Jump to content

New question.


FUTURE_OF_GM

Recommended Posts

I'm thinking about putting a new transmission in my '73.

The most likely candidate is a Super T-10

Here's the issue: Currently, I'm running the 406, a Turbo 350 transmission (with a shift kit), a 3:73 posi-trac and 17 inch wheels (Not sure on the tire size -- can you tell I haven't messed with my Camaros in a while? LOL)

Anyway, the tranny was rebuilt probably 11-12 years ago out of necessitiy, back when the car had the stock rear end and an old, weak 350. After the rebuild, it was a daily driver for about 4 years, then it was retired to semi-daily, and recently, super duper garage queen. Obviously, I've upgraded around the tranny and it has become the weakest link. It still shifts like a champ, but the main seal is leaking terribly. That combined with the stress and the fact that it's been doing a lot of sitting the past few years, makes me really nervous.

So, my thoughts are; I'm going to have to drop the transmission anyway to fix the seal. That means cutting the exhaust (hence my previous tech question) and presents a perfect opportunity for a replace/rebuild. Ultimately, I'm looking for some way to free the car up a little bit to at least be able to keep up with traffic on the interstate. It doesn't rev super high, but it's still to a point where I'm not willing to spin it any higher for long periods of time. (I'm REAL cautious with my cars and bad to baby them -- probably because I'm poor and can't afford to rebuild them readily, LOL) I don't run a cooler on the transmission or anything, but bear in mind that the car is driven VERY little (READ: TOO LITTLE). Probably less than 300 miles a year, and not even that in the past few years, and most of that driving isn't interstate.

My idea is that; since 4th gear in the Super T-10 is 1:1, it'll at least free the car up enough to make me feel a bit more comfy on the interstate. and it'll be more fun to drive with the stick.

I have 3 options. 1) Rebuild the auto 2) install the T-10. 3) Replace the seal and call it a day. The car WAS a straight drive at one time (despite coming from the factory as an auto) and accordingly, already has a 'dead' clutch pedal and a hole under the carpet for a shifter. If I go the Super T-10 route, I'll have to buy a tranny, shifter, et. al. Pay the labor AND weld on new exhaust. If I rebuild the auto, I still run the risk of straining it too much and killing it (eventhough I would install a cooler) and I still have to pay labor and weld up exhaust. If I just replace the seal, I get out cheaper. BUT I have to worry about what kind of shape the transmission is in.

What would you do?

Will the 1:1 4th gear in the Super T-10 actually work to free things up, or is it a waste of time?

Money is certainly a factor... In fact, this is all just pie in the sky right now. But it is really just hurting my heart to see these cars (my Camaros) sit, or just sit and idle in the garage and not be on the road. I've made a pledge to myself that I HAVE to get some momentum with these cars, or they'll eventually begin deteriorating. These cars are me and I am my cars. I refuse to see that happen. I'm out of school now (the reason I left to begin with) and making this car more roadworthy is a BIG step in gaining momentum.

Here's a wildcard option for you: I could always jerk the 3:73 out of the car (It has less than 1000 miles on it, by far) and go with a more tame rear end. That would certainly result in a financial loss even if I re-sold it. Thoughts?

Edited by FUTURE_OF_GM
Link to comment
Share on other sites

Your trans is probably just fine. It leaks because it sits so much.

A 3.73 isn't really all that radical and I would have no fears of hurting the trans by driving it at highway speeds for any distance.

That said:

- fuel economy will be awful

- the drone of the engine at highway speeds could get very old as the RPMs will be rather high.

As for your options:

The best bet for a swap would be an overdrive auto - driveability and mileage will both improve dramatically. It would also be less costly than a manual conversion.

If it were mine, I would probably go with an auto because the car was born with one. But it would be tempting to go with a manual since some of the hardware to do it is already present. If that's the route you follow, I'd go for a six speed/OD manual - it would make all of the work worth the effort as you would add driveability, economy, and fun all at once that would equal or better an OD auto.

From a value standpoint, the right answer is to simply repair the leaky seal in your current trans and remove the manual-related pieces.

So, you first need to decide what exactly it is that you want from the car.

Link to comment
Share on other sites

Your trans is probably just fine. It leaks because it sits so much.

A 3.73 isn't really all that radical and I would have no fears of hurting the trans by driving it at highway speeds for any distance.

I agree. What scares me about that is how much it's compounded by the wheel and tire size.

That said:

fuel economy will be awful

Back when I would do the interstate driving, I'd get 10-11 MPG.

be an overdrive auto - driveability and mileage will both improve dramatically. It would also be less costly than a manual conversion.

If it were mine, I would probably go with an auto because the car was born with one. But it would be tempting to go with a manual since some of the hardware to do it is already present. If that's the route you follow, I'd go for a six speed/OD manual - it would make all of the work worth the effort as you would add driveability, economy, and fun all at once that would equal or better an OD auto.

The only thing that made me not look at OD transmissions was price. LOL.

Link to comment
Share on other sites

You might consider tire diameter here... and the RPM you're at @ 60. I have 3.73s in the B-59, but the tires are tall and it will turn but 2500 @ 60 (TH400)- not bad with no OD & 3.73s.

That aside, this boils down to money & preference- little else. Your pattern of use (and even potential use) doesn't warrant hardware changes by itself (IE; you aren't drag racing or doing interstate travel with frequency). A TH350 in good shape is not overstressed behind a 406 just cruising. If it doesn't have 100K or thereabouts on it and you can handle the 'pussification factor' :rolleyes: of driving a "slushbox" :rolleyes:, I'd replace the seal for now... esp with such limited usage.

Not an option to put joints in the exhaust for possible future disassembly/trans work ?

Link to comment
Share on other sites

You might consider tire diameter here... and the RPM you're at @ 60. I have 3.73s in the B-59, but the tires are tall and it will turn but 2500 @ 60 (TH400)- not bad with no OD & 3.73s.

Tire diameter is roughly 24 inches. (measured it today) I'm usually spinning around 2500-2700 at 60 MPH.(IIRC) Problem is, NO ONE seems to do 60 MPH anymore. That's what makes me so nervous.

That aside, this boils down to money & preference- little else. Your pattern of use (and even potential use) doesn't warrant hardware changes by itself (IE; you aren't drag racing or doing interstate travel with frequency). A TH350 in good shape is not overstressed behind a 406 just cruising. If it doesn't have 100K or thereabouts on it and you can handle the 'pussification factor' :rolleyes: of driving a "slushbox" :rolleyes:,

Oh, you know me entirely too well... LOL. That has a lot to do with it. Not really that people might say things (because the car oozes testosterone) It's just that I miss driving a stick very bad. My Focus, though generic, even had a stick. Now with the Stang as my daily (with a slush box) and my Camaro having one as well....

The '68 does have a stick, but it's not as much my personality. It's probably a little too classy for me, LOL.

I'd replace the seal for now... esp with such limited usage.

I'll probably take that route now that you guys have talked some sense into me.

Not an option to put joints in the exhaust for possible future disassembly/trans work ?

I will check into that. Especially if I drop the $$$ for a new X-pipe.

Edited by FUTURE_OF_GM
Link to comment
Share on other sites

You are right in that no one does 60- it was just a point of comparison. If you're doing 2500 @ 60, you should be around 2900 @ 70.

But wait- a 24" tall tire ??? Wow that's short. RPM calculator sez 3.73 x 24" x 60MPH = 3217 RPM.

IMO you are entering into a range where an OD gear is a worthy consideration.... but still not in the case of your limited driving.

How about you post the exact tire size.

RPM calculator here : http://www.ringpinion.com/Calc_RPM.aspx

BTW : my B-59's numbers : 3.73 x 29.9" x 60MPH = 2582.

Well below tolerable and good thing; cause the OD trans for my projected level of TRQ is the 4L80E, about $5K with the electronics.

Link to comment
Share on other sites

The actual wheel/tire size is 26.25. (26.3) [P235-50R17] on the back. Guess my estimate was a little off.

So according to that calculator, I'm pulling 2936 at 60 MPH and 3180 at 65 MPH.

That sounds about right, because I remember trying to peg the tach at around 3000 on the interstate because I knew that was right around the speed limit.

My speedo is FUBARED because of the new rear end, so what I would do is set my pace based on the '68. My dad would take it up to 60-65 MPH and I would follow, gauging my speed by my tach.

(Funny how this is all coming back to me now)

I'm not gonna lie, above 3000 kind of makes me nervous. (Warranted or not) But it still doesn't seem to be to much cause for concern.

Link to comment
Share on other sites

Join the conversation

You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



About us

CheersandGears.com - Founded 2001

We ♥ Cars

Get in touch

Follow us

Recent tweets

facebook

×
×
  • Create New...