[Bob Timmermans]

Hi Guy's ,

I've been searching this forum for a parts 'recipe' on a 12 bolt I want to build for my car.
It gets somewhat confusing and I don't want to end up ordering the wrong parts.

I'll have to ship these parts to The Netherlands (kinda expensive) and I'd like to do this in one go.
What I want to end up with is a 12 bolt passenger axle with 3.31:1 gears , limited slip diff (3 series) , 1350 yokes and rear disc brakes.

I have the 12 bolt passenger axle , the parts I'd like to order from Summit.

If anybody could give me some advice on this it would surely be appreciated.

Thanks , Bob.

[Skip Fix]

Tom's Differentials has a whole lot of parts for really good prices but not sure how many are still there since he passed away and family running it now.

[Formulas]

I believe first I would determine what parts in your hands are currently serviceable and suit your intended goals

The 12 bolt gm passenger has a 8.875 size ring gear

Axle width if needed depends on which rear end you actually have and does it match the intended car?

[straycat]

How about joining Chevelle forums. Also check companies like Moser Engineering, Mark Williams, Strange engineering, Denny's Driveshafts to name a couple. Tom's had a good rep. Summit's tech I've read is not what it once was but their service is still good as far as shipping and returns. Jegs?

[Formulajones]

I like to use Quick Performance. Usually 9 times out of 10 better prices when I shop around.

[Bob Timmermans]

Thanks for the replies , I guess i've got a lot to check out.

[leeklm]

I have used and liked Tom's and QP. Did not know Tom passed away. Was on the phone with him quite a bit when rebuilding the 8.5" in the 73 GTO. Was kind of funny, Tom was convinced I did not know what I was talking about (which is not all that unusual for me) when explaining the 73 came with the 8.5" with bolt in axles. Sent me parts for the typical Abody 8.2", which were wrong. After I sent him pictures of the 8.5", he apologized and sent me a couple of Tshirts which was a nice gesture!

Sent from my SM-G965U using Tapatalk

[mrennie]

I called Tom's last year and they were still open selling parts. Just need to call your order in and see if they have what you need.

[crustysarge]

Guys, being overseas presents many challenges those in the States don't have, especially shipping and import taxes. He most likely wants to order from Summit because they (like Rock Auto) are export friendly, consolidate packages to reduce costs and deal with lots of overseas customers. In fact, Summit has some awesome shipping prices with DB Schenker overseas. I shipped a boxed TH400 and two 32x14.5x15 slicks to Frankfurt for $220. you cannot beat that period.

Bob, do you need the carrier or is the stock one OK? Also, do you need axles? Give some details on the car and the rear end you have. Why do you want rear discs? I think a lot guys would agree drums work just fine on the rear and are cheaper.

Another option is Quick Performance. He deals with overseas and supports/sponsors European Drag Racing Union. Here is link to 12 Bolt stuff:

https://www.quickperformance.com/GM-...-12P_c_77.html

[vertigto]

FWIW...I just ordered some stuff from Jegs and they showed up in less than 24 hours with FedEx. No joke...I was amazed.

[242177P]

Originally Posted by vertigto

FWIW...I just ordered some stuff from Jegs and they showed up in less than 24 hours with FedEx. No joke...I was amazed.

Original poster is in Europe.

[Bob Timmermans]

You kinda 'hit the nail on the head' with the Summit explanation.
I've been using them for years now and have no complaints what so ever with their overseas business.

I thought putting on disc brakes will prevent the axle from 'walking' out when a C-clip fails.
The carrier is oke just needs changing from leaf spring to coil.
I'ts going under the GTO .

[FrankieT/A]

Originally Posted by Bob Timmermans

You kinda 'hit the nail on the head' with the Summit explanation.
I've been using them for years now and have no complaints what so ever with their overseas business.

I thought putting on disc brakes will prevent the axle from 'walking' out when a C-clip fails.
The carrier is oke just needs changing from leaf spring to coil.
I'ts going under the GTO .

Not sure what you are saying here...
The carrier is the center section but you mention going from leaf to coil.
If the rear end housing is for leaf it cannot go to coil.
As far as internal parts Summit has everything you need. Believe it or not a lot of internal parts are interchangeable from 10 bolt to 12 bolt.

With that being said what parts are you starting with?
Is your housing for coil? or for leaf? Coil needs the loops cast on top.
Do you need a center section(carrier)?
Do you want to upgrade cap bolts to studs?
Do you want upgraded axles?
To go to 1350 not only will need two yokes you will need driveshaft alteration.
What trans do you have? T400 takes one yoke and 4Spd takes another...

[Bob Timmermans]

This axle is a coil application axle with controlarm provisions , that has been used on a leafspring car.
So I have to correct that .
For the rest it's got a series 4 gear carrier 4.56:1 gears and 1310 yoke.
The 10 bolt 8.2 under my GTO has a 1330 pinion yoke.

Summit only offers 1310 or 1350 for 12 bolts.
I'd rather be safe than sorry , so 1350 it is.

I'm gonna change the driveshaft accordingly.
It's all going to a th400.

[FrankieT/A]

Ok, that clears up a lot.

If it were me i would order these parts:

Eaton limited slip center section, 3 series
You may not find a 3.31 ring and pinion new you might have to go to 3.42 or down to 3.08. 3.31 is a ratio that the factory offered but sometimes hard to find in aftermarket.

Strange pinion yoke and trans yoke.
Strange axles are nice for the money about $250.00
ARP cap studs
Richmond gears
Richmond install kit; comes with bearings, seals, shims, etc.

If you want part numbers from Summit I will be glad provide them but cannot be responsible.

[crustysarge]

Summit sells house brand rear disc brake conversion kit. But if you convert to discs you really need to change proportioning valve and maybe even the master cylinder.

Listen, I am overseas like you but have you thought about just buying a complete rear from somebody like QP and put on a pallet? Sell yours to recoup some of the costs? Go with a Ford 9" and for less than $2k you can have it set up very nice. You will spend at least half of that if not more buying parts and you have to mod the perches on your rear and o the assembly too.. I went this route on my 70 Lemans and am very happy. Rear end fit like factory piece.

https://www.quickperformance.com/9-F...2_p_20386.html

[FrankieT/A]

Originally Posted by crustysarge

Summit sells house brand rear disc brake conversion kit. But if you convert to discs you really need to change proportioning valve and maybe even the master cylinder.

Listen, I am overseas like you but have you thought about just buying a complete rear from somebody like QP and put on a pallet? Sell yours to recoup some of the costs? Go with a Ford 9" and for less than $2k you can have it set up very nice. You will spend at least half of that if not more buying parts and you have to mod the perches on your rear and o the assembly too.. I went this route on my 70 Lemans and am very happy. Rear end fit like factory piece.

https://www.quickperformance.com/9-F...2_p_20386.html

That's another way to go...

[Bob Timmermans]

Originally Posted by FrankieT/A

Ok, that clears up a lot.

If it were me i would order these parts:

Eaton limited slip center section, 3 series
You may not find a 3.31 ring and pinion new you might have to go to 3.42 or down to 3.08. 3.31 is a ratio that the factory offered but sometimes hard to find in aftermarket.

Strange pinion yoke and trans yoke.
Strange axles are nice for the money about $250.00
ARP cap studs
Richmond gears
Richmond install kit; comes with bearings, seals, shims, etc.

If you want part numbers from Summit I will be glad provide them but cannot be responsible.

Thanks for the advice , Eaton and Strange are one my list.
For gears I think I go for US gear , they offer the 3.31.
I'm not decided on the installation kit , a lot of weird reviews all over the place.

[Bob Timmermans]

Originally Posted by crustysarge

Summit sells house brand rear disc brake conversion kit. But if you convert to discs you really need to change proportioning valve and maybe even the master cylinder.

Listen, I am overseas like you but have you thought about just buying a complete rear from somebody like QP and put on a pallet? Sell yours to recoup some of the costs? Go with a Ford 9" and for less than $2k you can have it set up very nice. You will spend at least half of that if not more buying parts and you have to mod the perches on your rear and o the assembly too.. I went this route on my 70 Lemans and am very happy. Rear end fit like factory piece.

https://www.quickperformance.com/9-F...2_p_20386.html

Mmmm . . . did you upgrade some stuff on the order and what was the shipping cost ?

[Formulajones]

Originally Posted by Bob Timmermans

Thanks for the advice , Eaton and Strange are one my list.
For gears I think I go for US gear , they offer the 3.31.
I'm not decided on the installation kit , a lot of weird reviews all over the place.

US Gear is excellent. It's my first choice, and also what the driveline shop up the street from me prefers to use on all their builds and they've been around 50 years..

I just did a 9" a couple weeks ago for a guy. I went with US Gear on the ring and pinion and setup kit. You pay a little more for the setup kit but it came with Timken bearings. I've used various setup kits over the years but it seems fewer of them are coming with Timken now. The last Moser setup kit I used had some weird bearing name I had never heard of, and while that might be okay, I tend to stick to stuff I know works.

There are a lot of different setup kits that come in various states of completeness. I think a lot of people are unaware of what they are ordering and that leads to a lot of strange reviews complaining of not having this or that. You have to pay attention to what it comes with and what you really need before you order. That's why some are priced at $80 and others are $130 and most people go for the cheapest they find thinking it's the same thing. It's not. Just a heads up.