some random engine/t case questions.

first question,
My jeep currently has a dana 20 transfer case in it with a amc 20 rear. I would like to put a dana18 back in it that way i gain the ability to use an overdrive and go back to the offset rear which i really like. Which dana 18 do i need? The single stick one found in the v6 jeeps or the twin stick ones behind the t90's?

will any chevy motor bolt up to a jeep t-14? or whatever trans happens to be behind my 225?
The 225 v6's require the same input shaft as say a sbc 350 or a 4.3 correct?

do buick bellhousings work for both chevy and buick motors? i have heard they are exactly the same(bolt pattern wise) but the the top center part of the bellhousing is different on one of them.

 

******* with the way you wrote your post I'm kinda confused. What are your intentions?
Buick bellhousings are different than Chevy, BOP bellhousing are the same, thats Buick, Olds, Pontiac. The t14 is Borg warner (read Ford transmission) it doesn't bolt up to anything GM as a direct fit with the exception of the rare 71 Dauntless bellhousing. The dana 18 should be from a v6 if you want to make it easier or at least a large hole case, the t14 was used with a large hole dana 18 case from the factory.

 

no real intentions just yet, but im just wondering for the future.

i have a 71 so im guessing i have that bellhousing, so i would be able to mate it to a sbc or 4.3 right?

i dont have a t14, my jeep has a saginaw 4 speed swaped into it. so from that i just assumed that both the 225 and most other gm motors use the same input shaft. My saginaw's synchros are gone so im looking for a replacment, i found one and its mounted behind a sbc right now. thats why i want to know if the input shafts are the same.

 

Certainly the T-14 is a downgrade from the 4-speed. Your only advantage might be a lower (numerically higher) ratio for 1st gear.

With a Saginaw, you'll have a GM bellhousing. Before '71, the bellhousing used by Jeep was the same as the GM bellhousing that came in V6 passenger cars, and was used with a plate adapter between the trans and bell. In '71, the plate was incorporated into the bell - I don't see any great advantage to this change, but Jeep must have had a reason. I haven't measured it, but I'd expect the stock '71 T-14 stickout to be different from the Chevy stickout (but ok with the plate adapter or '71 Jeep bell), that your 4-speed has a plain GM BOP bell in front of it, and that the Jeep bell that came with the T-14 is gone.

Yes, the input shaft stickout is standardized for GM. As Mike explained, BOP is different from Chevy, but only on the engine side. BOP or Chevy bell on the donor transmission won't matter.

 

According to JP mag. you can rebuild an 18 with 20 case, a tad stronger! I am going to do this rebuild to get the big hole for my jeep.

Dale

 

If synchro's are the only problem with the trans why not rebuild it? It's very simple. The Saginaws run several different first gear ratios depending on application. An easy way to tell with the trans out is to count the rings going around the splined area of the input shaft. 3 rings is the widest ratio with about a 3 1/2-1 first gear (what I run in the '5) 2 rings is a little closer ratio with a more even split in the gears, 1 ring closer yet, no rings is the closest ratio with a 2 something to 1 ratio.

The GM input shaft is shorter than the T-14 input and has a different pilot and spline diameter.
The Transmission side of the bellhousing is the same for the vast majority of GM transmissions.
The bellhousing side is different for different applications. Buick, Olds, Pontiac, and Cadillac rear wheel drive share a common bolt pattern but Buick has the starter pocket on the passenger side whereas the other's have it on the driver's side. That's why there were some factory bellhousings with a pocket on both sides, to accommodate all these combinations. There were some Pontiac Bellhousings that had a Ford and GM transmission pattern on them. Back in the day the Saginaw plant burned and so Pontiac used some modified Ford Toploader 3 speeds behind their GM motors to keep production up.

If it were me and had to choose between a twin stick 18 and a single stick, I'd go twin stick every time. Fewer moving parts and more options. I would opt for a large hole case. The 20 case is a good unit and is slightly stronger than a stock 18 large hole case and are generally more available. Make sure you get one with a fill hole on the side, not the back. If you have a rear output park brake you won't be able to access the fill hole if on the back of the case.
Nickmil

 

Ive never touched the inside of a tranny before so im a little hesitant to buy the rebuild kit and dive in. a local shop said they would charge me 150 for the rebuild and the parts would be around 120. I posted a wanted add on the HAMB forums and this guy has a bunch of saginaws, he wants 150 for one that has 50k on it, and hes only a short drive away. I dont have much money and this jeep is my primary mode of transportation so if i buy the rebuild kit and screw it up then.... im screwed.

 

Bear in mind the Saginaw was never used in a Jeep so they are custom adapted on the back end to bolt up to a Jeep transfer case. $150 sounds awful cheap for one that has been adapted and low mileage. I'd double check or you'll be tearing them apart anyway or end up with a transmission you can't use. The adapter kit alone goes for around $475. I wish you were closer, I'd help you out. I can do them in about 2-3 hours if that once out of the vehicle. Nickmil

 

i allready have the adapter and the tailshaft, the one im getting is a 2wd one, so i just have to ubolt the back end remove the 2wd tailshaft, put the AA tailshaft in and bolt the adapter on.

is simpler terms: the saginaw i have has allready been adapted, so im just gunna take off the AA parts and put them on the new saginaw.

 

If you can do that you can put new synchro's in at the same time. You'll have it all apart anyway to put the output shaft in the other transmission! Invest the $150 into your existing transmission that you have to completely disassemble to put the output shaft into another transmission anyway. You will be going no further than you would have to in order to go the other way anyway and will save some money to boot. Just because the other tranny only has 50k miles on it doesn't mean it's in good shape. Yours is a known quantity, at least you know it's not broken.
Looking above, I'm not sure you realize you have to completely disassemble the transmission to change the output shaft. Nickmil

 

hah i did not know that. i thought it just slid in the back for some reason R)

i guess ill buy the rebuild guide and cross my fingers R) do i need a press for anything?

i still have to open up the case and see what shape the gears are in, they are really expensive to replace. Im afraid that some of them may be chipped, i mean i grinded it like maby 6 times when i drove it, i cant imagine how many times the PO did it.

 

the output shaft on my tranny has 6 splines, which dana 18 is primarily 6 spline? I have one that was behind a t14 and it uses more than 6 splines.

some good news all the gears are in awesome shape no chips or anything! its got the 3 lines on the input shaft so it has better gearing than the regular saginaw. the brass rings for 3rd and 4th are cracked! i was not expecting that, also their was barely any lube in the tranny, it was maby 1/4 the level it should of been. It was grey sludge with gold sprinkles (synchros) I just bought the jeep less than a month ago so i didnt get to change the lube.

im ordering the parts on monday and next weekend hopfully i will begin rebuilding my first transmission.

oh also is it possible to test out a trans before putting it back in the jeep? or do i just have to rebuild it, put it back in and hope it works?

 

All the dana 18's were set up for the 6 spline bullgear with the exception of the one in front of the t14, its 10 spline. The bull gear is changeable, go to the Novak adapter website and look in the knowledge base, they give a chart for the bullgears. You can then get one from Herm the overdrive guy or R&P in oregon.