five7kid

iTrader: (14)

Got the BMR Trac Pak and panhard rod & support bar installed (barely - parts arrived Wednesday afternoon). Set pinion angle at -3 degrees, left the LCAs in the lowest RB hole - then I had to get the driveshaft shortened again.

First shot at the track was Friday night. It was a "club clash" race, when track prep isn't always the best. I decided to try the 26-9.50x14's Hoosier QTP DOT's again to see what would happen.

First TT, left the 2-step at 4300 and had 14 psi in the Hoosiers. It left straight, no hopping back end, hooked, but bogged down a good bit. 60' 1.999 (down from 2.01-2.09 with the hopping/slipping previously). DA was 9700', ET 13.73 (had run 13.7's at 9000 DA 2 weeks ago) @ 102.75 mph.

Second TT (only get two), I raised the 2-step to 4500 and put 15 psi in the slicks. Now we had a 20 MPH head wind. 60' went down to 1.944, but the tires did slip a little and there was still a little bog. DA 9400', ET 13.61 @ 102.38 mph.

First round of eliminations, wind died down, air and car both cooled off, DA down to 8700'. I left the 2-step at 4500, but dropped tire pressure back down to 14 psi. I dialed 13.55 (pure guess - weather station, using some old data, said 13.41 - I didn't believe that at all). Opponent (dialed .4 sec slower) red-lit really bad (.373), I dropped the hammer and rowed through the gears. Timeslip said 1.949 60', ET 13.42 @ 104.91! There was more slip, the 60' being close to the 2nd TT was probably due to the car and air being cooler.

After that, we got rained out.

So, not sure if I should try less pressure, or go back to the bigger slicks again. I could probably raise the launch RPMs more with the bigger tires, but not sure if I should keep messing with it, or just let it do what it wants to do at the hit. With better track prep, it may still try to hook with the smaller slicks.

I'll say this much for sure - it was a WHOLE BUNCH easier to drive when it just leaves the line vs. the nasty rear end bunny hop at the hit that it was doing 2 weeks ago.

Oh, fellow racer with a nice '90 GTA w/383/TH700/9" that runs 12.5's here watched the 2nd TT, and said it squatted slighted in the 1-2 shift. I didn't feel it, but it certainly was a lot calmer than the hop it took at each shift with the ladder bars. Also didn't get any video tonight.

xpndbl3

iTrader: (5)

Congrats on getting rid of that poor design from before, I'm sure you enjoy your car a lot more now I'm trying to think back to when I ran 26" slicks about 6 or 7 years ago and I "believe" I had them at 12.5 psi, you need to get a day with good prep to keep dropping it .5 until the 60' stops dropping off. Really if you have the gear for it I'd like to see some 28x10.5S which is the stiff sidewall on there and really let it eat. I use the middle hole on my relocation brackets, guess you could try that as well. My old T5 setup in the car would 60' in the 1.7s with my 13.03 305 with a big cam and some head work.

DIGGLER

iTrader: (1)

15psi in the tires at first, work your way down to 12.

factory hole in the rearend for the lower control arms. dont use relocations-yet.

launch rpm= 6000. dump clutch as fast as your foot will come off.

five7kid

iTrader: (14)

I was dumping the clutch at 4500 today, slipped every pass except the first (fresh cool track). I started at 14 psi, dropped them down to 13 on the 2nd pass, kept it there for the rest of the day.

60's were usually about the same, one bad one 2nd round of the first class I was running in, over 2 hours between passes, it slipped a lot more that pass and killed my ET. 2nd round of the 2nd class, I had a .007 package put on me that ended my day.

I was going through the traps at 5800 RPMs (shifting at 6000, rev limiter kicks in at 6200 - they don't like you hitting the rev limiter down track). 4.11 gears.

I'm going to try the 27's again, need to decide whether to keep the tubes or pull them. I'll try putting the LCA back in the factory location. Seems risky, though (lower risk if changing the LCA hole doesn't change the pinion angle). Have a drip at the right axle, need to pull it and put more RTV around the bearing. Next shot at the track with decent prep is a race car test night on Tuesday - doesn't give much time to get things changed/fixed.

Points races again next Friday and Saturday. Friday is the final race of the season in the class in which I am now leading (by one point). If I win two rounds and at least as many as #2 in points, I've got the season championship.

brandoz28

iTrader: (1)

changing the control arm hole shouldn't change your pinion angle with a torque arm

DIGGLER

iTrader: (1)

this car does have a 12 bolt or 9" correct?

if so, you should be knocking down 1.6x 60's on the 26" qtp's, imo.
you do not want to use relocation brackets at this point because you dont want the car to hit the tires any harder than it would in the stock holes. it would actually help if the car was lowered also.
you want to dump it at ~6k and spin the tires over 3-4 times as its leaving out. hit the tires too hard and it will dead hook and break something and/or bog. leaving at 4500 will bog every time.

five7kid

iTrader: (14)

Changing the LCARB hole shouldn't change the pinion angle. But installing the torque arm while leaving the LCA's in place shouldn't have changed the tranny to pinion distance, but it did (although that was probably from having the pinion angle wrong with the ladder bars). I'll check it out in the garage, and if it works out okay, I can try changing the LCA position at the track if necessary.

So many variables, so little time. . .

(Any opinions on tubes vs. no tubes?)

duckmanquacker

My prefference is tubeless, I get too much fluctuation of air pressure with tubes.

five7kid

iTrader: (14)

Really? I check tire pressures before each run. I haven't noticed a significant difference between tubed and tubeless.

I was more wondering about sidewall stiffness.

five7kid

iTrader: (14)

Sorry, missed this response.

Correct, 9". Strange nodular center section housing, Daytona pinion support, Detroit True Trac, Richmond 4.11's, Moser axles, housing from Quick Performance.

I'm spinning 2-3 times now. But, you're right, it does still bog down. I'm shifting at 6k, I should leave at the same RPMs? That's gotta sound nasty. . .

Both the 26's and 27's are QTP DOT's, that make any difference over QTP's? The 26's are tubeless.

Summary of your recommendations: 26-9.50x14 Hoosier Quick Time Pro DOT's, tubeless, 12-13 psi (?). LCA's in stock hole. Set the 2-step at ~6k, dump the clutch. Let the tires turn 3-4 times at the hit, watch 60' times drop like a rock.

DIGGLER

iTrader: (1)

are these tires actually 26/9.5/14's? or is that what you measured them at? a 9.5 dot tire is NARROW! probably 8" at the tread. you will want something more like a 26x11.5x15 qtp. which is roughly a 10" tread width.

these tires are spinning as your slipping the clutch?

i can tell you my suggestions worked great on my camaro. full weight with a cam, made 376rwhp. 26x11.5x16 et streets on stock wheels. it would knock down mid 1.5's all day and its best was a 1.53.
i would try putting it around 5kish at first. as the tree hits the 2nd bulb or whatever floor it then dump it. dont dump then floor it.

five7kid

iTrader: (14)

I'm quoting the numbers on the sidewall, not the measurements.

Slipping the clutch? No, I've just been releasing it. As in, "dump clutch as fast as my foot will come off."

I was thinking of going back to the 27-10.5x15's QTP DOT's, and starting at 5k on the 2-step. I've been running it up on the 2-step after I get staged, flooring it, then dumping the clutch on the 3rd amber. The 2-step releases at the top of the clutch travel. Did you have a different technique in mind?

I haven't had it on a dyno, but based on ET/MPH calculators, at this altitude I'm probably putting down around 300 HP. At sea level, closer to 370.

Oh, forgot to mention the axles are 31 spline.

Shagwell

I hate slicks w/o tubes. Most slicks were desigend to be run with tubes. - If you've had more pressure fluctuation with tubes than w/o, either the tubes were junk(leaking) or another variable changed(length of burn-out/wheel speed, surface temp, ambient temp, etc). I've run back to back passes on tires with and tires w/o tubes; I will not run w/o them again(in slicks that is).

Changing the lca hole should not make any noticeable difference in the pinion angle. I agree with Diggler, I'd go back up to the stock hole, or maybe one down. Get them fairly parrallel to the ground, or slightly uphill towards the back; it will allow the tires to slip a little more out of the gate while letting you launch closer to your shift point.

five7kid

iTrader: (14)

I guess I've been racing a slush box too long. Slipping off the line is counter-intuitive to good 60'.

The stock LCA hole had the front end below the back. If lowering is beneficial to achieve that, then I'm there in the stock hole (another $90 I didn't need to spend). I'll reposition them this evening, head out to the track for test night Tuesday, bolt on the bigger slicks (w/tubes) and see what happens.

I'm not going for any kind of ET record, I'd just like it to launch consistently and not break anything - having the rear tires stay on the pavement is a definite plus.

mw66nova

iTrader: (13)

man that's great news...and makes me want a clutch pedal all the more. after college i'm making some changes...i'm thinking a 408 with a jerico for me...unless there is an od trans that can take the abuse of a bottom 10/upper 9 second n/a combo (which is the plan for after college)

five7kid

iTrader: (14)

Best solution there - two cars. . .

mw66nova

iTrader: (13)

that's definitely an option...the fun car and the fast car...probably cheaper and easier on parts that way...

five7kid

iTrader: (14)

I have a feeling I'll be replacing axles. I moved the LCAs this evening, and had to pull the right axle to fix a leak. Then I discovered the stock LCA hole didn't quite line up with the RB because the bolt UMI included for the spacer to put in the stock hole is smaller than the LCA bolt. So, I had to drill those holes through, which required removing the brake backing plate and axles. The left axle showed some slight twist at the splines (less than half a spline, I'd say, but visible), but I didn't notice that with the right axle. Probably happened during one of the bunny hops a couple of weeks ago.

I believe I've heard the axles will twist some, but I might as well get a new set now and replace them before one breaks going down the track.

mw66nova

iTrader: (13)

yikes...makes me want to check mine

xpndbl3

iTrader: (5)

Moser axles have a 10 year warranty for twist at the splines, IIRC that's what you ordered?

five7kid

iTrader: (14)

Yes, they are Moser.

Guess I need to contact someone, I'll start with Quick Performance (where I got the housing, axles, and bearings).

DIGGLER

iTrader: (1)

it is fun until you get tired of replacing all the broken axles, pinion supports, clutches, driveshafts, differentials, gears, trans input shafts, trans output shafts, trans tailshaft housings, and u-joints.

DIGGLER

iTrader: (1)

if its not so much a street car, i would switch to a spool now.

five7kid

iTrader: (14)

I have considered getting a third member with a spool to put in for the track, and keep the True Trac for the street. The intent was primarily street with 6 or 7 stick shift races a year. It's turned into my primary race car for the time being.

Hope to have the LS1/4L60E car running soon.

five7kid

iTrader: (14)

Well, starting at 5000 RPM and 14 psi, got the 60' down to 1.92 at 5400 RPM and 15 psi on the 4th pass. Then, figuring on one more pass before they closed down, I set it at 5500 RPM and 14 psi, at which point the Trak Pak adjustment link was found on the track - well, most of the adjustment link, that is.

five7kid

iTrader: (14)

What they picked up off of the track:




This is known as "reverse bending fatigue".




The other end. Simple bending fracture.

brandoz28

iTrader: (1)

wow! that really sucks.


you probably needed to turn in the rod end at the top of the diff, its pretty easy to bind up those adjusters

mw66nova

iTrader: (13)

WHAT?!!? is bmr going to take care of you on that? you're not making that much power, there are guys running 8's and faster with that torque arm...

five7kid

iTrader: (14)

I'm not sure what you mean by that. Which rod end?

The key, I think, is the "reverse bending fatigue". I need to look at the other broken end still in the car (when I get it hauled home from the track this afternoon) to see which direction the bending was occurring. I'm thinking it was side-to-side, meaning the rod end joints on the diff aren't properly supporting the torque arm. If that's the case, I either need to brace the mount, or reinforce the Trak Pak adjuster.

That adjuster concerned me as I was installing the piece. I don't need it, as I have adjustment built in to the mount. The adjuster just looked weaker than the rest of the piece.

A reminder of what the torque arm mount looks like:




I called BMR. Of course, the guy who needs to address it wasn't available. But, the guy who answered assured me they will get back with me.

brandoz28

iTrader: (1)

on the actual torque arm, where it attaches to the bracket that attaches it to the housing, there's a rod end towards the top.


could've just been a freak failure though, there are guys with a TON more power than you that haven't broken those.

hope bmr takes care of it

xpndbl3

iTrader: (5)

I'm starting to think you have my kind of luck with things....

five7kid

iTrader: (14)

That seemed fine. No binding occurring there.

I did talk to Lee at BMR, he's baffled as well. I forgot to ask, but I believe they use the same adjuster on their Xtreme TA. He mentioned 200 MPH radial cars using the part without a problem. He didn't blame the torque arm mount, for what that's worth. He is going to send me the new parts, and wants better pictures of the installation (which I don't have yet).

I'm starting to wonder. I thought I had it all covered finally.

five7kid

iTrader: (14)

Let's just say it ain't pretty.

The pinion was pointed up at about 30 degrees. After I got the car up on jackstands, I confirmed that the reverse bending was side-to-side. Apparently the ends of torque arm mounts being able to swivel is a bad thing for the Trak Pak. But, there was more.

The front end of the torque arm had moved back, and when it went forward again, it was swiveled down. That kept the pinion pointed up - or so I thought. After prying it back over the top, the pinion was still reaching for the sky. I tried jacking up against the panhard rod mount to counteract the springs, but that barely helped. I finally figured out the bottom shock eyelet mounts were bent and almost broken off of the shock body.

But, there was more.

At the first quick look at everything, the transmission yoke was out about an inch farther than it was when I first installed it. Looking at the back driveshaft yoke, I finally figured out that the edges of the yoke had been peeled back by contact with the pinion yoke, so much so that the u-joint clips were deformed and about to pop out. So, now I know the driveshaft is toast - to say nothing of the groove worn in it by contacting the bolt that holds the front links on.

So, I proceed to remove the driveshaft, manage to get the pinion to point a little more level (have jacks on the back of the axles to try to promote that). I get the U-bolts out, and I simply cannot get the U-joint caps to move out of the pinion yoke. I tried several things, prying, banging, prying and banging - won't budge. I finally managed to get them out by moving the rear up and down on the jacks. It finally dawns on me that it isn't that the caps are stuck in the pinion yoke, it's because the tranny yoke isn't sliding on the output shaft. Now that the rear of the driveshaft is free, I cannot get the output yoke out of the transmission - banging, prying, among other things.

So, summary:
Torque arm adjusting link broken
Rear shocks bent
Front torque arm mount links tweaked (still not sure what that means)
Tranny output yoke stuck on output shaft (I assume the output shaft is damaged)
Driveshaft toast

I believe it all started because the torque arm mount that came with the rear end housing is not compatible with the adjustable torque arm. The housing manufacturer assumed the torque arm would be able to handle the side-to-side movement, and the torque arm manufacturer assumed there wouldn't be any side-to-side motion at the mount.

Back to the drawing board.

rustrider73

nevermind the drawing board, sounds like you need to have your banker drop off another truckload of cash to put that thing back together

five7kid

iTrader: (14)

Oh, there's also a big dent where the torque arm mount hit the floor, and a bit of a hole that the carpet is showing through at the edge.

mw66nova

iTrader: (13)

wow.

Pocket

iTrader: (24)

How is the TA moving side to side? Should stay pretty isolated with the panhard bar and trans mount. Could the TA be severely flexing under load and it look like side to side motion on the joints?

mw66nova

iTrader: (13)

look at the picture of the rearened housing he's using. there's pinion angle adjustment built into the mount. seems like a pretty great idea if you're using a non-adjustable torque arm. however, there's side to side movement in the rod ends. it's magnified by the second set of rod ends on the adjustable torque arm. so then it fatigues the metal in the adjuster sleeve. seems to me that the BMR arm is not to blame. it's cool that they're going to take care of it though.

so tim, what's the solution?

Shagwell

Damb man, sucks to see. - "If it weren't for bad luck......"

Bingo.

I'd switch the spherical rod ends in the tq arm mount out for solid ends(not sphericals), and then pending any flex I might add a "kicker leg" to the mount that extended over towards an axle tube; thus making that mount more of a tri-pod design.

mw66nova

iTrader: (13)

good idea. i invision some mounting tabs on the axle tube and on the TA mount, then an adjustable strut going to the TA mount so you can still have pinion angle adjustment out of the mount, yet no side to side movement possible.

five7kid

iTrader: (14)

The joints BMR puts between the mount plates and torque arm are not swivels, but eyebolts. However, they do not "squeeze" securely with the bolts holding them to the mount plates. With the swivel joints in the Quick Performance torque arm mount links, the torque arm swings back & forth at those eyebolts - think of it as bending in the middle. That fatigued the adjustment link, leaving about 1/4" material in the middle before the final fracture.

Either system would work fine by itself, but together, they are sudden death.

xpndbl3

iTrader: (5)

what torque arm does that housing manufacturer usually run? I know the moser fab 9 for 4th gens has a similar setup and their torque arm has no adjustment link on there. Midwest chassis also makes a torque arm similar as well with mounting points in the same general area.

five7kid

iTrader: (14)

Quick Performance doesn't say one way or the other what torque arm to use. I suppose they figure you'll be using a stock type.

http://www.quickperformance.com/Products/housings.htm , scroll down to the F-body housing (red in the photo).

Shagwell

By the design it does seem as though they intend it for a stock type arm.

Like I said, I'd keep the BMR arm as intended, and just re-work that mount a little to make it solid. You could indeed keep it adjustable as Matt noted, but there's not really a need with the tq arm being adjustable.

I do my 8.8 conversion similiar, but I build a custom tq arm that fits directly to it.

DIGGLER

iTrader: (1)

lol....

i hate it when this stuff happens, but it comes with the manual transmission territory. after looking at your housing, it would be REALLY nice if you could swap torque arms for the moser m9 style. that way you could ditch that extra mount thats in there. maybe you could get one made by racecraft or something and sell that bmr one?

the 60's are still way slow. i would have thought it would at least be knocking down high 1.7's. the car has got to be bogging, spinning, or the clutch is slipping. any more info on how the car is leaving?

five7kid

iTrader: (14)

That would be perfect.

five7kid

iTrader: (14)

The Moser torque arm is a straight-across tranny cross-member mounted type, makes exhaust difficult. Just no free lunch, huh?

It might be possible to merge the QP links with the BMR, to end up with something like shagwell makes. Or, local outfit that does roll cages & exhaust might be able to fab up one to pick up the QP brackets.

Of those three, I'd pick spinning and bogging. It just doesn't feel at all like a slipping clutch. At 5400 and 15 psi, it was still turning the tires, and just about got rid of the bogging. I had great hopes for that last pass at 5500 and 14 psi, which is when things got ugly.

You said 26-11.5 tires, these are 27-10.5, so a little off from your combo. And, the altitude costs me about a tenth in 60' from my previous experience.

DIGGLER

iTrader: (1)

the arm like shagwell posted is exactly what you need. that would allow you to get rid of that extra mount. i would assume you could have one made that could still use the bmr crossmember....?

i've been a 1.94 60' with some 17" summitomo street tires and a t-56 trans... you have alot to look foward to.

five7kid

iTrader: (14)

I assume so.

I've brought it down from 2.09 to 1.92, so it's not like I haven't made ANY progress. . .

Next, though, we'll see what an LS1/4L60E, shaved 317 heads, LS6 intake, LT Hawks, 3000 stall, 3.73 gears can do.

DIGGLER

iTrader: (1)

if the auto doesnt go 1.7's, there is for sure something wrong. maybe the track timers are 90' out. lol