HT32BSX115 (9/17/2024)
Thanks for that info!
I think I will probably have some "over" assist as you say but I think a hydraulic regulator might temper that. I was worried about having enough fluid volume with any of the master cylinders that had small pistons to actuate the front and back.
The front brakes on my 55 have single cylinder, SINGLE-Piston actuators. Only the top of the front shoe is actually "pushed" forward. (sort of like a boat trailer drum brake system)
The bottom of the front shoes are hinged together so they all contact the drum when the top of the front shoe is pushed.
I suspect they changed that in the mid fifties I just don't know when. Are your front wheel cylinders single-piston too?
I think I couldn't find replacement shoes either but a local Brake place in Tacoma (Cascade Friction Materials) was able to reline both front and back shoes nicely and they also turned my drums.
I am very lucky, none of the drums had ever been turned and all they had to do is take off a few thousandths to clean them up. The guy told me I would probably never have to find drums for it. (I don't think they exist anyway!!)
By then, I'll either be unable to drive at all or I'll put a DANA 80 on the back and a much more modern front axle on it with disc all the way around!
I think you said you're using a T98 transmission with a 2-speed axle. (5.83/8.11?)
Mine is a 6.80:1 axle but I also have an Eaton 1350 5.83/8.11 too. I am not sure I'll be using it with the E4OD.
The E4OD has a 0.71:1 over-drive ratio. With the 9.00-20's I have on the truck, (roughly 40" rolling radius) I figured I would see around 504 rear wheel RPM @ 60MPH. 504 x 6.8 would then be 3428 RPM in direct drive.
With the 0.71 OD in the E4OD (& torque convertor locked) the 60mph RPM should be around 2400 RPM (2434) maybe that's about right for my 272?
What size tires do you have and what RPM do you see @60 MPH with the 5.83 rear axle?
Using the 5.83 axle, I calculated with 40" tires I would see 2938RPM in 3rd gear (TC locked) and 2086 in OD.
That might be too "tall" in the gearing for my 272 except maybe on a level highway, empty with a tailwind!!
The 8.25-20 tires are of smaller diameter but Les Schwab told me they couldn't get them anymore. My only choice was the 9.00-20's
Now if I were to go to 22.5's or 19.5's I suppose it would be better but when I got my current set of 20" 5--lug lock-ring wheels no one was offering 19.5 or 22.5 wheels.
I think you have more choices in 6-lug wheels.
Brakes sound the same design as our truck. Primary and secondary shoe up front running off a "single servo" wheel cylinder. Hot tip, they don't work in reverse!
Our rears have dual, "single servo" style wheel cylinders that are very similar to the fronts.
I'd fight to the death to keep the 2 speed rear lol. Especially in the mountains, starting in 1st/hi, then having the ability to simply lift to downshift was a huge help when really pulling. Also helpful rolling over a crest to simply lift/stab down shift for engine braking.
All of your gearing math looks reasonable to what we saw. 2500ish is 48-49mph in 4th/hi. 3100ish was 58-60mph.
Les Schwab told me the same thing but I found a set of NuTec Super Traction rears and had them shipped right to Les Schwab. I'm glad I did, we really used them on the way home. They offered a different NuTec tie but it was the cheesy zig zag military cheapo pattern.
They also tried to tell me they couldn't balance lock ring wheels and bias ply tube tires, so I convinced them to try and prove they were right lol. They were very rough before balance and reasonably smooth after wards, which they assured me wouldn't last. 3,000 miles later including over 1,000 miles on dirt gravel, they are the same. Very acceptable.
I don't see a stock NA 272 pulling overdrive with a locked converter at 60mph. I guess it would depend on the local terrain. Tacoma isn't too far from flat, but there is hills in every direction!
We're from Moses Lake originally! Great place to be "from" haha.