Hey guys... I need your opinions on a drivetrain problem/issue I am having with a 50 chevy truck I am building. I took out the original drivetrain in this bad boy and am putting a chevy 292 inline 6 cylinder. I am pairing it with a 5 speed transmission out of an 88 S-10. I wanted to keep the 6 lug theme and have an open drive line, so I bought a rear end off a 55 chevy truck for 100 bucks. I was talking with a guy about repairing the pinion seal that was leaking, and he told me that the rear end I was using had really low gears and that I wasn't going to be able to go past 65 mph... Is this true?? He said I would be screamin down the highway at 65 tops... If so, what the HECK should I do?? I don't want to buy another rear end at all... Let me know what you guys think.. Thanks everyone, and have a merry Christmas!!
And, , , , what is the actual gear ratio? Bear in mind that the T-5 has an overdrive in 5th. To check ratio first determine if it is a posi; keep one drum from turning and see if you can turn the other. If so it is a single trac, in which case you see how many turns of the pinion it takes to make the wheel go two revolutions. With a posi you just go one rev.
If it's a stock '55 1/2 ton truck rearend, it's unlikely it is a posi. The most likely gear ratio is 3.90. Hmmm...seems like it might not be so bad with an 5-spd overdrive.
I looked for stamping on the rear end and I found something... AF915, and on the other side 236.. If that means anything.
Maybe your mechanic didnt realize you would be running an overdrive trans. Think of it this way, if you buy a brand new chevy tommorow, you can get 4.10 gears because of the overdrive trans. In fact, with that 6 cyl, your going to want the lower gears to run around with, then your T5 overdrive will pull it nicely on the freeway. Even if its a 4.56, which i doubt, you would be ok at 65, even 75. Its all about the overdrive Scot
If you really want to know the actual ratio, make sure the brakes dont drag on the drums, mark one of the drums and backing plates with a straight line. Turn the pinion gear and count the number of revolutions it take for the drum to go all the way around and come back to the mark you made. Example would be your pinion stops just short of 4 full turns, that would be 3.90 to 1 ratio just over 4 turns of the pinion would be a 4.10. Scot
Ok... I feel better now. I have been feeling lately I am going backwards with this project. Money is tight, and I don't want to shop anymore... Thanks guys!!!
I just got a 55 truck RE for my RPU project and found it to be 4:56 which is not standard for a 1/2 ton but was optional with the heavy duty transmission that was offered (still non-posi) My Firestones are 7.50x17 33"diam. so with a NP 440 OD trans I'm hoping for 2500 rpm @ 65MPH We'll see! BUCKD
Most all 1955 Chevy 1/2 ton pickups came with a 3.90 rear end ratio. The ones with Overdrive came with the 4.10. Either would be great with the T-5. It is a simple matter to remove the rear end cover and count the teeth on the ring and pinion to determine the exact ratio. Count the teeth on the small gear ( pinion ) and then the teeth on the ring ( large gear ). Divide the large gear number by the small gear number and then you will have the gear ratio.
For your information, there were at least two gear ratios offered in the 5-sp transmissions for the S-10, depending on engine. This included the final (OD) ratio. In my avatar, I've got a '92 S-10 5-sp that, evidently, came out of a 4 cylinder car and with a 3:73 rearend the old six is revving pretty good at 60 or so. Do a search on here and you can verify what tranny you have. Bottom line, don't sweat it. You've got a good combo there that will get you on the road and work well. You can always fine-tune it later with different rear gears, etc.
According to a cars and parts identification numbers guide FOR chevrolet trucks the 1955 rear axle is identified by letters and numbers. The first 2 letters indicate the year and truck series. The numbers indicate the date of manufacture. The A indicates that it is indeed a 55 chevy truck rear and the F indicates that its a 3100 designation. Which should have 3.90.1 gearing. I had this same rear end behind my hopped up 235 with a 3 speed and it worked great. Your T5 should work fine. I still have this rear end in my truck be a big block. It works fine. The 235 I had lurched a valve as my three speed popped out of gear and was over revved. I was doing about 70 at the time... I guess those transmisions have been known to do that in high gear... Your set up should work fine.
I too am stuck, I have a converted open drive shaft, 3100 Chevy Carryall. I want to keep the 6 lug axles, but also lucky that have a mid 50's OD trans. (I guess lucky having the OD unit may be debatable, I am looking to rebuild it. LOL) I found Ron's Machine service in MI. that has "off the shelf" new units, but only for cars. Do any of you know of a like service for Truck differentials...specifically mid 50's GM truck 1/2 ton units?? Or any sources that could help with my "Differential Dilma!"
Hi, you brought up an old thread that might or might not be pertinent to what you want to know. But I can't understand what your question is. Are you trying to repair a 55-59 Chevy truck rear end? or what? If so, what parts do you need?
The ring gear that I have howls badly, it is a "Mid 50's GM" that's all I know about it. I need it re built, I can't do it myself. Looking for someone to re build it or a replacement ring gear unit that has been rebuilt.
If it wasn't a T5 trans behind the 292 I'd agree with the guy. But even a 3.90 gear ratio wont result in extremely high rpm's when coupled to the T5 trans and in 5th gear on the highway. I have an OD behind my SBC with 3.73 gears, and 29" tires, and at 65 mph my tach says I'm at 2000 rpm's.
"Wes" 1971BB427's post number 16 is why Jim said that you are far better off to start YOUR OWN NEW THREAD when you have vaguely related question. Well being folks see and read post #1 and don't read through the comments to post #15 who reopened a thread that died 13 years ago. That style rear end was used in Chevy 1/2 ton pickups From Second series 55 through 63. and there should be new ring and pinions available. The Filling station shows a 3.38 gear set if you want to get away from the lower gears. Results: ring and pinion @ The Filling Station Store Classic parts shows the same gear set. Rear End Gears-3.38 Ratio-Classic Chevy Truck Parts (classicparts.com) You can probably find stock 3.90 gears though regular ring and pinion suppliers.
I couldn't find any. No 3.5 or 3.7 either. Most of the guys with pretty well stock TF trucks don't want to pull stumps they want to cruise down the highway at 65.
Get a Toyota 8-inch rear. They have plenty of modern support, have the correct 6-lug pattern, and can be had in appropriate widths.
Probably easier to find than a later truck rear...the 64-69 truck rears are 6 lug, 12 bolt, and the right width, but usually have 3.73 gears, and are usually worn out. But you can put 3.07 as well as several other ratios in them, and parts are readily available.
I have a '74 Blazer 6 lug rear end w/3.73's I am going to put in my '57 but it's about 1.5" wider than stock. So keep width and wheel size/offset in mind - there are charts online that can help. I also have a set of 3:08's with gov-lock I may use depending on what my transmission winds up being. Or you can do this: https://www.classicparts.com/1955-6...I5t2Z_PF2IzoQ67fZpjrQqBZHCeSY7nAaAqmUEALw_wcB
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