84 K10 gears

[caakes88]

I'm new to building trucks but
I just got a 84 k10 (long bed) this past weekend and hoping to do a lot of work to it.
By trade I work on boats. I work on cars a lot but have never done any custom work just repairs. The truck I got has had a
few changes done to it already,
like having a 305 to a 350 also a tranny swap. I don't know what he had in it befor but now it has a 700r turbo HD, at least that is what it says on the paperwork he had. The trany is a 3 speed auto but it had the a trany with the 3speed+OD in it befor. Gear ratio has got to be way off has no balls off the line. It has 31" tiers. How do I figure out the gear ratio that is in it now? and what should I change it to would be the next question. ( I plan on puting 35" tiers on it). Sorry if These are stupid questions. Any help is welcome. Thank you.

[vic_V8]

take the cover off the diff, count the ring gear teeth and then divide it by the number of teeth on the pinion

[caakes88]

Thanks for the info. After looking into it I think I'm going to have a shop change them out. Is there a standard most people are going with for the 700 tranny and 35" tiers? I know those are both pretty common.

[vic_V8]

4.56s go good with OD and 35" tires

[Emersonsdad]

I have 4.56's and has lots of get up off the line. If you have a 3 speed without overdrive then you have a turbo 400 tranny. 700R has the overdrive.

[vic_V8]

I have 4.56's and has lots of get up off the line. If you have a 3 speed without overdrive then you have a turbo 400 tranny. 700R has the overdrive.

His trans talk was throwing me off, I just figured we was backwards.

[GreaseDog]

pretty sure 84 could still have a factory Th350c

[Koots]

I'm new to building trucks but
I just got a 84 k10 (long bed) this past weekend and hoping to do a lot of work to it.
By trade I work on boats. I work on cars a lot but have never done any custom work just repairs. The truck I got has had a
few changes done to it already,
like having a 305 to a 350 also a tranny swap. I don't know what he had in it befor but now it has a 700r turbo HD, at least that is what it says on the paperwork he had. The trany is a 3 speed auto but it had the a trany with the 3speed+OD in it befor. Gear ratio has got to be way off has no balls off the line. It has 31" tiers. How do I figure out the gear ratio that is in it now? and what should I change it to would be the next question. ( I plan on puting 35" tiers on it). Sorry if These are stupid questions. Any help is welcome. Thank you.

Verify what transmission you have first and foremost, the way you word that paragraph makes it sound like you have no idea what transmission is in it.

http://chevellestuff.net/images/auto_trans_id.jpg

Once you are sure, then you can calculate your new gear ratio. But it sounds like you have the wrong transmission, something wrong with your engine (no power) or You have the lowly 2.73 gear ratio.


pretty sure 84 could still have a factory Th350c

That is correct. My brother had a truck with one in it, not sure if it was stock or not, but the shift indicator only had 3 forward gears. It had the electronic lock-up though.

[vic_V8]

pretty sure 84 could still have a factory Th350c

you could get either, but I'd bet most got 700R4s like mine