I have received several questions/requests about my underdrive. Tim Hardy makes the underdrives. He has made them in various ratios. I have been using the 1.25 unit since Moon Rocks event. The 3.29 to 1 unit is finished and will be installing it in a day or so.

The underdrive units replace the short shaft between the transmission and the X-fer case. There is no in/out shifter lever. Bolt it in and it works, don't need it simply remove it and put the short shaft back in. The underdrive fits in easily with no hassle in squeezing it between the tunnel and the X-fer case. Takes about 10 mins to do this.

The underdrives are a great way to go. If you are running a stock X-fer case and the stock 3.73 gears this is what you get

1st Gear = 3.652
Stock X-Fer Case = 2.268
Stock Ring & Pinon = 3.73

Stock Samurai Low Range
3.652*2.268*3.73=30.89 Okay with little 205-70-15 tires

With Tim's Under Drive = 3.29
Samurai Low Range
3.652*3.29*2.268*3.73=101.65 What a big jump to big tires

With the underdrive one can see the advantage of the low crawling gears, without having to purchase additional expensive stuff like Ring/Pinon & X-fer Case.

Now lets take the average modified Sammy with the 4.16 X-fer case and the Tracker 5.12 Ring/Pinon (The most popular converson to date)

3.652*4.16*5.12=77.78 Great ratio we have all used for years

Now lets add the underdrive
3.652*3.29*4.16*5.12=255.91 WOW!! Now that's crawling

I only used the mosty popular ratios. With these figures you can figure out your own advantage to these under drives.

A couple of Pics
http://www.calweb.com/~mgolub/images/underdrive1.jpg

http://www.calweb.com/~mgolub/images/underdrive2.jpg

As for the price of these under drives I cannot answer this question. The best way to get more information is just to call Tim's Shop at 530-626-9138. This is nighttime after regular work hors number. Tim works a regular job from 8 to 5 then goes to his shop. It might take a day or so for the return call.

SAR_Sammy
Mike

it has to mount somewhere to keep it from turnin circles under the truck right?.....just wondering.....:confused:

so, does this mean a poor college kid could afford it or not? I won't be able to call him for a while, so can you just give me a rough non-numerical estimate for the unit? SOmething like "it's gonna run ya the same as sumo t-case gears."

thanks for the pics.....planetary design answers my question.....will be callin soon....thanks again for the info

I'm with Nuttzack, can a college boy afford em'? What can we compare them to, for a price that is?

I have a wife thats an instructor and my kids quallify as classmates so I guess Im a poor college student also can I affrord them too??????????

The question stands?

Looks like a mounting point, maybe to the stock t-case via a small plate/adapter. I bet it costs what a 4:1 does, although it would be cool if it were cheaper. Also, don't forget you top speed in high would be somewhere around 30-40 mph with 3.73's and large tires. No free lunch.

Originally posted by Bill4rest
The question stands?

My guess, that's where the "torque arm", which keeps the housing from rotating, connects to.

3.652*3.29*6.09*5.89= 431:1 !!!!!!!?!?!?!?!?!? :eek: :eek: :eek:

heh, walk your dog with your zuk. put it in first, let it go down the road, check on it every day or two :D

how long has he been making these? why is this the first i've heard of them? seems like it would be a very economical way to get some extra gearing.

have any broke yet?

Originally posted by poppycock
have any broke yet?

I know he did it long ago, possibly around 1995ish? As I was told he stopped making them for awhile cuz they kelp breaking, I could be wrong though. it was a "I herd from a friend" kinda deal.

Yeah those were featured in an old how to build a Sami article in Petersons about 1995-6. I think the unit was out of a forklift or something...low gears, but better have a tow rig!

Originally posted by scwafish
Yeah those were featured in an old how to build a Sami article in Petersons about 1995-6. I think the unit was out of a forklift or something...low gears, but better have a tow rig!

Even with a tow rig I don't know. I do mainly rockcrawling so at first glance this sounded like a cool idea. Then I remembered we did 35 miles cross country on Sunday, at times going over 50mph down the washes and backroads. The higher ratio might work, but no way the 3:1 unit would, I still need to be able to move fast to cover ground. That higher unit might be interesting with an auto tranny like Zukster used since first gear is only about 2.4:1 compared to the 3.6:1 in the manual.

Boy go to work and look what happens to the posting when I get home...

I have received various PM's about the under drive's. Mostly about the price. Again I state I do not know as mine came to me in a friend kind of way. Tim & I were talking about them today while we were going thru my broken T-Case

(BTW the T-Case broke due to the front drive line bolts either came loose and fell out or they sheared off. What happens next is one bolt remains and the drive line goes off center. Then it drives the T-Case vertical and the mounts and body of the T-Case can't take the angle and SNAP goes the case)

He stated depending on how many people want them (those with $$ in hand) and if he can get the bodies mass produced the price will drop. The price right now is just around a grand. Sounds like allot but you must remember they are all hand made, case and all, and that takes time so it costs money.

Depending on your calls to him and demand he will go into production again.

As for your guesses on what/how they are made you guys are all wrong. Wish I could trell you how he makes them but I will honer his request and hold back.

One of the posts talked about them breaking. To this day only one has broke and it was because one of the owners felt he had to weld the U-Joint lock nut down and when the bad weld broke it messed up the input shaft. Other then a user modifacation not one has broke to date.

Why did he go out of production easy answer no call for them. Until now that Sammies are going to big axels and big tires. Now the demand appears to have returned.

Just call Tim he doesn't bite. The only draw back is that it takes time for him to call you back. If you are planning to call, Call this week or wait 2 weeks as he is leaving the the Ultimate Adventure again like last year if you caught him in the Mag.


Anymore questions I'll try to answer them for you....


SAR_Sammy
Mike

$1000!!!!!????? :eek: :eek: :eek: ok i thought these things would be like $200 or something... for a $1000 there are so many better options available.

Then make one yourself........

Nothing stopping you but you....

Then see how many hours it takes to build one by hand......

Then what would you charge :confused:


Mike

no i personally wouldn't use one. my point was that there other options when your gonna throw that kinda cash around.... i.e. a new friggin tcase for that money or 6:1 gearset and save $400 and have the high range still.

1K is not so bad considering all the other mods that would have to be made to get to that ratio ...
Is it not best to gear at the case ( or before) to save stress on other parts ?
10 min to go from streetable gearing to trail wild seems cool as well.

takes about 1 second to shift a tcase to low range... maybe if it could shift hi/low it could help justify the cost... but it still seems like too much for too little to me.

multiplies Originally posted by CragRat
Is it not best to gear at the case ( or before) to save stress on other parts ?


it multiplies as it goes back... seems like the furthest point forward would make it last the longest. just like where it's designed to go.

Really the point is that those of us who run the old 4 to 1's and have gone to really big tires as well as the expense of the other hardware to handle big tires and such. This is a viable alternative to shelling out the 1200 or so bucks plus shipping for a 6 to 1 that will only get you about 130 to 1 or so depending on your other mods. For less then the cost of a new X-Fer case one can keep their 4 to 1 and get a ratio as high as 300 or so to 1.

Hence a great crawl ratio to make your Sammy kick butt

I suppose that something like this would primarily be for a trailer rig?? You are right about losing a high range we are all used to, but to me a worth while sacrafice...



Mike

I still want one, but that is more than I expected.

It's worth every penny coming from Tim. He is a top notch guy and builds all kinds of wild stuff from hand :D. Think of the ratio and price compared to a klune V, plus I am sure it doesn't weigh as much. Shure you don't have selecta-shift but who else makes an intermediate gear reduction, let alone by hand he he.

:flipoff2:

I'd love to have one but don't have a grand to drop on it. I'm sure its well made and all, but I'm a college student and cannot afford things like this, not to mention food (I spent my grocery money for the month of may on yota axles :D ). But if anyone wants to sell their 4:1 to raise money for this thing, I'll buy it for 3-400. It does look like a quality piece, and for a thing like a rocky buggy or competition buggy, I imagine its worth its weight in gold.

lets see ...
3.652*3.29*5.81*3.73=260.3824 = :D

I want one ...

Why do you need that much reduction? I have 74 to 1 in my yota and it is more than enough. I met tim on memorial day and told him about one of his recent customers accident. Hes a nice guy judging from the 3 min. we talked. But any way if you have a 4 to 1 kit then the 6 to 1 will only cost about a 800 to 1000 depending on what you can sell to your buddies for. this would keep you well under or right with the price of a underdrive driveshaft and it does seem a hassle to get out and remove or instal it everytime you get or leave a trail. The only use for it I could see is a rock buggie. With a 4.89 to 1 tcase you can install the gears yourself and it's also cheaper. But if you are driving a sammi there is a good chance its your dd. If you resort to gear reduction to make up for tire size you are also sending tons of simulated torque to stock axle and the motor is still the same 1.3l or 1.0l in 85 and older. just think a $1000 DOLLAR DRIVESHAFT!!!!!!! Oh by the way very nice samurai mike I saw it memorial weekend on the trail a couple times very clean.

Originally posted by noodles
[B]Why do you need that much reduction? I have 74 to 1 in my yota and it is more than enough. I met tim on memorial day and told him about one of his recent customers accident.

Because our stock motors are completely gutless. Pull 2 of your spark plugs and that'll give you an idea of what it's like to drive a Samurai :D

I didn't have to pull 2 plugs on my last motor the holes went out for me:D That also explains my theory on you trying to make up for power with to much gear reduction. what good is it when you are in third gear goin through the sluice box? Why don't you spend the same amount of money and get and install a 1.6 sidekick or a 1.8 esteem motor? Cost is about $800. You are trying to make the 38 hp that makes it to the rear wheels actually do something.

Originally posted by Azrckcrawler


Because our stock motors are completely gutless. Pull 2 of your spark plugs and that'll give you an idea of what it's like to drive a Samurai :D



Thats too funny!!!!!!!!!!! I have a friend who said ( before I did the 4.3) that he had more Hp in one cylinder than I had in my whole 1.6. So I told him to pull 7 wires on his 400 ( In a Fiero) and I'd race him. :D :D :D :D :D :D

Well, since Tim loves taking credit for everything under the sun, I think I will point out that Ki (sp?) did a production run of these many years back. May have been the first gear set for the Samurai... I have no idea as it was long before my zuk days began. For all I know, maybe Tim did build the first ones.. You got the hell out of me.

By the way, it is just a simple planitary gear set. The trick is making it work. :smokin:

-Wayne

You are mostly correct. Time built one for Ki (sp?). Ki did not do any production run on these to my knowledge. Tim built a few and the demand ran out so he stopped. That is until now. Early in this thread someone mentioned an article. It appears in March 1997 Four Wheeler. In the article it describes building the ultimate Sammy. There the underdrive is pictured with Tim's and Ki's names describing trhe underdrive. Tim built it and Ki tested it, tried to break it, and couldn't.

Anyone who is attending the El Dorado County Fair, (Look for the Search & Rescue display) the SAR_Sammy (the vehicle) and I will be there. I can answer any questions and show you the underdrive.


Mike
SAR_Sammy

btt for people who can't seem to find 20 friggen dollars.

250to1 I'd be in for one. I'm at 98to1 with 36" tsl's my yota buddy's with the marlin crawler's are crawlin all over me ya I want one then go to 39'.