My '51 pacemaker is geared super low. 50-55 is about all it's got. That's taching 2500 @ that speed. I have located a '54 that had a dualrange hydramatic. I know they were geared better for the highway if they had a hydra but I'm not sure how much different. Current ratio is 4.10. I also know that the later Hudson's used a Dana rear. Mine is genuine Hudson. Would that be a direct swapout or does something need to be changed? Thanks for the help.
Hey Chuck, Are you talking about Don in Aurora? If so I picked up a rear from him today. He had all the answers I needed. Thanks. How's your Hudson coming?
According to specs, your pacemakers peak hp was developed at 4000 rpm. A cruising speed that uses 80% of HP rpm is perfectly acceptable. As such you should be able to cruise at 3200 Rpm with no ill effects to your engine. Why are you limiting your self to 2500 Rpm, when you have 700 Rpms in reserve?? Hudsons were road cars made to cruse at 60 with ease. What diameter rear tires are you running? Changing to a taller tire and utilizing your engine's comfort spot will be much easier and economical than swapping a rear end.
Using an online calculator assuming a 27.5 inch diameter tire, 2500, rpms with a 3.54 rear ratio equals 58 MPH, same peramiters with a 3.08 equals 64 MPH. Using 3000 rpm makes 69 with the 3.54 and 80 with the 3.08 I have a 4.11 rear end in my Plym. I run 60 or better all the time with 28 inch tires. This makes rpms about 3200. And my engine has a longer stroke (4 5/8 in) compared to the Hudson. I say drive it.
Yeah,Don-- It got shoved back-we're doing my son's VW bus,hey kids first...to bad you couldn't make it tomorrow..
Ken Thanks for stopping by with your son. Thomas hasn't stopped talking about it all day. So, if that rear end is a 3.08, you should be screaming down the highway in no time.... Don
I have a slightly different view. First of all, I think the peak torque, not horsepower, is the more relevant factor to work with here. Further, the amount of power (hp/torque) it takes to keep a vehicle running down the road at a moderate speed is actually quite low. And still further, one of the measurements of stress on an engine is piston speed in feet per minute. As I recall, 2500 feet per minute is about the upper recommended limit. A short(er) stroke engine, at any given rpm, has a lower piston speed per minute and therefore less friction and less wear for a given amount of time or miles driven and better tolerates higher rpm as a consequence. But we are talking relatively long stroke engines here. Where you asked, "why waste 700 rpm".......from the apparent viewpoint that it is "available" and not being used.....I see it as why "waste (use unnecessarily) ANY rpm that isn't needed to get the job done at the moment" I have a '49 Plymouth Coupe with a 230 Dodge flathead and a (I think) 3.90 rear end. When I first started driving this car (17 yrs ago) I was pretty unhappy with the engine screaming at 60/65 mph. I put in an overdrive trans ('55 Ply) and I was very pleased with the results. The car cruised easily at 60/65 and the engine sounded much more content. Now the above sounds like that was my "first rodeo" with either a stock flathead Ply or an OD unit. Neither is the case. Over many years time I have had several Mopars from the early '50s and have used an OD trans in at least one other. But the comparison between the non/OD and OD cars is dramatic. As applied to the OP's question 're his Hudson. IF he doesn't have an OD trans, and he doesn't say he does, I would agree that some caution be exercised in selecting a rear end ratio because that's what you are stuck with for all driving conditions. In that case, some trade off in cruise rpm may be justified to maintain the ability of the little six to pull most grades in 3rd (high) gear and to make it easier to pull away from a stop sign on a hill. In the Op's case, a Hudson OD trans or a 4 or 5 speed OD trans swap would probably serve his goal better than a rear end ratio swap. Ray
^^^ all noted above but a 3.08 rear without the torque converter of the auto might make launching it a bit hard in stop and go, and wih a load of passengers and stuff for travelling would be even more of a challange for the cork clutch. A little taller tire with his stock rear would give him a bit more relaxed cruise and the ability to start with a load or up a hill. the point regarding rpm is that it was not unusual for those engines to run down the road at around 3000 rpms. We have all gotten used to todays drive trains geared to have engines barly off idle at 65 mph, with electric fans and lots of insulation to keep engine noise to a minimum. probaly half the noise in an older set up is from the fan. 2500 rpm is a nice cruising rpm, but he can go a bit higher without worrying about the noise making the engine fly a part.
In my next to last paragraph I indicated that I agree the gear ratio selected should take into account the engine's limited power. While I did not specify a ratio, I agree with the recommendation of 3.54, or close to that, as a good choice IF an OD trans isn't utilized. Ray
I replaced the 4.1 Hudson R/E in my '49 SuperSix Coupe many years ago with a 3.08 from a Dual-Range Hydro Hudson. Difference is I have a Twin-H 308ci Hornet engine in the Coupe. No real specs or calculations, but figured the engine was running about 25% slower at the same speed. What a difference in highway cruising, tho--- The torquey 308 pulls the 3.08 easily, I didn't notice any difference in starting off except for more speed in First and second gears. I don't think that a 3.08 would work for you, but somewhere between 3.5 and 3.8 might be just the ticket.
I sure appreciate all the comments on this. I am still studying the whole matter. I also did the online calculators to figure my RPM. As far as specs go, my Hudson is a '51 Pacemaker 4dr, 232 flat 6, 3 spd no o/d. Currently the rear tires are 225/70/15. Have some 235/75/15's that are going on at some point. They're a little fat but that's the look I want. It's a perfect around town car as is. I just want to hit the road in this thing. I've had it at 65mph and it just doesn't sound like that's what it likes. As far as I know the engine has never been apart aside from me putting a headgasket on it in '05. I'd like to keep it together for many years. I am going to pull engine/tranny pretty soon to clean it up, paint it and finish installing the new seals and gaskets. I am also planning on doing a clutch at the same time. Again thanks for all the very knowledgeable comments, that's what I am looking for. Keep'em coming. How about some pics of these cars you all talk about, specifically the Hudsons.
Always enjoy coming up to get some parts and visiting with you. Hudson did have a great time. He was talking about it all the way home. Thanks for the good deal on the rear. I realized after I got home I forgot to get the wiper pulleys. Next trip I guess. Do you have any pictures of your driver Superwasp? I know someone who may be interested.
Just askin', but why? If I owned a Hudson, they'd have to pry the wet clutch from my cold dead hands. jack vines
I'm not opposed to the wet clutch but it's just another leak that needs fixing at this point. I'm not totally set on the dry clutch as I do like the wet clutch. Regardless the car needs a clutch.
I realize this thread is way old but thought I'd update it. Decided to leave the '51 untouched. So it's completely bone stock. I did put some H78-15 Remington WWW's all around. I love this car just as it is. It may someday get an engine transplant of a 250 chevy/2004r, just to make it a 70 mph highway car, but for now it runs perfect and I'm leaving it that way. I did however utilize the '54 Hornet rear w/3.08's for our '47 Hudson(avatar). It runs a 390FE/C6 so it needed the gears. It cruises super nice now at 65-70.
Reading through your thread, I see no one actually answered your questoin, only provided suggestions on cruising RPM... If you find another Dana Hudson rear, I swapped the Hudson Rear in my 49, for the Dana version out of a later model setpdown and it was a direct swap. The gears in mine are a 3.07 ratio. My car pulls that ratio fine, although it has help with extra displacement in the form of a DeSoto Hemi.
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