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8.5" 10 bolt in an Astro?

9K views 19 replies 7 participants last post by  doyoulikeithere 
#1 ·
I've seen a few different sources list the larger 8.5" inch rear axle coming in Astros from the factory. Does anyone know which model years/ option packages came with the 8.5"?
 
#2 ·
I think most/all of the Astro/Safari Vans come with the 10 bolt 7.5" rear end with 28 spline axles. Even my old Iroc-z only had the 10 bolt 7.5" posi rear end. Some of the G-body cars had 8.5" rear ends.....all the GN's did for sure.

What kind of plans do you have you need a 8.5" rear end? :layrubber:
 
#3 ·
I originally stumbled across an ebay ad suggesting that certain astros could come from the factory with the 8.5" 10-bolt. Then I checked napaonline and they carry parts for an astro with a 8.5" thru 1998. But who knows, it could just be a ghost in the parts books.

As far as plans- well, just the reliability of a beefier axle. I'm looking to buy a new van as my e250 is getting quite loose in all the wrong places. I'm strongly considering an astro and still want to be able to tow occasionally.
 
#4 ·
Interesting maybe someone will chime in with more knowledge about possible Astro/Safari Vans coming with a 8.5" rear end....... :think:
 
#6 ·
I know this is a little off topic.For me,I will go the Mr_Roboto route Ford 9" with a set of custom axles and a Chevy bolt pattern.

cgi/ib/ikonboard.cgi?act=ST;f=6;t=17717

The other option is Sraker Racing that I spoke to @ the Syr,NY Parts Peddler swap meet which would copy exactly a Astro off-set and mounting points with either a 28 or 31 spline axles,Chevy bolt pattern,nodular center section in a Ford 9".The nice part of this is the ability to easily change the center section for different gear ratios,for sure a greater stronger rear end,and bigger drum or the option of rear disc brakes.All that for only I think $1,250.Not a bad deal for a bolt on Ford 9".
 
#7 ·
Thats not a bad deal at all.....most places will charge you at least $900 for new gears w/clutch style posi, bearings, fluids, and install in your stock rear end. A 9" rear end in a Astro Van.............. :cool:
 
#11 ·
Do you know if you actually got the 9" installed? Or were he's been lately? I have got another 9" out of an old Econoline for $60. It has 31 spline axles, 3.50 gears and a posi. I had some other questions for him that you didn't discuss in his write up.
 
#12 ·
Yes Jim,he did get the 9" installed and has been driving that combo for about three yrs.I know he had a slight accident with his van and was going to slowly repair it.I have caught him on the site from time to time.Try to PM him and he might get back to you.I also know that he used a combo of two different size u-joint in the rear.(one the Ford size and one for the Astro driveshaft.)That the driveshaft didn't need to be shorten at all.The hardest part of a on-the-budget install is having Ford rear wheels and Astro front wheels.Kind of a pain.The overall size was 1/2 wider total.(1/4" per side)The bolt pattern change could be easily handled with a set of custom axles and I have seen them around for about $350.00 for the pair.I'll help with what I know about this swap if you can't get ahold of Mr_Roboto,just post with what you need to know and if I can tell you I will.
 
#13 ·
astro355 said:
Do you know if you actually got the 9" installed? Or were he's been lately? I have got another 9" out of an old Econoline for $60. It has 31 spline axles, 3.50 gears and a posi. I had some other questions for him that you didn't discuss in his write up.
Did you get ahold of him??.Man,grab the $60 dollar deal.
 
#14 ·
I read through the RPO's in both my '95 and '99 service manuals, neither list an 8.5" as an option. Just the 3 available gear ratios and the G80 posi unit
 
#15 ·
Gary said:
Yes Jim,he did get the 9" installed and has been driving that combo for about three yrs.I know he had a slight accident with his van and was going to slowly repair it.I have caught him on the site from time to time.Try to PM him and he might get back to you.I also know that he used a combo of two different size u-joint in the rear.(one the Ford size and one for the Astro driveshaft.)That the driveshaft didn't need to be shorten at all.The hardest part of a on-the-budget install is having Ford rear wheels and Astro front wheels.Kind of a pain.The overall size was 1/2 wider total.(1/4" per side)The bolt pattern change could be easily handled with a set of custom axles and I have seen them around for about $350.00 for the pair.I'll help with what I know about this swap if you can't get ahold of Mr_Roboto,just post with what you need to know and if I can tell you I will.
I did get that rear end. I just had the axles redrilled so they will also have a 5 x 5 bolt pattern. Its good to hear about the driveshaft, that makes it easier.
 
#16 ·
You got the "right" rear end for the swap, the Econoline has the proper offset to work with our vans. $750 included 1 tire, a $200 set of leaf springs (I went to steel you may be able to keep the glass ones if you're careful) had a buddy of mine weld perches on it, and re-doing the shock mounts as well as 2 wheels for the 5X5.5 pattern. The only thing I really don't like is that there are hardly any wheels for the 5X5.5 pattern. I want to redrill and get 5X5 on the back again, with the stock drums you can get the 11 inch drums for an LTD-II and it will work. I never got the E-brake going again but I think it would have been a matter of adjusting the tensioner. I also used the original prop valve for the brakes even though they were 11 inch drums and I thought it braked better afterwards. My drums with RWABS would lock up whereas these didn't. I eventually removed the accumulator from the RWABS and disabled it and the braking is VERY aggressive now. I think it has more in it with an adjustable prop valve too. I can get to .90G with the G-tech. Regretably mine has 3.00s in it, I would defniitely feel a lot better about the 3.50s. If you want help with the DRAC I would be happy to do so. It's beside the radio in the old school vans. Besides that the other thing is I used a stock driveshaft with a "long" pinion yoke and a 1330->1350 conversion U-joint Precision PN 459 I believe. You could have $40-50 into the joint and the new mounts, then if you had a welder you could have it in for 100-200 bucks even.
 
#17 ·
Where did you find the "long" pinion yoke? I know someone makes a replacement pinion yoke that will fit GM U-joints. I have never had any luck with the conversion U-joints. I have always broke them.
 
#18 ·
They come up on ebay now and again I got lucky a budyd of mine had what was left of an old car I got the yoke from. It should be 4.5" or so from where it goes into the actual third member to where the U-joint lip is. If it is 3.5" it is the short one. The Astro uses a 1350 the yoke I have uses the 1330. BTW, I put 25,000+ on the joint no issues. Maybe it's b/c it's a stock 4.3L but the 3.0 gears would have loaded it plenty IMO.
 
#19 ·
I saw one here on usedvictoria.com that had a 305 and a ford 9 inch.
It was pretty cheap like 1800 bucks or something for the whole van.
It used a ford rim on the back. was pretty cool, but I didnt buy it.

I see the gaskets listed in the books for the 8.5 inch when I go shopping but I've never seen one in a van either.
That option must have only come with the limited edition factory TPI 305 Safari Z28 package. LOL.
 
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