2 questions in one

[Silent2g]

first, when is a good time to put a 4 bolt into 90-91 car?

second
to weld the diff or not to weld. pro's and cons' wanted here

 

[jmc94gsx]

first, when is a good time to put a 4 bolt into 90-91 car?

Indicate how much mods you have and how much power you are making. It is good up to a certain point and also depends on how aggressive of a driver you are, as well as clutch you are using.

second
to weld the diff or not to weld. pro's and cons' wanted here

IMO this is generally not a good idea if you want your car to be a street car as well, cornerning and steering are compromised. The other reason is a safety issue, if the weld breaks you and your car will be sent off-course into oncoming traffic, barricade etc. So whoever is doing the welding make sure they have done this before and are proficient at it.
The positive aspect is that it is strong and will hold up against launches.

Research 4 gear spider diffs. that BM tranny and Speed Design as well.

 

[Silent2g]

i was thining of 4 bolting the rear next month when i get the fmic and cams installed. that way i know its done, and don't have to worry about it

my last dsm has a speed design center diff {the originators of it} was put in personally by the shop in st louis. worked great.
might do that or the vce eliminator. i want to be able to dyno, no awd dyno's here

 

[nowayout]

put the 4bolt in when the 3 bolt breaks.
Why waste the money when your current one is stillin working order.

Welded diff I've never tried yet so don't know.


Lue

 

[90GSX]

Buy a 4-bolt rear, but don't install it until you break the 3-bolt.

Instead of a welded diff, use a TRE "Spool" w/ VCE. It replaces the spider gears with a spool, similiar to what RWD Drags have been running for yars to lock their rear ends. I've had mine for a couple months, and am pleased with it. check out www.teamrip.com

 

[NJGSX96]

put a 4 bolt in when the 3 bolt breaks. May be sooner, may be later. I know people who have gone 12s and busted theirs, gone 11s and still have theirs and gone 13s and busted theirs. If you want, get one when you find one and hold onto it as a just in case. if you never need, just sell it. Always someone looking for one.

As for the welded diff, I have friends who love them and left it in and friends who hated it and took it right out. Luanching, from what I have heard is phenomenal on it. Low speed driving and turns suck. but I am sure it is all in a particular persons opinion. If you do weld it, have a shop do it. If not done right, the welds will not hold. I myself just got my Speed Design 4 spider back yesterday. Can't wait to put it in the new tranny. Only get the VCE if you plan to put it in only for dyno days. it won't last in a daily driver.

 

[NJGSX96]

Oh yeah, I forgot about the spool. Heard real great things about that!

 

[Silent2g]

what abou the welded diff at high way speeds and cornering above say 45 mph??

 

[jmc94gsx]

I didn't know TRE developed a spool, that's an excellent achievement for our cars.