The Stovebolt Site Forums The Shop Area General Truck Talk General speed question

52 Suburban - With a stock 261, two barell carb, headers, 3 spedd muncie trans and stock differential, how fast or what can i expect for reasonable crusing speeds? I got the truck on the highway this weekend and from the rev sounds and the 'whining' from with the trans or diferential, 45 was teh most i was willing to do - do these trucks just sound like that or is that all she has? thanks

This might be apples to oranges but my 56 gmc with 248 all stock seems to go 65 without any trouble, I have had it over 80(back in my youth, late 70's). Now I'll be the first to admit that was a stupid thing to do, but it brings up a question that I don't recall seeing before,(but I'm sure it has been asked), what is the red line number on these old sixes?

Even with 4:11 gears you should be able to do 65. Are you sure your speedo is correct. Make sure your motor is in good running order ie. tune up, adjust valves, timing, carb in adjustment, no vacuum leaks etc etc etc.

And best thing I've done for my old Chevs is go with better highway gears and or od trans etc.
Best of luck.

Honestly my speedo does not work - judging by the digital speed sign, it was a true 45 - the engine seems to be in good order and i would think that 55 shoudlnt be a problem - i went from a 2002 ford explorer to this so maybe i think it sounds louder and revier than it really is - the fact that there is slop in the steering wheel doesnt calm my nerves either even at 45 - thank you for the responses - first and second pull really well and sound great, its just on the highway that i begin to question things - no interior or sound proofing may be a culprit as well.

Yeah, these old rides can be noisy, first thing I noticed in my 47 coupe after change to 3:55 gears was noise level went way down.
You should consider better ratio gears, check with Patrick's Antique autos in Casa Grande, AZ.
www.patricksantiquecars.com/

You'd have a 4.11:1 rear end and 1:1 3rd gear ratio.
Suppose that your tires are about 29" in loaded diameter
Calculate your RPM

You would get about 2600 RPM at 55
You would get about 3100 RPM at 65

Everyone has a different opinion on the RPM "sweet spot"; I like about 2,600 RPM (for higher gas mileage and lower noise).

When my 1954 Suburban had the 3.90:1 rear end, I could travel nicely and quietly at 55-60 MPH. With the 3.55:1 rear end and all be rear bearings/bushings, I travel nicely and quietly at 60-65. I can cruise easily at 70 in terms of power, but it gets a little noisy, and my gas mileage decreases by about 1/3 (from 18 MPG to 12 MPG).

thank you for the replies - do the stock differentials tend to whine a bit or produce an audible 'wuring' sound when at speed?

It should not. In the old days, I think that some people would put sawdust in the rear end to lesson the noise in an old differential (and, then sell the vehicle).

http://www.jalopyjournal.com/forum/showthread.php?t=489889

I guess you could also service the differential and reset clearances and replace bearings/bushings (and hope that makes a difference).

Or, spend several hundred dollars and put in a 3.55 ring & pinion set with new bearings/bushings. I did this for better cruising, and my already quiet Suburban became even quieter.

oatmeal works better than sawdust, the gluten helps

your pinion bearing may need some attention, particularly if the 'whine' happens in a particular speed range and not all the time

Bill

Bill,

Thanks for for the excellent selection of an alternative "solution". I would have thought, however, that a far-northerner would have suggested barley flakes?

there's always oatmeal on hand, and it's not as gritty

Bill

A whining pinion bearing is nothing to ignore. It's not pretty when they let go or sieze up, especially at higher speeds.