Thread: Rear End

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what gear would my 84 10.5 boat rear end have in it it has a 305 motor??? what gear would i need to run to have a fast 1/4 and be ok to drive to work once a week???

new to hot rodding

It's prolly got 2.73's or 3.08's, a good replacement would be 3.55's, it's mean enough for the strip but, good enough for daily driving, a 4.10 would also work but, that's borderline.

thanks its limited slip is that good for the strip if no what could i do to it to be good but not to expensive lol thanks

Limited slip is fine, that means that it has some time posi, basicly posi in a str8 line but, becomes single powered wheel into a turn, it functions with a few clutches in the diff.

I'm sure he was just simplifying it down instead of writing a full on tech article about how a limited slip differential works. Whatever though.

Originally posted by Streets
You WISH it wuz dat simple... I love listenin' to the kids on CHR explain the inner workin's of an engine, tranny, and/or a rearend...

It's somthing along those lines. I'm not too familiar with limited slip, I understand posie and open diff. I know somewhat on how a manual trans works and I know nothing on how a auto trans works, other than they have clutch packs and bands, if I need 1 rebuilt, I'll take it to a shop, I think my dad could help me with a manual because he's rebuilt them b4. I understand how engine internals work. You should see the '32 3 window fendered model I'm building, I painted it stop light red, it's actully the color used to paint behind the chrome housings for the models that don't have the red colored plastic lenses and just the clear 1's. It was a pretty looking metallic red so I used it, I put it on the white molded body and I found it to be a transperrency color, it lightened it up and it's now a metallic red orangeish color, looks a lot like a true candy color but a little diffrent than like candy apple red. I painted the interior flat tan and the motor is gold. I hope to have it done this friday but, probably more twords next tuesday. I got that '25 T model done about a week ago, I'll post a pic when I get my camera software in my computer again, and 1 of the '32 model when I get it done. I got the compleatly clear ( even the bases ) model cases and I'm going to put 20 X mas light strands under each of the cases to light them up, should look nice.

Condensing is fine, if it's correct. It wasn't, so here's the tech article.

Limited slip is fine, that means that it has some time posi, basicly posi in a str8 line but, becomes single powered wheel into a turn. . .

Interesting logic, but, well, . . . . nope. It's pretty hard to understand posi, but not understand limited slip, since they're the same thing.

Start with the reason a limited slip differential is necessary. Because an open differential will always transmit an equal amount of torque to both rear wheels. If one wheel slips, zero torque is transmitted to the ground by that wheel. Zero torque is also then transmitted to the wheel WITH traction, so the wheel cannot transmit the torque to the ground to move the car.

Limited slip is a type of differential will (at least partially) split the torque to the wheels based on the amount of traction available to each. Positraction is a brand name (GM) for their limited slip differential. Other companies use terms like Traction Lok or TrueTrack. The reason it's called limited slip is because it needs to slip some when going around a corner, and it never fully locks up. However, limited slip does NOT mean that the positive traction effort goes away on the turn.

There are several types of limited slip differentials, but the most common in cars are the clutch type (like the GM Posi) and cone types (like the Auburn), or gear types (like the Detroit Truetrack). A these types of limited slip differential will continue to provide the torque splitting action, even going around a corner.

Your statement was closer to being accurate for locking differentials such as the Detroit locker. These differentials use a rachet action to lock the two axles together under power. When you go around a corner, they unlock - usually with a clunk - to provide true differential action. But, if you keep the power on, the axles stay locked, and an oversteer condition (push) occurs.

Originally posted by Henry Rifle
Condensing is fine, if it's correct. It wasn't, so here's the tech article.

Interesting logic, but, well, . . . . nope. It's pretty hard to understand posi, but not understand limited slip, since they're the same thing.

Start with the reason a limited slip differential is necessary. Because an open differential will always transmit an equal amount of torque to both rear wheels. If one wheel slips, zero torque is transmitted to the ground by that wheel. Zero torque is also then transmitted to the wheel WITH traction, so the wheel cannot transmit the torque to the ground to move the car.

Limited slip is a type of differential will (at least partially) split the torque to the wheels based on the amount of traction available to each. Positraction is a brand name (GM) for their limited slip differential. Other companies use terms like Traction Lok or TrueTrack. The reason it's called limited slip is because it needs to slip some when going around a corner, and it never fully locks up. However, limited slip does NOT mean that the positive traction effort goes away on the turn.

There are several types of limited slip differentials, but the most common in cars are the clutch type (like the GM Posi) and cone types (like the Auburn), or gear types (like the Detroit Truetrack). A these types of limited slip differential will continue to provide the torque splitting action, even going around a corner.

Your statement was closer to being accurate for locking differentials such as the Detroit locker. These differentials use a rachet action to lock the two axles together under power. When you go around a corner, they unlock - usually with a clunk - to provide true differential action. But, if you keep the power on, the axles stay locked, and an oversteer condition (push) occurs.

I thought positraction stood for positive traction, guess not. Thanks Henrey, that clears things up for me, at least now I know what's what when it comes to diffs.

Hi guys, I have been trying to find, (learn) out about diffs, eg, I have a GM 10 bolt diff in my Bucket. I don't know any more about it then that, and I almost forgot, it only smokes one wheel. The gears seem to be ideal for open road cruising, I think from memory when doing 60mph the motors is doing approximately 2000rpm. Question time.... what are the advantages of changing to a LSD apart from smoking both tyres??? How can you find what diff gears you have without dimantling the diff??? Should I just be content with what I have and start acting my age and drive more sedately

Okay guys I just searched this thread out again and I still have the same question,maybe I need to search (goggle) for the answers or I need alot more information to giv so that I get a more informed answer,but I am really a novice when it comes to the rearend of vehicles. One reason I am asking is that a modified car up my street seems to have a locked diff as whenever he turns out of our street one can hear the inside rear scuffs the tyre as if it is trying to drive the car around the corner also. The diff in my bucket only drives or skids only one wheel and I wonder if a LSD diff would be a better advantage to me. I have never drag raced my car on a strip although it is something I would like to try,but the car is more for street use.

Sounds like the guy up the street has a spool--solidly connects both axles with no slippage in turns, more of a drag race only deal, not good on the street. The 10 bolt GM had a limited slip differential available, think there's a couple different ones in it depends on which axle housing you have, maybe some GM guys will chip in on that... There are a number of aftermarket companies offering limited slip rears for a 10 bolt. For street use and maybe an occasional blast at the track might want to check and see what Auburn has available. A 10 bolt isn't the strongest rear end on the market, but in something as light as a T Bucket it should hold up ok with a limited slip installed.

So what is that saying....."if it isn't broken,why fix it".... Thanks Dave for the info. This hot street car up the street has really opened my mind to the different type of diffs and made me question what I have and what advantage changing my diff centre would make. When I purchased the bucket it had 14" wheels with 60 sidewall tyres which when I purchased the Halibrands I went to 15" with a taller tyre which has given the car better cruz'n gears for the open road. As I said I would like to try my luck just for fun on the strip to see if I am any good but I have heard that dragracing is very very addictive. Maybe if I put the old wheels back on the back just for the strip that could improve the diff ratio for strip work,only for fun ofcourse.

I've always used Detroit Lockers on my street/strip cars, They work good and are strong.

Not sure how my post got miss placed.....but here is what I said:


For a car that is already done,I am thinking you don't want to hear what I am about to post,but what the heck.No matter what rear end you choose,make very sure you don't choose a rear end ratio that would over rev your engine combo.

Given what you say you want to do,I think if you had a Ford 9' built for your rod,it would be the easiest to have both rear end gear ratios.One center carrier spooled for the strip and another posti for the street.Of course the one for the strip would be geared for that and the one for the street for highway cruising.They are very easy to swap and certainly are a stronger rear end than the 10 bolt.
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I have reached a age and decided I am only as good as what I leave behind for others to use and learn from.

Thanks Gary,Steve and Dave. I will be totally honest now and explain that I 'm one of those type of rodders that doesn't really understand the fine points of how the internal parts of certain auto bits work. Like I have absolutely no idea of how an automatic transmission works and really don't care to learn as if something broke in mine,it would be taken to the expert to be rebuild. But as my old Father used to say," the day you die,is the day you stop learning" and the other saying that I got from Jim Robinson is "the only stupid question there is, is the one not asked" so excuse me for asking,but that locked diff in that modified car really got to me as it sounds really healthy coming down the street then when he turns out of the street the car makes a real loud scruffing sound from the rear.