Want to bang gears...in an automatic - Third Generation F-Body Message Boards

galletti · 11-06-2009, 06:09 AM

I have an 88 IROC convertible. It's mostly a weekend cruiser but I'm getting ready to take it to the circuit track for solo events for some laughs. I don't really have the budget to go with a manual swap and was wondering if I should go with a full manual valve body and the Megashifter. From what I see on this forum this would give me pretty much a 4 speed "manual" tranny. My doubts are:
1. Does banging through the gears with the Megashifter work both up and down? I mean, on the solo track I'll be up and downshifting a lot and need to know how convenient this would be with the combo I mentioned.
2. What is the approximate cost of the manual valve body and what does the install involve? I have a stage two B&M kit on my 700r4 which I installed myself fairly easily so, how about it?
3. Is there any combination of valve bodies/shifters out there that will allow me to operate manual at the track and auto on the street? I really want full manual on the track to avoid unexpected shifting but would prefer to set to D and let it go when cruising.
Thanks a lot for any info/opinions.

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Stephen 87 IROC · 11-06-2009, 09:22 AM

As fun as it sounds, constantly manually shifting an automatic on the street looses it's appeal really fast. A manual valve body means the transmission will be in any gear you put it in no matter which type of shifter you choose to use. From a dead stop, you can put it into D and it will start off in third gear (and burn out the direct clutches).

Some shift kits have a partial automatic feature. You can still manually shift through the gears and the tranny won't change the gear selected by itself however if the shifter is put into D(OD), it will act like a normal automatic transmission for driving on the street.

galletti · 11-06-2009, 10:17 AM

Hey!!! That partial kit sounds like what I'm looking for. Any info as to make and model? Also, if I'm on the track, and get to shift to D, will it behave like on he street or do I get a choice?

Stephen 87 IROC · 11-06-2009, 09:10 PM

Once you're going fast enough and shift to D the tranny won't know any better but as you slow down, it will automatically downshift if left in D.

Do a search for shift kits or tranny reprogram kits. Jegs and Summitracing carry plenty of different types.

Using a manual valve body should be in a track only vehicle. If you want to shift gears on the street, install a manual transmission.

Pro Built Automatics · 11-21-2009, 04:19 AM

I carry the "modified" TransGo Performance Shift kit that will do what you need. Call me and we can go over your options. 909 795-1876. Dana

basiccamaro · 11-21-2009, 01:05 PM

Like a lot of other people, I like certain aspects of shifting a manual trans. But since I'm getting too old and lazy now, and live in the Seattle area, where it's VERY hilly, using a clutch on a DD becomes more of a pain. I even wear out brakes from stopping when going downhill faster than when I lived in the MidWest.

But my experience with trying to shift/downshift automatics is that if you try to downshift (like you would probably want to do in autocross or road racing or spirited street driving) the engines goes down to low rpm's as soon as you let of the gas and doesn't stay synchronized with the transmission/rear wheel speed and the car sort of "freewheels" with little to no engine braking under decelleration.
So if you haven't slowed the car way down, when you downshift an automatic, it jerks the car hard down from the speed the chassis is moving down to the speed the engine is running, or it jerks the tires off the ground and chirps them until the chassis slows down enough that things are synchronized again. Too violent and hard on parts, not good!

I've never had any experience with any thing other than very lightly shift kit- modded stock trannys though. Is there any kit (like the one Dana has linked to) that will make an automatic synchronize for manual downshifting as well as manual upshifting? It seems like it would be nearly impossible since you can't divorce the engine from the trans with n aouto to speed it up to match the tranny/chassis speed as you must when downshifting a regular manual transmission.

galletti · 11-21-2009, 05:43 PM

Thanks for the offer Dana. Also, thanks for the info basic. That actually makes a lot of sense. It hadn't occurred to me that I wouldn't be able to rev match on downshifts. Thae reason I want to do this is because my master plan is to go ls1/t56 but the budget does not allow for that now.

basiccamaro · 11-21-2009, 07:37 PM

The man who is generally credited with introducing the spoiler and later the wing to auto racing was a Texan named Jim Hall, with his famous Chapparal Can Am road racing - type of race cars. They were a sports prototype, kind of like a wide Indy car with a full, wedge shaped topless body and fuel injected BIG block Chevy engines. He also introduced true ground effects eventually by surrounding the entire bottom of his latest car, the Chapparal 2J, I believe, with flexible skirting and actually mounting and running a large fan that sucked the air out from under the car and created a vaccum underneath that totally sucked the car down to the track. It was both inventive genius and extrmemly controversial, and FAST!

Anyway, another of Hall's technological advancements was running an automatic transmission in his road racing Chapparals. There were enormous developemental problems but they did race them. The Chapparal automatics were very fast but broke down a lot. When they didn't break they almost always won, but unfortunately that wasn't often enough.
So somebody has somewhat successfully made an automatic work in leiu of a manual transmission and clutch when decellerating and using engine braking and engine/chassis speed synchronization in road racing situations. But I don't know if Hall was modifying a GM transmission or if was a specially built unit. And I don't know why the developement never carried on, whether it was rule changes or just financial or operational problems that stopped Chapparal automatic developement. Hall may have even died for all I know. I guess I need to go Google it now!

galletti · Yesterday, 09:18 AM

That's very interesting info. I think I heard something about Jim Hall on The Power Block on Spike TV some weeks ago. This is the Chaparral Cars web site http://www.chaparralcars.com/

Pro Built Automatics · Yesterday, 06:10 PM

You can "road race" an automatic, you just need to give it throttle at the same time you move the shift lever back to the next gear to "match" the rpm's of the motor and chosen quickly. It is like double clutching a manual transmission. When done correctly, the rpms of the motor and the gear you have selected will match in rpm's in about 2-3 tenths of a second. Once "matched" you can let off of the throttle to deaccelarate with engine braking if needed. You need to use the large .300" intermediate/reverse boost valve for maximum holding power in 1st & 2nd gears. The .500" main boost valve for 3rd & 4th gears. There are larger boost valves (.570" & .400") for both, but I don't think they have any real advantage here, I could be wrong though. Road racing is very hard on the fluid, I would use Monolec 7500 from Lubrication Engineers.