1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

mystery gears, speedo waaay off.

Old Mar 29, 2007 | 02:43 AM
  #1  
Enthu's Avatar
Thread Starter
Still has an RX7.
iTrader: (1)
 
Joined: May 2001
Posts: 1,015
Likes: 5
From: minneapolis MN
mystery gears, speedo waaay off.

So we finally got the SA on the road after doing some restoring to it and fixing some things. One thing is that we know little about the car or what was done to it in it's former life. I do know that it was an ice racing car, and that's about it.

After driving it, my brother claims 'nothing is as it seems" in the car. The speedo says he's going 50, but feels like 40. I rode passenger while he drove and noticed at 70 mph on the speedo it felt like it couldn't be much over 50.

So I am lead to believe it must be that the previous owner had changed the gears. That leads me to my question; Does anyone know what ratio the gears may have been changed to that would result in this? or did I somehow mess up the speedo when I pulled the tranny offf for a clutch? The speedometer is nice and steady, with no shaking.

It's got a 5 speed tranny now ( I say now because who knows what it may have had before) and it's a 79. It does have disc brakes in the rear though .I assume also an LSD.

I'll post Pictures of the car on Tuesday, when this rain is supposed to stop.
Reply
Old Mar 29, 2007 | 03:30 AM
  #2  
trochoid's Avatar
Old Fart Young at Heart
Tenured Member 10 Years
iTrader: (6)
 
Joined: Apr 2004
Posts: 15,145
Likes: 8
From: St Joe MO
Stock gears were 3.909. Stock aftermarket ones are 4.44, 4.88 and 5.12. I think there may have been a 4.56 thrown in the middle, but I'm not certain. If you make a mark on the driveshaft and another one on the edge of the tire tread, you can turn the shaft and count how many turns of the shaf tit takes to make 1 full turn of the drive wheel.

This ratio will give an approximation of the gearing. Test needs to be performed in 4th gear since it has a 1:1 drive ratio. Test will only be accurate with stock sized tires and wheels. Pull the lower plugs from each housing to make rotating the engine easier. Since the rear end is an LSD, andf the SAs didn't come with one, check the wheel bolt pattern. The manual SEs came with q 4.10 gearwset, all other models came with the 3.99.

Post back and let us know what you find.
Reply
Old Mar 29, 2007 | 01:56 PM
  #3  
Enthu's Avatar
Thread Starter
Still has an RX7.
iTrader: (1)
 
Joined: May 2001
Posts: 1,015
Likes: 5
From: minneapolis MN
I'll give that a try to figure it out. I want to get the car up in the air again anyway to check why my e-brake is not functioning.
Reply
Old Mar 29, 2007 | 02:21 PM
  #4  
Jonny2x4's Avatar
Full Member
Tenured Member 15 Years
 
Joined: Aug 2006
Posts: 93
Likes: 0
From: Loveland, Colorado
lol i have the same problem with my SA. I figured out its about 5mph over what im doing. The parking brake can be adjusted inside the car.(I did this yesterday) Theres a screw on your ebrake on the right hand side. It just tightens the line. Mine is tightened all the way and it still only catchs when its all the way up. But it holds alot harder now.
Reply
Old Mar 29, 2007 | 02:22 PM
  #5  
Jonny2x4's Avatar
Full Member
Tenured Member 15 Years
 
Joined: Aug 2006
Posts: 93
Likes: 0
From: Loveland, Colorado
lol i have the same problem with my SA. I figured out its about 5mph over what im doing. The parking brake can be adjusted inside the car.(I did this yesterday) Theres a screw on your ebrake on the right hand side. It just tightens the line. Mine is tightened all the way and it still only catchs when its all the way up. But it holds alot harder now.
Reply
Old Mar 29, 2007 | 02:22 PM
  #6  
Jonny2x4's Avatar
Full Member
Tenured Member 15 Years
 
Joined: Aug 2006
Posts: 93
Likes: 0
From: Loveland, Colorado
sorry work computer suck posted it 3 times

Last edited by Jonny2x4; Mar 29, 2007 at 02:28 PM. Reason: DAMN WORK COMPUTER
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
rgordon1979
3rd Generation Specific (1993-2002)
40
Mar 15, 2022 12:04 PM
manoflego
1st Generation Specific (1979-1985)
19
Sep 30, 2015 05:19 AM
Thor 18
3rd Generation Specific (1993-2002)
5
Sep 28, 2015 07:35 PM
Casual_John
Canadian Forum
4
Sep 26, 2015 01:47 PM


Thread Tools
Search this Thread

All times are GMT -5. The time now is 03:04 AM.