my speedo is out, and i dont know why!

[1jzfanatic]

hi everybody,
i have a question involving my jzx83 cressida.
i have a 89' GLX (series one, which means cable speedo / open wheeled diff)
jzx81 engine
w58 gearbox.

everything else has been left standard as such.(except my 17'' wheels)

can somebody tell me why my speedo is really REALLY far out? also is there a simple fix?

thanks heaps guys.
(when i say really out, im practically doing 10 or more k's over what it says... the gap gets higher the faster i go ect...)

[Cuzzo]

17inch wheels and non-standard gearbox.

IS the diff non-standard too?

[crowncustom]

Very possible that the speedo drive cog is the wrong one for the ratio of the diff.Plus the 17s will cause an error also.
Cheers Brett.

[1jzfanatic]

cuzzo,
the diff is just a standard open wheel diff that goes in a glx.

even with 17's i doubt it would be out so far out as it wasnt bad when i had the auto in with 17's on....

crowncustom, is there a way i could possibly check / find out which one i need? because that sounds quite feesable.... i simply assumed that all speedo gearsets were the same with all w series gearboxes.


cheers

[CrUZida]

The speedo gear in the box is to suit the diff ratio of the car it originally came from (assuming it hasn't been changed)

Have a search and a play to learn how it all works.

[crowncustom]

If you still have the old auto pull the drive from that and the one from the W58 and change and things should work fine.I had to do this when I changed the diff ratio in my MX 62 Cressi from 3.7 to 3.9.The drive should have the number of teeth stamped on them but if not just count the teeth.With the 3.7 I had 19 teeth and for the 3.9 it was 20 also the same when I converted my MX 10 to manual but just luckly that the W50 I used had ran the same ratio diff as the MX 10.
Cheers Brett.

[CrUZida]

W58 uses a larger gear than the W50 and auto's.

[crowncustom]

Well that stuffed that idea
Cheers Brett.

[1jzfanatic]

mmmmmmmmm... damn
i need to find a solution quick before i start getting fined.,.

what # toothed gear would i be looking for? (assuming i have 235/45 r17's on as well... if that makes any diffrence)

im unsure as to what i have at the moment, but i will count the teeth on it.
ALSO
could i t be possible that the cable is stuffed hence giving a wrong reading? i notice when im going slower (like apprx 30-40 k's) the needle seems to flick, not heaps but a little.


Grant

[CrUZida]

Cable will be getting old (hence the flicking) but won't greatly affect the reading.
Your tyres are close enough to factory to not affect anything.

You can buy a mechanical speedo changer box from CRS for about $130 I think.
Probably the most hassle free way to fix it.

[1jzfanatic]

i got told last night by a guy who's got a w58 in his cressy, that he used the standard (a340e?) auto box gear for the speedo! i've got a heap of these paperweigh.....er.... boxes laying about so ill try it out and let everyone know!

[1jzfanatic]

no deal! turns out he has no idea what he's on about, and ill show you why.

left is w58 drive gear, middle is jzx81 auto gear and right is mx83 auto gear.
the shafts are diffrent lengths, the outer diameter of the housings are waay diffrent, and nothing shall interchange! (i tried to swap the cogs over on the shafts, but to no avail (they dont fit properly)

anyone, somebodys gotta have done this before? how are the 2jz N/a guys doing it?

[greywolf]

My speedo is out, but luckily (?) for me , it's under. So I need to do 104 on the speedo to hit 100, and 115 to hit 110. I just used a GPS to get a rough idea of what speeds I need to be doing before hitting the major speed limits. As it's one of three different cars that I drive, it's not hard for me to remember a couple extra numbers.

I can understand wanting to get it fixed, but not if iit's going to be a huge cost of time and money ? If you are desperate, I'd look at the fix Cruzida suggested.

[DrNick]

If its any help, I was just swapping speed sensors over between two boxes and I counted the teeth.

The W58 box from 2JZA80 Supra has 32 teeth. I think the final drive on that car is 3.77 (but I am not 100% on the final drive).
The sensor I pulled from a JZZ30 soarer R154 box has the same cog on it and is 32 teeth too. These are both electric ones.

[DX20VT]

if you check bog standard cars you will find that speedo's are rarely accurate from new.

even brand new cars today, some are out by up to 10%.