Gearing it up
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Junior User
Joined: Aug 2013
Posts: 63
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From: WI
Gearing it up
ive got a 86 ford f 150 i6 4 speed, it doesnt want to go much faster then 55, lol. so what would i need for a rear gear set or axle to make it do least 75 for the lowest amount of money, i plan on taking it for a trip and the speed limits like 70, so i dont wanna be redlining all the way 12 hours to where im going, i believe its got the 3.55 gear set in it, i checked by rotating the tires and counting the drive shaft turns that about where i got the tag confermes it.
if anyone knows what i can put in to accomplish it, it would be appreciated
Thanks
if anyone knows what i can put in to accomplish it, it would be appreciated
Thanks
Moderator
Joined: Jan 2001
Posts: 56,983
Likes: 2,736
From: Virginia
Here are some places in Wisconsin that have 5 speeds for sale. Make sure to get one from a truck that had a 3.55 so the speedo reads correctly.
1991
Transmission
Ford Truck 150 NOF05 $575 D & E Auto Parts, Inc. RP+ Member USA-WI(Elkhorn) Request_Quote 1-262-742-2220 Request_Insurance_Quote
1989
Transmission
Ford Truck 150 TESTED GOOD 100123 $350 Hoop's Garage and Salvage USA-WI(Juda) E-mail 1-608-934-5534
1990
Transmission
Ford Truck F150 LARIAT XLT,4.9L,5 Sp 283,002 C A6358 $325 Accurate Auto Parts and Recycling, Inc. USA-WI(Greenbay) E-mail 920-494-6000 / 800-323-6943
1991
Transmission
Ford Truck 150 NOF05 $575 D & E Auto Parts, Inc. RP+ Member USA-WI(Elkhorn) Request_Quote 1-262-742-2220 Request_Insurance_Quote
1989
Transmission
Ford Truck 150 TESTED GOOD 100123 $350 Hoop's Garage and Salvage USA-WI(Juda) E-mail 1-608-934-5534
1990
Transmission
Ford Truck F150 LARIAT XLT,4.9L,5 Sp 283,002 C A6358 $325 Accurate Auto Parts and Recycling, Inc. USA-WI(Greenbay) E-mail 920-494-6000 / 800-323-6943
Lead Driver
Joined: Jul 2009
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From: Sheffield, AL
3.08 rear gears and 4 speed manual O.D. with stock sized tires [215/75 X 15] in my 1986 F150 with 4.9L engine gives 70 MPH @ 2000 RPMs. It is quite happy at that speed!
The O.D. ratio is 0.71:1.
The O.D. ratio is 0.71:1.
Last edited by 1986F150six; Aug 28, 2013 at 01:47 PM. Reason: Added O.D. ratio.
Moderator
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From: Virginia
Postmaster
Joined: Feb 2011
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your 3.55 gears are capable of running to at least 90 within the usable RPM range of your engine, though you won't want to take your truck that fast... i suspect your trouble has more to do with engine performance than with gearing.
if your 86 is in stock form, it'll have an electronic carb and computer-controlled timing. any problems in the system will have it in limp mode, locked into base timing and very poor on power as a result. assuming this is your case, you'll want to either repair the systems that are having trouble, or convert to a conventional carb and duraspark distributor. plenty of threads around here on the subject, so if thats what your rig needs, start reading!
if your 86 is in stock form, it'll have an electronic carb and computer-controlled timing. any problems in the system will have it in limp mode, locked into base timing and very poor on power as a result. assuming this is your case, you'll want to either repair the systems that are having trouble, or convert to a conventional carb and duraspark distributor. plenty of threads around here on the subject, so if thats what your rig needs, start reading!
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Junior User
Joined: Aug 2013
Posts: 63
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From: WI
your 3.55 gears are capable of running to at least 90 within the usable RPM range of your engine, though you won't want to take your truck that fast... i suspect your trouble has more to do with engine performance than with gearing.
if your 86 is in stock form, it'll have an electronic carb and computer-controlled timing. any problems in the system will have it in limp mode, locked into base timing and very poor on power as a result. assuming this is your case, you'll want to either repair the systems that are having trouble, or convert to a conventional carb and duraspark distributor. plenty of threads around here on the subject, so if thats what your rig needs, start reading!
if your 86 is in stock form, it'll have an electronic carb and computer-controlled timing. any problems in the system will have it in limp mode, locked into base timing and very poor on power as a result. assuming this is your case, you'll want to either repair the systems that are having trouble, or convert to a conventional carb and duraspark distributor. plenty of threads around here on the subject, so if thats what your rig needs, start reading!
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Postmaster
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well, i also happen to have a truck with the same engine/tranny/gear combo, and i wish it had deeper gears so i could get enough RPMs to maintain highway speed. i'm certainly not over-revving it, but it would be a damn miracle if i were to get it up to 75 on anything other than a long downhill
for what is on your engine, it might be done right, or it might be very wrong and causing horrible performance.
for what is on your engine, it might be done right, or it might be very wrong and causing horrible performance.
Cargo Master
Joined: Apr 2003
Posts: 2,408
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From: Parkesburg PA
Is your truck 2 or 4wd? If you have 4wd you'll have to match the front and rear axle. Around here the average price to setup gears is $350. Add to that a set of gears, bearings and miscellaneous stuff and you're looking at about $700 for everything.
Junkyard rears can sometimes be almost as expensive. The best thing would be a trans swap as you'll get the best of both worlds. You'll still get good off the line performance and good highway performance.
What size rear tires do you have?
Junkyard rears can sometimes be almost as expensive. The best thing would be a trans swap as you'll get the best of both worlds. You'll still get good off the line performance and good highway performance.
What size rear tires do you have?
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Joined: Nov 2007
Posts: 22,415
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From: Denver Metro Area, CO
Sounds like this engine has had half of a DSII swap done to it - changing the carb and blocking off the vacuum devices - but with the same computer-controlled ignition that's now not advancing the ignition timing like it normally would.
What does your distributor look like? Does it have a module with 5-6 wires attached to it? Or, alternatively, does it have a vacuum hose attached to the front and about 3 wires in a round plug?
I agree, this should be able to do lots better than it is... replacing the rear end is not the correct answer IMO, diagnosing the engine is.
What does your distributor look like? Does it have a module with 5-6 wires attached to it? Or, alternatively, does it have a vacuum hose attached to the front and about 3 wires in a round plug?
I agree, this should be able to do lots better than it is... replacing the rear end is not the correct answer IMO, diagnosing the engine is.
Postmaster
Joined: Mar 2013
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From: Over There
I agree with the previous, something is up here. A 4 speed manual with 3.55s shouldn't have any issue doing 55. We are missing 2 figures in figuring out ratio stuff. Tire size and X rpm at Y speed in 4th. If it's 4wd would help a lot in making a recommendation to.
Any chance it's 4wd and stuck in low range?
Assuming a 30" tall tire you should be spinning about 2200RPM at 55, this match your truck? Just for kicks if it was say 3.55s, 30" tire and stuck in low range it would be spinning about 5700RPM at 55. This and so slow in granny really sounds more like what your describing.
Any chance it's 4wd and stuck in low range?
Assuming a 30" tall tire you should be spinning about 2200RPM at 55, this match your truck? Just for kicks if it was say 3.55s, 30" tire and stuck in low range it would be spinning about 5700RPM at 55. This and so slow in granny really sounds more like what your describing.
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