Great thread! That's a monster of a motor! I had a 87' T-Top I put a 351w in in high school. Probably only made 300whp but it felt like a thousand to a 17 year old high school kid, and I still got in plenty of trouble
80 in a 75 is a bit bogus and I would have to feel that was a youngster profiling situation. As I near 7 decades I remember having the same issues you had when I was in my teens and 20s. I got stopped a lot , usually talked my way out of it , but got a few tickets for just a few miles over. Being young with a fast , fun car is a draw for many in Law Enforcement and actually they are often right on the money- ha. Like you noted and I mentioned , we both were stopped alot, emphasis on alot !! Since we talked our way out of many it was always the few we got that frustrated us the most because we viewed them as lightweight speeding citations.
The older I got I began counting all the tickets I got out of and I began to figure the times I got caught were substantially lower than the law of averages.
Talked my way out of the 120mph one because the Officer had a 1989 Z28 and I mentioned I had a 89 Firebird Formula 350 with the different cats ( factory ) and he had the same set-up. This was good for 5 more HP, ha. The 98 in a 60mph had me going to Court , but I had a compelling reason and the Judge let me off with a warning.
Overall, now, I am pretty darn good at keeping the speed quite reasonable except on the track -- best and safest place to go faaasstt!!
Personally I'd buy some axles stock or otherwise and use the 28 spline Trutrac. There is nothing wrong with 28 spline until you're making 700+ in a drag car and launching hard. I know Chris Robins(guerilla motorsports) is still running 28 spline in his road race car making similiar power to yo
I've been thinking over rear end upgrades as well. I've landed on a Torsen 28 spline for reasons Casey outlined- seems like the 28 spline axles are fine at these power levels and under these conditions.Semi-successful weekend working on the Mustang. I had plans to install the Eaton TruTrac I picked up from a fellow AutoCrosser. It's a 28-Spline to replace my stock differential. It would also be a great opportunity to install the rear Cobra brake setup and longer ARP studs that have been sitting on my desk at work.
Well, as usual, my plans didn't go over so well. I got the rear diff cover off and immediately realized that the diff I was looking at wasn't stock. It's an Auburn unit. I still couldn't tell which axles I had installed, though. I got the passenger axle pulled out aaaaand...31-splines. I counted to be sure, but could tell by the size immediately.
I went ahead and installed the Cobra brake setup and the ARP studs. I left the Auburn alone. The gears looked great, like they were just installed yesterday.
So, now I have to decide what to do. At one event earlier this year, I was only spinning one tire. I haven't noticed that issue since that one event. I can either go ahead and buy a new 31 spline TruTrac or just keep the Auburn and hope it keeps doing well. If I buy the new TruTrac, I'll probably put the Auburn in the old truck. It just has an open diff and the Auburn would probably live forever in it since it doesn't get abused like the Mustang.
Personally I'd buy some axles stock or otherwise and use the 28 spline Trutrac. There is nothing wrong with 28 spline until you're making 700+ in a drag car and launching hard. I know Chris Robins(guerilla motorsports) is still running 28 spline in his road race car making similiar power to yours.
I've been thinking over rear end upgrades as well. I've landed on a Torsen 28 spline for reasons Casey outlined- seems like the 28 spline axles are fine at these power levels and under these conditions.
I had a follow-up question, though- do people break c/clip axles in road racing and autocross? Is it necessary to upgrade to 9" ends like the drag racers do?
Yea, you're absolutely right. By the time you buy shafts you'll be downgrading for almost the same money. I had not considered what you paid for the diff in the first place. If you want to get rid of it...I may be interested. My trac-loc has already been an issue on higher speed right handers with spinning the inside tire. I need to be able to do donuts left AND right, haha!Fair points, and exactly why I bought the TruTrac when this opportunity came up. The guy that sold me this unit was upgrading to 31 spline in his car. His is a road course and AutoX primarily Factory Five Cobra that's about 1000 pounds lighter than my car and makes 20hp less. He doesn't drag race it often, but he was still breaking an axle or two every year. Usually at Holley Ford Fest during the drag racing part.
With a road course and AutoX car that never hits the drag strip, it may be fine forever. One of my issues there is that I would like to try this thing out on the drag strip, but I'm scared to because of the failure points...i.e. my TR-3550 trans rated for 350 ft-lbs, my standard duty torque arm rated at 330 ft-lbs, what I thought were 28 spline axles, etc. I darn near tried it out at the strip this year in spite of those, but the power steering pump decided to lock up and took that choice out of my hands.
I'm also not a big fan of downgrading in general, especially if I have to spend more money to do it. I'd be looking at spending $250 or so on new, stock-like 28 spline axles (I could go cheaper from a junkyard, ofc). Using the 28 spline TruTrac I picked up, I'll have about $500 in the setup. $100 more and using my existing axles, I could have a 31 spline setup that I would feel more comfortable testing out at the strip. So if I can sell the 28 spline TruTrac for what I got it for and put the cash toward a new one, I'll probably go that route. Plus, I just installed my longer ARP studs in the 31 spline axles.
On the C Clip question, people do upgrade to 9" ends, but not near as often from what I've seen. I wouldn't say it's "necessary", but over a certain power level, on wide 'n sticky tires, with good suspension, being driven hard, it probably isn't a bad idea... Some of the main benefits are reduced pad knockback (so more consistent braking), less noise from the brakes, the axle (and wheel!) staying in place if an axle fails under power, etc.
I only have 295's though... I need to buy wheels so I can get grown up size tires too.
Being able to work on your car at your house makes all the difference in the world. My dad has a shop and lift 5 minutes away but it's just not the same as being able to wander out to the garage to tinker and end up knocking something off the list that you've been putting off for 6 months. I can't wait for the day I actually have a shop.
Congrats man! Looks nice. Could you fit your car in the garage on the back side of the house?