70mph with 727 in an a108/a100?

If I need to do at least 65 and upwards of 70mph for 2-4 hour stretches am I crazy to attempt it with a stock 727 and rear gear in an a108/a100 or do I need to plan for an immediate 518 swap?

Will the rpms be too much?  Overheating likely? Or will it just be a bunch of wind noise?

Should be no problem with a 3.23 rear end gear.

figuring 28.9 tire height that means would mean just shy of 2700 rpms...is that going to be fairly loud / much for the motor for long stretches?

with a 3.23 i drive mine at least 2 to 5 hours @ 70 mph every summer out on the highway
going to different van runs

That should really be no problem. Just watch the engine temp, to spot real problems.

I tested the A100 with approx. 3200 rpm @75mph (just for a short run, 3.23) and had no problems (except it is loud ).

Oh, and you'll hear almost NO wind noise, cause the engine is louder inside, especially the fan I can hear

And I do 70-80mph with my Charger @2500-3000rpm for 3 hours with no problem at all. It has a 727 as well, but long highway axle (2.76). No problem to go even faster for extended time.

Thanks everyone. I use to do high 60s with my 68 Must with a c4 (same as 727) and 2.79 rear but you could tell it didnt love being up at 70s for the long haul.

I also installed a higher stall converter like an idiot and that added a ton of heat which likely overwhelmed the cooling system.

I would agree with that. Lower the stall and that will help a lot.

nyc108hopeful wrote:If I need to do at least 65 and upwards of 70mph for 2-4 hour stretches am I crazy to attempt it with a stock 727 and rear gear in an a108/a100 or do I need to plan for an immediate 518 swap?

Will the rpms be too much?  Overheating likely? Or will it just be a bunch of wind noise?

look on the ID plate and it'll tell you what the rear gearing is, that plus rim/tire size will determine rpm's at speed.

there are rpm calculators on the internet you can use to figure it out.

back before we had o.d. transmissions, everyone buzzed down the highway at 70 and never gave it a thought. had a c-40 that turned 5500 at 55 miles an hour and ran it every day like that and several trips where it turned 5500 for hours at a time. you could just buy better mufflers!

when these a100's were built no one knew what a overdrive was [well a few,but] speed limit was 70mph everywhere and everybody drove 80

in the 70's i was running a ford econoline with a 302 ,325 gears ,it literate went all over the country at 70-80 mph. was the rpm high.no not for back then ,seems like 3200. but that was just norm. probably had like L60's on the rear.

oh yea steppenwolf was blaring as loud as those 6x9's could handle in my craig 8 track player, so engine noise was just part of it.

those were the vanin days

they still are the vannin days

the vannin days here in kansas are gone,i roll down the street in my old choptop,people hardly know what they are seeing. we have a population of around 550k ,i would guess that theres 4-5 older vans in the area driving down the street

Thanks for all the reassurances....hope to be an owner by this fall or Spring 2018 at worst

Yea, even 3:55's should be OK. But keep in mind these things can be a bit of a handful at 70MPH. I have 3:91's according to the build tag (need to confirm), it'll do 65 OK but it is pretty loud, not exactly a new Town and Country!

I would say 70 is about as fast as you would want to go in one of these, regardless of gearing.