AX-15 or Top Loader 4-Speed?

[rguest3]

I am doing a Frame-off Restoration of a Bronco that will have a 410 Cleveland in it. With the Aluminum Heads, Roller Cam, Intake and EFI I would expect about 500HP. Very Old School engine with lots of power/torque and a blast to drive.

To go along with this engine I have a Newly Rebuilt Top Loader 4-Speed with a lower 2.90 first gear and Centerforce Clutch set-up. I also have a New AX-15 with a Centerforce Clutch and B&M Shifter. Both of these transmissions will be pretty sporty to shift and also be fun to drive.

The Top Loader is a very strong, compact transmission with No Overdrive. The AX-15 is also very capable with Overdrive, but is the 410 Cleveland too much power for it even if driven with a hair of caution? This is the real question. I have had the AX-15 behind a very nicely built 351W with No issues what so ever. This Cleveland is not the same motor.

Both transmissions are complete and already assembled with the Transfer Cases. (D-20s) Both transmissions can be installed without changing the Driveshaft lengths. The Bronco already has a 1" Body lift, so that is not an issue either. I will also make a new trans cover on the floor, each will be different since the shifters are in different locations.

This will be a mostly street driven truck. Honestly, I will probably hardly ever drive this Bronco on the highway. Although, the Cleveland could easily be happy on the highway with either. The truck will also have 4.11 Gears (Already installed) and 305/70/17s.

Which Transmission would you choose?

 

[Broncobowsher]

You didn't build the Clevo to be mundane. You are going to drive it hard. 4-speed. You said little to no highway, don't need the overdrive.

If you are going to run trails, that need lower gearing, you probably need a granny like a ZF. But that isn't a fun 4-speed.

 

[RODRIG3911]

I've had a 4 toploader in mine ever since 2004 and it is pretty nice. I installed a hurst competition short throw shifter with twin stick T-case shifters and it's even better now.... That said, I actually have an AX15 with B&M shifter that i'm swapping in. In your case the Toploader might be perfect since you say you won't off road it much. I've had my linkage bind a few times over the years and it makes it difficult to shift it back in to gear when it does, but that only happens when 4X4ing it very hard. The lower 1st gear of the AX15 is the main reason i'm switching mine out.

If you do the Toaploader, my gearing is 4.11 with 33" tires and it's perfect! Does 75MPH on freeway at around 2400 RPM and goes decent off road in 4 low

 

[rguest3]

This is what happens when you spend a lot of time finding and collecting parts for that "Next Build".

I agree, the Twin-Sticks help as well. Both are Twin-Sticked already.

Highway speeds with the Top Loader will really not be an issue with this motor either. 2500RPMs all day long if I need to.

Again, the Main Concern is the Capability, or the destruction of, the AX-15 behind this motor???

I was initially thinking of putting a 4R70W behind the Cleveland, but that's not as fun as either of the Manual transmissions.

 

[bmc69]

Hard to beat that top loader for toughness. But that said, I have zero personal experience with th AX 15.

 

[DirtDonk]

Toploader.

Paul

 

[rguest3]

Thanks Paul. Top Loader, period. I like that. I have been leaning that way because I really don't feel like exploding a New AX-15.

Great. Now my signature line and build threads are all messed up.

 

[fordfan]

Definitely the transmission with the highest fun factor is the toploader! The toploader is far stronger than the AX-15 too! How long do you think an AX-15 would last behind a 900 horsepower FE in a 4000 pound car powershifting it with 14" slicks!?! NOT!%)

A buddy of mine races a '64 Galaxie as described and has broken about everything in the driveline, but not the transmission! He's had the tires slip on the rims, shear the lug studs, break axles, break pinions and ujoints .... but not the trans! All this in the period of 20-30 years... Now it has an automatic, because he can't shift it fast enough!

With enough power in a Bronco, there's weaknesses that will show up. The output of the Dana 20 is one area of suspicion, the axles better be good 31 spline at a minimum, the motor mounts, and the chassis itself. My Rattler Bronco twist the chassis to the point that the top seam just behind the drivers door under the driprail is impossible to keep it from cracking the seam sealer. This is partly because a Bronco is much like the theory and engineering behind the old Gasser race cars. Shorten the wheelbase and lift it! This transfers more weight to the drive axle and makes it hook up really hard.

 

[nvrstuk]

I had the SB toplaoder 4 spd. Can't beat it for fun. I've said this on this forum probably at least a half dozen times... I'm on my 7th trans in the same Bronco and the most fun trans out of all those was the toploader.

What will fail on the toploader is the Advance Adapters output shaft. I went thru two of them and finally gave up. Hopefully they have improved the QC on them now.

 

[rguest3]

I've decided that the Stroked Cleveland will have a 4R70W and an Atlas behind it.

My 77 with a 351W will be paired up with the AX-15. Really nice motor but not the Stroked Cleveland.

My Boxwood Green 71 with the 351C (non stroked) will have the Top Loader behind that. Similar to Fordfan's Rattler.

 

[nvrstuk]

My .02 is to build the 4r for the stroked Cleveland. 300M intermediate, upgraded clutches, etc. Been running my built 4r70 which is smooth as silk behind my 418 for years and upon pulling the pan when replacing with the 6r you could barely see a light coating in it.

Worth it.

Have fun!