transmission & gear help

[blazemobile]

I have a few questions here...First of all...what are the stock gears in an '85 S10 Blazer? How would a Turbo 350 act with the stock gears? I have a turbo 350 that I'd like to use but I've been told that I'd have to change out the gears. If that doesn't work out i gotta get a rebuilt 2wd 700R4($250, at local shop) but then I'd need a B&M converter lockup control($150) cuz my motor isn't gonna have a computer. In the end...if i need different gears, would that be cheaper than to buy a whole transmission and stuff or what?

I don't know much about transmissions.

[Tink]

The gear codes can be found in the RPO list in the glove box. Here are some common ones:
GU2 - 2.73 Rear Axle Gear Ratio
GU4 - 3.08 Rear Axle Gear Ratio
GU5 - 3.23 Rear Axle Gear Ratio
GU6 - 3.42 Rear Axle Gear Ratio
GT4 - 3.73 Rear Axle Gear Ratio
GT5 - 4.10 Rear Axle Gear Ratio
HO4 - 4.11 Rear Axle Gear Ratio

If the gears are something like 3.08s and you go with the THM350, then it will most likely, be running too high rpms on the highway... Also, you'll need to factor tire size in somewhat... For the THM350, I'd recommend the 4.10s/4.11s...

What tranny does it have now? There was a 700R4 in the 85 Blazer I owned....

[KRUZER1]

mine is an 89 and it has and came with a 700R4. Tink i gotta question could be a brain fart but you said if goes with 3.08s and a THM 350 the rpms would be too high on the freeway, if thats the case wouldnt 4.10s or .11s make the rpms even higher on the freeway?

[Tink]

Oops, you are right Kruzer1... that is what I get for posting before I have had my coffee this morn! That was backwards... 3.08s would be better than the 4.10s... would have lower rpms on the highway. If you went with the THM350 with gears such as 3.73s or 4.10s, I'd recommend Gear Vendors... (www.gearvendors.com (http://www.gearvendors.com))

[Sparky2263]

Yup, I'd call that a brain fart. ;)

You don't need a lock-up controller to have lock-up. You can use a vacuum switch to dis-engage under load and an on-off switch to that to totally disengage lock-up. The 700R has pressure switches that the TCC solenoid will use for ground. These inhibit TCC operation until the specified gear has been reached. Most wire it into the 3rd gear hydraulic circuit.

The 700R4 is advantageous because it allows you to run a higher (numerically) gear like 4.10's yet have reasonable RPM's in overdrive.

[T Man]

On the 700 R4's newer than 86 you do not need to run electronics to the 3 prong plug. Older 700's you will however or you risk burning up the trans

[blazemobile]

What should I do if there are no numbers in my glovebox?

[KRUZER1]

Oops, you are right Kruzer1... that is what I get for posting before I have had my coffee this morn! That was backwards... 3.08s would be better than the 4.10s... would have lower rpms on the highway. If you went with the THM350 with gears such as 3.73s or 4.10s, I'd recommend Gear Vendors... (www.gearvendors.com) (http://www.gearvendors.com))

thank god i thought i was losing it

[Tink]

thank god i thought i was losing it

Nope, I was smoking crack... :o



blazemobile, if there aren't any RPO codes in your glovebox, you can determine your rear end gear ratio by making a mark on one rear tire and another on the pinion flange or driveshaft. Put the tranny in neutral, block the front wheels, then jack up that one wheel... get under the truck, and turn the driveshaft while counting how many driveshaft revolutions it takes to get one rotation of the tire (this is assuming it isn't posi or limited slip rear)... So, about 3 and 1/2 would most likely be 3.42s.

[<-~Jo~->]

i hope your not going for milleage if you want a th350 .. ive got one with some 3.73 in the rear it launches great its awesome but on the highway at 70mph its at about 3.700rpm crazy loud and hard on gaz for a v-8 altought its right in the lower part of the power band ...

i was looking at those gear vendors under/overdrive system but how expensive are they ? anybody has an idea ? ... because i always hear of the 700r4 breakin down under power and my dad pulls our rv trailer 32foot with a 1 ton van and we blew 3 trans all of them where 700r4

[T Man]

You can buy a bulletproof 700 R4 for about half of a gear vendors overdrive, I think they are something like 2500 bucks

[KRUZER1]

I spent 900 on my tranny while i was in Iraq and all of that money was for parts at cost, A good buddy of my stepdad owns a tranny shop, he built it and promises i wont be able to break it, so ive been trying ever since.

[indigo s10]

Here's the prices http://www.gearvendors.com/prices.html I agree with T man. You can buy what you need for half the price.

[blazemobile]

I'm asking all of these questions because I don't want to start swapping the motors and find out I have to order something and it takes a week to get any parts.

1. What should I do to get rid of all of my wires that are for my computer?(it's gonna be carbureted)
2. Will my driveshaft have to be longer or shorter or same w/ a TH350?
3. Will I be able to hook up my headers to the exhaust myself?
4. Will headers that were on a 4x4 Blazer work?

I wont be driving on highways for long distances. I want it to be quick (for games like stop light tag) and I want to be able to beat my dad's Cobalt SS...when he bought it, he got it for gas mileage and looks...and i hated it but man it flies..it snacks on mustang gts(he got a 3" pulley and has 270 HP in it[pretty impressive for a 2.0 I4]) we were cruisin down the highway going 100 in mid 4th gear
anyways...this is what i want out of my blazer in the end. those are my goals. Anybody know the quick and easy way to this?

[ZR1-S10]

1st and 2nd gears on the TH350 are numerically lower then the TH700 wicth means your engine will rev slower, have less torque mult. and your off the line power will suck. To make up for the loss you should go up 2 steps in the rearend (if you have 3.08 then go with atleast 3.42). If you want to play stop light tag then get the 4.10s.

[blazemobile]

would 3.73s work? cause that's what i got

[T Man]

3.73's are probably the perfect ballance. They will still run a pretty high RPM on the highway, but not as high as the 4.10's, and be much better off the line than the 3.42's

[Sparky2263]

. those are my goals. Anybody know the quick and easy way to this?

Yeah, but it ain't cheap.

:D

[T Man]

Cheep Reliable Powerful - Pick 2

[<-~Jo~->]

^^^^^^ you said it T-man... only 2

[Tink]

2. Will my driveshaft have to be longer or shorter or same w/ a TH350?


Well, the 700R4 is a little longer than the TH350...