[gonewithwind]

Informative thread. It is going to be helpfull to many jeep lovers.

[trammway]

Originally Posted by svsantosh

Siva - Like this? This is from our Dear Abhimanyu's ride.

I was quoting about under bonnet water proofing... wait and watch out the changes in my Jeep you will get some idea in the future. Until then it is a "brema ragasiyam"

[trammway]

Guys,

The jeep performed extreamly well during the first OTR after the engine change. I also had an opportunity to drive the jeep for around 200kms on the highway to test the performance on the highway overall good. However I feel there is a back compression is present on the engine as I could see bit of smoke coming out of valve door breather tube.

More information about my yesterda's otr could be seen in the excursion section here in this like:

http://www.team-bhp.com/forum/4x4-ex...galapuram.html

[trammway]

This post is like giving life to my lost thread. I hope many of you enjoy this one.

Almost 2 years of my waiting time has come to end finally. Yes, here you go.

In simple terms an overdrive is the final/cruising gear. It reduces the power output by lowering the gear ratio. The overdrive mechanism increases fuel efficiency, and saves strain on the transmission and the drive train.

Warn has developed a overdrive for Jeeps, It is a very old design that has been around for decades. The same has been bought over by Saturn Company then ATV Mfg. started rebuilding it or producing the same for the niche market.

The Warn overdrive is a simple 2 speed gearbox that mates to the Jeep's transfer case and provides a 25% drop in engine rpm when engaged. Instead of creating the final gear as overdrive, the Warn overdrive model introduced new gear ratio between each gears. Hence a transmission in which the highest gear ratio is less than a one-to-one ratio. This means the drive shaft turns faster than the engine crankshaft. The overdrive feature saves fuel and, because the engine runs slower, engine wear and noise are reduced.

What I have got is the same Warn Design reproduced by ATV Mfg. for Mahindra Jeep transmission/transfer case specification. What makes the Mahindra Jeep different from its American cousins is that of Tooth and Spline counts in the transfer case, hence the regular or used Warn Overdrives will not fit directly into Mahindra Jeeps. Herm Till ford reproduced the gear with 29tooth and 15 spline count to suite the Mahindra Jeeps. The same is what I have got and going to be placed into my Jeep.

Instead of the normal 5speed gearbox with overdrive that provides an additional gear to rotate faster than the engine(crankshaft) RPM, The warn overdrive actually sits on the PTO port of Dana/Spicer T-19 transfer case and takes the input from transfer case main gear shaft and converts into different gearing ration and sends it back to the actual transmission. Because of this particular model, the warn model overdrive can introduce as much as double the number of existing transmission gears.

Currently my Jeep equipped with KMT-90 4 forward and 1 Reverse transmission, hence I'm running the Jeep with 10 gearing ratios including the 4 wheel drive Low mode. By installing the Warn Overdrive I will get 20nos of gearing ratio that will enable to choose huge range of gearing ratio according to my need.

The moment I enable the Overdrive all the gear ratio will be on the higher side, hence going to give me a smoother noiseless ride. Whenever I need to do Offroad the overdrive will be temporarily disabled by pulling the Overdrive lever back to the driver side position. Practically the overdrive will be left in engaged mode all the time as most of the time the jeep is driven on the road.

Now I will let the pictures talk about what are the items came with the Herm Tillford supplied overdrive baggage(Who brought this baggage all the way from USA?).









Come back to this space to see more on the installation side, then comes the actual driving experience part.

[whicked wheels]

Hi Trammway thats really good over drive, i have read that it can also be used in 4wd low is that true. Have you fitted it , lets us know how the jeep performs. How much did it cost you.

[Samurai]

This is very interestng Siva. Now, where does this thing go. I mean, most of us have our skid plates installed right under the transfer case. Will this extra connection stay above the skid plates, or force you to lower it.

[trammway]

Originally Posted by whicked wheels

Hi Trammway thats really good over drive, i have read that it can also be used in 4wd low is that true. Have you fitted it , lets us know how the jeep performs. How much did it cost you.

Thats right. The same reason to mention 10 gear ratio on KMT-90 (4+1 on 2H & 4H and 4+1 on 4L) and gets 10 extra gear ratios when OD is engaged so 20 gear ratios.

The installation is not taken place, I'm planning to do the installation next weekend.

Complete details of before and after performance will be posted in this thread.

I'm expecting a good FE and noise reduction as my Jeep is currently running with XD3P and reducing engine power on the normal road use with OD is a welcome fact. These days I could move the jeep in 2nd gear from static position. This is because lots of torque found in the 1st gear which is unnecessary for highway or regular drive.

Originally Posted by Samurai

This is very interestng Siva. Now, where does this thing go. I mean, most of us have our skid plates installed right under the transfer case. Will this extra connection stay above the skid plates, or force you to lower it.

The overdrive installation will not have any issue with the skid plate. The simple reason is that the overdrive gets into the PTO port which is parallel to the rear drive shaft on the transfer case. So the OD will set parallel to the rear propeller shaft horizontally not on the bottom side of the transfer case.

See this pic below to see how the OD is installed on the old T-90 transmission and Dana T18 transfer case. The big drum shown in the picture is emergency/hand/parking break carrier plate that goes on the rear propeller shaft of a old jeep. (Picture courtesy: Jeep Transmission* Saturn Overdrive Swap information)

[whicked wheels]

Hi Trammway here are some more pics but this is on a three speed gearbox.

[trammway]

Originally Posted by whicked wheels

Hi Trammway here are some more pics but this is on a three speed gearbox.

Amazing! see 4 gear levers in this jeep. I'm already getting too many questions why I have 2 levers now my jeep will have 3 levers.

[whicked wheels]

Originally Posted by trammway

Amazing! see 4 gear levers in this jeep. I'm already getting too many questions why I have 2 levers now my jeep will have 3 levers.

Yes you are going to have three leavers since your jeep transfer case is a single leaver shift type.

[svsantosh]

Wow - Its a tiny mechanism compared to the benefits it offers...

Congrats - This is a serious MOD technically speaking. Please post WIP pics when it starts

[trammway]

Ok, I have received few PMs about how did I get the 20gear ratio with my KMT-90 gearbox setup and OD. Here is the calculation:



I hope this helps, soon I will post the difference in top speed figures after working on the spreadsheet. Though the formula is very simple:

[svsantosh]

http://www.team-bhp.com/forum/4x4-te...ml#post1445477

Anna - I wanted to ask you 30mins ago where is the PTO (Above Link) that our UBS'Ji brought? How are you going to Fix the PTO and Herm OD toghether...

But I took the initiative and found the answer. For you guys who want to know what can be done with a Jeep's Gear box - here you go.

(Image Courtesy - hermtheoverdriveguy DOT com)

How the OD will look after being fit to Xfercase.


Remove the rear cover to access the center drive


Attach the PTO's hub... (Siva has a different PTO in the link)


The completed Unit (this can compete with the BA10 for its size )

Originally Posted by trammway

I'm already getting too many questions why I have 2 levers now my jeep will have 3 levers.

Siva - guess what - you will end up with 4 levers and further confuse the public...

[trammway]

Originally Posted by svsantosh

http://www.team-bhp.com/forum/4x4-te...ml#post1445477

Anna - I wanted to ask you 30mins ago where is the PTO (Above Link) that our UBS'Ji brought? How are you going to Fix the PTO and Herm OD toghether...

But I took the initiative and found the answer. For you guys who want to know what can be done with a Jeep's Gear box - here you go.

(Image Courtesy - hermtheoverdriveguy DOT com)

How the OD will look after being fit to Xfercase.
Attachment 243470

Remove the rear cover to access the center drive
Attachment 243471

Attach the PTO's hub... (Siva has a different PTO in the link)
Attachment 243472

The completed Unit (this can compete with the BA10 for its size )
Attachment 243473



Siva - guess what - you will end up with 4 levers and further confuse the public...

Good find.

The PTO unit shown in your post is actually a front mount Winch PTO or any other front side PTO device. The one I have is actually for rear PTO applications. Guess what a Generator, Waterpump, Agriculture equipment, Air Compressor and many other applications are already on the lookout.

This is exactly is what in my mind. However since I have the navigator(CJ3B) with me I may install the PTO unit into that Jeep. But who knows I may change my mind to keep this setup as you posted.

Now think of CJ3B with two lever transfer case and OD(Tooth and Spline count may not be same as KMT-90 combo, however there is a possibility of me getting the required setup again) with PTO.. 5 gear levers Aiyooda Ippavae Kanna Kattuthe!

[trammway]

The newly installed XD3P engine on my Jeep often shown it's age factor and latest by last weekend. I took it to my home town and slowing the temperature increased to 100degs.

I stopped the jeep and checked if radiator got some issue and the fan. Also try to push the jeep in neutral to see if brakes were jammed. But all were at good. I continued to drive the jeep and again with in 20kms the temp increased and slowly the oil pressure showed below 1 point.

Knowing the difficulties of low oil pressure, I stopped the jeep for a while and awaited for the jeep to cool down and oil to get down to the sump. After about 45mins of gap I checked the oil level and it was in little below the first mark in the oil dip stick. So I bought 1ltr of 20W40 castrol CRB plus and topped up in the value door.

All the while I was in 90-95kmph speed, this time I reduced it below 60kmph and the temperature stationed at 90degs. But the oil pressure didn't come to 3 points.

While coming back also the same state and I was not rushing the engine RPM and sticking to standard 50-60kmph speed. Checked the Fan belt and alternator belt etc for any loose connection and nothing hand issue. So I've confirmed to myself this is the time for engine overhaul. (already I'm seeing my breather tube emitting lots of hot air and oil above the engine)

The milege also drastically went down and now getting only 7-9kmpl.

Yesterday I visited Mahindra Dealer and placed an order for Short engine, Hence I will be getting a Brand new XD3P engine block without Head, Values, FIP, Alternator, Starter motor and Ply wheel.

As I could see the going rates for used XD3P has come down and wanted to use the these components that are in good condition in my Jeep's XD3P instead of selling it for steal price. What you say guys ?