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Limited Slip Differential

 
  #61  
Old 02-20-2012, 08:44 AM
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Originally Posted by qikcat View Post
I am getting to the point that a LSD would be a huge advantage. I did think about getting another assembly from a junkyard and just welding it and swapping it in for the track for a easy in the meantime solution.
Leave the welding one on during the summer and put the open one on during the summer...
 
  #62  
Old 03-03-2012, 10:12 PM
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So I got an old 8.8 Traction-Lok differential in my hands, and measuring it up it is very similar to the QDF3W unit. It seems to have about 0.020 to 0.030 more offset than the Quaife unit [ring gear closer to the pinion in the nominal position], but that is solvable if necessary with a little machine work [or shims]. Next thing is to get the STR core in hand [have an email in to the salvage yard] and measure that up to see what needs changing.

The good news however is that if a QDF3W can be made to fit then there is a very good chance that a Traction-Lok or TrueTrac should be possible as well.A used Traction-Lok is pretty cheap and the TrueTrac should be ~1/3 the cost of the Quaife.

cheers,

TonyL
 
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  #63  
Old 03-04-2012, 08:04 AM
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We're digging this info. Tony. Please keep it up. Cheers.
 
  #64  
Old 04-15-2012, 10:46 PM
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LSD update:
good news and other news:
The good news:
I have the 2006 STR differential assembly apart and after some quick initial measurements, it looks like the 28 spline Traction-Lok is compatible. It rides on the same bearings and seems to be the same bearing spacing, but I will need to setup more carefully to verify the R&P offset and the exact bearing locations.

The other news:
Interestingly the case has only has one bearing cap, the other side has a big snap ring. This means that the traction lok pumpkin does not just 'drop in' because it is much 'plumper' than the stock pumpkin. It will take some work to get it in there.

I can understand why the gentleman in the UK is not keen to give away his hard work because it is not particularly simple to mod the assembly enough to the get the LSD unit in there.

My first go will be to get the Traction-Lok to fit because I have it. However it does appear that the TrueTrac might go in easier with less modification.

I little bit about me: I spent 7 years as a fabricator and gearbox specialist for a professional formula car race series back in the late 80's. I was responsible for service, setup and repair of 30 gearboxes each season, so I have some familiarity with differentials, bearings and precision assemblies. For the past 14 years I have had a regular job as a mechanical design engineer for an aerospace company.

So my question is this: what level of interest is there in getting one of these either a Traction-Lok or a TrueTrac? My thinking is that for me to tackle any more beyond my own I would be willing to do for about $200 over cost.

A quick WAG would be: $400 for a good used diff, $200 for a Traction-Lok, estimated $200 in machining and a couple three hours of my time hand fitting the case plus setting up the backlash [in reality probably much more labor than that, hence the hefty price from the gentleman in the UK].

That means for one in hand [meaning you don't pull yours first], about $1k for a Traction-Lok, about $1250 for a TrueTrac. Make that $600 and $850 if you pull yours and wait for its return.

Keep in mind that this is NOT an offer yet, just a Wild "Approximate" Guess [WAG]. Not included in those numbers are shipping, new bearings, side seals, anything else needing work. Once I get real costs of the mods I can work up an accurate cost breakdown.

If there is a big enough interest I can work on some volume pricing from the machine shop and try to get the unit cost down, so what says folks?

cheers,

TonyL
 
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  #65  
Old 04-16-2012, 07:57 AM
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I'd be down for one. One wheel peels at the strip suck.
 
  #66  
Old 04-16-2012, 09:40 AM
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If you can do it between 600 and 850 I will send my Quaif back and not even mess with trying it. Hell I have that much just in that unit not including machining to make it fit. I am down if it happens within a few months, I don't want to wait around a year for this to come to reality, I would just continue forward with mine.
 
  #67  
Old 04-16-2012, 01:27 PM
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qikcat,
based on the Quaife dimensions, the problem is about the same whether it is the Quaife, TrueTrac or Traction-Lok. Since the Quaife has been done before you know it is solvable.

cheers,

TonyL
 
  #68  
Old 04-16-2012, 02:18 PM
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Tony, count me in for a Tru-Trak. As you're likely aware, to fit any other unit than stock, the knob of material inside the pumpkin that'll need to be ground down. You can contact Mafioso, for he recently had the Quaife installed but had to bring her back for re-shimming. Now it works fine, allowing his STR to achieve a 12.8 1/4 mile without a pulley, just: K&N a/f, Mafioso air intake tube, hi flow cats, and x-pipe.
 

Last edited by bfsgross; 04-16-2012 at 03:50 PM.
  #69  
Old 04-16-2012, 06:00 PM
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Originally Posted by bfsgross View Post
Tony, count me in for a Tru-Trak. As you're likely aware, to fit any other unit than stock, the knob of material inside the pumpkin that'll need to be ground down. You can contact Mafioso, for he recently had the Quaife installed but had to bring her back for re-shimming. Now it works fine, allowing his STR to achieve a 12.8 1/4 mile without a pulley, just: K&N a/f, Mafioso air intake tube, hi flow cats, and x-pipe.
Very impressive Mafioso! Do you know if he was on street tires and if he iced down the block/SC between runs?
 
  #70  
Old 04-16-2012, 07:56 PM
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Bacardi, Mafioso did the 12.8 on street tires (295's) and XKR TCM file installed in the ZF. He claims the motor hit the limiter on all upshifts.
 
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  #71  
Old 10-09-2018, 10:31 AM
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Originally Posted by tonyu47 View Post
LSD update:
good news and other news:
The good news:
I have the 2006 STR differential assembly apart and after some quick initial measurements, it looks like the 28 spline Traction-Lok is compatible. It rides on the same bearings and seems to be the same bearing spacing, but I will need to setup more carefully to verify the R&P offset and the exact bearing locations.

The other news:
Interestingly the case has only has one bearing cap, the other side has a big snap ring. This means that the traction lok pumpkin does not just 'drop in' because it is much 'plumper' than the stock pumpkin. It will take some work to get it in there.

I can understand why the gentleman in the UK is not keen to give away his hard work because it is not particularly simple to mod the assembly enough to the get the LSD unit in there.

My first go will be to get the Traction-Lok to fit because I have it. However it does appear that the TrueTrac might go in easier with less modification.

I little bit about me: I spent 7 years as a fabricator and gearbox specialist for a professional formula car race series back in the late 80's. I was responsible for service, setup and repair of 30 gearboxes each season, so I have some familiarity with differentials, bearings and precision assemblies. For the past 14 years I have had a regular job as a mechanical design engineer for an aerospace company.

So my question is this: what level of interest is there in getting one of these either a Traction-Lok or a TrueTrac? My thinking is that for me to tackle any more beyond my own I would be willing to do for about $200 over cost.

A quick WAG would be: $400 for a good used diff, $200 for a Traction-Lok, estimated $200 in machining and a couple three hours of my time hand fitting the case plus setting up the backlash [in reality probably much more labor than that, hence the hefty price from the gentleman in the UK].

That means for one in hand [meaning you don't pull yours first], about $1k for a Traction-Lok, about $1250 for a TrueTrac. Make that $600 and $850 if you pull yours and wait for its return.

Keep in mind that this is NOT an offer yet, just a Wild "Approximate" Guess [WAG]. Not included in those numbers are shipping, new bearings, side seals, anything else needing work. Once I get real costs of the mods I can work up an accurate cost breakdown.

If there is a big enough interest I can work on some volume pricing from the machine shop and try to get the unit cost down, so what says folks?

cheers,

TonyL
Sorry to bring this back up, but did you ever figure out if Traction-Lok would work? I have an STR and would rather not dump thousands into a Quaife Differential. Plus, I am state-side so those are abundant for me.


Many thanks
 
 
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