To weld or not to weld an fd diff

leefitz · February 17, 2011, 02:39:45 AM

Hey, this is for the drifter so will not be on the road but was wondering what your views on it are. Cheers
Lee

clive · February 17, 2011, 09:46:27 AM

I raced an Escort many years ago and had very little money so I ark welded the planetary up and away I went and it was ------------------- HORRIBLE, as it created huge amounts of undesteer, not what you want to Drift and it either had loads of understeer or loads of oversteer and was both unpredictable and slow

For others reading this, if you try and drive this on the road any distance you will just scrub the tyres straight out because when you turn any sort of corner on any vehicle the inside wheel will always try to turn faster than the outer wheel, hence the need for a differential so this can happen,

With no diff the inner wheel will scrub and skip like mad making the car real bad to drive

At the end of the day you have a real good diff in the car as standard that will lock both wheel when on power :Thumbs-up

There is more info here if you wish to find out more http://www.mazdarotaryclub.com/forums/showthread.php?t=33863

Hope this helps,

leefitz · February 17, 2011, 10:18:24 AM

cheers clive. well the diff now has over 55k miles so would a rebuild be worth doing or keep the money for an upgradded diff at some stage? reason for this questioning is that im wondering if im gettin the most out of the current one. my road going rx7 has a 1.5 so to try and compare the 2 wouldnt be right and only makes the drifter feel poor in comparesin. so the question would be, rebuild or not to rebuild ?

clive · February 17, 2011, 09:03:22 PM

I would have said stick with the 1.5 then :3gears-lh:chat

leefitz · February 18, 2011, 01:22:29 AM

ha haa, pity its in the road car

stock diff in the drifter will have to do for new. torsen diff i read and not able to be rebuilt, is this correct?

rx7boy · February 18, 2011, 01:47:37 AM

I have a purpose built drift Fd and have also had all four types of diff,

Stock torsion diff : shat itself after 3 outings and never really fully locked up.

Welded diff: Awesome for serious drifting, would not recommend for any car that touches the road though as it will unpredictable.

1.5 diff: was only in the car for a week, shouldnt have bothered for the drift car, ideal for a circuit car but not locking enough for hard drifting.

2way : the one I currently have is a custom Re-A Nismo and is epic, your main issue with 2 way diffs is noise during parking ornalow manoeuvres. The kazz is notorious for it\'s noise. However if it\'s a drift car is the best option but the most expensive.

If you can afford it go for the 2 way, if not then a welded one. That\'s based on the fact is only a drift car and hardly ever sees the road.

infernal · March 03, 2011, 01:01:54 AM

Hi all!

I thought I should ask here rather than make a new thread...
I recently installed an FD torsen diff in my FC. What I observed is that I now have some wheelplay. That is, with the prop-shaft and one wheel held still, the other wheel can move approximately 1/6 of a turn back and forth.
Is this normal?
The open diff I used to have didn\'t have that much, but yet the torsen is of different architecture. It\'s not coming from the ring&pinion backlash as it was set correctly, and also not from the axles.

Any experience from FD owners?

Thanks a lot!
Marios

leefitz · March 03, 2011, 10:19:19 AM

I noticed this on my fd drifter too but it works fine and locks up under power with no prob. Maybe a few more ppl will confirm thats fine.

A question though, how do you set the backlash on the ring an pinion?
Cheers

Ricco_04 · March 03, 2011, 12:57:38 PM

I havnt finished installing mine yet (fd into fc) Hopefully will have the rear end bolted on this weekend - Diff has been set up correctly so I will check what wheel play I have if I get it finished.

infernal · March 03, 2011, 06:22:57 PM

Thanks guys!

Yep mine functions properly too. Maybe in a torsen due to the helical gears the tolerances are bigger... Or maybe it\'s just worn lol!

The pinion position is very hard to adjust, but hopefully if you don\'t mess with the pinion there\'s no need to so.
To set the backlash you basically use a dial distance indicator and follow the instructions on the FSM, page M-34 and on. When you are done, use some gear marking compound to check the outcome.

:Thumbs-up

leefitz · March 04, 2011, 09:22:53 PM

cheers, will have to get myself a FSM soon. well im hopin to get my hands on a second fd diff, weld her up and just do a straight swap to try it out for a day on the track. if i dont like it, then ill just take her out and put the origanl one back in so hopefully not mess with too much stuff.

infernal · March 04, 2011, 09:32:01 PM

It\'s a shame to weld a torsen solid. Just weld the OEM open diff of the FC. It\'s cheap and noone wants one. A torsen on the other hand...

Oh and if you weld it there will be nothing to try out. You will just have a solid rear axle and lots of understeer with oversteer bursts if you try to grip.
You gonna suck at parking too. Been there! :rollin

Here\'s the FSM. Clive has made a nice writeup. http://www.mazdarotaryclub.com/forums/showthread.php?t=66749
Choose the right one for your car. :Thumbs-up

leefitz · March 04, 2011, 11:14:29 PM

Cheers man, The car is a sole drifter so grip driving won\'t be required.

Will an fc diff fit straight in? I was under the impression it wasn\'t that straight forward? And what sorta price is an fc open diff?

infernal · March 05, 2011, 10:46:14 AM

Given the fact that the torsen bolts right into the FC (even with the same FD bearings - only the ring should be changed), I assume that the FC diff should also bolt right into the FD. I\'m talking only about the carriers. The cases are not interchangeable.
Just get the open diff from an 89-91 turbo FC, as 86-89 had the weaker design that is incompatible with the FDs.

Here the price for an open diff FC carrier is about 100E or lower, that is less than 85 pounds. In UK I expect prices to be a lot less.

dthebuk · March 05, 2011, 11:44:36 AM

Quote from: rx7boy;743505I have a purpose built drift Fd and have also had all four types of diff,

Stock torsion diff : shat itself after 3 outings and never really fully locked up.

Welded diff: Awesome for serious drifting, would not recommend for any car that touches the road though as it will unpredictable.

1.5 diff: was only in the car for a week, shouldnt have bothered for the drift car, ideal for a circuit car but not locking enough for hard drifting.

2way : the one I currently have is a custom Re-A Nismo and is epic, your main issue with 2 way diffs is noise during parking ornalow manoeuvres. The kazz is notorious for it\'s noise. However if it\'s a drift car is the best option but the most expensive.

If you can afford it go for the 2 way, if not then a welded one. That\'s based on the fact is only a drift car and hardly ever sees the road.

a 1.5 way should be just as clunky as a 2 way when parking, unless you\'re reversing. As for it not locking enough that is also not down to it being a 1.5 way, its more the make and set up of the diff itself. Sounds like you\'re 1.5 didn\'t lock much and your 2 way locks loads. Tbh if its a skid car I\'d just weld it. If anything (in my experience) welders are much more predictable than lsd\'s which can lock up as soon as you touch the power. I ran a welder in my FC for over a year with no issues, the largest problem with running a drift car on the road is the stiff suspension and crazy geometries. If you solid mount the diff and the subframe it should make the wheel hop a lot less noticable

At the end of the day if its a drift slag which is going to be abused why fork out hundreds of pounds for a proper diff which may perform slightly better. Additionally you\'ll have to maintain it and theres more to go wrong.