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1984 subaru brat 5speed conversion problems


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12 replies to this topic

#1 superbrat84

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Posted 25 July 2011 - 11:21 PM

I got a 5 speed tranny out of a 1986 subaru coupe (xt i think) but i discovered the other day that according to the speedometer 0-45 the speedo needle read 5 miles per hour below. and then 55 on the speedo is 65. and 65 on the speedo is 75 and etc. did i get the wrong trannsmision? or is my speedo broken. thanks

#2 GeneralDisorder

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Posted 26 July 2011 - 01:23 AM

What size tires are you running?

GD

#3 superbrat84

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Posted 26 July 2011 - 09:39 AM

185/80r13

#4 Qman

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Posted 26 July 2011 - 02:51 PM

That should make your speedo about 6% slower than actual.

#5 GeneralDisorder

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Posted 26 July 2011 - 04:00 PM

Yeah - either it's not as far off as you say, or something is wrong with your speedo head I would say.

GD

#6 ShawnW

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Posted 26 July 2011 - 04:43 PM

He said he put an XT trans in, did you put a 3.70 trans in where a 3.90 one was?

#7 92_rugby_subie

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Posted 26 July 2011 - 04:44 PM

I agree with GD. It cant be that far off... I ran 195/60/15 and didnt see 5mph difference in my speedometer reading... maybe 2-3mph off from GPS (Speedo say 35, be doing 33 according to GPS)

#8 Qman

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Posted 26 July 2011 - 05:38 PM

He said he put an XT trans in, did you put a 3.70 trans in where a 3.90 one was?


Excellent catch. However, are not all the non-turbo 4wd transmissions 3.90/1?

I would tend to believe that the speedo gear in the trans could be worn or possibly different which could represent the difference in readings.

And, if the OP states his speedo is that far off then I tend to believe that it is. Just because your speedo doesn't match that doesn't mean his doesn't... :rolleyes:

#9 superbrat84

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Posted 27 July 2011 - 01:08 PM

well i was driving with my friend and his android phone had an app in which he could read how fast he was going and we also timed it between mile posts and according to speedo going 65 it took 47 seconds to go one mile. thats 75 miles per hour.and i had a regular d/r 4speed in it did i get the wrong tranny?

#10 Qman

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Posted 27 July 2011 - 02:10 PM

The only way to be accurate is to go to a speedometer shop with a dyno that measures speed.

Now, that being said, you could explain the slower speed by using a 3.70 transaxle. Have you engaged 4wd yet? It should not be 10 mph off by changing to a 5speed as long as the correct final drive ratios were matched.

#11 superbrat84

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Posted 27 July 2011 - 07:56 PM

driveline is in the shop picking it up tomorrow so do i have a wrong gear ratio. it did come out of a subaru coupe?

#12 Mykeys Toy

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Posted 27 July 2011 - 10:40 PM

The best way to know for sure is to look at the rear diff of the donor car, it will have a tag with gear ratio 3.7, 3.9.

#13 superbrat84

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Posted 29 July 2011 - 06:56 PM

well got my drive shaft back from six states and installed it a couple of odd occurences happened. got the drive shaft in and bolted it on and tried to drive the car (brat was in 2 wheel drive) and was very resistant and almost wouldn't move. so i put the brat on 4 jack stands and put it in 4 wheel drive lo let out the clutch a little resistant and then it just started working. so i took it off the stands and drove just fine. any one have a similar experience.




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