SLC 24 Howard Jones

[Ken Roberts]

Howard, I would pay particular attention to the correct installed length of your axles. I remember when you upgraded to the X Tracker bearings and you reused your original length axles. The rest of us that did the upgrade had to increase the length of each axle by one inch.

 

[Howard Jones]

I will call The Driveshaft Shop with my dimensions and see what they say. I still haven't taken it all apart and cleaned it up to get a good look yet. Thanks Ken.

Here's the clocking video I have in "my car stuff" folder in my youtube.

And when you forget how to put it back together:

 

[Mesa]

The C7 rear bearing modification can be done without the need of a spacer on the stub axle bell or a longer axle. Although it does require a longer bell on the end of the C7 spline as made by the DSS. If the "Mitsubishi" bell is used, no spacer needed, at least on a Ricardo. I would venture to say the same might apply to all DSS supplied Superlite axles.

 

[Ken Roberts]

Mesa, I haven’t heard about a Mitsubishi stub shaft. I thought that the RCR Upgrade came with a 30spline two piece Nissan stubshaft. The C7 bearing requires the larger DSS one piece 33spline stubshaft.

Howard , the correct axle shaft length is fairly easy to determine. This picture of my shaft will show you why. The mounting flange of the body of the cv joint is equal to the end of the axle shaft in the picture. In this position you can see that the star on the shaft is perfectly centered to the body of the joint. So the correct length for the axles would be the distance between stubshaft flanges at ride height. In other words the axle shaft length is equal to the distance between mounting flanges.

 

[Howard Jones]

I've been reading up on 930 CV joints and it appears that the primary failure mode is the cage breaks as mine did. Very strong cages made of chrome molly and even 300M steel are available but the cages themselves cost at least $50-60 per cage and up to over a hundred for the 300M cages. I think it might be a good idea to build up my own CV using the methods illustrated in the posts by Ken, Chris, and Dave.

By the way, there are well over $1000 CVs out there......EACH!!!! The goal will be to learn enough to spend wisely and get what I need but not what Rodger Penske can afford.

Ken, thank you for that. That is exactly how I measured my axles and came up with my fit-up. On my car with its original style uprights, the setup required the same length axles before and after the rear "C7" upgrade. However, this is all good stuff, I'm sure it will help the next guy and thanks for the detailed pictures

Here's a representative vendor for internal 930 CV parts.

CV Balls, Cages & Stars - Kartek Off-Road

CV Balls, Cages & Stars for offroad racing in the King of the Hammers, New Zealand Taupo 1000, Dakar Rally, Tatts Finke Desert Race, Score International Baja 500 or Baja 1000, Mint 400, Vegas to Reno, Silk Way Rally, Crandon International, East African Safari Rally, Rallye Aicha des Gazelles...

www.kartek.com

 

[Mesa]

Mesa, I haven’t heard about a Mitsubishi stub shaft. I thought that the RCR Upgrade came with a 30spline two piece Nissan stubshaft. The C7 bearing requires the larger DSS one piece 33spline stubshaft.

I am currently in discussion on updating my axles and CVs with DSS. Notice I didn't day "upgrading". The early Superlite upgrade was a 36 spline axle, with a corresponding bespoke CV assy. These were high HP capable and possibly overspec for most builds, including mine. 12-ish years later the DSS offerings have evolved to where apparently the 28 spline shaft (assuming 300M) is rated about 1000 hp in "Dodge Demon". More information as the discussion evolves.

Yes, Ken. I was speaking of C7 33 spline stubs with a much deeper "Mitsubishi" bell welded on the end, maybe that bell is not available for the 30 spline stubs, I do not know. I have photos of the two bells side by side, I'll try to locate.

 

[Howard Jones]

So Mesa was right. The original high-power axle option was a 36-spline axle from DSS. I have them too. After discussing options with DSS I have decided to switch to the more standard 28 spline axles and the recommended CV joints. The CV joints use a Chrome Molly cage so that ticks that box.

I have completely re-measured my axle length and have come to the exact same conclusion as before. I don't and didn't need to change axle length when I changed to C7 bearings. My axles for the record are 23 inches long. That is using a Porsche G50.

The main reason to change over to the 28 spline axles is cost. DSS says that their current 28s axle is as strong as the 36s axle I have from about 15 years ago. However, by using them I can use the more standard and much more wildly available 28s CV that is about 50-60% of the cost of the special 38s CV's and comparable in strength.

I have taken all four of the CV's apart and found wear on the other 3 that did not fail which makes them unusable on my car so I need new 4 CV's in any case. All in all the cost will pretty much be a wash.

The 36 spline axles look good and I would re-use them if the matching CV's were not so expensive. I expect to replace CV's on a time-change schedule in the future. I have not settled on a frequency as yet but I'm thinking every two seasons would be pretty close to leaving 33% of their life in them. I'll watch wear and see how it goes.

Does anybody need 36 spline axles? I have them............. really cheap.

 

[DaveC]

Howard, I stumbled across a couple of photos I took of my Porsche CVs back when I prepped them. Before and after. Quite a difference getting the machining imperfections off before the ball does it and adds metal debris to the grease. These are GKN CVs.

 

[Howard Jones]

Ken, Are those new stars, or are they used in the "before" pictures? Mine show similar wear spots but the wear is much deeper. How much material can be removed from the ball race before it's too much? I'm thinking a thou or three.......... Certainly not enough to "fix" a worn star.

 

[Roger Reid]

Howard, Polish the stars with a diamond impregnated rubber polishing tool. You can find them at myraceshop dot com. I'll quote from his site. " It allows you to polish the factory rough surface where the balls ride to avoid material being deposited into the grease that would normally wear quickly in the "CV break in period". This allows you to run the CV much longer before an initial service. It also allows for higher joint angles before bind if the CV is being used in high articulation applications. racereadyproducts dot com has something that looks the same. The cv joint will, given time, polish itself. Pre polishing it will keep the grit from contaminating the grease.

 

[flatchat(Chris)]

Cratex.com Rubberised abrasives

 

[DaveC]

Howard, if you were referring to my photos above, they are both brand new stars, the lines before polishing are factory machining marks.

 

[Howard Jones]

It's been a while since I updated the never-ending saga of my SLC. After running the car enough to really begin to understand what works and what doesn't I have concluded that the brakes are just not what I would say are really really good. I have reached the conclusion that the car stops ok but not really outstanding. I even think that my GT40 feels more balanced in the end. So why? What is the difference?

GT40: front calipers 4X 1.75 pistons rear 4X 1.38 pistons with a 5/8 tandem master and a proportioning valve in the rear circuit. I have it turned down to reduce rear pressures by about 10-15%. All 12.06 X 1.25 rotors

SLC : front calipers1.62, 1.12, 1.12 6 pistons Rear 4X 1.25. Front rotors 13.03X 1.25 Rear 12.88X1.25 Ballance bar set to bias the fronts a lot. Front master .7 rear master .625

The big difference is the front calipers. I have come to believe that there just isn't enough piston area. So I changed them to these. I should note that I have tried several different master sizes .75, .7, .625 in both positions front and rear I just never seem to be confident in the front of the car stopping aggressively without requiring excessive leg pressure and very little modulation range, They will lock up the fronts but with a very narrow margin of leg pressure. I hope that helps define the problem but you just have to feel it I guess.

Wilwood Disc Brakes

Part No: 120-13263, calipers, dynapro, dynapro 6, big brake, dynalite, dynalite pro, forged dynalite, d52, superlite, sl6, sl4, tc6r, promatrix, w6ar, rotors

www.wilwood.com

Comparisons of the two cars and old to new SLC calipers

Gt40 piston areas F 4.8 R 3.0 (reduced to about 2.5-2.6 or so)

SLC before F 4.4 R 2.46
after (new) F 5.18 R 2.46


And on to the engine project. I'm building a new motor. 400 CI SBC based on a DART SHP block with a 4.125 bore and 3.75 stroke, custom cam and AFR race ported heads. The target HP is 540 or so. That is about 100 more than the 350 I had in the car before. Why 540hp? Because that is the number that I believe the G50 I have in the car will be OK with. IMHO that s the HP number that a lot of stuff like Cv joints, axles, GRBX's, and clutches etc. start to get out of hand budget-wise.

So we'll see.

AND!!!!!! a new set of tires. This will be my first NEW set of slicks...............................

 

[Randy V]

Sounds like you’re going to be generating a whole lot more torque as well…. Be careful putting all that to the ground with those sticky new tires…
I didn’t look back, but am curious what sort of cooling you have on that G50?

 

[Howard Jones]

I have a pump, hoses fittings, and cooler ready to go on car. G50 was plumbed at California Motorsports when we built it. I just need to make a couple of mounts and wire the pump into the dashboard. Easy prezzie

Randy at CMS says he's good with 500 Ft/Lbs in my G50, so we will tune for that on the engine dyno when the motor is finished,

 

[Frank Clark]

And on to the engine project. I'm building a new motor. 400 CI SBC based on a DART SHP block with a 4.125 bore and 3.75 stroke, custom cam and AFR race ported heads. The target HP is 540 or so.

You may be a bit north of 540 . I have a 383 here with 11:1, AFR 220cc. With a healthy street cam and hydraulic rollers, makes 531hp on the dyno @6500 with 93. That's with a single plane intake that fit under a 2" raised C3 corvette hood and long tube headers. Those 400s unshroud the valves some so you may see more than the 17cid increase.

 

[Howard Jones]

We'll see Frank. Your motor is pretty close to what I am building although I am running a cam with watered-down trans am specs.
My heads are the 195 race heads. I called AFR and they recommended them for a 400-inch road race engine. I am most interested in the torque curve plot and keeping it at about 500 ft/lbs or so. I will post the dyno chart when I get it. We are going to use a dyno that is certified for the SCCA series TransAm engine suppliers so it should be a fair dyno number. I am thinking that about 1.35 - 1.45 HP/CI ought to be about right on pump gas. As I said, we'll see.

195cc SBC Race Cylinder Head

Cylinder Head Specialists

www.airflowresearch.com

 

[Neil]

It's been a while since I updated the never-ending saga of my SLC. After running the car enough to really begin to understand what works and what doesn't I have concluded that the brakes are just not what I would say are really really good. I have reached the conclusion that the car stops ok but not really outstanding. I even think that my GT40 feels more balanced in the end. So why? What is the difference?

GT40: front calipers 4X 1.75 pistons rear 4X 1.38 pistons with a 5/8 tandem master and a proportioning valve in the rear circuit. I have it turned down to reduce rear pressures by about 10-15%. All 12.06 X 1.25 rotors

SLC : front calipers1.62, 1.12, 1.12 6 pistons Rear 4X 1.25. Front rotors 13.03X 1.25 Rear 12.88X1.25 Ballance bar set to bias the fronts a lot. Front master .7 rear master .625

The big difference is the front calipers. I have come to believe that there just isn't enough piston area. So I changed them to these. I should note that I have tried several different master sizes .75, .7, .625 in both positions front and rear I just never seem to be confident in the front of the car stopping aggressively without requiring excessive leg pressure and very little modulation range, They will lock up the fronts but with a very narrow margin of leg pressure. I hope that helps define the problem but you just have to feel it I guess.

Wilwood Disc Brakes

Part No: 120-13263, calipers, dynapro, dynapro 6, big brake, dynalite, dynalite pro, forged dynalite, d52, superlite, sl6, sl4, tc6r, promatrix, w6ar, rotors

www.wilwood.com

Comparisons of the two cars and old to new SLC calipers

Gt40 piston areas F 4.8 R 3.0 (reduced to about 2.5-2.6 or so)

SLC before F 4.4 R 2.46
after (new) F 5.18 R 2.46


And on to the engine project. I'm building a new motor. 400 CI SBC based on a DART SHP block with a 4.125 bore and 3.75 stroke, custom cam and AFR race ported heads. The target HP is 540 or so. That is about 100 more than the 350 I had in the car before. Why 540hp? Because that is the number that I believe the G50 I have in the car will be OK with. IMHO that s the HP number that a lot of stuff like Cv joints, axles, GRBX's, and clutches etc. start to get out of hand budget-wise.

So we'll see.

AND!!!!!! a new set of tires. This will be my first NEW set of slicks...............................

Brake pads can make a big difference in stopping power and the ability to modulate the deceleration. What pads are you using?

 

[Howard Jones]

Wilwood "B" s on the front and "C"s on the rear. I think I might try their BP30s on the front and maybe the 20s on the rear after I run the car one more time with the new calipers sizes.

 

[Frank Clark]

On the Sprint Cars, we went to BP-30s on the front and -40s on the back with Super Alloy rotors. No brake problems since, have been very happy.