irwin7638

Measure the bottom bracket shell also. The Gran Prix I rebuilt had a shell that was 73mm wide rather than the standard 68. You can use a VO threadless cartridge to replace it, but be sure to order it with a longer axle to account for a wider BB shell if that is the case. They work really well, and you don't have to worry about the threads. Those are really nice frames, well worth the trouble.

Marc

redneckwes

The late production, '77-'79 Grand Prix's represented the ultimate development of the basic 20-30 (High-ten) Raleigh bicycle. Things like cotterless cranks, Alloy bars and Suntour Derailleurs. I really like the ride of the 20-30 frames, I have several Raleigh "Super Course' bikes as well, honestly sometime I forget if I'm on an upgraded Grand-Prix or on of the 531 bikes.

Several of mine have been converted to tapered spindles using the factory BB cups, I.I.R.C. use a "7" marked spindle with the wide Raliegh bottom brackets.

A favorite upgrade path for me is a stock set of late 70's Raleigh cotterless cranks, a basic 25.4 alloy seat-pin. "SR" branded alloy stem and bars, late Huret Derailleurs or Suntour VX. (Pretty much any Suntour works brilliantly.)

A set of alloy rims laced to stock "Normandy" high flange hubs and a Brooks B-17 finishes it out. Rides better than a new bike you could build for the same price and keeps the classic look.

PennyF@rthing

Hello,

I have some new and mildly frustrating news. I brought the bike into a cool LBS to get it sized up for a new BB and crankset. The mechanic did some quick measurements and presented a shiny new crankset and BB (I couldn't wait to get home and put them on). The BB was a Shimano square taper UN55 68 X 122.5 mm BB. Just to be sure that it would work he thought it would be a good idea to check the threading to see if it was 24 or 26 TPI. After awhile, it was determined that it was 26 TPI, which is not the common threading nowadays, so the BB that he had just pulled out would not fit. To double-check, he screwed on some 26 TPI cups and they went in just fine, compared to the 24 TPI BB which did not want to thread on. So one idea he had was to try to find the old style 26 TPI cups with the new style square taper BB. It seems like this would work because he used the 26 TPI cups to test this idea with the square taper spindle, but it was a part for the shop and it wasn't for sale (dang). He also pulled out a VO 122 mm threadless BB which I guess doesn't screw on but instead is a pressure fit? I didn't purchase this though because it was about twice as expensive as the Shimano BB.

Also, another interesting bit of information is that my shell is between 69 and 70 mm, but he assured a 68 mm BB would work.

He was a lot of help but the only thing I left there with was $2 worth of headset bearings. So alas, no BB and crankset for me yet.

Therefore, any thoughts on the best remedy. I haven't started looking online for parts yet (the 26 TPI cups with the square taper spindle) but that's my next move.

Noglider- you addressed the 26 TPI issue earlier and suggested the threadless BB. What do you think about the 26 TPI cups with a square taper spindle? Can those be found easily?

Thanks

Ol Danl

As mentioned earlier, Raleigh went to cotterless cranks for the lower end bikes in '77. My '77 Record came with SR cranks on a 5S spindle with the 26tpi cups. The BB shell measures 71mm, and the shell of my '71 Record measures about 70.8mm, so you're probably looking at the same size shell on the Grand Prix. I have tried a 7 series spindle in one of these but it seemed too long. I have bought a couple of 5 series spindles -- a 5N and5J -- on Amazon, and they fit, but they're fairly hard to find new. I've seen a nutted 5S spindle on the Husky Bicycles website under "bottom bracket parts," and it was only about $4. Have only seen one 5 series spindle at the local coop. If you go to just a square taper spindle with your 26 tpi cups, you are probably needing a 5 series one.

oddjob2

I would suggest taking your bike along with the cleaned up bb cups with bearings inserted to the local coop. Let them help you scrounge up a bottom bracket spindle and crankset for your GP. As your first bike mechanic suggested, a 68mm spindle may fit because the adjustable cup is what it is, adjustable. An extra 2-3 turns and it might take any play out of the spindle moving side to side. You may need to locktite the cup in if the lock ring doesn't have enough threading.

cycle_maven

Or, buy an inexpensive bottom bracket and file off all but 3 rows of threads on the body and the cup. Three rows of 24 TPI threads will screw into a 26 TPI bottom bracket shell just fine. And those 3 rows will hold the BB in place. That's what I did to my Raleigh 20.

lostarchitect 

Uhm. Ok. And then pedal really, really slowly.

-holiday76

i'm not doubting you did this, but this makes zero sense to me. TPI stands for threads per inch, right? Are you saying you only threaded in 3 rows of the , what, 26 or so that should have been threaded in?

Either way this sounds like a horrible idea.

redneckwes

I've never seen a set of 26tpi Raleigh spindles that were beyond use, a little discoloration in the races won't have any real effect, new bearings and a "5" spindle ( Thank you "Ol Danl") and you are good to go.

PennyF@rthing

Okay thanks guys. I've done a bit of searching for a "5 series square taper spindle" on ebay and Amazon and I haven't found anything yet. Well at least not in the correct size (122mm). I'll also try 5N and 5J search terms as suggested by Ol Danl. I'll keep trying different combinations on Amazon and Ebay. Any other ideas on where to find these types of spindles?

oddjob2

Your local Boston bike cooperative

PennyF@rthing

Right, my local Boston bike cooperative was the bike shop I went to a couple days ago where they figured out that it was 26 TPI and suggested looking for a square taper spindle online. They had that spindle at the shop but it wasn't for sale. But there are a bunch of bike shops nearby so I'll call around and see if anyone else has one.
Thanks.

Ol Danl

Try "5n bottom bracket spindle." I think the 5n is 122 mm. Also, if the 5s on the Husky bicycles is the same that came in my bike, it's probably 124 mm.

Ol Danl

I think the "5n" I bought on Amazon lists the middle dimension as 54 instead of 55 -- which is what is supposed to be that measurement for a 5 series spindle. It works in the bb shell of my bike, but I haven't used it with a crankset -- actually, the crankset I was trying to use with it works better with the original 5s. There is a spindle length chart for 3, 5, and 7 series on the Yellow Jersey website, and there used to be a very detailed (more spindles listed) one referenced on a thread here. I made a pencil copy of it a couple of years ago -- printer was out of ink. I don't know where to find it or who posted it.