reamer Posted June 7, 2018 Share Posted June 7, 2018 Assuming 29" tires and similar trans gearing to my NV3550, you won't be to your torque peak in 1st gear until 21 mph, and you'll need to drop to 3rd gear at 60 mph to get to your torque peak. Personally I'm a fan of bigger engines with lower torque curves that can pull the taller gears strong. But if I had built a fire-breathing 302, I'd want gears that would let it breathe, something like 4.10s. I'm running 275/60R15 tires which are just a hair over 27" OD, almost exactly the same as the originally supplied tiny 215/75R15's. I should have this thing on the road in another week or two so I'll soon be able to test out the new set-up. Part of the reason for installing the 5spd was to get the overdrive so I can take this thing on a trip once in a while. Gas right now is $5/gal here...and that's for 87 octane. 91 can be as high at $6/gal, so I'd prefer if the thing isn't screaming on the highway. It was running at 2350 RPM @ 60 MPH in top (3rd) gear previously, which will be the same (1:1) ratio as 4th gear in my 5spd. If my math is correct, with the 0.80 ratio 5th gear, it should now be running about 1900 RPM @ 60 MPH on the highway. If it happens to be too sluggish on the hills at 1900 RPM, I can always drop it back into 4th. In any case, I don't mind changing the diff gears if need be, but it's still too early to tell. Congrats Cory! Just keep in mind Gary's write up on the air filter housing, Stock with cool-air snorkel vs "shiny chrome things" Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2018 Share Posted June 7, 2018 Congrats Cory! Just keep in mind Gary's write up on the air filter housing, Stock with cool-air snorkel vs "shiny chrome things" You mean this one: Fuel Systems/Air Cleaners? I just shared that link on Facebook as the discussion there was going off the rails. It is amazing how much misinformation there is out there on this subject. Someone asked the question if there was such a thing as a cold air kit for these trucks. What?!?!? That's exactly what the factory air cleaner system is! Another person in that conversation said that's only for fuel-injected engines. Whoa! That's actually the exact opposite of where the need is. EFI systems have air temp sensors and compensate for the incoming air temp by varying the amount of fuel injected to get the right mix. Yes, they can also benefit from the added oxygen that is in the more dense cooler air. But it is carb'd engines that need cooler air the most as the carb has no way to know the air temp and, therefore, can't adjust for that variable. (I know a very few carbs did have temp compensation, but they were few and far between and weren't very effective anyway.) So a carb'd engine gets a double whammy with hot air - reduced oxygen in the cylinder as well as the wrong air/fuel mixture. There's an interesting article that was done several years ago by Four Wheeler magazine. They were trying to get MPG and HP out of a 460. And while it was an EFI system, their work on the intake air plumbing was relevant to carbs. Link to comment Share on other sites More sharing options...
Nothing Special Posted June 7, 2018 Share Posted June 7, 2018 I'm running 275/60R15 tires which are just a hair over 27" OD, almost exactly the same as the originally supplied tiny 215/75R15's. I should have this thing on the road in another week or two so I'll soon be able to test out the new set-up. Part of the reason for installing the 5spd was to get the overdrive so I can take this thing on a trip once in a while. Gas right now is $5/gal here...and that's for 87 octane. 91 can be as high at $6/gal, so I'd prefer if the thing isn't screaming on the highway.... My Bronco with a stockish 302 is running 33" tires with 4.10 gears behind the NV3550. That's equivalent to 3.35 gears and 27" tires. I really like the setup because, like you, I don't want it screaming on the highway. But most people tell me that I shouldn't "fear the gear" and that it would be a lot better with lower gears. I don't doubt that it would pull stronger, and probably wouldn't even get significantly lower mileage with 4.56 gears (equivalent to 3.73 with 27"). But it would be buzzier, and I'm happy enough with the performance I have. But that gearing will make your new-found power harder to find. If it was me (and I know it isn't!) I'd want to be able to get at that power easier (even though I probably wouldn't use it a lot). And with 27" tires and a 5 speed OD trans I'd probably go about 3.73 gears. .... In any case, I don't mind changing the diff gears if need be, but it's still too early to tell. Absolutely! I'm definitely not suggesting you regear as a preemptive strike. Drive it and decide what YOU want. My opinion (especially without having driven your truck) MIGHT be worth your time to read and consider, but it's definitely not worth your making changes to your truck! Link to comment Share on other sites More sharing options...
Rembrant Posted June 7, 2018 Author Share Posted June 7, 2018 Congrats Cory! Just keep in mind Gary's write up on the air filter housing, Stock with cool-air snorkel vs "shiny chrome things" Haha, understood Reamer (And Gary). The shiny part is not really of great interest to me...it could also have been black. It's just that 99% of them are shiny...lol. I installed it mainly for the sound...with a much smaller percentage of my reasoning being for appearance. If this was going to be a daily driver truck, I would probably lean more towards a stock air cleaner assembly, but at the end of the day, my truck is just a summer weekend machine that will likely only ever see a few hundred or a thousand miles a year. Maybe more...you never know. It is supposed to be a bit of a hotrod, so that's where my reasoning is coming from. I had the benefit of trying a whole bunch of different air cleaners on the dyno last week, and that was interesting. However, that was testing air flow, not air temperature. Link to comment Share on other sites More sharing options...
Rembrant Posted June 7, 2018 Author Share Posted June 7, 2018 But that gearing will make your new-found power harder to find. If it was me (and I know it isn't!) I'd want to be able to get at that power easier (even though I probably wouldn't use it a lot). And with 27" tires and a 5 speed OD trans I'd probably go about 3.73 gears. Yes sir, good point. I get it. All I have to compare to is how the truck was previously with the stock 302 and a sloppy shifting 3-on-the-tree, and anything will be an improvement over that I am certain! 3.55's or 3.73's may end up being a better fit, but I'll play with it a bit and see how it feels. Swapping gears isn't a big deal or a big expense, so it may very well end up on the to-do list. I'll be back with real world driving results in a couple weeks;). Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 7, 2018 Share Posted June 7, 2018 But that gearing will make your new-found power harder to find. If it was me (and I know it isn't!) I'd want to be able to get at that power easier (even though I probably wouldn't use it a lot). And with 27" tires and a 5 speed OD trans I'd probably go about 3.73 gears. Yes sir, good point. I get it. All I have to compare to is how the truck was previously with the stock 302 and a sloppy shifting 3-on-the-tree, and anything will be an improvement over that I am certain! 3.55's or 3.73's may end up being a better fit, but I'll play with it a bit and see how it feels. Swapping gears isn't a big deal or a big expense, so it may very well end up on the to-do list. I'll be back with real world driving results in a couple weeks;). You may find you like your current combo. Getting the R's down to 1900 at 60 MPH should work nicely for most driving, unless you live in a really hilly area. And the lower R's will help both the MPG and the noise. Link to comment Share on other sites More sharing options...
Rembrant Posted June 8, 2018 Author Share Posted June 8, 2018 So, this modification might look a little redneck to you guys, but it's what I decided to do. I bought an offset 1994-1996 M5OD-R2 transmission crossmember for a 2wd truck, and it didn't fit my '84 100%. I originally thought that this crossmember would fit the original holes in the frame, but it turns out it was off by a little over an inch. Once I had everything mocked up with the trans mount centered in the crossmember holes, I had to move everything back 1 3/16". NBD. I cut the corners out of the brackets and added a small extension so that I could add another set of holes. This will allow me to use the two bolts that are already in the frame (The ones I can't remove because the cab is in the way). Anyway, I tested it all last night and everything fits OK. Today's goal is to get everything all finished behind the engine. Remove transmission to lube clutch splines, and re-install. Install new crossmember and brackets, new rear mount, and lock down. Install drive shaft Install speedo cable (My original speedo cable reaches no problem, but haven't tried it yet) Splice reverse switch wiring (Connect M5OD plug to Bullnose wiring.) Fill and bleed hydraulic clutch. Finish trimming hole in rubber floor to mount 5Spd shifter boot. After that, everything should be firewall and forward. Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 8, 2018 Share Posted June 8, 2018 So, this modification might look a little redneck to you guys, but it's what I decided to do. I bought an offset 1994-1996 M5OD-R2 transmission crossmember for a 2wd truck, and it didn't fit my '84 100%. I originally thought that this crossmember would fit the original holes in the frame, but it turns out it was off by a little over an inch. Once I had everything mocked up with the trans mount centered in the crossmember holes, I had to move everything back 1 3/16". NBD. I cut the corners out of the brackets and added a small extension so that I could add another set of holes. This will allow me to use the two bolts that are already in the frame (The ones I can't remove because the cab is in the way). Anyway, I tested it all last night and everything fits OK. Today's goal is to get everything all finished behind the engine. Remove transmission to lube clutch splines, and re-install. Install new crossmember and brackets, new rear mount, and lock down. Install drive shaft Install speedo cable (My original speedo cable reaches no problem, but haven't tried it yet) Splice reverse switch wiring (Connect M5OD plug to Bullnose wiring.) Fill and bleed hydraulic clutch. Finish trimming hole in rubber floor to mount 5Spd shifter boot. After that, everything should be firewall and forward. That's an ingenious solution and I don't see anything wrong with it. Lots easier than my approach of pulling the cab bolts, raising the cab by 4", and drilling new holes in the frame with a right-angle air drill and a cut off bit. Looks like you'll have all that stuff buttoned up today. Link to comment Share on other sites More sharing options...
Rembrant Posted June 8, 2018 Author Share Posted June 8, 2018 That's an ingenious solution and I don't see anything wrong with it. Lots easier than my approach of pulling the cab bolts, raising the cab by 4", and drilling new holes in the frame with a right-angle air drill and a cut off bit. Looks like you'll have all that stuff buttoned up today. Well, it seems to have worked OK. It's all bolted in and locked down now. Everything fit nicely with no strain, so all the holes I drilled lined up properly. I have a question though. Any idea how much thread engagement there is supposed to be on the 6 bellhousing to block bolts? I saved the 6 bolts from the original trans/bellhousing (3-spd manual), and I just reused them on the M5OD trans (Only have the four longer ones installed at the moment), but there's only about 1/4" of threads on the bolts where they thread into the block. I wonder, is the M5OD supposed to have longer bolts? Or is that normal? Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 8, 2018 Share Posted June 8, 2018 Well, it seems to have worked OK. It's all bolted in and locked down now. Everything fit nicely with no strain, so all the holes I drilled lined up properly. I have a question though. Any idea how much thread engagement there is supposed to be on the 6 bellhousing to block bolts? I saved the 6 bolts from the original trans/bellhousing (3-spd manual), and I just reused them on the M5OD trans (Only have the four longer ones installed at the moment), but there's only about 1/4" of threads on the bolts where they thread into the block. I wonder, is the M5OD supposed to have longer bolts? Or is that normal? The easy answer is that your bolts aren't long enough. The rough rule of thumb says you should have at least one full diameter of the bolt in engagement. And those should be 7/16"x14 bolts so you need at least that much engagement. As for why they aren't long enough, I'm going to guess that the originally tranny had a cast iron bell housing and that the M5OD has an aluminum bell housing. Cast iron wouldn't need to be as thick as aluminum to provide the same strength. But I'm not finding the proper bolts in the catalog. So, just get longer bolts - which probably are G5's. Link to comment Share on other sites More sharing options...
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