I am planning on pulling my motor (394) here soon for a rebuild, and while I'm at it, I think maybe the trans should get some attention too. Between my service manual and owners Operating manual, I am looking for any info on the trans. Hydramatic is the only referenced title. Is this the Jetaway Roto 10 trans? In your opinion would you rebuild (refresh) or replace ? If I were to replace, what trans would you recommend? Thanks for any help........Dave

 

You have a RotoHydraMatic 10, or sometimes it's called a Roto 375. It's also commonly called Slim Jim and plenty of other impolite names!

KQQLCAT had a great thread on putting a T400 in his 61 D88 post, using Ross Racing Engines' adapter kit http://rossracingengines.com/c/5/old...early-catalog/ to couple a later TurboHydraMatic to the 394. Your biggest obstacle is you WILL have to modify the trans tunnel to get it in there. KC's thread showed what he did with that.

I'm normally a keep-it-stock kinda guy, but a Slim Jim is one exception to the rule. It's not that they're terrible transmissions, they're just finicky and hard to find anyone who'll work on one. Plus throttle rod adjustments are critical with this transmission.

A 394 hooked to a THM is a killer drivetrain- the torque and raw power of an early Rocket combined with the smoothness and ease of servicing of Turbo HydraMatic. I daresay RRE could adapt a 200-4R just as easily, then you'd have overdrive too.

 

Thanks Rocket, Lots of good info there. I appreciate your help. Dave

 

You can update to a later model trans also. I contacted Tanson Transmission and had them modify a T-350 for use behind the 394 in my 61 Olds 88.

0404_PHRP_01_z_054-57-OLDS.jpg

They can do the needed work on several different trans depending on what one you want. I used a T-350 because it fit under the stock floor. I kind of wish I had gone with an overdrive unit. Here is a link to Tanson

http://www.forwhatyouneed.com/transm...conversion.htm

 

Very interesting, RC. I don't have an early-sixties Olds, but I'm keeping this link just in case - it seems like a custom-modified 200R4 may be just the thing for these varmints.

- Eric

 

Hey Thanks RC..........Tanson is only one hour from me. Will definitely be checking them out. BTW your 88 is BADAZZ.............

 

Looking for the KQQLCAT thread I found another one where someone had put a 700R4 in a 63 Starfire and that was a neat install too. I don't like the 700 as much as the 200 because of its gear spacing (though the 700's wide-spaced 1-2 shift is really very much like the SlimJim) but at least you can find shops who will work on them- unlike the SJ, whose very name strikes irrational fear in the hearts of transmission guys.

 

I have a 1963 with the roto 10, and so far, have not have any problems with it in the past 4 years. It sounds like your trying to be pro-active to address the transmission while the engine is out. If your budget can stand it, go ahead and replace it with something else if that gives you peace of mind. I would lean toward not altering the tunnel area if possible. As for myself, I will try to stay with the roto 10 and rebuild it when the time comes. Keep in mind that as others have stated, that carb and linkage adjustments are critical on these slim jims to make them shift properly. Good luck in what ever you decide.

 

Our trans assemblies fit in 49-64 Olds with very min work if any to the tunnel.....I guy with minimal skills can install with hand tools....... compaired to our competition.....and we for sure have the best assemblie on the market......check them out,Thanks