Rear Differential Differnt Ratio. How bad could it be

[Lordpaxin]

This is a thread to help my question, aswell as any others who are doing a 5 speed, auto swap.

This is the question.
Everyone says
you must repalce the rear diff when doing the swap, but I didnt.
And for 9 monthes, i have had no problems.
only it car doesnt seem to roll as freely as a factory 5speed car.

on vfaq it shows that they are definatley different., but what can happen, if there is a difference, and if so, why havent i expierenced it.

 

[BISHILVR]

you are probably SLOWLY destroying the rear end and possibly the transfer case and front diff....if the ratios are different between the front and rear diff what you are doing is forcing the diff to slip to take up the difference. this is likely why you notice the car does'nt roll as easy as it should. one of these days it may not roll at all, i've been through that and trust me it sucks to have to tear the rear driveline apart once not to mention twice. when my rear went it caused a real nice FIRE in the rear of the car due to the gear lube in the diff boiling and coming out the vent on the diff case and then spilling on to the nice hot exhaust!!....maybe next time you take a good long drive somewhere stop and feel the rear diff with your hand (carefully) to see how hot it's running...that might give you some idea of whether it's actually overheating right now or not.....

 

[Lordpaxin]

it doesnt have the LSD rearend.
i mean, it feels just like it ever did, i put around 4000 miles on it like this.
several people told me i didnt need to swap, and the same amount told me i should.

could my tranny being a JDM have differnt specs?

 

[BUCK]

Rolling resistance is typically a rear brake caliper starting to bind up - Very hard on clutch.

 

[Lordpaxin]

well, in cold weather if i use my E brake it will be locked up when i try to release it.

so that might have someting to do with it.
also,

the rearned didnt feel warm when i came home tonite.
the AWD still works good.
according to vfaq.

the Xcase tooth ratio is the same on both.
Final is 4.929 4.062(at)

center diff is


3.307 (43/13) GVVR4


3.545(39/11) 1g AT

ratio / tooth

so, what is happening, if this is the case. and if its the wrong rear, why is it still workin and if its been this long, What can i expect the life to be.

and, say it burns up, or whatever, can i swap out the parts that get trashed when i swap the tranny I am using into another car, from the other cars tranny parts?

Does a jdm galant have differnt ratio

 

[GTM]

Originally posted by Lordpaxin

...

Why don't you jack up one side of the car, put in 4th if direct, if not 5th will do. (pull the plugs if you want to make things easy) Make a chalk mark, masking tape, etc. at front and rear tires at BDC. Rotate engine 4 complete revolutions, again more tape but on the pulley and t/c from whre you start. If you can't determine anything another 4, and another 4 etc. They are either identical or they are not, the same or one will be ahead of the other!!! No if, and, but, or, nor for... exact or not.
.................

Some 4WD (AWD???) vehicles _DO not_ run the same ratio... don't panic YET.

Let us know what you find.

Cheers,
GTM

 

[Lordpaxin]

Thanks.
Ill try that soon, Im out of town for 2 days.

um, the big thing is, if its the wrong ratio and its mashing teeth or whatever, what could break, and how hard would it be for me to steal the boken parts from a spare tranny so i can fix my jdm tranny.

and if i have already put 4k miles with NO ill affects, will it last another 3k til i swap it into the opther car

 

[CYCLONE]

You probably will not break any gears, but you are slowly
burning up your viscous coupling in your tranny.
The VC acts like an LSD between the front and the rear
and your are forcing it to slip due to the different gearing.
Which would explain why the car doesn't roll freely like other
5 speed awd's.

 

[GTM]

Originally posted by Lordpaxin
Thanks.
Ill try that soon, Im out of town for 2 days.

um, the big thing is, if its the wrong ratio and its mashing teeth or whatever, what could break, and how hard would it be for me to steal the boken parts from a spare tranny so i can fix my jdm tranny.
...

It's not mashing teeth, it may be overloading teeth, bearings, and tires. You have driven 4000 miles and nothing broke that may be a good sign.

I would inspect tires, I'd run my hand over them from side to side and back and forth for sometimes you can feel cupping that you can't see. Noises will start as a whine that echos off K-rails, buildings etc. which keep getting louder over time. Check oils, (weekly? ... monthly?) if you don't have magnetic drain plugs buy or make them.

Teeth can break, bearings wear, the magnets will tell the story. I wouldn't be trying to smoke tires until some conclusion has been reached. I can't make a prediction on what will be the weakest link in the drive train. I don't have answers on what parts will fit Anyone else???

Cheers,
GTM

 

[Lordpaxin]

I see.

The only noise i hear echo is from my exhaust

how deoes a tranny come apart? is the VCU just laying in there and you unbolt it, and bolt in another one?

I have a 4bolt rear out of a Galant VR4 laying in my garage. should i take a weekend and swap them out.
will the galant shit work? its the same rearend out of the car my tranny is from. the jdm,.

how lows does the swap take and how hard.
will the gvr4 parts work.

it has 4 stud rotors, but the other parts should work.
any ideas on that.

also, will i need 4bolt axles? or does the axles stay the same.

 

[BISHILVR]

Tell ya, this is a tough one.....cause i'm not sure if the ratio's are different or there was some other reason for not using the rear, but if their is a difference in the ratio like i said your gonna end up with damage....maybe you can go to mitsu and check and see if they have different p/n for the two rear ends from auto to manual??? but i can tell you that their probably is and if their is then their is a good reason for it!! cause mitsu don't build different rear end part numbers just for the heck of it....anyway like i said earlier your probably SLOWLY ruining your tranny/diff running it this way...why it has'nt failed yet who knows, if it's running cool who knows maybe it'll last for years this way and then again it may come apart when you least expect it. best just to do some more checking just to make sure....good luck bro'

 

[Lordpaxin]

i see waht you mean,
the axles are differnt, on has 4bolts one has 3,

anyone have spare axles?>

 

[Lordpaxin]

PHUCK IT

im gonna put in that 4bolt, its an upgrade and will solve the problem.
I am going to put Minimal miles on my car until this is complete.

i need to get axles and the cups for wheel side. i already have the rearend, but its out of the galant and the axles are to wide.

so if anyone has spare 4bolt axles or cups, or can help me locate any thatd be super schweet

 

[BISHILVR]

good idea bro' ....all i got is some lousy 3 bolt axels

 

[Lordpaxin]

Got the axles and cups on the way, be swapping next week.

anyone did the swap, any PITA's or any breakable parts?
thanks.,