I've seen that the 88 caliper torque is 74 ft/lbs and for the bridge bolts also. Is this really a mis-print from the GM shop manual?? I seen also for the front wheel bearing hubs the 3 torx bolts are speced at 220 ft/lbs. That's unreal. (If we compare the 3 rear mounting bearing hub bolts they are speced at 62 ft/lbs. I guess the front will be sufficent same as the rear...?)

Also the 88 shop manual states that the caliper mount bolts are 35ft/lbs. They got 2 different torque values listed for the same part.

Finally should these caliper be torque at both 35ft/lbs for the mounting bolts and bridge bolts??

Thanks for any input...

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. All original.

The bolts that run from the caliper to the knuckle need to be reef'd on, and possibly some loctite as well. I usually give 100ftlbs to those bolts.

The wheel bearing bolts would probably be closer to 35ft/lbs.

Per the GM/Helm factory Service Manual, 74 ft-lb (dry) is correct for the '88 caliper attach bolts and bridge bolts (Ref p. 5F-1). Just "reefing" on them is not recommended; always use a torque wrench.

220 ft-lb for the hub attach bolts is wrong ... a well-known error. (200 ft-lb is correct for the much larger rear axle nut.) The correct front-hub-to-knuckle torque is probably 62 ft-lb (dry) ... which is the value specified in the FSM for the identical-spec rear hub attach bolts (Ref p. 3D-3).

When in doubt, always verify that the torque specified in the FSM is within the normal limits for bolt size, grade, and lubrication using one of the many reference charts available. Note that these torque values assume clean threads, that there is a significant difference in torque between dry and lubricated threads, and that thread locker usually acts as a lubricant during fastener tightening.

[This message has been edited by Marvin McInnis (edited 11-30-2010).]

I would use loctite on the caliper to knuckle bolts - I have seen these loosen and back out after being properly torqued to 74ftlbs. They have blue locktite from the factory. Not sure about the bolts for the saddle? 74 seems high to me as it is threaded into aluminum? I do not have a FSM handy at the moment.

Pat

quote Originally posted by katatak: I would use loctite on the caliper to knuckle bolts - I have seen these loosen and back out after being properly torqued to 74ftlbs. They have blue locktite from the factory. Not sure about the bolts for the saddle? 74 seems high to me as it is threaded into aluminum?

1) I have personally seen several '88 caliper attach bolts that have backed out, but I have never seen one back out after it had been properly torqued to 74 ft-lb. I agree that blue thread locker is probably a good idea in any event. (New GM caliper attach bolts are packaged with thread locker already applied.)

2) The '88 bridge bolts thread into the cast iron bridge, not into aluminum.

3) You will find the specified torque values on the FSM pages I cited earlier.

[This message has been edited by Marvin McInnis (edited 11-30-2010).]

The Haynes book says 40 ft lbs on the caliper bolts .

quote Originally posted by Dgzfiero: The Haynes book says 40 ft lbs on the caliper bolts .

INCORRECT FOR '88s!!! The FSM does indeed specify "38 ft-lb" (front) and "30 to 45 ft-lb" (rear) for earlier year caliper attach bolts, but we are discussing '88s here. Wrong information can injure people! 74 ft-lb is the correct torque value for '88 bridge bolts and caliper attach bolts.

[This message has been edited by Marvin McInnis (edited 11-30-2010).]

Was looking in the wrong part of the book. I gotta redo mine now. Thanks for pointing it out.

[This message has been edited by Dgzfiero (edited 11-30-2010).]

Maybe that (insufficient torque) is how some '88 calipers come loose.

Thanks Marvin and Pat !!

It's a little late now, but you don't have to remove the calipers to change the pads on an '88. There are two ways I know of to replace the pads on an '88 ... remove the roll pins or remove the bridge ... and neither requires removing the caliper. Of course, you do have to remove the caliper to lubricate the slider pins if needed.

[This message has been edited by Marvin McInnis (edited 12-02-2010).]

quote Originally posted by Marvin McInnis: It's a little late now, but you don't have to remove the calipers to change the pads on an '88. There are two ways I know of to replace the pads on an '88 ... remove the roll pins or remove the bridge ... and neither requires removing the caliper. Of course, you do have to remove the caliper to lubricate the slider pins if needed.

If needed? I find that my slider pins need greasing about twice as often as my pads need replacing. I've never done a brake job without finding that the slider pins are dry, and I grease them every time. I don't even consider NOT greasing the pins when doing a brake job. It's like replacing the o-ring after removing the distributor. It's a no-brainer now.

Hmmmm. As long as the rubber seals remain intact, the '88 slider pins shouldn't need to be relubricated very often. I check mine when replacing pads, of course, but I have had to lube them only once (plus during caliper rebuilds) since I bought the car.

quote Originally posted by Marvin McInnis: Hmmmm. As long as the rubber seals remain intact, the '88 slider pins shouldn't need to be relubricated very often. I check mine when replacing pads, of course, but I have had to lube them only once (plus during caliper rebuilds) since I bought the car.

Hmmmm, again. Maybe it was the grease I was using. I had some of those ketchup packets of disk brake grease from AutoZone or Advance Auto. I ran out, so I had to get some more on my last brake job, and I wound up with something different. Also, this time I didn't use just enough to grease all the sliding surfaces. I filled the rubber seals about 50-75%. Hopefully, it will last longer this time.

quote Originally posted by Marvin McInnis: 1) I have personally seen several '88 caliper attach bolts that have backed out, but I have never seen one back out after it had been properly torqued to 74 ft-lb. I agree that blue thread locker is probably a good idea in any event. (New GM caliper attach bolts are packaged with thread locker already applied.) 2) The '88 bridge bolts thread into the cast iron bridge, not into aluminum. 3) You will find the specified torque values on the FSM pages I cited earlier.

Not to argue with you Marvin but both my 88's have aluminum calipers - piston half and bridge half. Myabe I have some Uber rare racing calipers

quote Originally posted by katatak: Myabe I have some Uber rare racing calipers

You must. I just went out into the shop and used a magnet to check four spare OEM '88 calipers (2 front, 2 rear). The caliper bodies were all aluminum, as expected, but the bridges were all iron. You might want to double-check yours and see what you have.

quote Originally posted by katatak: ... both my 88's have aluminum calipers - piston half and bridge half. Myabe I have some Uber rare racing calipers

I'd like to see those too!

quote Originally posted by Marvin McInnis: Hmmmm. As long as the rubber seals remain intact, the '88 slider pins shouldn't need to be relubricated very often. I check mine when replacing pads, of course, but I have had to lube them only once (plus during caliper rebuilds) since I bought the car.

Well dude I find that the sliders need to be done at least twice a year on my car. Good luck with the boots. I have some of those POS boots from The Fiero Store. They are incorrect in several dimensions and the rubber is stiffer than the factory. I have found a source for the correct boots, but I havent got the $$ to purchase a case of 2000. Dont forget to lube the brake pad sliders also. I use blue locktite on the caliper bolts, and the slider bolts and yes it is 74ft lbs.

Caliper bolts...
Yeah. I've heard many occasions of them backing out. Wiped out one of Jazzman's wheels and shattered a rotor when it happened to him.

I just tighten the hell out of them with a 14" ratchet.
I always use blue loctite. If I'm out of loctite, I will wait until I have some.

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Raydar
88 4.9 Formula IMSA Fastback

Read Nealz Nuze! Praise the Lowered!

quote Originally posted by solotwo: Well dude I find that the sliders need to be done at least twice a year on my car. Good luck with the boots. I have some of those POS boots from The Fiero Store. They are incorrect in several dimensions and the rubber is stiffer than the factory. I have found a source for the correct boots, but I havent got the $$ to purchase a case of 2000. Dont forget to lube the brake pad sliders also. I use blue locktite on the caliper bolts, and the slider bolts and yes it is 74ft lbs.

It funny that these 88 slider boots aren't available anywhere's. Just TFS seems to have them, but like you mentioned and others too in the past; there crap.

If suppliers are rebuilding these 88 specific calipers, I wonder where their getting the boots...?

[This message has been edited by fierogt28 (edited 12-04-2010).]

So, what's the consensus? 74 ft-lbs for the bridge bolts AND the caliper bolts? That seems high for the caliper bolts. I don't remember what the FSM calls for (which is what I use), but I've never used that much torque on them, and I've never had one back out.

quote Originally posted by solotwo: I have found a source for the correct boots, but I havent got the $$ to purchase a case of 2000.

What do they want for a case of 2000? Like you, I don't want 2000, but I'd be interested in 20 or so.

quote Originally posted by Formula Owner: So, what's the consensus?

Consensus? This isn't a new field of research or an opinion poll. You go right ahead and use your favorite among the guesses offered. Me? I'll just continue to use the value specified by the manufacturer and verified using standard reference tables.

[This message has been edited by Marvin McInnis (edited 12-07-2010).]

quote Originally posted by Marvin McInnis: Consensus? This isn't a new field of research or an opinion poll. You go right ahead and use your favorite among the guesses offered. Me? I'll just continue to use the value specified by the manufacturer.

Well, there's some disagreement over whether the "value specified by the manufacturer" is accurate. I HAVE been using the torques specified in my Helms manual, but I'll stop doing that if they're wrong.

quote Originally posted by Formula Owner: Well, there's some disagreement over whether the "value specified by the manufacturer" is accurate. I HAVE been using the torques specified in my Helms manual, but I'll stop doing that if they're wrong.

Yeah, and that's my question too. The 86GT calipers are spec'ed at 35 ft/lbs, but the 88 models are spec'ed at 74ft/lbs. Unless due to the fact the 88 had / has a better suspension set-up GM "upped" the tightness for a higher torque for the improved suspension. Is this the case??

Comments welcomed...

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. All original.

The '88 brakes are totally different than earlier years, including the way the calipers attach to the knuckles. Different design => different loads => different bolt size => different torque.

quote Originally posted by Marvin McInnis: The '88 brakes are totally different than earlier years, including the way the calipers attach to the knuckles. Different design => different loads => different bolt size => different torque.

Just as I thought....thanks for the quick detailed "to the point" discription...

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fierogt28

88 GT, Loaded, 5-speed.
88 GT, 5-speed. All original.