Adding 4.10 gears greatly enhances the acceleration and a definite must-have for modular-powered Mustangs of any variety. The gear helps these cars thanks to the lack of torque from the 4.6L combo. "I know Ken didn't want the extra rpm on the highway, but the 4.10 gears work great in these cars. It helps the car accelerate quicker on the track. Between the weight, the automatic, and the power, the 4.10 gears are definitely needed," comments Radovich. He also went on to tell us that the higher numerical gear ratio will benefit our future modifications, which includes a stroker naturally aspirated Two-Valve engine. Silver Stealth Stang desperately needed the FRPP Trak Lok. It is tougher than the stock unit, which was toasted when we inspected the rear's guts. That is a big problem with high mileage cars, the diffs get wore out from years of abuse. The spider gears were shot when we inspected the internals. While the rear was in pieces, Radovich suggested adding new axle bearings too. The other modifications we made to the driveline included a lighter aluminum driveshaft from Axle Exchange and a looser torque converter from Pat's Performance Converters (P.P.C.). The Axle Exchange aluminum driveshaft is a super nice piece. A neat tidbit about the company is that it is only 15 miles from MM&FF Command Central in northern New Jersey. That worked in our favor by saving money on shipping. We popped in during a lunch break to pick up the driveshaft before heading to Radical Racing. Radovich had this to say about adding an aluminum driveshaft, "Adding a lightweight aluminum driveshaft helps the car accelerate by shedding rotating weight." He also informed us that over time, the stock driveshaft's rubber coupler starts to break apart, causing the 'shaft to become unbalanced. That leads to noise and a rougher ride. That was definitely the case with Miele's daily beater.
I have to admit, to me an aluminum driveshaft is a simple device that gets balanced. That certainly isn't the case, and Neil Welks of Axle Exchange took the time to educate us on just how much goes into a 'shaft. Driveshafts are much more than just some thick-wall aluminum tubing with ends welded on. An Axle Exchange driveshaft costs a little more than the average run-of-the-mill driveshaft, but the extra expense is worth it. There are some products on the market that are far less expensive but it comes at the cost of quality.
Starting with the 'shaft, Axle Exchange uses Alcoa Driveshaft seamless tubing, which is a four-inch diameter with a 0.125-inch wall. The difference between Driveshaft tubing and regular stuff (with the same dimensions) is that the Driveshaft tubing has been accurately measured to carry a consistent thickness throughout the length of the tubing. The other stuff may look identical but inside, the wall thickness can vary greatly.
Moving to the weld yokes, the ones used by Axle Exchange are proudly stamped Made in the USA. Not only does it invoke pride, but it also shows quality. The weld yokes are rated to 4,000 lb-ft, nearly double the stock yokes' 2,300 lb-ft rating. Do not get these ratings confused with torque output of an engine; this rating is used for stress that includes power, weight, and shock. Overseas yokes are rated at a paltry 1,800 lb-ft, far less than even a stock yoke. Most of the cheaper aluminum driveshafts utilize the cheaper off-shore yoke, meaning it is weaker than stock. The U-joints are top-of-the-line Spicer high-performance pieces. The weight difference between the two driveshafts is five pounds, which is rotating weight, and that is a big difference when spinning something.
Two simple changes made a profound difference on the dragstrip as Miele pounded Silver Stealth Stang at Englishtown, right before it closed for the winter. Our initial run, was a best of 13.97 at 97.50 and was accomplished in really good fall weather conditions. Our post testing of the 4.10s and aluminum driveshaft was done in slightly better conditions. Based on the experience of everyone involved in this buildup, we felt the final track testing conditions were worth a tenth of a second quicker than when we ran 13.97. We are setting you up for a major drop in e.t. from just a gear swap and aluminum driveshaft. Miele cooled the car in the same manner, simply popping the hood and letting the car sit for an hour or so before making a run. On track, the car blistered a 13.62 at 99.93 with an outstanding 1.95 sixty-foot time.
Upon removal of the rear cover,...
Upon removal of the rear cover, we noticed metal shavings in the bottom of the housing. As it turns out, the differential was coming apart.
We removed the cover and drained...
We removed the cover and drained the fluid out of the rear. Be prepared, rear gear oil stinks--badly.
Using a lift makes the job...
Using a lift makes the job so much easier
Another ailing problem due...
Another ailing problem due to high-mileage are leaky axle bearings.
The ring gear is bolted to...
The ring gear is bolted to the differential; be sure to put Loc-tite on the bolts. Torque the bolts to 65 lb-ft.
The bearings are pressed onto...
The bearings are pressed onto the differential.