I have driven my 1926 Model T coupe with a stock 350 for 20K plus miles now with an open Ford 8" rear with 3.80 gears and a 700r4. I recently rebuilt the engine with probably 100 more HP. Now that open rear end has got to go. I don't have a clue about positive traction devices. Never messed with them except for the spools in the race cars, but that's not quite the same. I see there are lots of different types and widely varying prices. What are you guys using? What is available for an 8" rear that works well? All during this pandemic I have been doing upgrades to my T coupe. I think posi-traction is next.
That thing is bitchin'! I have a regular Ford Trac Loc in my 8" and it works fine, no noise or clunks and two tire peel. But the big dogs swear by the aftermarket units.
Yea, more people are going to the Track Loc, True Track, or "helical gear" type differential. No clutch plates to wear, no springs to break or go soft, no special gear lube required. I have them in three (Ford, Winters Quick Change) cars and just bought one for an "off topic" car. Mike
What about a Jag rear end. Were they posi. know they were traditional. Nice looking coupe by the way.
I'd give serious thought to upgrading the whole rear axle. A built 350 will be pushing the envelope hard with a 8" in terms of strength. Connect both tires to the ground and you may start breaking stuff. Keep in mind that Ford limited their OEM use to 'standard' 300 inch and smaller motors in the lighter cars; anything bigger or HiPo got the 9". You might look at the Ford 8.8" rear as found in Explorers, Rangers, and Mustangs. Same wheel bolt pattern, nearly as strong as a 9", lots of them in the yards, a very good selection of ratios, and most will have a posi already in them. I haven't priced them lately, but $200 or less would get you a complete one not long ago.
I often use the 8.8's. Tough units. Lincoln in the avatar has one with limited slip and discs. The tag on the rear states the ratio, 3.23 and even 3.73 are common. Look for the tags that have a "L" - ie; 3L_73 on the tag is a limited slip 3.73 ! Summit sells a very good and reasonably priced posi unit if you wanted to completely freshen one easily.
We are only talking about 350 HP here. I have thought about changing rear ends. I used the 8" because it is exactly the right width, 56.5", to fit the car. Changing out the rear goes a lot deeper than just swap it in. Narrowing, gear ratio, brakes, 4 bar brackets, driveshaft length and with my luck probably a half dozen other things that I haven't thought of. If I was going to swap it out, I would put a 9" in it, but I really am not looking for that big of a project. If it breaks I can always swap it out then, but this car doesn't get driven hard. I have other cars for that.
You can buy the Ford 8" Trac Loc for under $300, but then you'll need to swap your ring gear on it, and get an install kit with bearings, shims, etc., and set it up, or have it set up. Most rearend shops will set yours up if you take it to them, and do so for around $200. So you'll be in about $800 by the time you're done. So the question is how badly do you want to keep the same rear axle? It might be cheaper to find another axle and swap it into your car, if you don't mind doing the installation. And the perfect axle will be a drum brake 8.8" Ford from an Explorer. They are 59.5" wide, but when you do the short side axle swap, it ends up right where you want to be at 56 5/8" wide. The posi 8.8" runs about $200, and short side axle another $20. Then cutting one tube to accept the short side axle runs about $50-$75. After that it's just welding on the brackets, and putting it under the car. Or for around $300 you could buy a Powertrax mechanical locker to go into your existing differential and change it to posi. The cheapest, easiest route, with less work. https://www.summitracing.com/parts/pwt-1810-lr
Go jag mk10 daimler fits under a T , inboard big disks, multi piston calipers and all pre 65, Daimler’s are lim slip, don’t chrome it, HPC coat it (it won’t go brittle) .... I got mk10 front and rear under my T coupe,,, but it’s considered OT here, so I don’t post it, Gm stud pattern and tough as nails,,, just my 2 c worth,,, very very nice coupe though, it’s a credit to you Sent from my iPhone using The H.A.M.B. mobile app
It's not so much the HP as the torque. A stock 350 is marginal for the 8" torque rating, lean on the motor and now you're at or beyond it. I wouldn't run it, but it's your call... Again, Ford wouldn't use them behind anything larger than the 'standard' 302 for a reason. You'd never find one in a full-size car either, no matter which motor it had.
I highly doubt he will brake his rear end. I have a s10 7.5 posi rear with 370 hp. I haven't broke it yet and believe me I've tried.
Thanks for this answer. I am definitely rear end knowledge challenged. We have raced circle track almost my entire adult life. There have been rear end problems, but I had a buddy that helped on the pit crew and he was a rear end guru. I never had to learn rear end gear setup. He's gone now. I wish I had paid attention. I guess I was always busy on some other part of the race car. I can change out the chunk, but I never mess with it. I have a fella now that swapped in my 3.80 gear set with all new bearings, etc. about 3K miles ago for 100 bucks. Quick Performance has a Trac-Lock unit with the required bearings and longer bolts for about $350. Is that all I would need? I would only be in about $450 or so. Not sure about lockers. Don't they ratchet and make noise? Thanks for the info.
Crazy Steve is right on with the 8.8. My nephew just scored an 8.8 with TracLoc and 3.55 gears for $125 from our local pick a part yard. Sent from my iPhone using The H.A.M.B. mobile app
Unless you're planning on running super sticky slicks with glue and adding weight the the rear, breaking any rearend won't be much of a consideration. Your tires will break lose way before the rearend.
I'm pretty sure the 8.8 is close to the right length, my memory says 56-58", I've got one under my '51 Shoebox with a 302, 270 HP-ish
A stock 8" Ford might not hold up to a lot, but if you change out the side gears to 31 spline, and put better axles in them, they'll hold up to a fair amount of HP. A friend has one done this way under his early Nova gasser with a 350 SBC and 6-71 blower that's about 600 hp, and runs it hard at the dragstrip. It's held up just fine, so I'm a believer now that properly set up they're strong enough.
You nailed it in post #8. Don't turn a mole hill into a mountain by reworking the entire rearend/suspension. Aftermarket "posi" units are pretty cheap, as was pointed out. Lynn
Get a True Trac with the geared posi and you don't have to worry about wearing out the clutches in the posi or using gear additive. I just bought two from Summit for 9" Fords and Jegs had them at a reduced price. I usually buy from Summit, so they agreed to match the price. Appx $500 and got them for about $450 while on sale.
I have a Yukon gear posi unit in the 8 inch in my t bucket. works well. car is so light I sometimes get that locked rear end chirp going around corners if the pavement is real smooth. Dont have enough miles on the car yet to really evaluate, but I've not been easy on it. little over 400hp 350 , 33x12.5 tires, spinning after most stops, and from a roll, no complaints yet
Let's evaluate the situation at hand. Good little engine? Check Good transmission? Check Good rear end? Check 10" slicks? Nope! Good to go with the 8" rear. I'd do some research on the Lincoln locker. It's a hot item. Very reasonably priced.
True tracs are really the best street rod setup and they are durable. I have beat the $#!+ out of one in my 10 second street rod anglia with 4 speed stick (12 bolt) for a really long time. Every customer I have put one in has loved it.
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