying all of that, I may end up using a 4L80E in my car in the future. BUT it will be because I already have 2 of them and I have that box I mentioned and don't mind shifting it manually......and it would make the 4.88's a little more friendly. Even though I have most of what I'd need to convert I still am likely to just stay with the TH400.

 

[303Radar]

At your power level, I would advise you to go with a nice long tail TH400 and put all the $$$$ you save towards the gas. It'll be at least half the cost of the 4L80E. Sure you'd get better mpg's on the highway with the OD, but for anything other than highway driving you won't. Also you're 3.54 gears aren't so low that they'll "require" an OD for highway use.
A 4L80E will require a computer and harness along OR a "Little Black Box" so that you can use it as a Manual Valve Body. It'll also require a custom crossmember and it's not as long as a Long tail TH400 so you will have to do more mods to run a 1 piece driveshaft. A stall convertor for the 4L80E is big bucks too, unless you stick with a stock one. Also, have you ever lifted one of those things? (Not that a TH400 is light by any means, but it feels like it is compared to the 4L80E.) Forgot to mention that a TH400 crossmember is available from Showcars so you don't have to fabricate one. I'd estimate a 4L80E conversion will set you back at least $3000. You could probably do a rebuilt TH400 with quality convertor for half that. If you find a used transmission you could do it for under a grand. Around here, used TH400's that are claimed to be good pop up often for $150 or so on craigslist. Taking a gamble that way, but I've seen lots of people get good used transmissions.

After saying all of that, I may end up using a 4L80E in my car in the future. BUT it will be because I already have 2 of them and I have that box I mentioned and don't mind shifting it manually......and it would make the 4.88's a little more friendly. Even though I have most of what I'd need to convert I still am likely to just stay with the TH400.

The electronics for the Franken WRat's fuel injection and coil packs are already setup to control a 4Lx0 transmission, I'll just need the wiring harness. Because of the offset on the Jag Rear, I'm counting on mods to the tunnel for a 1 peice driveshaft already. Not too worried about mods for the cross member, I was already counting on it. To minimize the mods, I was thinking a 3" diameter chromoly drive shaft from Mark Williams - http://www.markwilliams.com/driveshaftGroup.aspx?CategoryID=122
depending on the critical speed.

Monster Transmission sells a 4L80 built for 500 - 550 hp for 2700'ish (pan with drain plug, higher stall, shipped, no core exchange). They have one rated for 750 hp for 3100'ish (pan with drain plug, higher stall, shipped, no core exchange).
Or I can buy a kit for 1000 and source a 4L80 locally and have shop locally rebuild it.

I do have TH350 handy, but it wasn't build for more than 300 - 350 hp. It might hold up for while, but it won't the last transmission I'd need either.
The cost, well, something about forgiveness versus permission. Besides, I'd hate to hear my wife if I said I put the wrong transmission in and we need a different one

 

[1961BelAir427]

Considering that you've got to do all that anyway....and already will have a computer cable of controlling it.....the 4L80E sounds like the right way for you to go. I'd pay a little extra for one rated to more power than you are going to make. The extra insurance will be worth it.