Well no wood needed here.
last weekend i went for it again. But only 4 passes for the weekend. 3rd round of qualifying was cut short and round 2 of eliminations turned into a right turing second gear wheelie that touched the center line.
I even tried a new exhaut housing and even with the exceptional short first gear combo. (4.11 on a 24 tall tire) i saw 28 lbs of boost by the top of first gear in round 1. Ill get that taken care of for next year. (solenoid/pressure switch combo that malfunctioned in first)
If my butt tells me correct. i saw a 1.50 60ft on the rear tires.
I think its time to go back over the data logger info and compare it to old runs and see how much faster 1st gear pulls out with new housing.
As far as what r&p is used in my box. Couldnt tell you. I leave that up to Kevin at Trans West. All i know is, it is out of the their good stash of r&p's.
Anyone have a picture of what a good ring to pinion pattern should look like. I am also interested in how to set up that spacer behind fourth gear on the pinion shaft.
I am very interested how the 1st gear thrust washer is mated to the flipped 4th pinion gear. As i understand it the diameter on the end of 4th gear is machined so the thrust washer can be pressed down whith a "snug" fit. But on what surface will the washer work against? Just a flat machined area in the gear housing or is there another steel washer there?
And how do you measure and adjust the play?
//Roland Just building a Gusseted Rhino case, Weddle sidecover, shotpeened 3,88G R&P and maybe a thrust washer on 4th gear!
The 1st gear thrust washer has the two "nubs" ground off the OD, and the ID is cleaned up a bit. The 4th fixed gear is flipped over, and the raised center "boss" is turned down to accept the washer (.001"-.002" interference fit is fine).
The intermediate housing is machined to accept a similarly cleaned up diff thrust washer (again, with OD nub machined off). 36hp flywheel shims are OD ground to match the OD of your cleaned up diff thrust washer. The various flywheel shim sizes help zero in on the proper clearance. (The kit I used to sell also had 3 different thickness color coded intermediate housing gaskets.)
The flywheel shim(s) go against the housing, with the diff thrust washer placed on top. Trial assembly is done with the pinion stack only, and the small end pinion bearing left out to allow feeler gauge access. (Our housing had a machined-in side access hole for measurement purposes.) Clearance measurements are taken all the way around, and then double-checked with the pinion rotated to four different positions. So long as the clearance is kept to an absolute minimum without touching, the thrust washers will do their job at helping the intermediate housing limit forward pinion movement.
I did very few drag transmissions with the stock alloy housing. While our aluminum housing lasted indefinitely, the stock alloy housing will wear a bit. Not much, but it will require resetting -- certainly at the end of a race season. Using more than just one flywheel shim will help reduce this minimal wear.
Keep in mind that contact between the two thrust washers only occurs for an instant during launch (and possibly when flat-shifting into 2nd in a monster car). But this instant is when virtually all dragrace related pinion failures begin.
Thank´s a lot Pablo for the information! By the way...what´s your thoughts about shootpeening the R&P? I have heard about 30% more torque capacity through the gears before crack´s develops.
//Roland
Shotpeening is an excellent idea, but the 30% figure would probably apply more to road racing than drag racing. Aggressively champhering the sharp edges is a very good idea, and isotropic normalizing (ultra polishing procedure) may be of some benefit.
I just sent the R&P to a Shootpeening company that does the Shootpeening on Volvo´s 4 wheeldrive systems so i hope/think they do it right. Before i take out the Pinion from the "donator" transaxle i measure the distance from the pinion nose to the ring gear centerline, the distance was 59,067mm (2,32547"). Do you think that i should set it at this distance when i put it my race transmission,or how much should it differ from that? This is the first time i have measured the distance, on the earlier boxes i built i have looking for the pattern on the pinion using dykem. Now i have the distance that Vw think was right hopefully i will get a better result from this.
Sounds like you're doing it right. The whole idea to our HD aluminum housing was to provide a "brick wall" to limit forward pinion movement to the clearance set between the thrust washers, which allowed the factory setting. Prior to this mod, everyone had their own ideas as to how much the pinion would move forward out-of-mesh with the ring gear, and most guys would try to compensate somewhat for this with a deeper pinion setting. It was a complete crapshoot, evidenced by racers with 2-4 spare transmissions at any serious weekend drag event. While the chromoly 4-bolt retainer was a huge help, main case flex still existed.
Doing the mod with a stock housing will certainly help, but it just isn't going to do the same job as a T-6 aluminum housing. The standard alloy is more flexible and there are voids in the casting. So a (reduced) flex issue still remains. Don't neglect the other mods referenced in this thread --
Last edited by Pablo on Wed Oct 20, 2010 6:32 pm, edited 1 time in total.
Where do you usually see the first signs of cracks on the pinion? The ones that i have seen has cracks from the top of the big end halfway to the nose and about 1/3 down from the top of the teeth.
How much do you take away from the gear housing? i was thinkin of about 1,5mm or something like that.
One more thing...the bolt that was shown earlier in this thread that goes from side to side when using a Rhino case, have you noticed any good results from that? It seems like a quite simple operation so i think it´s worth it even if it doesn´t help that much.
//Roland Looking for 9 sec this year, 10,27 last year
The cracks you are seeing are typical. With a powerful engine/heavy car/ violent launches, you will see these begin to develop no matter what you do. But following the outlined procedure will slow the start of and subsequent development of the cracks dramatically.
I don't recall offhand how much to machine from the stock housing for the thrust washer/shim stack. (It's been almost 20 years.) But I don't think I'd dive in with an initial cut of 1.5mm (although you may end up there). I'd start with about .030" and take a look-see.
The through bolt is absolutely essential, and is the main reason I recommend using a (steel-sleeved) Rhino case. Don't bother with the rest of the mods if you aren't going to do this.
Pablo, what about cryogenics? I have read/heard where this is beneficial, too. Still, I believe that no matter what you do, with the HP of a lot of cars today, failure is inevitable.
While cryogenics has been shown to have minimal benefits for things like cast iron brake rotors, cutting tools, and a few other items, it has been shown to have NO benefits whatsoever on high quality gears. I accept that there MAY be some small benefits for somewhat lower quality gears, such as those found in mass production --- and VW factory R&Ps could *possibly* fall under this catagory. (It is interesting to note that everyone is in agreement that the greatest cryo benefits are seen in the treatment of cast iron components such as brake rotors. And yet Brembo, one of the best known names in brake components, spent over 100K in scientifc testing and found any benefits to NOT be worth the effort.)
I coincidentally had a discussion with one of the best known metalurgists/heat treatment specialists in the country (Roy Kern) on this subject a number of years ago, relating to an improperly heat treated batch of gears we had received. While he felt that judicious application of cryogenics may have helped in the transformation of abnormally high levels of retained austinite in our particular situation, it was of no benefit to gears in general. (We exported those gears back to the manufacturer.)
People don't realize that cryogenics already plays an important role in the heat treatment process (2-3 hour step #5 in an 8-step process), and to cryo treat properly carburized materials after-the-fact can have negative effects. In other words, a heat treatment facility already includes the highest caliber cryogenic capability, while the majority of cryogenic specialists don't have nearly the same level of expertise in the treatment of high grade steels.
If cryo treatment could be shown to be of ANY benefit to a world class heat treater or gear manufacturer, he would be on it in an instant. It would provide him (and his customers) with a very distinct advantage. Good heat treaters never stop learning. They are possibly the most progressive and open minded segment of the industry. They MUST be --- materials and heat treatment methods are improving every single year.
The hot ticket these days in gears isn't cryogenics -- it's isotropic normalizing -- a process in which minute imperfections on gear faces are evened out through a special chemical bonding and "polishing" process, yielding gear surfaces that are so smooth that they appear to be chrome plated. The effect in some road racing transmissions is dramatic -- a 20 degree reduction in oil temperature, and measureably longer gear life. We have done this with a fair number of R&Ps and have seen no significant benefits, but I certainly give this treatment a higher level of credibility. And certainly the benfits of shotpeening are very real and measureable.
I realize that there are a few race teams that will swear up & down about the benefits that they have personally seen from cryogenic treatment of their gears. I don’t have an answer to this sort of 3rd party hearsay. I am only reiterating the information that I have been given from experts far closer to the source, and in whom I place more faith.
Ill get that taken care of for next year. (solenoid/pressure switch combo that malfunctioned in first)