I have an 86 gt with a 4 speed and usually cruise around or 70 mph. The rpms are a little high (about 3,000 rpm at 70 mph) but it doesn't seem to have affected anything negatively yet. I even get around 26 mpg. Although the grooves in the road from wear are pretty bad in some places and at those speeds my car can be a bit tricky to control in those lanes. My brother's automatic formula is up at 3500 rpm at only 60 mph but I think his torque converter might not be locking up. So how fast do you all drive?
It's been a while since I had 4-speeds, the last being 4-5 years ago, but I had no problem running it up to the 85 mark, and a few times well over it. If the engine is solid with good oil pressure, it will cruise at 70-80 without any bad effect. Bouncing around on the highway berms can be in part to either worn suspension parts, improperly aligned, or both. The Fiero just isn't wide enough to fit down in those semi truck tracks. Driving in the left lane, at or above the speed limit of course, can make driving more relaxing since trucks are prohibited on most triple lane roads.
Part of the reasoning behind the 85 MPH speedometer is left over from the 55MPH speed limit days. Most people like to drive with the speedometer hand at or near straight up. If I recall, 55 is just a little one side or the other of the 12 o'clock position.
Originally posted by RilesOfSmiles: My brother's automatic formula is up at 3500 rpm at only 60 mph but I think his torque converter might not be locking up.
His tach is probably reading too high, which is quite common.
I usually cruise about 60-65 86 GT auto. Mine too is low geared as at 65 mph my tach is sitting around 3200-3300 rpm. A little high but does give good low & midrange grunt. Kit
Originally posted by RilesOfSmiles: Although the grooves in the road from wear are pretty bad in some places and at those speeds my car can be a bit tricky to control in those lanes.
Fix your ball joints, steering, or whatever is loose. And if you have fairly old tires, you might need new ones, even if they have some tread left on them. if you're having problem controlling the car at 70 MPH on grooved roads, then something is loose/worn and needs replaced.
Where you live, it rains a lot I'm sure, and grooves are cut into highway roads to aid with drainage in heavy rains. Plenty of the roads down here are the same. It's not due to wear on the road, but because the road was designed/made that way.
I normally set my cruise control at 5mph over the posted limit. I increased my caster with the GM washer kit. I have 9mm in the rear and 3mm toward the front of the upper control arm bolt. Caster plays a big role in higher speed stability.
I wrecked my 87 GT 5 speed a half year ago but I cruised at 80 all the time. I don't remember the RPM's but they weren't excessive and the engine made a nice humming noise not excessively loud. In Calif everyone goes 80 on the freeway all the time. I try not to go faster as the fine goes way up at 15 MPH over the speed limit.
70-75mph at 2500rpm with a 4t65e. Not sure that the lockup is always engaged. I had problems with it in the past. Oh, forgot that I have a 3800SC engine. (how can I forget that?)
I'm really starting to not like my TH125, 55mph @ 2500rpm. What would be a good upgrade for the 2.8 that doesn't require a controller?
THM440T4 or whatever you wanna call it, from older vehicles. (1985+?). The earlier ones are cable controlled vs electronic, irrc. Not sure if you need larger hubs or not, haven't looked into it. Here's the first thing that popped up under a search, gives you an idea what to look for.
THM440T4 or whatever you wanna call it, from older vehicles. (1985+?). The earlier ones are cable controlled vs electronic, irrc. Not sure if you need larger hubs or not, haven't looked into it. Here's the first thing that popped up under a search, gives you an idea what to look for.
The ones in the early '90s were designated 4T60 and from what I've read, the latest ones had an additional friction plate or whatever it's called, so they are better.
I cruise at "ten over" pretty much everywhere. You pretty much have to in Atlanta, or you'll get run over. On 55 MPH roads (such as the I-285 "perimeter" highway) everyone drives at least 70. I try to not be the fastest. (Some of us are just damned crazy.) But I let the fastest ones "beat the bushes" for me. I try to get where I'm going while still blending in with traffic. As a police officer friend once advised, I "always attempt to maintain a low profile." I don't use a radar/lidar detector. I have found that when I do, I still drive at about the same speed, and I'm a lot more paranoid, and distracted. It's not like they're after the people driving just "ten over" anyway. They'd have to stop everyone.
My cruising RPM at 80 is ~2800 (standard Getrag gearing.)
[This message has been edited by Raydar (edited 03-14-2014).]
The ones in the early '90s were designated 4T60 and from what I've read, the latest ones had an additional friction plate or whatever it's called, so they are better.
The 440T4 and the 4T60 (Non "E") are essentially the same tranny. There was just a change in the naming convention. (Similarly, the TH125 is the same as a 3T40.) The earlier ones were fragile. The newer they are, the more improvements were made. They changed to "E" (electronic control) in the late 80s / early 90s, depending upon application. By my way of thinking, one of the better 4T60s to grab would be one from a 90 Deville. (The 91 switched to the 4T60E.) Since it was sturdy enough to handle a Deville, it should be able to handle most anything we would throw at it with a 60 degree V6. The governors would likely have to be changed, since the Caddy shifted at lower RPM than the V6.
[This message has been edited by Raydar (edited 03-14-2014).]
I am usually between 5 and 10 over when cruising, regardless of limits. That would max out in the low 70's around here, as our state max limit is 65. I cannot say what the engine is turning over at, but isn't unpleasant. (V6 4 spd btw in my 85 SE).
If your wandering a lot, might want to check your steering stablizer....
