**Overdrive auto info for those looking to do a trans swap**

Bump for newbies...;

 

WOW am I SO happy to have found this thread!

Just last Sunday I was convinced by another post to forget about rebuilding my ST300 in favor of a 200-R4. So, now I'm looking for a core, and I think I may have found one. I spoke to a guy today and he says the one he is selling came off his '86 Regal with a V6.

In reading this thread I think I am understanding that ANY BOP 200-R4 will work, but the INTENT drives the decision as to which core to purchase.

Therefore, If I am only looking for a replacement for the ST300 on the back of the 300V8 in my weekend family cruiser ('67 Skylark convertible), I will do fine with a core from a V6 car.

Can someone please confirm this?

Best Wishes,

 

Correct my freind!

 

Thanks Sean,

Again - this is an awesome thread!

 

I'm also looking at doing this swap for a '67 Skylark convertible. I have an article from an older Car Craft or Hot Rod mag doing this exact swap using a '67 Skylark. They ran into an issue with clearance from the tranny pan to the crossmember. The tranny mount is close enough to the back of the pan it wouldn't clear the wide, flat crossmember Buick uses. They fixed the issue by switching to a crossmember from a Chevelle and modifying its mounting pad to work.

It could be they used a wrong or worn out rubber or such, but I also have to wonder why they didn't just notch out the crossmember. I haven't crawled under mine to check to see if that looks feasible. Hopefully I'll get a chance to pull the 'vert out this weekend & I'll take a peek then.

Is anyone able to comment from personal experience on this clearance problem? I can scan & post the article if there's interest.

Also,
I'm curious on the wiring. On the single wire cars, if they only lock up in 3rd & 4th anyway, does it really need to be wired thru the brake pedal? It seems to me as you slow down it should down shift out of 3rd and therefore automatically unlock. Or am I overlooking something?

Thanks

 

Ken has done this with the 64 and it should be the same for the 67 but i could be wrong.

 

A most excellent thread Sean!

Thanks for answering my questions before I knew I had them! :bglasses:

 

I'm waiting for the stand alone controllers for the new six speed from GM. Its modular so all we would need is someone to cast the bellhousing piece for our olds/buick/pontiac style engines. Its a complicated piece, clutch to clutch engaging and internal electronics but it can take a huge torque limit (800ft/lbs) and first gear is a stump pulling 4.03 and sixth is .67 overdrive.

T400 is 2.48 first gear and most 4 speed autos are in the low 3 range so you could run a 3.08 rear diff with the 6 speed and it would hit you like a T400 with 4.56 rear gears!!! AND still give you a .67 on the highway.

Right now only in higher end SUV's and trucks but in 09 they will be moving across the line of trucks so should become more common and less expensive. They also fit where a 4L60e will fit. For that tranny I would lose my originality :TU:

 

Good points Tim, and I agree that the 6 speed will be an awesome option in a year or so!

 

Greg,

I installed a 200r4 in my '66 and had no crossmember interference. I do have to slide the crossmember back a little to access the 2 rear pan bolts though.

Not sure if the '66 and '67 crossmembers are different.....

Brian

 

One bit of caution on this swap (I don't think anyone has mentioned this specific issue yet). Due to the lockup nature of the 200-4R, you have to be sure that the rear gears you're using are low enough (numerically higher) such that the engine speed will be sufficient at your freeway cruising speed (65-70 mph or so)to lock the converter. If you keep your 2.73 highway cruiser gears with the 200-4R's .67 overdrive, the resulting rpm at freeway speed may not be high enough to engage lockup, resulting in slippage. This will seriously shorten the life of the tranny.
I've heard that actually anything higher (numerically lower) than 3.42:1 gears (which is one of the reasons why GM used that ratio in the GNs, 442s and Monte Carlo SS cars)and you'll run into the problem I'm referring to.
Anyone out there back up my reasoning on this?

 

Someone please comment on Smokum's gear discussion. I am planning to pick up a 200R4 today - but not if I MUST track down a new set of gears. I was thinking I might CHOOSE to put the 3.08 gears out of a '65 GS into my '67, but if that won't help then I may have to reconsider the whole thing.

I am a novice at best here - probably out of my league, but aren't there lockup control switches out there to solve this problem?

Thanks,

 

You can get different kits to lock up the convertor using MPH or the factory pressure switch. I think the B&W kit you can set it to lock at any desired RPM, but I did not use that set up.

My set up is: vacuum switch-->brake switch-->4th gear pressure switch-->lock-up solenoid. I run a 3.90 gear, so the rpm wasn't a concern.

Brian

 

Smokum raises a valid point.

A 3.08 gear will act like a 2.06 once it goes thru the .67 OD. Apply that to the typical 2.73 & you're effectively in the 1.80's...

But how low is too low? A GN 3.42 is all the way down to a 2.29. The 3.08's OD'd to a 2.06 might be enough (?)

 

There are lots of ways to set up the lockup switch. But the main question is what is the highest gear you would want to run with an overdrive. It is also a fact that if you are in overdrive you do want to run locked up the majority of the time or you will have premature transmission failure from excess heat.

I run 3:73's and a 28 inch tall tire. Around town often have to put the transmission in 3rd or manually unlock the converter because my motor does not like being locked up below 1300 rpm. If I had a motor with less cam (TA 413) this would be less of a problem.

In my opinion I would not use a 200r4 with 2:xx gears. Just seems like a waste unless you are going to cruise at 100 mph. The 3:42 gear is really ideal for this transmission.

 

Good Points, when using a non overdrive trans, I don't suggest higher than 3.42 gears for mostly street cars.

With the overdrive a 4.11 gear would be great because you will be able to lock the converter in 4th gear at 70 mph and still have a high enough rpm that you wont cause excess heat in the trans.

I used to have an th-350C with the lockup converter and 2.56 gears and that trans ATE converters due to heat even with a cooler. The main cause I think was that the rpms were too low for the lockup unless going REALLY fast. So I'd say yeah! Go with a higher ratio rear gear ratio when upgrading to overdrive since with a 3.08-2.56 gear the overdrive is non even needed in my opinion.

use the rpm converters online where you can input the final gear in the trans, rear end ratio, tire diameter. There is some converter slippage as well but the calculator can give you a good feeling on what rear gear to chose when you go overdrive. With a 26" tire, a 3.73 gear and a 200r4 would be a great combo for a Buick 350 in my opinion.

 

I'm also doing 4.10 out back on my 66...keeps the motor happy at around 1900 rpm cruising speed using those calculators.

I like that this thread is still alive and well

Wayne S

 

Hey, Wayne are you not getting about 18 mpg with your 5000 pound jeep with that 4.10 gear? I know you were at 14 mpg with the stock 2bb.

I can not wait to get my 4x4 81 Silverdo on the rd with the Buick 350!

 

Holding around 17 in the Jeep with the 4bbl swap and a Holley on top, but I I'm loosing a bit...I think it's time to go through the tranny and find a good AFB. The Holley leaks because I don't drive the Jeep often enough and I'm holding off on the tranny until I finish the "other" project and then I'm going to swap in a new front diff with disc brakes and see what I can stuff in there that's newer in the transmission department.

The 66 that is getting the overdrive is a *cough* PontiacLeMansConvertible.
Sporting a 389 that is bored out sixty over (gotta love those old blocks that you could bore out to ninety if needed). You can see how far the tranny is from the firewall here

This shot is just to be mean...Pontiac had cool colors on the motorp

Can you say.......Future Cross-country Summer Cruise? She is in paint now :bglasses:




Wayne S

 

:gp: I run a BRF code 200 4 r from a GN in my 72 GS and run richmond 390 gears. I run about 2700 RPM's at 70mph. food for thought. In addition I only run fourth gear lock up by way of a pressure switch change.