Welded Diff - Bad idea?

[Ron Earp]

I've been looking into getting limited slip for the JH I'm building now. However, these things are almost impossible to find, out of production, and were only available in Europe in the 70s I'm told.

What do you think about welding the differential? Have done this on a drag car with good effect, but was wondering how such a thing would treat me on the track? Any comments? Might could also try the Phantom Grip too, but I'm just exploring options at the moment.

Ron

------------------
Ron
http://www.gt40s.com
Lotus Turbo Esprit
BMW E36 M3
RF GT40 Replica
Jensen-Healey: IT prep progressing!

[apr67]

I've driven a Welded diff in a FWD car, and I love it. It is very reliable and is responds the same way every time.

The phantom grip is not the hot ticket from what I've read. OPM or housman motorsports might be able to make a diff for you.

Alan

[Tristan Smith]

Ron, if you can't find a lsd for your car, then you really don't have any other option than a welded diff. They work fine for road racing, although having a lsd is better. The biggest problem with the welded diff is that it's hard to push around the shop/paddock, and there is a bit more wear and tear on axles and such.
With a rear drive car, you won't have to change driving styles all that much with a locked rear end. Wet weather driving will be a bit more twitchy, but again nothing that can't be overcome. I would stay away from phantom grip. I have not heard much positive about them, especially in race cars.

------------------
Tristan Smith
Buffalo's Southwest Cafe
ITA Nissan 240sx #56

[Ron Earp]

I'm going to keep trying to get the LSD but if I cannot then we'll weld it. A couple of guys on my forum for GT40s have tried the Phantom Grip and it didn't work. But, it was also behind a 525 hp SB Ford too, so the out come was sort of indeterminiable.

Prepping an older car has some advantages, i.e. simplicity, but any Brit car isn't the easiest thing in the world to get a good selection of parts for.

------------------
Ron
http://www.gt40s.com
Lotus Turbo Esprit
BMW E36 M3
RF GT40 Replica
Jensen-Healey: IT prep progressing!

[Mark LaBarre]

On a short, twisty track like Blackhawk Farms, a welded diff in a front drive car is a blast. You can really flaten out the turns by launching the inside tires, and the outside run an arc that just hits the curb.

[itascca]

Be sure that if you weld the differential that you weld both the spiders...and between each of the gear teeth. Just realized that this is what was causing us to scatter welded rear ends. They work fine for orad racing...

Ed

[JeffYoung]

Guys, get this, the LSD for the Jensen-Healey was only offered on something called a "Vauxhall Dropsnoot Firenza." Too much.

Ron, I'm back from CMP. Lots of stories, one of which is I met a guy who has a shop in Charleston, SC who specializes in J-Hs. He has a limited slip. I'll talk to you tonight.

Wonder of wonders.

Jeff

[Tom Donnelly]

Ron,

Another person to talk to is Tom Fowler at OPM. www.opmautosports.com (http://www.opmautosports.com). He has a NC contact who can build a LSD for almost anything. And a damn good one too.

Tom Donnelly
ITS 240z #54

[racer_tim]

Ron, I've been running a welded diff on my VW's for about 10 years. Like stated above, it's just a little bit more bother makine 90 degree turns in the paddock, but once you get over that, it's a blast to drive.

No, there is NOT more wear and tear on the CV's and hubs. As part or normal maintenance, you should change out your CV's and hubs every year anyway. I've only lost 1 CV joint while on track the last 10 years.

I broke more front end stuff with an open front diff while auto-crossing thatn I have done road racing.



------------------
Tim Linerud
San Francisco Region SCCA
#95 GP Wabbit
http://linerud.myvnc.com/racing/index.html

[Knestis]

You might not be asking the right question in your parts search. I would not be at all surprised if the diff weren't some third-party assembly, given the relatively low production numbers involved.

The Vauxhall Firenza "Droopsnoot" was part of a family of cars that were all essentially the same critter under the bodywork. There were several high-performance variants of the Cavalier (a little bigger) and Chevette (a little smaller) offered in Great Britain.

You might try the vintage rally people in England or Europe, or even the lunatic fringe of the rallyist fraternity here in the states. The Chevette (RS?) and the Opel Kadett (they were all GM Europe brands) were very popular club rallying platforms and the guts of the third members MIGHT be the same.

K

[grayracer]

I ran a welded diff on my ITS 240Z for several years. Obviously not as good as a well set up LSD but waaaaaaaaaaaaaaaay more affordable. Absolutely zero failures but then again I took it to a guy who knew how to properly weld it up. I kept an open rear to swap out on really wet tracks and did just fine.

Before I welded it up I used an open rear...the welded set up got me around 2-4 second decrease on lap times depending on the track.

Note that you will end up with a noticeable push and have to adjust your sway bar settings to compensate.

Overall the best performance mod I ever made given my limited budget.

[Roy Dean]

<font face=\"Verdana, Arial\" size=\"2\">Another person to talk to is Tom Fowler at OPM. www.opmautosports.com (http://www.opmautosports.com). He has a NC contact who can build a LSD for almost anything. And a damn good one too.</font>

I have an OPM unit in my Suzuki Swift. After hard testing at both tracks and hillclimbs, I can honestly say that it is absolutely worthless except for wet situations...

[Tom Donnelly]

Roy,

Did you ever discuss this with Tom at OPM? Yours is the first complaint about a diff I've heard of since I've known Tom (about 4 years). I know of several ARRC winners using an OPM diff.

Tom

[wbp]

The OPM and the Phantom Grip both are torque sensing units. The more torque they are handling, the more they hold. They won't work on the Suzuki Swift because it lifts a front wheel in the corners. It can't apply torque to a wheel in midair, so the limited slip doesn't hold. Welding is the best solution for the Swift, but the OPM or Phantom Grip work fine in most all front drivers.

[joeg]

Hey WPB--did you ever actually try a "Phantom"?

[wbp]

Joeg- Yes we run the Phantom Grip in all our Hondas, and have been for 5 years. Fifty races on one before the car was totaled at VIR. Pulled it out, inspected it and put it back in the replacement car. Two ARRC wins, SARRC Champions, etc. Bring an ITC to Atlanta Motor Speedway this weekend and you are likely to finish no better than third behind our cars with the Phantom Grips. (g)

[spnkzss]

I run a Phantom grip in my Honda ITC car also. I noticed a HUGE difference in comparison to an open diff. It's only been in since the begining of this year, so I don't have any reliability advice for you.

wbp, could you hit me up via email sometime? I have a couple questions about my Honda if you have a few minutes and are willing.

Thanks

[wbp]

See your e mail.

[Jiveslug]

Ok, so this thread is a bit old, but the discussion about the Phantom Grip got my attention. For those of us who will be running on a limited budget, it seems pretty attractive. Would those of you who have experience with it say its better than a welded diff? Ive also heard about the reliablitiy factor, but does that come into play with a car that has HP figures that are less than 160 (i.e. ITA and ITB cars)?

[Spinnetti]

It works fine, but is tough on the components and a real Bi*ch to move around the paddock. I also managed to brake a high quality axle this way (11 other years with LSD never broke one)


Originally posted by rlearp:
I've been looking into getting limited slip for the JH I'm building now. However, these things are almost impossible to find, out of production, and were only available in Europe in the 70s I'm told.

What do you think about welding the differential? Have done this on a drag car with good effect, but was wondering how such a thing would treat me on the track? Any comments? Might could also try the Phantom Grip too, but I'm just exploring options at the moment.

Ron

[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