11 MPH OFF! and some other difficulties

[Boostin4Life]

My 87 Turbo Supra's speedometer is off by 11 mph. I had a friend cruise around 65mph and then I would pace him and once we reach the desired speed my speedometer was showing 76mph what do I do to fix this?

also I have play in my shifter where do i buy the shifter bushings, i heard something about the green truck gasket?? anyt information woud be helpful

also I need to put the ac belt on my supra back on is it just slip it on and go or does it require more work? such as take off any covers? or take off belts?

 

[billspreston01]

there are a few factors to the speed thing, which tranny you're using, which speedo gear you are using, and which differential you are using. If you aren't running the speedo gear that matches the diff then it will be off (I don't know if the gearing in the tranny's is differnet or not) somebody else?

ac belt....loosen the tensioner pulley,slip the belt on, and tighten it down. I'm pretty sure it's the belt on the outside so you shouldn't have to take any other belts or anything off...piece of cake

 

[Nick56289]

If you have larger than stock tires(meaning taller) your speedo will still assume u have stock sized tires. Therefore it will say you are going faster than you really are. This also affects your ABS because even though you are goin 65 it assumes you are going 76 and can really mess things up.

 

[Boostin4Life]

i just bought it and its a 87 turbo supra stock 5 speed tranny and rear end and everything. and it has 215's tires on it so they are actually pretty thin and they are on 18's konigs.

 

[Nick56289]

i just bought it and its a 87 turbo supra stock 5 speed tranny and rear end and everything. and it has 215's tires on it so they are actually pretty thin and they are on 18's konigs.

215 is actually the width of the tire. 215mms. But I was confused earlier, bigger tires would make you go faster but would tell the speedo you were going slower.

 

[IJ.]

255/35/18's will get the speedo back to almost stock and fit the rims MUCH better......

 

[Nick M]

If you have larger than stock tires(meaning taller) your speedo will still assume u have stock sized tires. Therefore it will say you are going faster than you really are.

That is actually backwards. Taller gearing increses speed. Think about it for a minute.

I am assuming he does have to short a tire. The sotck diameter is approximately 24.7 inches. Each tire will vary slightly.

 

[IJ.]

Stock
225/50/16 = 24.9" speedo @ 60

255/35/18 = 25" road speed = 60.4

215/35/18 = 23.9" road speed = 57.5

nowhere near your 11 mph error.

 

[jimi87-t]

Your tires are WAY too small.....

 

[7M-GTE]

It could be that you have an NA diff... b\c that's exactly how far mines off @65 and I have an NA diff with the turbo tranny...

 

[Jeff Lange]

Is your odometer correct?

 

[IJ.]

LMAO @ "Afro Zoidberg"

 

[Boostin4Life]

odometer as in the mielage? if so yes. i have yet to get any answers lol!

 

[jimi87-t]

i have yet to get any answers lol!

yes you have, one problem that is "hit yourself in the face" obvious is your tires are WAY to small, as in the pics you posted of your car, that will throw off your speed. What size tires are they (in the rear), and we could figure out how far off they are messing up your speed.

 

[IJ.]

odometer as in the mielage? if so yes. i have yet to get any answers lol!

I guess I'll have another bash at it as you don't seem to have read my last reply...

Stock
225/50/16 = 24.9" speedo @ 60

255/35/18 = 25" road speed = 60.4

215/35/18 = 23.9" road speed = 57.5

nowhere near your 11 mph error.

The tire size alone doesn't account for the error you're seeing so you either have a swapped Diff or the incorrect Speedo Drive gear to suit the Diff that's in the car.

Fix: Get a set of tires that fit as above the 255's are close enough and get the Speedo Drive gear that matches the Diff, for this you need to work out which Diff Ratio you have.

 

[Jeff Lange]

odometer as in the mielage? if so yes. i have yet to get any answers lol!

So when you drive 5 miles according to highway odometer tests, your odometer reads correctly? If so, your speedometer can be calibrated to fix the error, if your odometer is not reading correctly, you have a tire size/gearing issue.

Have you confirmed that your odometer reads correctly?`

 

[Boostin4Life]

i understand the mph issue i will get bigger tires soon how about the shifter bushings and gas pedal

 

[jimi87-t]

For the gas pedal there is an adjustment under the hood on the throttle linkage that will take the slack out, it looks like a bolt that the cable goes threw. The "bolt" will have 2 nuts on it and it threads threw a bracket. Loosen the nuts and turn the bolt until the slack is gone.

 

[theDon]

I'd agree with the rear gear ratio not being what it should be.