Welded Diff - Bad idea?

[zooracer]

Hey wbp, I also am campaigning a swift in ITB. Actually just finished the schools and am looking for some set-up information.
I am having a big problem with understeer, and then drive out of the corner. I know that all FWD cars have drive out of corner problems, but this car is especially bad.
Right now I'm getting it corner weighted and adjusting the alignment.
I have a phantom grip, and cannot tell the difference from an open differential. I thought it was the differential, but you said swift's tend to pull up their inside front's.
So, I was wondering if you know of solutions for this with the swift's. I run 350# front springs with no swaybar, and 600# rears with the stock 19mm sway bar. I run 1.7 neg. camber on the front, with zero toe. I'm getting caster bushings for the front end for more positive caster.
At my last school at CMP I had a chance to follow a red ITC civic that ran third at the ARRC. It was obvious from following and watching the civic, that he had better "hook up" out of the corners, and more grip overall. He was running huge hoosiers, which may account for some of this, but not all...
matt

[zooracer]

Also, from reading some posts on here it would seem I should just go and get the diff welded, rather then spend a grand on a LSD...
matt

[Ron Earp]

I've done a lot of research on it here and in other places. My conclusion - limited slip or welded - no phantom grip from what I can tell. LSD is is the best, when it is working right which it does most of the time, but it is pricey.

A welded diff is cheap and will work, no doubt. If your axles are known for breaking or known to be weak that might not be a good idea. But, in my case the axles seem really big and welding should be fine. Plus, I had no options....

R

[zooracer]

Ok, here is the 64,000 dollar question.
Why is an LSD better than a welded diff?
Has anyone on here done a direct comparison with the same car between the two? If so, what was the difference in lap times?
On one hand, I wouldnt mind saving some money on a welded. But, on the other, I dont want having a welded diff keeping me from a championship.
If there is a speed difference, I will cough up the money for an LSD.
matt

[HounDawg]

I've run a welded diff on my ITS Z with no failures (the Z's drive shafts or halfshafts are pretty bullet-proof). I didn't notice much of an understeer. In theory (if not in practice), the welded diff should produce the most push entering a turn.

[zooracer]

Yes, with a RWD I can understand that. And I can see how a LSD may be faster.
But, on my FWD swift, I am not seeing why a welded would be slower. I do realize, from what I've read, that a welded requires a somewhat different style of driving through the corner. Kinda of like throwing it in with oversteer, then countersteer, then full throttle, and it pulls you through the corner ?
matt

[apr67]

Matt.

If its slower you might tell Chris Ablin that. He's consistantly fast with a welded diff in both IT VW's (A1,A2,now A3) and in production (GP Golf).

I think that a welded may be slower for low horsepower cars at highspeed tracks. The welded diff scrubs power a bit on the straightaways. But in the corners it is awesome. First, it means you can't lock a front tire. You have to lock them both.

The other thing is, once you are on the throttle, the car has a tendancy to pull into the apex of the corner on its own.

[Knestis]

Arguing diffs is a little like discussing religion at the office but I've got my KAAZ-made clutch unit from Bildon for the Golf and am pretty excited about it. I was very pleased to find out that, from the factory, it goes to 100% lock-up under power and backs off to 50% otherwise. A really good compromise in my book. By the way, these get called a "cam and pawl" diff by some manufacturers, I think...

K

[zooracer]

I understand about argueing, but that is not why I'm here. Just picking brains of guys who have already spent the time and money, so I dont have to.
I dont think I can find a Kaaz unit for a swift. Unfortunately it is a rare car, so that presents a problem.
Well, I always thought that if the fast guys are doing it, it must work. If Chris Albin's car's are fast with a welded, then I guess that is enough for me.
And cheaper is always better...
matt

[seckerich]

The swift is a tough customer to get a good diff for. I have built some with good luck and others that dont work well. The problem is that they are so small there is just no surface area to get enough friction packs in. I have also repaired a few of the comp units for the swift and they break the bearings off the end or shell the spider gears. The later units have bigger gears if you can find one, and they seem to work well when modified. Give OPM a call if you want to try one.

[Knestis]

You might see if the rally community has a parts pipeline for the Swift - particularly in Canada. It was an FIA homologated car in both Group A (which would probably do you no good) and - I think - in GrN, which might.

K

[zooracer]

yes the tranny's are the swift weakpoint, no question about it. Thankfully I have two spares...
I can find quality LSD's (like suzukisport) but wanted to see if there is really a performance advantage over a simple welded. I understand about some additional friction affecting a low hp car with the welded, and the possiblity of broken axles.
But, if fast guys are using them...
I reckon I can always go with welded, and if I dont like it, get a LSD.
matt

[Ron Earp]

an't hurt to have both. One will cost you only $100 to have welded probably, so, keep it around. This 260z I've been working on came with a LSD installed and a welded diff in the spares box, however, I don't know if it had a purpose at certain tracks or was simply there to be used in case of LSD failure.

------------------
Ron Earp
http://www.gt40s.com
Ford Lightning
RF GT40 Replica
Jensen-Healey ITS
My electrons don't care if they flow through OEM wires, do yours?

[Tom Donnelly]

I have 3 diffs for my 240z. Two welded and one nismo comp. I don't use the welded, I bought the diffs for the ratios and swap them out if needed. I intend to buy one more ratio and another LSD. The welded chirps the tires around the padock and when loading the trailer, I don't have a good comparison at speed. The welded diffs are a good backup. I wish IT allowed diff coolers.

Tom

[zooracer]

well I spoke with Steve who builds OPM's LSD's and I'm convinced that he is the way to go. He talked me out of a welded, and he has some great references for his LSD.
I'll let ya all know what happens.
matt

[kthomas]

Originally posted by Tom Donnelly:
I wish IT allowed diff coolers.

Tom

Tom, are you using the BG additive?

------------------
katman

[Tom Donnelly]

katman,

I run 90 wgt with a friction modifier. What should I be using? Sometimes the paint gets burned off.

Tom