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Topic: Help! 7.5" Axle to 8.8" Trouble! (Read 56640 times) previous topic - next topic

Help! 7.5" Axle to 8.8" Trouble!

I have a 8.8" Rear End from a 88 TurboCoupe and want to put it in my 88 Cougar which has a 7.5".  I want to keep my rear drum brakes, and accoding to the 8.8 TurboCoupe paragraph on Cool Cats  it can be done by swapping the 7.5" axle into the 8.8" rear.

Has anyone ever really done this before? I have two problems:

1) The 7.5" Axle does not go in enough leaving a much larger gap for the drum brake shell plate from where the wheel stud plate is.

2) There is a bracket that has to be cut for the rear drum plate to sit flush against the mount.  Hate to do this because maybe I will do rear disks some day...

See the Pictures:






V6->V8HO 88 LS
5.0L V8 87 XR7

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #1
I kind of did this swap about a year ago and maintained the disk brakes but I used aftermarket mustang axles.  I think the mustang axles are the same length as the cougar with drum brakes but I may be wrong.  The reason I did this because I switched to a truck posi with 31 spline and mustang axles are easier to get then to custom make the t-bird ones.

I had to cut the mounting bracket for the disk brakes and mount it behind the puppies.  Had to be ajusted slightly with washers to center it.  I cut the other bracket you wanted to cut and welded them so they were shorter.  you may be able just to leave them off but the factory had them there so I left them there also.  I did not use the dust sheild.

Don't know why your axles are too short?

See some pictures here, I hopes this helps.
http://www.msnusers.com/CadTBird/shoebox.msnw?Page=5

Good luck.
TED


Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #3
I believe the only solution for the bracket is to bend or cut it....

For the axles you can get some NAPA axle saver bearings(they are longer and extend outside the housing). This is what Ronnie(chrome302jr)did...

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #4
Thanks for all the info, its obvious its not a simple substitution :disappoin .  That was a good past thread I missed on this.

It looks like the drum axle from the 7.5" rear needs to be at least 1/2 inch shorter to fit into the 8.8" rear to get the drum stuff to align right, just like Chrome302jr said.  Chrome, if you are out there, how difficult was it to make it work?

So I have to ponder the options of:

1) Give up the 8.8" rear (along with ability to add quad shocks, and have a 3.55 gear with traction lok) and just keep the stock 7.5"

2) Update the 3.08 7.5" rear with a traction-lok differential (I may know where to find one  ;)

3) Do the disk conversion..

4) Figure out if I have the skill to use spacers, axle saver, etc. to make the 7.5" axle work in the 8.8" like Chrome did..

Thanks All!






To make it work, I guess something like this is needed:


V6->V8HO 88 LS
5.0L V8 87 XR7

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #5
Mustang rears are 3/4" per side shorter than t-bird rears and therein lies your problem.
Just use the stock mustang drums.

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #6
Quote from: dominator
Mustang rears are 3/4" per side shorter than t-bird rears and therein lies your problem.
Just use the stock mustang drums.


He has a Turbo Coupe 8.8(same as Ronnie). The 8.8 TC housings are appearntly the same as a 8.8 Stang....

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #7
Hey man, sorry I didnt see this earlier. Im glad someone else experienced the same problem I did. As Tom said I used NAPA axle saver bearings, which placed the bearing surface and seal further out on the axles. This works for me and Ive ran it this way for over 3yrs. BUT, this method does not line up the drums perfectly on the brake shoes, it is about 1/8 still too far out, which has not presented a problem for me. Do you have the 8.8 axles?? Measure them if you do. Then measure the 7.5 axles. Id like to get some numbers on both. What I plan to do is order some Moser axles for a TC eventually. Thanks for posting pics to let folks know exactly the problem you ran into. Also I bent the TC disc brake bracket out of the way, and bolted on the drum brake assembly with my own bolts. The hardest part of installing the NAPA bearings is removing them with a slide hammer, after that its a simple matter of tapping them in. If your capable of the step required to remove the axles, and putting up with the horendous smell of gear lube, then you'll be fine. Let me know if you have any more questions. I cant reply on my hotmail account for the next week or so, so reply on here. Good luck.

Ronnie
1988 Tbird Stock bottom end 306, Windsor Jr's, Explorer intake, 125 shot.
Best ET: 12.11 Best MPH: 113.8 1/4 mile

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #8
JeremyB: I noticed the dimensional chart you had in the earlier post is all for drum brake vehicles.  Do you also have a copy of the dimensional chart for the 8.8" and 7.5" Disk Brake configuration?

Here is what I found out:

The 88 TurboCoup 8.8" rear disk brake axle and 88 Cougar LS 7.5" rear axle are the same lengths, but the total length of each rear from tube-end to tube-end is different.  Shorter on the TurboCoup in order to allow space for the ABS gear and rotors I guess.


TurboCoup 8.8" rear with disks

Axle Length 29.5"  (from end of spine side of shaft to the inside of the wheel stud plate)

Rear End length 56"

Length of center pumpkin 16.5"

Cougar 7.5" Rear with drums

Axle Length 29.5"  (from end of spine side of shaft to the inside of the wheel stud plate)

Rear End length 57 9/16"

Length of center pumpkin 16.5"




V6->V8HO 88 LS
5.0L V8 87 XR7

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #9
Ok then, that confirms it. The 8.8 rear IS narrower than the 7.5 rear end. So, who on here has aftermarket axles in a TC 8.8 WITH drum brakes. Would Moser be able to make them?
1988 Tbird Stock bottom end 306, Windsor Jr's, Explorer intake, 125 shot.
Best ET: 12.11 Best MPH: 113.8 1/4 mile

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #10
Do you think the stock Mustang axles would work with the T-bird/Cougar drum brakes?  If not I bit the stock Mustang brakes would work just fine.

TED

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #11
I have used a mustang 8.8 with the cougar 10" drum bakes with out any problems. I have just done this in May.

As it has been said, the mustang rear and axles (3/4" shorter per side) than the cougar/t-bird rear & axles. I don't have any dimensions at the current time to compare the turbo coupe rear to the mustang rear.
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02 Explorer XLT 4.0L
04 F150 FX4 Supercrew 5.4L
02 Saturn SL1 1.9L
09 Vstar 950 Tourer

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #12
Quote from: bondocougar
JeremyB: I noticed the dimensional chart you had in the earlier post is all for drum brake vehicles.  Do you also have a copy of the dimensional chart for the 8.8" and 7.5" Disk Brake configuration?

No. The disc version doesn't change any signification dimensions though.

I thought we'd gone through most of this discussion here. I'm more knowledgeable now than when I started the thread. ALL Fox/SN95(up to 1998) Mustangs, Mark VIIs, and 1983-85.5 Tbird/Cougars use the same width housing. The puppies of the bunch is the 1985.5-87 Tbird/Cougar, whose puppies-puppies width is 1.5" wider. The only thing that confuses me is that the drum offset is different between the earlier and later Tbird axles. One would think that wider axles + wider housing = same drum, but it doesn't.


The earlier axles have a bit of an offset.-----------The later drums have almost no offset.
-----


This suggests that the housing puppies-to-axle puppies dimension changed.

I put on a late model drum when Advance Auto accidentally gave me one while changing drums on my '85 (narrow width). It left a significant amount of drum shoe showing.

On edit:
I reckon the backing plate could have changed.

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #13
I think getting some 8.8 TC specific length axles minus the disc brake hardware on the axle would work. Im going to call Moser up to see what length they have specified for TC axles compared to the 56in measured.
1988 Tbird Stock bottom end 306, Windsor Jr's, Explorer intake, 125 shot.
Best ET: 12.11 Best MPH: 113.8 1/4 mile

Re: Help! 7.5" Axle to 8.8" Trouble!

Reply #14
I called up moser and the guy was pretty familiar with the difference between disc brake and drum difference in axle lengths. He said it would be roughly 1/2in difference, which is what I expected. But in order to get the right axles made, he needs both 7.5 and 8.8 axle lengths as well as both rear end housing-housing lengths. Ive got one source here that both 7.5 and 8.8 axles are the same length, any more sources? He claims the axles are 29 3/16in long. I need to get some exact specs on rear end lengths now. Keep ya'll posted.
1988 Tbird Stock bottom end 306, Windsor Jr's, Explorer intake, 125 shot.
Best ET: 12.11 Best MPH: 113.8 1/4 mile