Tranny Motor Tire Combo

[Ramenk00ker]

Greetings bus folks


I recently acquired a 1966 camper. It’s a great bus and the PO did lots of work to make it reliable.

The PO had the transmission rebuilt to a freeway flyer with RGBs and put big General Grabber tires (27 x 8.5 r14) on as well. The bus still has its original 1500cc engine.

To make a long story short, I am getting killed on hills. Even the slightest incline or headwind and the bus is bogging.

I’m Trying to decide where to start in fixing this matter. New Engine? Tires? Re-gearing the transmission? All or some of the above? Tires would be the most cost effective for me currently but really would like to hear what you guys think and how the 1500 and freeway flyer would pair with more stock sized tires.


Thanks in advance for your feedback. Looking forward to it.

[Malokin Martin]

More than 2000 cc, dual port, webers, mid transmission mount and tall 4th. Build the engine, then have them build the tranny to suit the engine. Drive the speed limit and enjoy.

I spent way too much time drinking the stock Kool-aid.

[BulliBill]

There are a lot of directions you could go with this on a Transporter. We don't yet know of your desires and goals.

Without more definition and details from you, if it were me, I'd go right back to a stock-ish drivetrain. Back to stock sized tires ("D" rated of course). Stock transaxle gearing with reduction boxes. Maybe beef the engine up to a 1600, maybe even a 1641 or 1776? But I'd keep it a single port engine, with a fully rebuilt/rebushed 30PICT-1 carb, rebuilt vacuum-advance distributor and rebuilt German fuel pump. I run what I've described in a '67 Camper (mine is a 1600 SP) for many years and it's a dependable, cool-running and pretty trouble-free drivetrain overall. You won't break any land speed records, but you'll be surprised that it should pull the easier grades pretty nicely.

You'll get lots of other opinions soon, but until you tell us your driving hopes and goals for the Bus, none of our guesses will be "correct"...

Bill
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Thanks for any help!

[Ramenk00ker]

Thank you guys for the insight. Looking forward to more.


My end goal is to be able to cruise comfortably at 65 and have enough juice to get up hills on the highway, not crazy grades (I live in Southern California).

Not looking to break any speed records. I drove a 69 bay window camper for years with stock trans and a 1600dp engine. It was enough for me. I guess I was hoping I wouldn’t need to replace all 3 things, (trans, tires and motor) but that might be the most realistic way to get me where I want to be. Unfortunately I am on a budget so I’m trying to get the most bang for my buck.

[Chuey]

First thing you mention that you can try is the most obvious. Tires. Replacing those first will be the cheapest and have the most effect per money spent. A 27" tire is great on a real stock drivetrain in my experience. But adding them with a higher final drive ratio in the trans is going to be tough on a stock engine.

From the sound of it, you can go pretty stock and be happy. You may even be able to trade transaxles with someone who wants a higher ratio and has stock to trade. Good luck!

Chuey

[Eric&Barb]

First there are at least two freeway flier transaxles, one with 3.875 R&P, and the other with 3.44 R&P. The lower the number in gearing the higher the geared it is. So you need to sort out which R&P you have.

Yes, either trade for stock geared transaxle, but expect to wind the engine out enough to reduce longevity of it and have MPG drop to do the speed you want to do, or build an engine with more torque to work with the FF transaxle you have now.

Personally have a 1641cc (slip in cylinders) SP engine with CW crankshaft, 3.875 R&P and .82 fourth. Happy with it at around 58 to 60 MPH @ 3,000 RPM depending on the size of the rear tires. Have now over 150,000 miles on that engine getting 23 MPG on the highways, and it has same power as it did newly rebuilt.

Sure, would love to take any hill with never slowing down, but not interested in the downsides of doing that. Used to have to rebuild engines about every 30,000 to 40,000 miles and got 18-19 MPG with big bore 40HP engines, back when we ran stock geared transaxle (small nut RGBs) with engine @ 3,000 RPM just to do 55 MPH.

It is acceptable to us on the very steepest hills to just downshift into the top of third doing 45 MPH @ 3,000 RPM. Find that we are much more often than not, faster than the semi trucks on those steep hills.
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[Willin]

Before you replace those 27" Grabbers, measure the rolling circumference,( with wheels on bus.) Circ. divided by PI 3.1416 = diameter.
I found mine to be 81" circ., so 25.7" diameter. New tires. Close to what a 185-195 is supposed to be.
You can't go off advertised sizes.
Something to consider.
But smaller tires would be better if you have a FF trans. ( I suppose)
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[BarryL]

I'd be inclined to find a used tire shop and have a set of 155 R 14" tires mounted just to feel the lower gearing overall. Then decide how permanently you want to change things.

[Eric&Barb]

[Ramenk00ker]

Thank you alll for your insights. Will report back as I sort through this.

[Clara]

Ya, with a 1600 (doubt the engine is still a 1500, that was rare back in the 90s) the stock gearing is perfect.
With taller gearing it will, as you say, just slow on slight hills. I had a 3.88 in a 65 with a 1600, and really wished it was a stock gearing. I like a 1 ton bus with 1600 sp and stock size tires and stock gearing. Drives happily about 60-65 on the freeway even while carrying a ton of gear. I have 60K miles on the motor in the 66 kombi with this set up, and Muir says thats about all you get out of a motor in a bus until its time for a rebuild.

There are few dozen threads on this. Any which way you go (bigger motor, or back to stock gearing) will cost time and money, unfortunately.

and like E&B said, 'freeway flier' means 'taller than stock gearing', doesn't really say what's in there.
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[pyrOman]

The "gearing & tires size combo" is extremely important! I know I've posted this before on many a thread, but here it goes yet again. I was running with TALL tires and reduction boxes doing quite well. But after doing my "IRSing", for the engine to be at the happy spot, it was doing 95 mph!

Went into the "tire size calculator" and replaced the TALL ones with a more respectable size. Now it runs a a very comfortable 65 to 75 mph around 3200 rpm.

https://www.discounttire.com/learn/tire-size-calculator
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[Ramenk00ker]

Good morning, wanted to circle back and thank all who replied.

I ordered a set of 185r14 tires and removed my governor from my carb.


Happy to report that the bus is driving much better with stock sized tires. Pulling hills much better than before. It’s still a stock bus so I’m still downshifting when needed. But it’s much, much better. That brings me to my next topic.

I currently have a 30pict1 on my 1500sp and am contemplating going to dual carbs and maybe a slightly larger exhaust. My goal would be to squeeze a little more hp out of the motor. Any thoughts or advise on that subject? I love the simplicity of the single carb but am willing to try duals if there is an added performance benefit. Thanks in advance.

[Eric&Barb]

With dual carbs you might get better MPG.

Without increasing valves size and muffler size at same time, you are not going to notice much if any HP increase in the lower RPMs with stock sized engine.

Know of a fellow bus owner who went all out for the HP engine of his dreams, in the end about six months later he was trading off the big HP parts for stock ones because of the lack of torque in the lower RPMs. He was having to really rev up the engine to just get off the stop line due to low end torque.

Better to build a new engine if you feel the need. Either bigger P&Cs and/or stroker crankshaft. The latter is better for more low end torque, and torque is what gets you off the stop line and the hill climbing much better. Then keep your present engine for backup.
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