I have just finished rebuilding a 4kc for my ke55. i have been driving it around and when the speedo says i am traveling at 80KM/PH i am actualy going 100KM/PH. so i jacked up the back of the car and descoverd that i turn the wheel 4 times and the tailshaft turns 9 times. This is unusual as I'm sure the diff ratio is supposed to be 4.11 not 4.9 . THis is got me in a pickle. How can i fix my speedo and have i calculated wrong with the diff?

 

Any help is apreciated as i wish for my licences sake i can get the speed fixed.

 

Thanks sam

You need to change the speedo drive in the end of the gearbox to suit your diff ratio.

You need to change the speedo drive in the end of the gearbox to suit your diff ratio.

 

What speedo drive would you recomend?

What speedo drive would you recomend?

 

At the risk of sounding like a smart arse and repeating myself - One that suits your diff ratio!

 

So you first need to 100% confirm what diff you have. Was the car originally manual or auto?

You then need to source the correct drive gears, matched for that ratio.

 

Also worth asking - what wheels are on the car? Stock, or 17's etc?

At the risk of sounding like a smart arse and repeating myself - One that suits your diff ratio!

 

So you first need to 100% confirm what diff you have. Was the car originally manual or auto?

You then need to source the correct drive gears, matched for that ratio.

 

Also worth asking - what wheels are on the car? Stock, or 17's etc?

 

I'm not sure what it was origionaly i bought it off rundell it was manual.

http://www.rollaclub.com/board/topic/34552-ke55-not-running-cheap-sold/page__p__378848#entry378848

 

i have low profile 14's which is virtualy the same size as the 13's which where on it before. On the diff is there something on the housing which might give me some extra info?

I'm not sure what it was origionaly i bought it off rundell it was manual.

http://www.rollaclub.com/board/topic/34552-ke55-not-running-cheap-sold/page__p__378848#entry378848

 

i have low profile 14's which is virtualy the same size as the 13's which where on it before. On the diff is there something on the housing which might give me some extra info?

 

There should actually be a little tag on one of the bottom bolts that hold the cover plate (borg warner diff) on the back of the diff. Depending on weather this has ever been taken off it might not have been replaced though. Have a look anyway. The tag is thin steel about 1cm wide and 5'ish cm long.

There should actually be a little tag on one of the bottom bolts that hold the cover plate (borg warner diff) on the back of the diff. Depending on weather this has ever been taken off it might not have been replaced though. Have a look anyway. The tag is thin steel about 1cm wide and 5'ish cm long.

 

Ok just beat the storm to have a look. The plate says it is 4.11 . and i turned the wheel 4 times and what do you know the tailshaft turned 11 times. so thats the diff sorted. where can i get a 4.11 speedo dtive?

That's not the way the ratio works. 4.11 means the diff has a 4.11:1 ratio (the :1 goes without saying). You should for every 1 turn of the wheel get 4.11 turns of the pinion (or tailshaft).

That's not the way the ratio works. 4.11 means the diff has a 4.11:1 ratio (the :1 goes without saying). You should for every 1 turn of the wheel get 4.11 turns of the pinion (or tailshaft).

 

ok well i went out there with a texta and colourd in the end of a bolt and put a mark on the tyre flush with the leaf spring. For every turn of the wheel i get aprox 2.18 turns of the tailshaft.

 

I copied everything on the little plate on the diff

 

P/N 7334-42-001

RA110 4 11 SER N9 2199

Edited December 7, 201015 yr by KE55SE

2.18 isnt very approximate! thats very specific! haha

 

good to see you measuring stuff and trying to understand!

 

you want to be turning the tailshaft and measuring the wheel turns, as thats how the ratio is devised.

 

or you could flip the ratio i guess, 4.11:1 is 1:0.24. but that doesnt match up with the numbers your getting.

 

wait...how are you measuring this? are you just jacking up one rear wheel and spining it? cause that will cuase the differential to work, and I'm not sure how this effects you results.

 

best to jack up both rear wheels, spin the tailshaft 4.11 times, and BOTH rear wheels should spin one complete revolution.

 

if you find that one wheel keeps spinning whilst the other one stays still, find 2 friends, one on each wheel and get them to keep them spinning at the same speed, one might need some resistance so it forces some torque through to the other wheel. i don't think i have explained this all that well, hopefully you get an idea.

2.18 isnt very approximate! thats very specific! haha

 

good to see you measuring stuff and trying to understand!

 

you want to be turning the tailshaft and measuring the wheel turns, as thats how the ratio is devised.

 

or you could flip the ratio i guess, 4.11:1 is 1:0.24. but that doesnt match up with the numbers your getting.

 

wait...how are you measuring this? are you just jacking up one rear wheel and spining it? cause that will cuase the differential to work, and I'm not sure how this effects you results.

 

best to jack up both rear wheels, spin the tailshaft 4.11 times, and BOTH rear wheels should spin one complete revolution.

 

if you find that one wheel keeps spinning whilst the other one stays still, find 2 friends, one on each wheel and get them to keep them spinning at the same speed, one might need some resistance so it forces some torque through to the other wheel. i don't think i have explained this all that well, hopefully you get an idea.

 

Yea i was just jacking up one side. ill jack up from center of diff tomorrow. see if we have any different readings. Thanks.

Good point Dave..... although you mixed it up.

 

Having both wheels jacked up could cause issues as the diff can free wheel. If you only jack up one side and leave the other touching the ground then the diff HAS to work as designed and will give you an accurate ratio.

 

Oh and I hope you're using jacks stands while getting under the car!?

 

 

On another note, as I said above the tags often get lost when the backing plate is removed. I think that you can safely assume from this: That the backing plate hasn't been, hence the centre hasn't been removed, hence the 4.11 on the tag should be correct. :wink:

Good point Dave..... although you mixed it up.

 

Having both wheels jacked up could cause issues as the diff can free wheel. If you only jack up one side and leave the other touching the ground then the diff HAS to work as designed and will give you an accurate ratio.

 

Oh and I hope you're using jacks stands while getting under the car!?

 

 

On another note, as I said above the tags often get lost when the backing plate is removed. I think that you can safely assume from this: That the backing plate hasn't been, hence the centre hasn't been removed, hence the 4.11 on the tag should be correct. :wink:

 

ok well i will wait till tomorrow Hopefully no more rain and yea i was using axel stands :doh: ill try again as they say 3rd time lucky.

ah good point..

 

although technically my way may work as well, just a little more complex...and higher potential for error.

 

ive spent the last 5-10mins scribbling down diff schematics on my notepad here....trying to get my head around it...

 

i think i need to jack up my car and check it out for myself:P

ah good point..

 

although technically my way may work as well, just a little more complex...and higher potential for error.

 

ive spent the last 5-10mins scribbling down diff schematics on my notepad here....trying to get my head around it...

 

i think i need to jack up my car and check it out for myself:P

 

OK if you get a chance jack up 1 side and tell me the result you get.

 

Thanks :dance: