Hey! New here, have a few questions. Okay, a LOT of questions...
I have a bone stock 1975 Monza CA 350. Right now the rear axle is the typical 7.5" 4 lug 2.29 open diff.
I'm going to be building it up to street/strip, converting to 5x4.75 using Aerospace rear disks and S10 spec Moser axles, but there's a few things I want to be sure of before I pull the trigger.
The car is going to be a built 350 and eventually get a stock LS1 as its end-game motor so it won’t need to hold more than that, at least on this axle
So, right now my parts list is:
Quick Performance package set (4.11 gears, Truetrac posi, 28 spline, solid pinion spacer, 1981 and Older 7.5)
https://www.quickperformance.com/GM-75- ... 22625.html
Moser A102807 S10 28 spline C clip
https://www.moserengineering.com/a10280 ... 0-2wd.item
Aerospace Rear Drag Brake kit (with lines and master cylinder)
https://shop.aerospacecomponents.com/re ... 1-1-1.aspx
misc rebuild parts (anyone know a good kit for these?)
Questions:
1) I have $1000ish set aside for all the setup and machine work, is it recommended to machine the housing for an S10 bearing instead of the conversion bearing (and what's the real part number for the conversion bearing? all my usual sources are way out of date)
2) Will it hold the 400 MAX HP with 4.11s on the street and occasional strip with an automatic? I've seen both. Will be on 235 radials, but probably sitting closer to 300hp (leaving headroom)
3) Any recommended tricks for building? I.e. I've heard 4.11s over 4.10s because the 7.5 pinion is tiny and the H body has a different spline count? Stuff like that that you wouldn't know from googling.
The budget is currently $3,000 including the 1k setup, is that doable nowadays?
Am I forgetting anything? Please link me if so.
1975-Specific 7.5 5 lug swap questions
Re: 1975-Specific 7.5 5 lug swap questions
Well strip is where you will be at a disadvantage... WHAT are you expecting to do? How often?
The build: 4.10 is better than 4.11 as even GM has realized that as they do not use that ratio anymore.
4.11 is 9 - 37
4.10 is 10 and 41
MORE teeth give you more touch point and bleed the heat off better so 4.10 will be stronger on paper than the 4.11... I say this because if you buy an inferior gear set. which in a kit like that you do not know what the heck brand your getting....
Next- machining the housing --- so who will be doing this work? That sounds like a major deal. We just machine the pinion shaft to fit the stock bearings. which will be more cost effective...as the 7.5 rear is only going to hold so much torque so I think your splitting hairs with that machine work.
You definitely DO NOT want to do the bearing trick...we agree there. (pain in the butt and never seems to shim good in the long ring plus surface area of the bearing is way smaller than stock s10 or monza / H body bearing to race surface area.
Rear brakes - Disc brakes are a trick- I know nothing of the AERO space disc brakes - Mainly because we just try to stay away from brake jobs all together these days.
They cost us more time and headache as these companies just can not get the boxed up parts right these days.
The fitment on a H body for disc brakes really requires a shallow offset and you risk having the caliper rub the inner fender wheel ...which is also the frame on a h body so you can not just cut or relieve that area.
Axles : we make a exact correct length Moser axle shaft for the h body through moser so the seal does not ride up the radius of the shorter s10 axle shaft. 26 3/4" is the s10 axle and the H body is 26 7/8" Does not SEEM like much but it can cause headaches after you find out the carrier is not quit centerd from your gear set up and install... so one axle will be slightly tighter distance than the other ....
ALL this info is from Years of doing this set-up build. Our hardest thing now is just FINDING a monza / vega rear end to build and or scavenge the brackets from.
Daughters street monza launching at the track with street tires and 2.56 gears boat motor 350 V8 from summit budget table long block...lol 14.50... she loves bracket racing it...she kills the lights with it and it makes most made because it is slow and consistent....XD
Both daughters were Jr Dragsters for Years... so they eat the lights up.
Daughters Chassis old school bracket car 9.60 at 3/4 throttle 140 mph Will see when she can go full throttle.... no rush there. she is 20 years old.
My Race car - 9.95 136mph 1/4 mile 1.300 60 foot which was my daily driver years ago turned into race car after it started to deteriorate on the lower rear suspension. 8 point cage so I am at my limit....
NONE of these cars are cream puffs...But we like them a lot they are fun and get the job done.
The build: 4.10 is better than 4.11 as even GM has realized that as they do not use that ratio anymore.
4.11 is 9 - 37
4.10 is 10 and 41
MORE teeth give you more touch point and bleed the heat off better so 4.10 will be stronger on paper than the 4.11... I say this because if you buy an inferior gear set. which in a kit like that you do not know what the heck brand your getting....
Next- machining the housing --- so who will be doing this work? That sounds like a major deal. We just machine the pinion shaft to fit the stock bearings. which will be more cost effective...as the 7.5 rear is only going to hold so much torque so I think your splitting hairs with that machine work.
You definitely DO NOT want to do the bearing trick...we agree there. (pain in the butt and never seems to shim good in the long ring plus surface area of the bearing is way smaller than stock s10 or monza / H body bearing to race surface area.
Rear brakes - Disc brakes are a trick- I know nothing of the AERO space disc brakes - Mainly because we just try to stay away from brake jobs all together these days.
They cost us more time and headache as these companies just can not get the boxed up parts right these days.
The fitment on a H body for disc brakes really requires a shallow offset and you risk having the caliper rub the inner fender wheel ...which is also the frame on a h body so you can not just cut or relieve that area.
Axles : we make a exact correct length Moser axle shaft for the h body through moser so the seal does not ride up the radius of the shorter s10 axle shaft. 26 3/4" is the s10 axle and the H body is 26 7/8" Does not SEEM like much but it can cause headaches after you find out the carrier is not quit centerd from your gear set up and install... so one axle will be slightly tighter distance than the other ....
ALL this info is from Years of doing this set-up build. Our hardest thing now is just FINDING a monza / vega rear end to build and or scavenge the brackets from.
Daughters street monza launching at the track with street tires and 2.56 gears boat motor 350 V8 from summit budget table long block...lol 14.50... she loves bracket racing it...she kills the lights with it and it makes most made because it is slow and consistent....XD
Both daughters were Jr Dragsters for Years... so they eat the lights up.
Daughters Chassis old school bracket car 9.60 at 3/4 throttle 140 mph Will see when she can go full throttle.... no rush there.
she is 20 years old. My Race car - 9.95 136mph 1/4 mile 1.300 60 foot which was my daily driver years ago turned into race car after it started to deteriorate on the lower rear suspension. 8 point cage so I am at my limit....
NONE of these cars are cream puffs...But we like them a lot they are fun and get the job done.
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J D Race
Re: 1975-Specific 7.5 5 lug swap questions
Moser axles on Ebay -
By the way everything at MOSER just increased in price AGAIN this year.
comes with new metric studs like s10
https://www.ebay.com/itm/265827869700
By the way everything at MOSER just increased in price AGAIN this year.
comes with new metric studs like s10
https://www.ebay.com/itm/265827869700
J D Race
Re: 1975-Specific 7.5 5 lug swap questions
Awesome thank you!
Shows how much I know, getting the 4.11/10 and thinking it was the housing not the pinion being machined. It's fun trying to piece together 20 year old FAQs and facebook posts from private groups lol.
Definitely going to go with the correct length axles, most of the S10 swap apparently needs the 76+ brakes which makes no sense to do (S10 is supposed to be the cheap swap so buying newer 70s brakes makes it more expensive)
It's going to be a professional gear setup and a garage brake install so brakes will be a Me problem, (un)fortunately.
The plan for the car is built 350/stock 5.3 for now, 4l60, and 235s. I don't fit in the car with a cage which limits my time, and a friend has a similar weight car that runs 11s on a 3.73 but desperately needs 4.10s. Same combo, too, so it should be pretty similar when my car is done. It's definitely going to need the overdrive, because I like 80mph freeways and not being at 4000+ rpm (the 2.29s are great for that with the 3spd). I'm going to be driving it more than racing it, but this combo seems to be a solid move for a street car, similar to a 4th gen Camaro
Shows how much I know, getting the 4.11/10 and thinking it was the housing not the pinion being machined. It's fun trying to piece together 20 year old FAQs and facebook posts from private groups lol.
Definitely going to go with the correct length axles, most of the S10 swap apparently needs the 76+ brakes which makes no sense to do (S10 is supposed to be the cheap swap so buying newer 70s brakes makes it more expensive)
It's going to be a professional gear setup and a garage brake install so brakes will be a Me problem, (un)fortunately.
The plan for the car is built 350/stock 5.3 for now, 4l60, and 235s. I don't fit in the car with a cage which limits my time, and a friend has a similar weight car that runs 11s on a 3.73 but desperately needs 4.10s. Same combo, too, so it should be pretty similar when my car is done. It's definitely going to need the overdrive, because I like 80mph freeways and not being at 4000+ rpm (the 2.29s are great for that with the 3spd). I'm going to be driving it more than racing it, but this combo seems to be a solid move for a street car, similar to a 4th gen Camaro
Re: 1975-Specific 7.5 5 lug swap questions
Gears, My race car is only 3.73 gears and run those numbers.. and pull the fronts.... BUT REMEMBER...my car is a RACE car ONLY. Does not go on the street.
BRAKES- think your a little mixed up on that stuff too.
THe BACKING PLATES must be used from 1977 - 1980 9.5x2 drum system
the 75 76 did have 9.5 x 2 but you likely needed a bigger motor to likely get that rear drum brake size.
normal 75 76 is 9 x 1.5" drum internal diameter and shoes width.
All the 9.5 x 2 drum parts are the same as all GM drum brakes. camaro, chevelle s10 95-2004 (wheel cylinders are the difference)
monza uses a smaller ID wheel cylinder like 7/8 or something.
I still run rear drums 9.5 x 2 with a 9.95 car and s10 front disc brakes. No issues...And I use the Aluminum drums as they are lighter than even the wilwood thin drag race rotors. Cutting the reciprocating mass is what snaps the car out of the hole.
BRAKES- think your a little mixed up on that stuff too.
THe BACKING PLATES must be used from 1977 - 1980 9.5x2 drum system
the 75 76 did have 9.5 x 2 but you likely needed a bigger motor to likely get that rear drum brake size.
normal 75 76 is 9 x 1.5" drum internal diameter and shoes width.
All the 9.5 x 2 drum parts are the same as all GM drum brakes. camaro, chevelle s10 95-2004 (wheel cylinders are the difference)
monza uses a smaller ID wheel cylinder like 7/8 or something.
I still run rear drums 9.5 x 2 with a 9.95 car and s10 front disc brakes. No issues...And I use the Aluminum drums as they are lighter than even the wilwood thin drag race rotors. Cutting the reciprocating mass is what snaps the car out of the hole.
J D Race
Re: 1975-Specific 7.5 5 lug swap questions
Ah, I think I'm getting it now. So, for the rear brakes: 76+ backing plate and Monza wheel cylinder with any junkyard S10 95-04 for the rest of the parts? That seems like it would be easy.
While I'm here, do you have any recommendations for where to reinforce first? The car is totally stock/rust free and I'd really like to keep it un-twisted.
While I'm here, do you have any recommendations for where to reinforce first? The car is totally stock/rust free and I'd really like to keep it un-twisted.
Re: 1975-Specific 7.5 5 lug swap questions
wELL A CAGE IS THE BEST WAY TO KEEP IT FROM TWISTING. the CAR SHOULD NOT TWIST IF YOU ARE STREET BouND.
My kid races hers ...BUT it is 2.56 gears with a V8 270hp Boat motor from the summit racing scratch and dent table...LOL. Really it was a 500.00 long block sbc motor. 14.50 et 1/4 mile with 2.56 gearing street tires. 350th trands, 7.5 rear with 28 spline axles and camaro torsen 2 series posi unit.
Drums in the back are Aluminum from a GN / Formula .... they had the aluminum rear drums as an option. They are light... I also use them on my race car too 9.90 car.
My kid races hers ...BUT it is 2.56 gears with a V8 270hp Boat motor from the summit racing scratch and dent table...LOL. Really it was a 500.00 long block sbc motor. 14.50 et 1/4 mile with 2.56 gearing street tires. 350th trands, 7.5 rear with 28 spline axles and camaro torsen 2 series posi unit.
Drums in the back are Aluminum from a GN / Formula .... they had the aluminum rear drums as an option. They are light... I also use them on my race car too 9.90 car.
J D Race