I know there are a lot of 55-59 chevy truck guys out there. i need some rear end advice. Rebuilding the 235 and really only plan on upgrading the CAM, Offy or Clifford 2 carb Intake, and probably a set of Fenton headers as recommended by friends. Since my truck is currently a 4 on the floor, I'm going to most likely run a T5 for my trans. I'm not sure what my total HP will be, but reading online those mods should gain approx 50% of my 120 which could possibly put me at a stunning 180HP. With the T5 being a 0.78 5th gear ratio, i want to make sure what rear end i put in there, I'll have enough power to pull 5th gear. Disc brakes would be a preference and of course the same with. I know the stock 390 rear end will work, but if there's something out there with disc brakes, a little lower ratio then .390, and my truck could handle, thats what i'm looking for. Would be nice to go to the Junkyard with a list of a few candidates so i can easily obtain something that would work. thanks for your help guys. i posted a thread about my disassembly progress. i attached my current status. thought about throwin a bucket seat on here and driving it around like this.
Stick with the 3.90 unless you never go where it's not perfectly flat Slight hills, but real l-o-n-g ones, on the highway will be your downfall if you go too low...then downshifting is not an option IMO Why disc rear ? .... not needed. Keep it simple.
the overdrive will give you a 3.04 final drive ratio (3.90 x 0.78) which is probably as low as you want to go.....I agree with leaving it stock, assuming the rearend is in good shape. I'd pull it apart and see, first.
Outside of a sports car, rear disc brakes are a marketing tool more than anything else. I only put them on 4x4 stuff to get rid of 70-90 lbs of un-needed drum weight from a 1-ton axle. Keep the stock rear. You already have it, and it is already in there, as Squirrel says, assuming it is in good shape. Open it up and have a look.
thanks guys. havent decided on the front end yet. everything i've read points towards the mustang II and a power steering option which seems like it would really help, plus the discs up front. i've been researching the drop axle for the front which keeps the stock suspension and lowers it 4 inches like the rear with the leaves under the axle conversion package. a 4" drop all around should give it a much nicer stance. i dont need to get too low. with the drop axle in the front at least i'd have 4 matching 6 lug rims for the time being. if i convert over to the IFS i dont think 6 lugs rotors is an option, so i'd have to get 2 sets of different rims. seems like a pain in the ass as far as rotating tires goes. seems like i'd rather have 6 all around or 5 all around. is there a 5 lug drum conversion for the rear if i end up going IFS for the front so i can have 4 matching rims?
You can get the rear axles and drums re-drilled to match the new pattern in the front; or, you could even get the front rotors re-drilled to match the rear. Either can be accomplished by a competent machine shop, for not too much green.
i'm putting a t-5 in my '58 and keeping the stock rear which i believe is a 4.10... i am running l78 bias plys in the rear which are fairly tall, so that is also something to consider... and especially w/ the 235, rear discs are really unnecessary
I think your current, stock 3.90 ratio is about ideal for a lightly modded 235 with a .78 OD T5 (3.90 x 0.78 = 3.04). I don't know about the trucks, but on '59 through '62 Canadian Chevs and Pontiac passenger cars with 235s (and 261's standard in the Pontiacs) and 3-spd sticks. a 3.08 rear gear was a common available "economy option' and worked ok. That was with an proximately 27.5 inch tall tire. Unless the tires on your truck are going to be apprecuably more than 28 or 29 inches tall, I'd stick with the the stock 3.90 ratio. Don't be fooled by the seeminly low 'horsepower' numbers either. Remember that the 235's forte is its very good low and mid-range torque - with a nice flat curve too - rather than high rpm horsepower, so it can pull a higher rear gear than the actual hp would seem to indicate. Mart3406 =======================
I have a 8.5 10 bolt out of a 70s Camaro/firebird and installed 3.73s/posi. I left teh drums as they are adequate and put disks up front so I have 4 3/4 all the way around. As well I have 7.50x16 Coker radial whitewalls which are about 30in tall...5 gear is highway only. I have the blown 270 GMC out right now for freshening up and have a stock '57 235 motor with dual exh,long tube headers, that runs great, but as said a hair down on power in 5th and hills. I have a 4inch drop axle and drop mono-leafs up front...it's low and even with the monoleafs...still rides like an old truck. I am adding a toyota ps box that you can mount a bit further back toward the firewall to lessen bump steer. I'm making a custom tilt column that tilts under teh dash so it still looks like a stock small diameter tube column, so will have U-joints and can move teh box even closer to the firewall than with a normal column though. I drove many many miles in mine with stock 3.09s, T5 and original motor iwth those tall tires, with original brakes set up right even the drums do an adequate job
Good to see you doing your home work Jesse. Sumter County swap meet is this Sunday, you might find some parts for your project. Dallas and I both run modified 235s with t-5s. We run 336 rear gears and it feels perfect. Our tire size is probably a little smaller than what you will be running.The tire size you run will be a factor and determining what your size will be is a good idea.
A Ford Explorer rear end is 60 inches wide ... ( 1 inch per side ) more narrow than the original Chevrolet rear end. Many are available with 3.73, POSI and disc brakes. They have the real common 5 on 4.5 Ford car wheel pattern ( like a lot of the Mustang II conversions ). And the Explorer rears are cheap to buy. Most every Pick - A - Part has rows and rows of them.
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