Jack O'brien of O'brien 4 Wheels West is still in business

A friend of mine had a '51 with a bored/blueprinted 327, at 8 grand it woald still be running without a miss.
I ended up rebuiling the t90 twice and the rear end once before he sold it.
Even the D18 survived.
The Warn OD was never an issue.
Dumping the clutch at 6K really will rip all of the teeth off of the input shaft.

 

Interesting thread.
I have just sent the money for a D18 3.6:1 Rockeater gear set.
It is my plan to take pictures and post them up here in a build thread.
The rebuild sounds like a standard build. Some grinding on the top inside (same as teralow) for intermediate gear clearance.

I have wrestled with this for a while and here is my choice for Jack O'Brien Rockeaters over the TerraLow.
I am the 3rd owner of 70 CJ5, mostly stock. The great internal war over restoration and what I want it to be rages most of the time.
I have looked at T18, T98, SM420 and SM465. All of these require escalating changes that include, but are not limited to, the bell housing, the front transmission bearing cap, the transmission output main shaft, adapter to the D18, cross member and drive shafts. Cost is from $1200 to $2000 depending on my limited skill set and where you get the parts.
The TerraLow kit is nicely priced at $1100ish (over drive option with 4.88s in the axels), but only buys back the speed increase I lost going to the taller tires.
Jack O'Brien 4-Wheels West 3.6:1 (rounded from 3.59) gears at $1800 take my crawl ratio (transmission 1st gear, xfer case, axel gears) to 54.5. These gears are designed to be used in off road racing, that is why the price is large.

T14A - Dana 18 w Rockeaters - Dana 44
3.1 x 3.6 x 4.88 = 54.5 crawl

T14A - Dana 18 - Dana 44
3.1 x 2.46 x 4.88 = 37.2 crawl

T14A D18 W TeraLow - D44
3.1 x 3.15 x 4.88 = 47.7

SM465 - D18 - D44
6.55 x 2.46 x 4.88 = 78.6 crawl
This option has large gaps between 1st and second, even with the OD.
It has the most components that need to be altered.
This can cost almost as much buy the time you are done.

below is the before and after graph for my upgrade.
the graph shows the speed at RPMs for each of the six gears, OverDrive.

 

very interested in this thread..
have been toying with options for Tcase in my CJ6 and low gearing is one of my concerns...

might just give him a call today and chew the fat..

 

I got my gears last week and spent time this weekend dry fitting them in the case.
Amazingly easy. The only hard part was the machining of the front bearing cap. I have access at work and had a guy do it for me, took less than half an hour.
I will put together some details and have more pictures.

 

rejeep,
did you ever call Jack?

 

Does anyone know what's up with the need to machine the front bearing cap with a Jack O'brien 3.6:1 gear set? I am considering this mod...

 

I could be wrong but I believe a member here Posimoto has one in his Jeep.............send him a PM.

 

Will do. Thanks.