gear ratio. turned tire 1 rev and driveshaft went 5

[derf]

Those gears would never last. They are all made for racing. Racing gears may be strong but they wear out quick.

Never buy an even gear ratio such as 4:1 or 5:1 and put them into a street vehicle. The reason is if the gear ratio is 4 to 1 then every time the ring gear rotates each tooth will mate up with the same tooth on the pinion gear. A small nick on one tooth will quickly wear the tooth on the other gear. If the gear ratio is 4.11 then the gears will wear much more evenly and last much longer.

A racer wants much more selection of gear ratios. The 9 inch ford rear end has a removable third member. The team can quickly swap out the third member to get just the right gear ratio for that course. They never expect to get very high mileage out of thier gear sets.

A gear set for street use is very hard (for high mileage) but not very strong. A racer may break one of these teeth because they are slightly more brittle. Compare this to a tap that is much harder than a bolt but much easier to break if you turn too hard.
A gear set made for racing is very strong but not very hard. The teeth may flex to the slightest degree but they don't break. Instead they will wear quickly if put in any vehicle that puts on much mileage.

You'd think that they would put some kind of warning on those gear sets if that were the case. It's not that I don't believe you. I understand how the teeth pattern doesn't mix all teeth eventually. But I had never heard about it causing rapid wear. All of those gear sets come with the same 1 year warranty as any other ratio.

I can see that racing gear sets would be hardened differently than those intended for street use. But I would think that would apply to any racing gear set and not just the "even" teeth gears.

I tried searching on google for some more information but I'm not coming up with much. Do you know a good place for an engineer like me to go read up on the topic?

 

[BusaDave9]

I can see that racing gear sets would be hardened differently than those intended for street use. But I would think that would apply to any racing gear set and not just the "even" teeth gears.

I didn't mean to imply the ring and pinion sets with even gear ratios were made with different metal. These are 2 different issues that both affect the long term wear of the gears.
It was years ago that I first read that a ring and pinion with an even gear ratio such as 4:1 would not wear as evenly or last as long as other gear sets.
The metals that are used for gear sets are a separate issue.
I will do some searching for on-line references.
The book, "Differentials: identification, Restoration & Repair" by Randy Lyman is an excellent reference. He talks a little about the metals in racing gears but for the most part the book is about gears and differentials as they apply to jeeping.

 

[derf]

I didn't mean to imply the ring and pinion sets with even gear ratios were made with different metal. These are 2 different issues that both affect the long term wear of the gears.
It was years ago that I first read that a ring and pinion with an even gear ratio such as 4:1 would not wear as evenly or last as long as other gear sets.
The metals that are used for gear sets are a separate issue.
I will do some searching for on-line references.
The book, "Differentials: identification, Restoration & Repair" by Randy Lyman is an excellent reference. He talks a little about the metals in racing gears but for the most part the book is about gears and differentials as they apply to jeeping.

I wasn't thinking different metals so much as different hardening levels depending on intended use. But I suppose different alloys would be used too.

I'll go look up that book. And if you can find any more references, I'd like to read those too. I'm seriously under-educated on this topic and anything I can do to learn is a good thing.

 

[johnbilt]

Must be a Dana 18 Tcase if you have an offset rear axle. The Dana 20 has a centered output. The D18 has some advantages as the low ratio is 2.43 and you have an option of an Overdrive unit. The Dana 20 is quieter because the main output is driven direct in 2WD rather than through the countershaft. No Overdrive options with the Dana 20 .

 

[1986cj7]

I bet it's a 4.88. It was just shy of 5 turns. my guess was 4.9. Thanks. I just posted some pix. Is the rear a 44? What about the front? I definitely need to upgrade to power brakes and steering. I will have to search the forum for my options. I hope it's not too difficult to do. Steer me in the right direction if you would be so kind... anyone. thanks brothers...and sisters, maybe?? Never know.

IMO power steering would come before power brakes, I have manule brakes on my 86 and they work just fine. Don't know how anyone else thinks but I think manule brakes are better if you happen to stall out on a hill. Just my .02

 

[BusaDave9]

IMO power steering would come before power brakes, I have manule brakes on my 86 and they work just fine. Don't know how anyone else thinks but I think manule brakes are better if you happen to stall out on a hill. Just my .02

I agree. I have 36 inch tires with manual brakes and power steering. I stop just fine although I press a little harder on the brakes than others. If I had manual steering I wouldn't be able to get around on the rocks or other times at slow speeds.

 

[BajaEdition]

IMO power steering would come before power brakes, I have manule brakes on my 86 and they work just fine. Don't know how anyone else thinks but I think manule brakes are better if you happen to stall out on a hill. Just my .02

you must remember you have far superior brakes to his late 60s Jeep
if you have disc, he does not, and if you have shoes, they are 2 inches bigger than his plus wider
when we compare here we need to compare apples to apples not apples to kumquats.

 

[JR74CJ5]

IMO power steering would come before power brakes, I have manule brakes on my 86 and they work just fine. Don't know how anyone else thinks but I think manule brakes are better if you happen to stall out on a hill. Just my .02

I agree. I have 36 inch tires with manual brakes and power steering. I stop just fine although I press a little harder on the brakes than others. If I had manual steering I wouldn't be able to get around on the rocks or other times at slow speeds.

Totally agree ^

Only reason I can think of for power brakes, is if say you're planning to tow heavy. And that opens another can of worms.

(Edit: Does the disc vs drum also have something to do with brakes staying cleaner one way or another? Or heating up and cooling better etc? I suppose those could also be reasons one way or another...)

Even still, Uncle tows a pretty heafty trailer up the hills and down, we use the gears a lot to slow us, and pay attention to whats going on a little further ahead than normal. Manual brakes should be sufficient, but again, your ride man! So it is doable for sure!



~ JR

 

[BusaDave9]

you must remember you have far superior brakes to his late 60s Jeep

Good Point!
I am amazed how well my manual brakes stop me but my CJ is a '79 (disk brakes up front)

 

[BajaEdition]

guys, once again let me point out
all of you are driving jeeps with far superior brakes to a late 60s jeep, the brakes on jeeps from about 69 and older are small in diameter and narrow in width, and the are shoes, not disc
almost any modern owner has put on better brakes soon after getting the Jeep, unfortunately if you have read the thread, it is near impossible to put power brakes on with out a major reengineering job to the pedal placement, firewall and other linkages effected

 

[jwillys]

Ive driven very little without power brakes. I agree though that if the engine stalls manual brakes are better. As far as power steering, I am going to install that fir sure.

 

[JR74CJ5]

you must remember you have far superior brakes to his late 60s Jeep
if you have disc, he does not, and if you have shoes, they are 2 inches bigger than his plus wider
when we compare here we need to compare apples to apples not apples to kumquats.

True true I did not se this before posting my response. Mine and Uncles are 72 and 74.

guys, once again let me point out
all of you are driving jeeps with far superior brakes to a late 60s jeep, the brakes on jeeps from about 69 and older are small in diameter and narrow in width, and the are shoes, not disc
almost any modern owner has put on better brakes soon after getting the Jeep, unfortunately if you have read the thread, it is near impossible to put power brakes on with out a major reengineering job to the pedal placement, firewall and other linkages effected

Baja,

Would it be easier, and not lack much gain, from swapping in a Dana 30 front from a 72-75? It would not be power still, but be better? (larger brakes, still use same system otherwise??)

Probably pick on up for much cheaper, and easier to put in than power conversion (again, unless set on power ) or am I forgetting a Narrow track change of width during that timeline...

Now sitting here to learn

 

[BajaEdition]

in my 67 I swapped in a Dana 30 with disc knuckles, so that would be a 77 or later
one of the big advantages was the spindle of the Disc Dana 30 has the spindle you need for Disc hubs, the Shoe brake spindle is different. I had tried to get disc on my D27, ( I do not mind maintaining closed knuckle ) but found that you have to do some conversions to get them to fit the spindle, well they use the same specs for the outer spindle so they do not have to change the brake hardware in later Dana 30 shoe brake axles.
So if you pickup a Disc break axle you are ahead of the game and just use common bearings front and back of the hub, not different ones. etc.
then I looked at my GM brake setup and realized I had to cut off the mounting hardware for the Jeep brakes.
I wanted to use the GM brakes as they are much stronger than the jeep ones.
so I mounted the mounting plate and put all the stuff on with the GM brakes, did a few single jack adjustments to the angle of the plate and Blamo, I had disc brakes.
I had already put in a 2 piston M/C and divided the brake lines.
now, when you go from shoes to disc you need to find the back pressure device and get rid of it. Disc do not require back pressure like shoes do.
Once I had the front done I decided to do the rear also, I already had converted to full floating so all I had to do was get a Gm to Dana 44 kit and mount it, get rid of the back pressure device and cut in a proportioning valve.
My brakes stop me fast now. and hold like glue on slopes. No they are not like power brakes at all, a set of power brakes on 4 GM 3/4 ton disc on a early CJ5 and I would need a net in front of the window to catch the glass every time I braked.

 

[johnbilt]

No offense intended, but I have a hard time accepting that these ratio's would actually cause any real world difference. The reason that we have the specific ratios available is due more to diametric pitch and the mechanical limitations of the gear profiles. Plus the gear has to fit within the case and on the carrier. I have never seen an even number ratio, although 3.08 or 4.11 is close. Are these common in a quick change gearset??

 

[BusaDave9]

No offense intended, but I have a hard time accepting that these ratio's would actually cause any real world difference.

. . .
I have never seen an even number ratio, although 3.08 or 4.11 is close.

I have never seen an even ratio gear set either until Derf pointed them out to me. As far as the ratio is concerned there is almost no difference between a ratio of 3.08 and 3.00. But the big difference is the fact that a ratio of 3.00 means there is exactly 3 times as many teeth on the ring gear as the pinion gear. What that means is each time the ring gear rotates each tooth will match up with the exact same tooth on the pinion gear. That is the reasoning that I have read that the gears will not wear as evenly. A small nick on one gear will wear the tooth on the other gear since it always meshes with the same tooth. It makes sense to me but I am having trouble finding a source to reconfirm this.
If the gear ratio is 3.08 then each rotation of the ring gear will have teeth meshing with different teeth on the other gear. Much more even wearing of the gears.

 

[johnbilt]

Interesting - Something I have never considered. My Limited metallurgy knowledge tells me that most mated metal surfaces work best when worn in together. Kind of like a cam and a lifter. Wouldn't a damaged gear tooth on a pinion wear all the teeth on a ring gear since it does not a have a even ratio?

I've found that once excessive wear begins to occur, the chunks usually travel around and distribute that damage equally eventually. Broken spider gears are excellent for this! And I'm always the last one to find out!

 

[BusaDave9]

Even Gear Ratios - I did some more checking on the ring and pinion gears that have even gear ratios of 3 to 1 or 4 to 1. These gear sets are considered Non-Hunting Gear Sets.

Most Ring and Pinion gear sets are Hunting Gear sets such as a 4.11 gear set. That means with each rotation of the ring gear the teeth of the pinion mesh with different teeth this gives even wear to the gear sets.

Non-Hunting Gear sets have even gear ratios such as 4 to 1. These gear sets are uncommon but if you do buy a Non-hunting gear set it must be timed. This is to make sure the correct teeth of the ring gear mate up with the correct teeth of the pinion gears. This will ensure long life of the gear set.

Semi-Hunting Gear Sets have a gear ratio of something like 3.5. This means that after 2 or 3 rotations the same teeth will mate up. Semi-Hunting Gear Sets also have to be timed.

How do you time a Non-hunting or Semi-Hunting gear set? Easy, the manufacture paints a tooth on the pinion gear and a tooth on the ring gear. They made those 2 teeth similar enough to be an exact match. I don't know how they do it but that is why new gear sets that have even gear ratios don't have a problem with wearing out early.

Here's my sources:
This first one is a Google book: Automotive Fundamentals By Glen Merrill
Automotive Fundamentals - Glen Merrill - Google Books

Another Google Book: Automotive Service: Inspection, Maintenance, Repair
By Tim Gilles
Read the section "Hunting and Non-Hunting Gearsets"
Automotive Service: Inspection ... - Tim Gilles - Google Books

In this PDF look for 3 sections on Hunting and non-hunting gear sets.
http://www.ellum.ch/forum/Cougar67/...nd mustang Shop Manual/group 4 Rear Axle.pdf

 

[BajaEdition]

well I keep learning more and more here at Jeep-CJ.com

I can see why we are starting to pass other sites up, in tech knowledge we keep pushing the envelope. I mean who else would be discussing the subject of gear matching to the degree we are here.

 

[derf]

Even Gear Ratios - I did some more checking on the ring and pinion gears that have even gear ratios of 3 to 1 or 4 to 1. These gear sets are considered Non-Hunting Gear Sets.

Most Ring and Pinion gear sets are Hunting Gear sets such as a 4.11 gear set. That means with each rotation of the ring gear the teeth of the pinion mesh with different teeth this gives even wear to the gear sets.

Non-Hunting Gear sets have even gear ratios such as 4 to 1. These gear sets are uncommon but if you do buy a Non-hunting gear set it must be timed. This is to make sure the correct teeth of the ring gear mate up with the correct teeth of the pinion gears. This will ensure long life of the gear set.

Semi-Hunting Gear Sets have a gear ratio of something like 3.5. This means that after 2 or 3 rotations the same teeth will mate up. Semi-Hunting Gear Sets also have to be timed.

How do you time a Non-hunting or Semi-Hunting gear set? Easy, the manufacture paints a tooth on the pinion gear and a tooth on the ring gear. They made those 2 teeth similar enough to be an exact match. I don't know how they do it but that is why new gear sets that have even gear ratios don't have a problem with wearing out early.

Here's my sources:
This first one is a Google book: Automotive Fundamentals By Glen Merrill
Automotive Fundamentals - Glen Merrill - Google Books

Another Google Book: Automotive Service: Inspection, Maintenance, Repair
By Tim Gilles
Read the section "Hunting and Non-Hunting Gearsets"
Automotive Service: Inspection ... - Tim Gilles - Google Books

In this PDF look for 3 sections on Hunting and non-hunting gear sets.
http://www.ellum.ch/forum/Cougar67/...nd mustang Shop Manual/group 4 Rear Axle.pdf

Looks like I have lots of good reading coming up...

 

[johnbilt]

Excellent Info - Thank you very much for the research and links! I have a good book on performance differentials and another on making gears. I don't think I have come across that discussion. I'm going to dig my books out again. Great stuff.