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Title: Speedo Gears Post by: FC_fer_me on February 20, 2007, 10:16:49 AM Hi, could anyone tell me if there are different ratio driving and driven speedo gears available for the 3 speed crash box. I know they were available for the red all synchro box but I'm not sure about the grey box. I have changed my diff ratio from 3.89 to 3.55 and the speedo is 5 MPH out now. Cheers, David ???
Title: Re: Speedo Gears Post by: mcl1959 on February 20, 2007, 11:01:52 AM No other gears were available for the grey box. When you think about it, there were no options in manual driveline for FX to EJ with no wheel diameter change and no diff ratio changes. Therefore there was no need to have different ratios available.
Ken Title: Re: Speedo Gears Post by: Martin on February 20, 2007, 01:48:17 PM Ken,
15" rims on FX & FJ, 13" on later models. Was the diff ratio different? Martin Title: Re: Speedo Gears Post by: RET on February 21, 2007, 12:10:18 AM Same diff ratio, but the gear-box itself for 48 and FJ is different. Not substantially so, because FJ utes and vans produced post-FE introduction use the FE-EK box.
There are two different drive gears though, one for 48-FJ and one for later models. To answer David's question, the speedo head can be adjusted by specialists, or you can look into adaptors - CRS used to sell one, not sure if they still do. They used to be quite common. Bear in mind that rolling circumference of tyres impacts speedo accuracy as well, so settle on what size tyres (ie wall height) before spending money on speedo calibration. If it's only out by 5mph, it might not be worth the expense. cheers RET Title: Re: Speedo Gears Post by: RodM on February 21, 2007, 02:34:18 AM High Dave,
I did this conversion a number of years ago (there is a thread on this site somewhere). There are two different speedo gears for a grey taking into account 13 and 15 inch wheels as discussed. One has 19 teeth and the other 21 (i think). Anyway I changed them and now the speedo reads pretty close. In actual fact I just check this on the freeway on the weekend. I was doing 60mph on the speedo and it read 98kmh on the indicator. Not bad considering 62mph is 100kmh. Do a search of the site and you find the finer details of the discussion. Cheers Rod Title: Re: Speedo Gears Post by: mcl1959 on February 21, 2007, 10:44:06 AM Oops wrong again ;D
Need to put brain into gear before letting fingers loose on the keyboard. Apologies Ken Title: Re: Speedo Gears Post by: FC_fer_me on February 21, 2007, 12:11:08 PM Just checked my gears and it has 23 teeth. I found on an old post that 1 tooth equates to 5% difference in the speedo reading (in k's) so if the FJ gear has 19 teeth that would be 20% or 20 k's ( 12 mph ) at 100k's . Maybe someone out there knows how many teeth the FJ driven gear has? I assume that if the driven gear has less teeth then the driving gear must be different too. any info appreciated, Cheers Dave ???
Title: Re: Speedo Gears Post by: RodM on February 21, 2007, 10:42:01 PM Hi again Dave,
As I indicated I think they were the number of teeth on the gear. Can not be exactly sure as it was a number of years ago. However as I indicated with the different gear the speedo is almost spot on given by the highway speed indicator. Better than what it was with the original gear. Rod |