205 Question - Great Lakes 4x4. The largest offroad forum in the Midwest

Go Back   Great Lakes 4x4. The largest offroad forum in the Midwest > 4x4 Talk > General Tech
GL4x4 Live! GL4x4 Casino

greatlakes4x4.com is the premier Great Lakes 4x4 Forum on the internet. Registered Users do not see the above ads.
Search
Reply
 
Thread Tools Search this Thread
Old February 23rd, 2012, 12:02 PM   #1
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default 205 Question

Can you run a divorced 205 backward to get overdrive or would it chew itself up due to oiling, bearings, other?
I'm not the first person to think this up so the idea is not totally out there. It has been asked before with vague answers as to what would go wrong. If it could work I would leave it in .51/1 at all times only shifting into 1/1 for 4wd use. I would probably use royal purple 75w140 in it to lessen the noise.

Just want to get some info on this from knowledge base.
I was just wondering why it would not work. Or what I need to do internally to make it work.
cerial is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old February 23rd, 2012, 12:05 PM   #2
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

It would be used behind another transfer case so only the rear axle would see the increased rpm just under 4000 rpm.
cerial is offline   Reply With Quote
Old February 25th, 2012, 04:38 PM   #3
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

Been looking into this more. The 201 is a ps drop rear output. In order to keep the 205 between the frame rails I would need to use a Gm passenger side drop that would become a drivers side drop when turned around. Because I am just using this as a overdrive and the passenger side front output would become useless. I am wondering if I could remove the gear set yoke and bearings from the passenger side front output and block off the ends the front/rear passenger side leaving just the idler gear set and main rwd output/input gears and the rear output shift lever.
Removing the passenger front output gear set would be done to reduce wear of the useless output. The added room would allow for more fluid to be in the case providing better cooling and quieter operation.
Also cause I am turning this around and using a short shaft which I am guessing is going to be 6-10" center to center(need to measure the parking break clearance and )would I be alright retaining the rear gm rear output(that would become the input) slip yoke or be better off going with a fixed yoke?
cerial is offline   Reply With Quote
Old February 26th, 2012, 05:15 PM   #4
Torg38
TorgFab
 
Torg38's Avatar
 
Join Date: 07-01-10
Location: Howell Mi
Posts: 168
iTrader: (4)
Mentioned: 0 Post(s)
Default

The np205 has a 1.96 Low. If you ran it backwards would cut your axle ratios ~in half (ie 4:1 into 2:1) It's possible but there's better was to do it. You can use an 55-64 old gm three speed with 10spline in/Out It's a little transmission about the size of a football. The you would have 2 overdrives and on 1:1. Here's a pic http://www.google.com/imgres?q=GM+ca...429,r:17,s:115
Torg38 is offline   Reply With Quote
Old February 26th, 2012, 07:26 PM   #5
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

Those put out a .70/1 ratio I really need a .51/1. They are long and use electronics to shift. Would be really long as a divorced unit. There is also a free wheel at slow speeds where I will need the engine gearing and do not work in reverse. I looked at those, bronie boxes, and gv overdive. The 205 is the strongest most compact option. The cost to get one rebuilt is around $1000 where as the cost to rebuild a 205 is considerably less. They are around still but the parts are getting harder to find. The 205 is available and cheap which is why I consider trying it.

Think I will get a GM 205 remove the front output gearset and shift fork as it is not needed. Place a temp sensor in it. Then run it in reverse with a drill at 3000 rpm to see what happens. If nothing happens in the first hour I will check after 5 hours. if nothing happens after 10 hours I will tear it apart and check the bearings, seals, rings for abnormal wear. That's the current plan anyway.
cerial is offline   Reply With Quote
Old February 26th, 2012, 07:29 PM   #6
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

Some info on the 3speed od for those interested. It is nice but really picky as to what it works with.
http://www.chevytalk.org/fusionbb/sh...hp?tid/172013/
cerial is offline   Reply With Quote
Old February 27th, 2012, 07:03 AM   #7
Torg38
TorgFab
 
Torg38's Avatar
 
Join Date: 07-01-10
Location: Howell Mi
Posts: 168
iTrader: (4)
Mentioned: 0 Post(s)
Default

Quote:
Originally Posted by cerial View Post
Some info on the 3speed od for those interested. It is nice but really picky as to what it works with.
http://www.chevytalk.org/fusionbb/sh...hp?tid/172013/
Nope. Wrong one not the od style. Ive got both sitting on the plate i will snap a pic.
Torg38 is offline   Reply With Quote
Old February 27th, 2012, 09:45 AM   #8
Torg38
TorgFab
 
Torg38's Avatar
 
Join Date: 07-01-10
Location: Howell Mi
Posts: 168
iTrader: (4)
Mentioned: 0 Post(s)
Default

Click image for larger version

Name:	np203vs 3spdtrans.jpg
Views:	28
Size:	56.6 KB
ID:	89641

Here's the transmission next to a np203. The 205 was in a darker part of shop. But with the transmission. You run in back ward and you have two overdrives and direct. These are crazy tough. I ran one on the back of a circle track car for years with no issues what ever. 7000rpm x2 every lap :)
Torg38 is offline   Reply With Quote
Old February 27th, 2012, 10:03 AM   #9
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

^^^That's damn impressive.
So you ran it manually? I did not think it was possible to run these in reverse.
How did you do it?
What would need to be done to make it divorced?
More info on what model you used and any tips/tricks you leaned please.
cerial is offline   Reply With Quote
Old February 27th, 2012, 01:02 PM   #10
Torg38
TorgFab
 
Torg38's Avatar
 
Join Date: 07-01-10
Location: Howell Mi
Posts: 168
iTrader: (4)
Mentioned: 0 Post(s)
Default

It's 10 spline in and out. So if your wheel base is long enough, They came in both short shaft (in pic) or long shaft. Just mount it and roll. I think the GM 435 was 10spline so you can steal the yokes from it. As for the name, No one I every found knew the name of it. They just called it the old gm 3spd. 1955-1964 That sure made it a bitch to get parts for. Just find a parts guy with some grey hair, you'll be all set. It's all large gears and needle bearing inside, real easy to build. I always ran atf in it. Never had any issues, Nope,None, Any. For running it in reverse, That's not an issue. The sycro's have back cuts to hold in both forward or reverse. Otherwise under engine brake it would pop out of gear. Let me check around for some specs on it.
Torg38 is offline   Reply With Quote
Old February 27th, 2012, 01:20 PM   #11
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

So, I finish up my break and go back to work and start thinking about a reverse mounted transmission instead of the 205 transfer case. I like the 3 speed idea but wanted to see if I could use something more redly available. After a bit of searching I find the column shift t-90 from the old jeeps. It is very compact, parts are easily available, and it is fairly strong.
Then I start to think about the torque that would be put into the reverse mounted t-90 and realize why I wanted to go with the 205.

Example(I am just rounding the ratios up/down to keep it simple).
A engine that puts out 200 lbs of torque at low rpm mounted to say a 420 (with a 7/1 1st)then ran through a 203(with a 2/1low) would put out around 2800 lbs of torque in 1st gear/low. So a divorced 205 behind that setup would have around 2800 lbs of force being applied to the input yoke. This setup has been done quite a bit without any issue. The 205 has proven itself in this application.

Now placing a t-90 or a 60's 3 speed behind that 203 with the same 2800 of force being put into it has me thinking about detention.
I do not see any reason why a divorced 205 can not accept the same force running in reverse.

In your case of running the reverse 3 speed in a high rpm car to get overdrive makes sense because you were probably running 3/1, 1/1 or even a overdrive with a engine making less then 500 pounds of torque. That would produce 1500 or so pounds.

I could be wrong maybe you were running a 420 (reving high in reverse to get unstuck) and had 500 pounds of torque putting around 3000 ft/lbs into the 3 speed and it held up like a champ. In that case heck yea I'm all for using the 3 speed. But, for the most part the thought of detention by using a 3 speed has me looking at the proven 205 as the current solution.
cerial is offline   Reply With Quote
Old February 27th, 2012, 01:21 PM   #12
Torg38
TorgFab
 
Torg38's Avatar
 
Join Date: 07-01-10
Location: Howell Mi
Posts: 168
iTrader: (4)
Mentioned: 0 Post(s)
Default

SM318 is what google is calling it. Search images....
Torg38 is offline   Reply With Quote
Old February 27th, 2012, 01:33 PM   #13
Torg38
TorgFab
 
Torg38's Avatar
 
Join Date: 07-01-10
Location: Howell Mi
Posts: 168
iTrader: (4)
Mentioned: 0 Post(s)
Default

Your close but I still think you slightly off. Even a gear vendors overdrive will only handle 1200ft/lbs. What this system is used for is only for Highway speeds to allow to run steep gears. Then on the high way. Shift to OD and drop the engine Rpm's I would never suggest you Crawl/bog with the 2nd transmission in anything execpt High. You are right in thinking that FT/lbs x Gear ratio =input torque. But even the 205 can't handle it comning in the other way. The issue is that power is going from the large gears to the small gears when it's ran backward. If your going for OD the small trans is the right direction. But running ANYTHING backward with a monkey on the throttle will make it explode.
Torg38 is offline   Reply With Quote
Old February 27th, 2012, 02:04 PM   #14
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

Even in 1/1 high the input yoke on the 205 is still seeing 2800 lbs. of force when used as a doubler. The output is only 2800 though because it is not being multiplied.
My concern is that the 3 speed output shaft/gears would sheer off in high range. Where as the 205 has been put through this amount of torque or more before and has survived.
Running it in reverse means that the rear half(front normally) would receive 1/2 the torque then it is use to because instead of being doubled it is being reduced. On the flip side the input(rear normally) would be receiving exactly the same input torque as if it was running in high1/1 ratio.
cerial is offline   Reply With Quote
Old February 27th, 2012, 02:14 PM   #15
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

The setup I want to use this in is with a engine making a max of 200 lbs of torque with a max rpm of 2000 rpm, a 420, and a 203 to this overdrive unit. I am just using worst case situations that could happen.

Plan B is to run a chain driven sprocket to a second sprocket 1/2 its size to give a .5/1 ratio. Then put a divorced ford 205 to that. It would be moving at only 4000 rpm max and in the correct direction. It would require thick and heavy sprockets in a heavy box with heavy duty bearings and a heavy chain that would need to be adjusted. I also played around with the idea of running one using gears similar to a timing gear setup to get the .5/1 ratio.
This would give me the .5/1 ratio in high and a .98/1 ratio in low. I would just adjust my tire pressure slightly.

Last edited by cerial; February 27th, 2012 at 02:15 PM. Reason: .
cerial is offline   Reply With Quote
Old February 27th, 2012, 03:57 PM   #16
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

OK the .51/1 ratio box sounds better and better the more I think about it. It won't be cheap(guessing around 2k) or quiet. But I think I can have SCS make one easily enough that will be bullet proof. Then I could marry a 205 right to that and run it in the normal direction.
cerial is offline   Reply With Quote
Old February 28th, 2012, 10:28 AM   #17
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

The 5.1 gear box idea is stupid it makes the drive line way to long.

My other option (it it will work) that I think will work is using a spicer 5831F, or 5831G brownie box. The G has a 2/1,1.27/1 and 1/1. The G has a 2/1,1.31/1, and 1/1. Turn them around and you get 1/1,.78/1,.5/1 or 1/1,.76/1,.5/1.
They put these things behind diesel motors sporting low ratio transmissions so strength is not much of a issue.

I need to talk to more people about using them in reverse. But, this looks like the best fix. There are parts suppliers for these and they are not as hard to find or as rare as I originally thought.
cerial is offline   Reply With Quote
Old March 2nd, 2012, 02:57 PM   #18
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

After looking more into it a reverse brownie will not work. The gears would push out against the bearings and destroy the case.

So I am taking a much simpler approach going with a chain drive .5/1 box and mounting a second 201 behind the first turning in the correct direction.

I have a 201 in there currently that is ps drop rear output.
I am going to make a case that has chainpack inside and has a 1/1 gear running to a .50 sprocket. I am thinking of using 3-5 chains with a load strength of 4k pounds each. I will talk with some manufactures and get some advise on what will be the best sprockets and chains to make this work. I am going to have the chain box go from the 201's ps output to the location center transmission location then mount another 201 to that. Then I am going to connect the hi/low shift levers in both 201's. When in HI the front will be in 1/1 and rear will be in .5/1. When in low the front will be in 1.96 and rear will be in .98/1. The only downside of connecting the shift rods in the 201's is that I will loose 2wd HI. But, I will still have 4wd HI and will not need to cut into the floor to install new shifters.

By using chains instead of gears if at a later time I decide to install a center diff rear axle I will only need to get longer chains, make new shift rod connectors, and machine a new box.

This is the most simplistic, strong, and proven system that I have come up with.
cerial is offline   Reply With Quote
Old March 2nd, 2012, 03:07 PM   #19
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

Meant to say I would loose 4wd HI there^^^.
Running it in 4wd hi would give a 1.0 in the front 201's output and a .5 ratio in the rear 201's output.
cerial is offline   Reply With Quote
Old March 4th, 2012, 12:07 PM   #20
cerial
Senior Member
 
cerial's Avatar
 
Join Date: 09-06-08
Location: Caledonia,MI
Posts: 1,756
iTrader: (3)
Mentioned: 1 Post(s)
Default

OK I finally settled on what I am going to do.

I am going to get a spicer 5831 F 2/1, 1.27/1, 1/1 or 5831 G 2/1, 1.31, 1/1. I am going to make a .5/1 gear box and mount it directly to the spicer 5831's input. Then I am going to mount the .5/1 5831F behind the 201's transfer case. The .51/1 box would make the 5831F ratios into 1/1, .78/1, and .5/1. I could split the 420's gears for towing and would have highway speeds with very low rpm. For 4wd use I would simply put the 5831 in low providing 1/1 operation.

Now all I need to do is find a 5831 F/G that is or can be rebuilt.
cerial is offline   Reply With Quote
Reply
Great Lakes 4x4. The largest offroad forum in the Midwest > 4x4 Talk > General Tech
Tags
overcomplicateseverything

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 05:28 AM.


Powered by: vBulletin, Copyright 2000 - 2012, Jelsoft Enterprises Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
Page generated in 0.29584 seconds with 81 queries