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R200 went boom


scottyMIz

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Hey guys i had to report the durability of the r200.I've beat the crap out of mine to the best of my knowledge it's the stock 76z rear but it is a r200.I was doing some burnouts yesterday well two to be exact and the first was a good one the second well as the title of the post says didn't go to well.It just squealed and then i heard a big boom and some grinding and crunching sounds.I was 15 miles from hom and managed to limp back to my house going 20 mph.I was going to go thru the rear this winter but i guess i'll definately have to maybe sooner.I think either the bearings in the pinion are bad cuz it felt like as long as there was pressure on the ring gear it would be find.But if i let off the gas or push in the clutch it would start clunking and making very loud booms.I guess i'll just have to get a new 390 rear.I'm thinking maybe an lsd or i'll just weld the new rear i put in.I'm not sure what i should do any ideas?

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Guest Anonymous

Sorry to hear about the unfortunate boom. glad you made and your car made it home in once piece. I do have a question though: when was the last time you replaced the gear oil in the diff?

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Nothing burns up a diff faster than big burnouts in a single track. Cuts grooves in the spider gear shaft increasing clearance and decreasing strength. All this metal contaminates the oil which takes out the other bearings. If you are going to drag race the car, gonna have to go limited slip. The sudden traction leaving the bleach box can grenade as well, but sounds more like a bearing since you were able to drive it home. Let us know what you found...

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I found the problem guys i took it out today and found that the holes in the carrier where oval icon_eek.gif Not round like they should have been.They are the holes that the pin for the small gears goes thru and that explains my play in the rear before .Well the force ended up snapping the shaft so i just got out the old welder and welded everything up so i can drive it to work and back for a day.I would have fixed it the right way but the woman was complaining that i wasn't working on the house.So when it gets the engine pulled i'll take out the diff again and do it right.I'm thinking the limited slip is the way to go.Anyone know where to get one?Oh ya i'm not rich so the cheaper the better icon_smile.gif

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Yup, you have found the weak point of an open R-200 when you start making HP. Since a Quaife is out of your budget, then the only choices you have are: a) Run another open diff - cheapest option. B) Buy a LSD - expect to pay about $400 c) Run a welded diff - if you can live with the negatives.

 

Whatever you do, do not run a 3.90. The LSD is 3.70 and with the HP you are starting to make, a3.54 is better for you than a 3.90 because of the turbo and stock RPM limits. If you have absolutely no choice and have to do option C, I have a 3.54 you can have cheap if you are willing to pay to ship it. However, if this your only car, then I would advise against option C.

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Guest Anonymous

If it's not your only car keep your money and stay with the welded icon_biggrin.gif I've driven mine welded for 2 months now .I love it ! A lil squeal on Slow tight turns .No driving in the rain.

All non beleivers I drive around town On the beltway ETC .Saved me when I spit a Shaft 85 miles from home .I limped too the shop at 55 And put in the spare I carry.Just tie all the weld too center shaft fot strength. I will take pics of the 411 That just got finished And post If I have Time today. twak.gif

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The bearings are bad in my rear i can hear it making all kinds of noise wheni drive down the road.It is neat to have the tire squeal a little when i turn.Scottie are you saying that the 3.90 is bad for the bottom end of the performance?It has a hell of a take off and is still drivable on the street.Will the sd from a 300 fit in the r200 case?If so i'll get one of those from some where.What would the difference be comparing the one you have and the 3.90?What other negativities(sp?) are there in a welded diff?I kinda like the idea of whipping donuts no problem icon_biggrin.gif Let me know guys what i can do i need options.Oh ya scottie i have four other cars not counting the z.But i do want it drivable i use it to go to work and to go to shows and on trips.

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I'm not putting down the power like Scotty, but like him I run a 3.90, and this has got to be the single upgrade that made the most difference in the performance of my turbo Z. It is much easier to drive in traffic, and the off-boost performance is much improved. Maybe because my exhuast is only 2-1/2" I don't get the most on-boost torque that can result from the greater torque load the 3.54 puts on the motor, but I sure don't notice any holding back when I get into the throttle. The 3.90 is also perfect for my T5 gearing - with the 3.54 I wasn't shifting into 4th until right at the traps, so it was either hit the rev limit or shift, both hurt my 1/4 times. Now 4th gear is useful, and it still cruises nicely in 5th.

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When I welded it I didn't get all the places i'll have to touch it up when i take it out to replace the bearings.I like the 3.90 it has alot of pull thru all the gears.So far the highest speed i've ad it to is 140 with a whole lot to go rpm and throttle wise.I have three other r200's so that's no problem.I don't know what gearing they are but i have them.Scottie what would you want for that rear?

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Guest Anonymous

It takes about an hour 1/2 with hand tools too switch the diff .I drive 85 miles too Colonial Beach Va all the time.Lots of highway windy roads etc .If you have 4 cars I would definitly weld it .A spare open if you pull it yourself is 35-100 .You can always switch it out.A friend in FL has run his solid for 3 yrs runnin 10's with 28x 10.5 ET Streets .

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Guest Tom Scala

I think what ScottieGNZ means when he says to run a 3.36 or 3.54 instead of a 3.90 is that you have to gear the car for trap speed at the end of the 1/4 mi. If your going to add power to run say 115MPH in the 1/4 a 3.90 with normal diameter tires will have you taching near 6500rpm in 4th gear through the lights,thats too much. Not to mention the traction problems you would have with the added power and low gearing. A 3.54 would put you just under 6000 at the finish line which is much better for a turbo car and should hook up better out of the hole.

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When Scottie says the 3.54 is better, he is talking about a turbo Z. The problem with going with a 3.9 or 4.11 is that the engine is not loaded down in first and a bit in second gear. The turbo doesn't get enough exhaust gas to give you any appreciable boost. The only car this doesn't apply to is 4wd turbo cars like a talon. They use a ridiculously low first gear and use their traction advantage which is good for killer race starts. However if you don't abuse it, you are left with a big soggy sandwich in first.

 

It is crucial to match gearing on a turbo car, it is a balancing act. The 3.54 and 3.7LSD are probably the best route.

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Great responses, guys.

 

To sum up, where a NA with a hot cam likes to rev quickly, a turbo performs better when it is under load and has a little more time to build boost. You cannot apply NA thinking to a turbo setup, especially when dealing with gearing and cams. When I ran the 5-spd, I used a 3.70 because I had an LSD.

 

I know some folks are dead set against a welded rear and I am not pushing the concept or trying to sell mine. I keep tripping over the dang thing icon_biggrin.gif and since I will never use it again, maybe someone else can if they understand what they have.

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I second what Clint had to say.

First gear in my AWD Talon absolutly sucks, unless I dump clutch at 6500 rpm icon_eek.gif Even when I do launch it hard, I only see about 14 psi in first while every other gear is about 16 - 17 psi.

 

Scottie,

If Scotty doesn't pick up your welded R200 by February, I'll stop by and pick it up while I'm in Orlando. I've been meaning to weld up an R200 with provisions for the CV axels (my stub shafts on the diff side refuse to come out icon_mad.gif ) for some time now.

 

-Andy

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