Milling Bridged Style Heads to fit Roller Rockers

[What It Was]

Hey people, As if you all can't tell I'm new to this site/club. I'm neck deep into my Jeep Project and I'm at a stand still with my motor. (Milling the stud bosses to fit the Roller rockers)
First off, let me describe my "Project"
--It's an Multi year CJ-7--
89 wrangler tub, 82 Frame, T-18b tranny, Not sure if Dana 20, Ford 9" rear with 3:50 gears, stock dana 30 front with 3:54's, 1 1/2" shackle Lift, 3" bodylift, 35" tires, 6 point roll-cage, and my motor is a biggie (over $5000 biggie).
Edelbrock 600 cfm 4bbl
Edelbrock Performer Intake
DynoMax Hedders 1 3/4" to 3" collectors
3" Purple Hornies Hedder Mufflers
Comp Cams 280H Cam (.490 lift w/1.6 ratio, .520 lift w/1.7 ratio), Comp Lifters/Valve Springs/Retainers/Keepers/Comp Hi-Tech Roller Timing Set, Comp One piece magnum pushrods
Harland Sharp 1.7 Roller Rockers 7/16" stud
Heads Resurfaced, valve job w/ new valve guides
Block has been bored and resurfaced. Lifter Valley drilled tapped for extra oiling/New cam bearings and freeze plugs, crank turned 10/10 SCAT FORGED RODS ROSS FORGED 10:1 RACE PISTONS (9.5:1 w/60cc heads).
Well, here comes the questions.... Sorry people! But, I haven't been wheeling in over two years due to this "Project" work, and 2 kids ;D And I'm itching to throw some mud and try her on some rocks. With all of that being said... Here are the questions.
Has anybody taken the bridged style heads (74 and up) milled them and then drilled and tapped for roller rockers? If so, how much did you take off?
I was told to mill to the height of single style heads and then mill off the thickness of guide plates plus the nut thickness on the stud. But, I don't have access to those early single style heads... to measure the height.
Any info would be highly appreciated... I have a few more questions about Transfercase Identification... I'm sure I'll thumb thru some threads and find the info needed. the other and final question is... what gear ratios will work with my 9" and stock 30 front axel? I found a D 60 rear... tempted but one "Project" at a time.
Thanks: Rich

[toynrnd]

Kenny should have an old style head for you to look at/measure. He doesn't get on these forums, but you can e-mail him at [e-mail]. As far as the t-case, if it has 6 bolts in a circle where it bolts to the tranny (or adapter), it'll be the Dana 300, if the t-case bolt pattern/mounting flange looks like "Texas" it'll be either a Dana 20 or if you're lucky a Scout Dan 300. Did you get the T18 and the t-case together, or were they already in your Jeep when you got it?

[What It Was]

Thanks for the info, I'll send him an email and hopefully I can get what I need to finish the motor. The tranny and transfercase came with the Jeep, Let me run outside and check what it looks like.... Alright just got back from under the Jeep.... It looks like "Texas" with the speedometer cable on the drivers side... (not sure if that helps to identify or not, a buddy said if speedometer cable is drivers side then it's a Dana 300) But, the more I learn the more I wonder.... I have some pics of my ride before I started, during and my 1st engine build (304). I'll post them once I figure out how.

[toynrnd]

The Dana 20 and Scout 300 look the same. The Dana 20 is 2.03:1 low range, and the Scout 300 will be a 2.61:1 low range. If you have the Dana 20, you can always do this...
www.jeeptech.com/convxfer/2.46-20/

[What It Was]

Thanks for that site... I might need to go that route!... What do you guys know about T-18b trannies? When driving in 2wd I can't use 1st... as soon as I touch the gas I have to shift... 7mph is the max in 1st 2wd... in 4wd low I can't touch the gas because she moves at a snails pace.... she makes all the noise in the world like she's on a race track.... My little 304 (RIP) was a little snot-rocket until I kept her @ 7500 on and off... My bearings didn't like it too much... Hedders glowing and under-tub paint bubbling!!

[What It Was]

Would anybody know the 1st gear ratio for a T-18b tranny is it either 4.02 or is it 6.32 or something there abouts? I'm trying to figure this stuff out... and it's pretty hard finding stuff on a T-18b I know they were from 76-79... and that the B means Reverse is far right and up.... If I am wrong please correct me... thanks.

[toynrnd]

Sounds like you got a 6.32 first, huh?

[JeepCJ5]

Yep, sounds like 6.32 ... If your rolling at 1 or 2 miles per hour and its grinds trying to go into first, that is also a good indicator of the unsynchronized lower gear.

[Chuck]

The T-18 with the granny first gear is a great transmission. In a Jeep (or anything else with a T-18 or the even steeper geared NP435) you shouldn't need first gear unless you're either trying to crawl or pull something heavy -- you would normally drive it like a three speed.

[What It Was]

1st gear doesn't get used much... I accidently started it while working on it and it about ran me over... (Stupidity almost got me ran over by my own Jeep). I couldn't pull it out of gear so I just let it run into the tree and she just sat there bucking trying to run the tree over... I thought that it would've stalled... Hmmm, I should've figured other-wise!
While driving let-a-lone rolling I can't put it into 1st... I appreciate everybodies input.... I'm sure you all will be sick of answering my questions in due time... Thanks again!
Rich

[Chuck]

Oh, and I meant to comment on the rear axle earlier, and forgot -- I wouldn't bother with the D60. The only advantage the D60 has over the 9" is full floating axles. Aside from that, the 9" has slightly better ground clearance, and a stronger ring and pinion with pinion snout support (third bearing on the pinion nose). Rather than wasting your time and money on a D60 swap, sell it to some other unknowing sucker and get yourself a nodular centersection, 35 spline locker and 35 spline axleshafts to match (I believe there are already non-custom shafts for this application, much cheaper, but I don't have time to look right now ).

You'll be way ahead of the D60 on strength, with a smidge better ground clearance, and without having to screw around with your bolt pattern. Plus, there are disc swaps that aren't too tough or expensive, if you're willing to do a little scrounging.

[What It Was]

I was told that a full floating axel is great because it takes the majority of the stresses off of the axels and places it on the gears... and what about the DANA 60 large axel Bearings... they're huge and dependable... I guess large tube axels on the 9" with dana 60 bearings would be a good thing.. and then make it a full floater.... (Just like a 9" Currie axel). Just alot cheaper right? Just as long as I'm doing the work myself.

[Chuck]

There are two advantages of a full-floating axle. Number one is the axleshafts don't see any shear stress from the weight of the vehicle, they only see shear from torsion (driving force to turn the wheel). Number two is you can break an axle and still drive it home as long as you have a locker. With the D60 these two advantages only apply on the full floating version, they were available as semi-floating axles also (like the 9", 8.8", D35, D44, etc).

As for the bearing size, the D60 outer bearings are HUGE, but I wouldn't expect a huge difference. The D60 uses a Timken 382S race, 387A cone combination, which has a C90 rating (maximum continuous radial load to last 90 million revolutions) of 4,910lb and measures 3.8125". I couldn't find the bearing number for the 35 spline 9" carrier/third member, but it's a 3.250" race, and the closest Timken bearing I could find (my best guess) has a C90 of 4,390lb. That's not a huge difference, and since the carrier bearings don't see that much stress (particularly continuously) I'd be suprised if it made a difference.

I don't have weight figures for the 60 or the 9, but I've been told the 9 is lighter by anywhere from 50-100lb, depending on who I've talked to. No personal verification on this at all.

The main thing to make sure of when you're comparing cost is that you're comparing total cost ... a FF D60 will also require you to purchase wheels that will clear the hubs, as well as changing over your bolt pattern on the front. The 9" will be 5 on 5.5 (stock CJ as far as I know), so no wheel change necessary. On the other hand, if you're certain you're going D60 in the front, going D60 in the rear will net you the same bolt pattern on both ends.

I guess it really depends on what direction you want to go long term. In my case I'm usually not too throttle happy, so I was planning to run a solid D44 I already have and a 9" under my next project (when I get around to it in a couple of years).

[What It Was]

I have another question.. maybe I'm stupid or something but, for the life of me I can't figure-out why a 9" rear axel can't be configured to work in the front... a little help or explanations would be highly appreciated.. this way I can put my mind at ease. There has to be a way... I need to get prints of the dimensions of the 44's 60's and 9's... Maybe I can figure somethin out... bring them to the shop and machine them to work on my free time... Imagine stuffing a 9" inside a 44 and then cramming large tube axels on both sides etc etc... It has to be possible... Even if I have to make adapters/spaces... I'll figure it out!!!! But until then... Maybe you guys might have some answers for me.

[Chuck]

It certainly can be done, and has been in various configurations. It's mostly a matter of getting custom axleshafts made up, and finding an axle fabricator good enough to put D44 or D60 ends with the proper adapter work on the outside ends of tubes that will fit in the 9" main housing.

If you want a little teaser, check out Chris Durham's ride. He's running Unimog axle outers with 9" centersections, front and back. If I remember right the Mog portal ends have about a 2:1 reduction ratio, which means you can run a very strong 2.75:1 ratio in the 9" (higher ratios are always stronger due to the larger diameter pinion, the ratio also lowers the tooth contacto forces) and still have around a 5.50:1 total axle ratio. It also cuts the torque in the axleshaft in half because of the reduction at the wheels, which makes the 35 spline 9" shafts equivalent to a shaft twice as strong in a non-portal application. On top of that, thanks to the portal ends, the bottom of his diff is right around the centerline of his wheels. ;D