7.5 IRS Questions- high HP Cars Driven Hard
12-27-2015, 04:11 PM
#26
Administrator
BTW, this was really the main disadvantage I found with the 7.5. Since Ford dropped it and basicly disowned it they now offer no support what so ever for it. What that means is while you can still buy factory parts fairly inexpensively for the 8.8 everything for the 7.5 must come from the aftermarket. A complete new tractionloc carrier unit for an 8.8 is right around $200 as was the 7.5 version until a few years ago. Now you can still buy a new unit for a 7.5 but only from Yukon for around $400. The rebuild kits are the same story. The 8.8 clutch packs are half the price of the 7.5 version with less components from the aftermarket.
If I was starting from scratch I'd go with an 8.8 and deal with the less exhaust room. With the carrier unit I chose I shouldn't ever have to go back in and rebuild it once its set up assuming I keep after the oil (I had a drain plug installed for quick oil changes). Clutch packs wear and need replaced. I would not want to look for those parts for a 7.5 another 5 years from now.
-Jason
12-27-2015, 05:52 PM
#27
V8 Miata Fanatic
Thanks, that's what I figured but could not find confirmation. Yeah, sucks that Ford abandoned the 7.5, especially considering the amount of them on the road. I see there is a tuetrac diff available and may go that route down the road, just don't have the funds now. I have a 3.27 LSD, and figure if I rebuild it and stack it tight (similar to the performance 8.8 method), I have get a good amount of use out of it.
12-27-2015, 06:22 PM
#28
Administrator
Thanks, that's what I figured but could not find confirmation. Yeah, sucks that Ford abandoned the 7.5, especially considering the amount of them on the road. I see there is a tuetrac diff available and may go that route down the road, just don't have the funds now. I have a 3.27 LSD, and figure if I rebuild it and stack it tight (similar to the performance 8.8 method), I have get a good amount of use out of it.
I'm banking on the relatively friction-less mechanism of the TrueTrack to be substantially cooler running than the TractionLoc's clutch packs. The research I'vd done as well as my rear end guy's experience shows I should be ok.
The funny thing is quite a few people have been fine with the 7.5/TractionLoc combo, even on the track. One customer of ours road raced his for four years without a drop boiling over. The only reason for this I can fathom is that his clutch packs were actually worn to the point where they were not creating the heat mine were. On a side note, my rear end guy checked how much life was left in the old unit when he took it out. It was only operating at 30% or so.
-Jason
12-27-2015, 08:02 PM
#29
V8 Miata Participant
I do think that a 7.5 is fine for any Ford V8 Miata. However, keep in mind that if you are going to push it hard with the TractionLoc you may run into the same overheating issues I had, expecially with a fresh set of clutch packs. The overheating has nothing to do with the strength or capability of the 7.5; the issue is the oil capacity which is less than half of that of an 8.8. V8 builders back in the day (When Fords ruled and Rover V8 builders were the minority group amoung us) ran into this issue as well and would run 6' long tubes on the diff breathers to handle it. Some even had catch cans hooked up in the trunk to keep the boil over off the road.
I'm banking on the relatively friction-less mechanism of the TrueTrack to be substantially cooler running than the TractionLoc's clutch packs. The research I'vd done as well as my rear end guy's experience shows I should be ok.
The funny thing is quite a few people have been fine with the 7.5/TractionLoc combo, even on the track. One customer of ours road raced his for four years without a drop boiling over. The only reason for this I can fathom is that his clutch packs were actually worn to the point where they were not creating the heat mine were. On a side note, my rear end guy checked how much life was left in the old unit when he took it out. It was only operating at 30% or so.
-Jason
I'm banking on the relatively friction-less mechanism of the TrueTrack to be substantially cooler running than the TractionLoc's clutch packs. The research I'vd done as well as my rear end guy's experience shows I should be ok.
The funny thing is quite a few people have been fine with the 7.5/TractionLoc combo, even on the track. One customer of ours road raced his for four years without a drop boiling over. The only reason for this I can fathom is that his clutch packs were actually worn to the point where they were not creating the heat mine were. On a side note, my rear end guy checked how much life was left in the old unit when he took it out. It was only operating at 30% or so.
-Jason
01-02-2016, 12:22 PM
#30
V8 Miata Follower
Thread Starter
The 7.5 will be fine. That is what I am using. The vast parts selection is the only thing that makes the 8.8 appealing to me. It also has a larger fluid capacity which could be beneficial on a road raced car.
The lack of traction will be the weak link followed by the axles. Remember that everything has a weak point.
What special voodoo are you going to use to get to that 500-550whp? Or even to that 400whp?
The lack of traction will be the weak link followed by the axles. Remember that everything has a weak point.
What special voodoo are you going to use to get to that 500-550whp? Or even to that 400whp?
Well, voodoo has been applied
With the A trim it made 420/420 at 8lbs. Dyno'd it again this week with the S trim at 11 lbs and it made considerably more.....
I've been playing with it on the street and it
Lays the power down VERY well with a couple little tricks......
So far so good on the 7.5 rear........fingers crossed....
The following users liked this post:
V8droptop (02-20-2016)
01-03-2016, 07:05 AM
#31
V8 Miata Fanatic
I do think that a 7.5 is fine for any Ford V8 Miata. However, keep in mind that if you are going to push it hard with the TractionLoc you may run into the same overheating issues I had, expecially with a fresh set of clutch packs. The overheating has nothing to do with the strength or capability of the 7.5; the issue is the oil capacity which is less than half of that of an 8.8. V8 builders back in the day (When Fords ruled and Rover V8 builders were the minority group amoung us) ran into this issue as well and would run 6' long tubes on the diff breathers to handle it. Some even had catch cans hooked up in the trunk to keep the boil over off the road.
I'm banking on the relatively friction-less mechanism of the TrueTrack to be substantially cooler running than the TractionLoc's clutch packs. The research I'vd done as well as my rear end guy's experience shows I should be ok.
The funny thing is quite a few people have been fine with the 7.5/TractionLoc combo, even on the track. One customer of ours road raced his for four years without a drop boiling over. The only reason for this I can fathom is that his clutch packs were actually worn to the point where they were not creating the heat mine were. On a side note, my rear end guy checked how much life was left in the old unit when he took it out. It was only operating at 30% or so.
-Jason
I'm banking on the relatively friction-less mechanism of the TrueTrack to be substantially cooler running than the TractionLoc's clutch packs. The research I'vd done as well as my rear end guy's experience shows I should be ok.
The funny thing is quite a few people have been fine with the 7.5/TractionLoc combo, even on the track. One customer of ours road raced his for four years without a drop boiling over. The only reason for this I can fathom is that his clutch packs were actually worn to the point where they were not creating the heat mine were. On a side note, my rear end guy checked how much life was left in the old unit when he took it out. It was only operating at 30% or so.
-Jason
02-18-2016, 08:13 AM
#32
V8 Miata Follower
Thread Starter
Update.....
2 months of driving the car hard at between 400-460 rwhp. The 7.5 rear end and axles are holding up fine.
I did develop a vibration that was pretty nasty over ~70-75mph.
Just like papa bear said was likely to happen.....U Joint had begun to fail!
I don't know how old the u-joints were that were in it......I replaced the U-joints with new non-serviceable units and had the driveshaft balanced and problem solved!
2 months of driving the car hard at between 400-460 rwhp. The 7.5 rear end and axles are holding up fine.
I did develop a vibration that was pretty nasty over ~70-75mph.
Just like papa bear said was likely to happen.....U Joint had begun to fail!
I don't know how old the u-joints were that were in it......I replaced the U-joints with new non-serviceable units and had the driveshaft balanced and problem solved!
02-21-2016, 02:12 PM
#34
V8 Miata Follower
Thread Starter
I've been an avid drag racer for many years and have learned the weak links in the fox body drivetrain up to 1000whp. I'm having to learn the ropes in the IRS rears......so far, I'm relatively impressed with the little 7.5.
Thread
Thread Starter
Forum
Replies
Last Post
jwmezzanotte
V8 Miata Wiring, Electrical, and ECUs
3
07-29-2010 06:54 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
